Main Report Consultancy for hydraulic modeling Enhancing Resilience of Mekong Delta Region Secondary Cities Grant support to the proposed Scaling up Urban Upgrading Project (SUUP) Contract No. 7182300 Client: Work Bank Main report Consultancy for hydraulic modeling Enhancing Resilience of Mekong Delta Region Secondary Cities Grant support to the proposed Scaling up Urban Upgrading Project (SUUP) Contract No. Client Report No Status Date 7182300 World Bank SIWRR-7182300-B Final report 6 November 2017 Project manager Tran Ba Hoang Hydraulic modelling team leader Pham The Vinh Contract No. 7182300 Main report TABLE OF CONTENT 1. Overview 2 1.1. Introduction 2 1.2. Objectives of Assignments 3 1.3. Major activities 4 2. Input data - collecting and verification 4 2.1. Geographic data 4 2.2. Meteorology 5 2.3. Reference projects 17 2.4. Other related documents 17 3. Numerical model setup and flooding scenarios 18 3.1. Hydrology model 18 3.2. Hydraulic model 27 3.3. Flood mapping 39 4. Simulation scenarios 39 4.1. Simulation expect outcome and scenarios construction principals 39 4.2. Simulation scenarios 40 5. Structural dimension specifications 41 5.1. Ben Tre City 41 5.2. Vinh Long City 44 5.3. Bac Lieu City 47 5.4. Vi Thanh City 49 5.5. Long Xuyen City 51 5.6. Tan An City 53 5.7. Soc Trang City 55 5.8. Summary table of canal restoration and supplement structures 57 6. DESIGN WATER LEVELS 59 6.1. Simulation purpose 59 6.2. Design standards and regulations 59 6.3. Design specifications calculation result 60 7. BUILDING FLOOD MAPS FOR 7 CITIeS 61 7.1. Building flood maps principal 61 7.2. Simulated scenarios used for flood mapping 61 Southern Institute of Water resources research i Contract No. 7182300 Main report 7.3. Flood mapping results 61 7.4. Flood area results for 7 cities 62 7.5. Conclusions 75 8. Long-term vision 78 8.1. Urbanization impact 78 8.2. Climate change impact 78 9. Conclusion and recommendation 84 9.1. Conclusion 84 9.2. Recommendation 86 Appendix A - Ground elevation maps Appendix B - Existing land use map Appendix C - Land use planning maps Appendix D - Flood maps on channels Appendix E - Maximum water level simulation results Appendix F - Maximum flooding area simulation results Appendix G - Flood maps for whole cities region Appendix H - Overview of feasibility studies information in seven cities Southern Institute of Water resources research ii Contract No. 7182300 Main report LIST OF TABLES Table 1: Maximum daily rainfall (mm) at different hydro-station corresponding to probability .............................................................................................................................. 6 Table 2: Local stations used in urban drainage simulations .................................................. 7 Table 3: Annual maximum 180 minutes rainfall at each station .......................................... 7 Table 4: Total 180mins rainfall at each city in corresponding to probability...................... 10 Table 5: 10% probability occasional rainfall distribution ................................................... 11 Table 6: Maximum water level probability at different stations along the coast for sea level boundary preparation ........................................................................................................... 13 Table 7:Design flood discharge at Kratie (base on water discharge distribution of 2000) . 14 Table 8: Rainfall evolution according to RPC4.5 (%) ......................................................... 15 Table 9: Water level rise according to RPC4.5 (cm) ........................................................... 16 Table 10: Water level rise according to RPC8.5 (cm) ......................................................... 16 Table 11: 180mins rainfall corresponding to probability projected with CC at 2050 ......... 16 Table 12: Basin area for concerned canal in this project ..................................................... 19 Table 13: Manning coefficient in flooding area .................................................................. 21 Table 14: Coverage coefficient ............................................................................................ 21 Table 15: Calculated rainfall for each city corresponding to 10% ...................................... 21 Table 16: Current water resistance area and Time of concentration ................................... 22 Table 17: Current water resistance area and Time of concentration conform land use planning ............................................................................................................................... 23 Table 18: L Runoff reduction factor .................................................................................... 25 Table 19: Water discharge for each basins .......................................................................... 26 Table 20: Percent of standard deviation explained (R2) at control points........................... 35 Table 21: Percent of standard deviation explained (R2) at control points........................... 38 Table 22: Simulation scenarios combination ....................................................................... 40 Table 23: Comparison water level in different scenarios of land use and SUUP intervention .......................................................................................................................... 42 Table 24: Proposed canal restoration and supplement structures in Ben Tre City .............. 43 Table 25: Maximum water level in different scenarios of land use and SUUP intervention (10% hydrological condition) .............................................................................................. 45 Table 26: Proposed canal restoration and supplement structures in Vinh Long ................. 46 Table 27: 10% maximum water level in different scenarios of land use and intervention .. 48 Table 28: Proposed canal restoration and supplement structures in Bac Lieu .................... 48 Table 29: 10% maximum water level in different scenarios ............................................... 50 Table 30: Proposed canal restoration and supplement structures in Vi Thanh City ............ 50 Table 31:10% maximum water level in different scenarios of land use and intervention... 52 Table 32: Proposed canal restoration and supplement structures in Long Xuyen City ....... 52 Table 33: 10% probability maximum water level in different scenarios ............................. 54 Southern Institute of Water resources research iii Contract No. 7182300 Main report Table 34: Proposed canal restoration and supplement structures in Tan An ....................... 54 Table 35: 10% probability water level in different scenarios of land use and SUUP intervention .......................................................................................................................... 56 Table 36: Proposed canal restoration and supplement structures in Soc Trang .................. 56 Table 37: Proposed canal restoration and supplement structures in 07 cities ..................... 57 Table 38: Maximum water level for water defense structures............................................. 60 Table 39: Minimum water level for design structural stability analysis.............................. 60 Table 40: Water level for inland navigation base on accumulation hourly water level ...... 60 Table 41: Maximum water level for construction period .................................................... 61 Table 42: Simulation scenarios combination for flood mapping ......................................... 61 Table 43: Flood area for each scenarios in Ben Tre city ..................................................... 62 Table 44: Flood area for each scenarios in Vinh Long city ................................................. 64 Table 45: Flood area for each scenarios in Bac Lieu city .................................................... 66 Table 46: Flood area for each scenarios in Vi Thanh city ................................................... 68 Table 47: Flood area for each scenarios in Long Xuyen city .............................................. 70 Table 48: Flood area for each scenarios in Tan An city ...................................................... 72 Table 49: Flood area for each scenarios in Soc Trang city .................................................. 74 Table 50: Flood area for each scenarios of the current investments in 07 cities ................. 76 Table 51: Flood area for each scenarios in 07 cities ............................................................ 76 Table 52: Maximum water level on channels in cases of current conditions, land use planning and CC 2050 ......................................................................................................... 78 Table 53: Adaptation for climate change up to 2050........................................................... 80 Table 54: Existing status of concerned channels in Ben Tre City ..................................... H-1 Table 55: Existing situation of concerned channels in Vinh Long City ............................ H-4 Table 56: Exisiting condition of restoration channel in Bac Lieu City ........................... H-11 Table 57: Existing condition of concerned channels in Vi Thanh Cities ........................ H-14 Table 58: Present condition of canal in Long Xuyen City .............................................. H-19 Table 59: Existing siotuationif canal in Tan An city ....................................................... H-20 Table 60: Existing siotuationof canal in Soc Trang city .................................................. H-22 Southern Institute of Water resources research iv Contract No. 7182300 Main report LIST OF FIGURES Figure 1: Locations of seven cities include in SUUP project 3 Figure 2: Hydro-meteorological stations locations 5 Figure 3: rainfall corresponding to 2% probability at different meteo-stations 6 Figure 4: Annual maximum 180 minutes rainfall at My Tho 8 Figure 5: Annual maximum 180 minutes rainfall at Can Long 8 Figure 6: Annual maximum 180 minutes rainfall at Bac Lieu 8 Figure 7: Annual maximum 180 minutes rainfall at Soc Trang 9 Figure 8: Annual maximum 180 minutes rainfall at Chau Doc 9 Figure 9: Annual maximum 180 minutes rainfall at Can Tho 9 Figure 10: Mainstream hydro-stations locations in low Mekong Delta 12 Figure 11: Hourly water level data at Vung Tau Station 12 Figure 12: Hourly water level data at Rach Gia Station 12 Figure 13: Water level hydrograph of 2% probability at My Thanh station 14 Figure 14: Kratie location in Mekong basin 14 Figure 15: Kratie discharge corresponding to probability 15 Figure 16: Basin partitions in NAM model 18 Figure 17: Calculating water discharge at Cai Son canal in Long Xuyen city 27 Figure 18: Hydraulic model network for Low Mekong Delta and South East Vietnam region 28 Figure 19: Detail hydraulic network in Vi Thanh City 29 Figure 20: Detail hydraulic network in Bac Lieu City 29 Figure 21: Detail hydraulic network in Long Xuyen City 30 Figure 22: Detail hydraulic network in Vinh Long City 30 Figure 23: Detail hydraulic network in Soc Trang City 31 Figure 24: Detail hydraulic network in Ben Tre City 31 Figure 25: Detail hydraulic network in Tan An City 32 Figure 26: Storage area in the low land of the model 32 Figure 27: Comparison water level at Tan Chau 33 Figure 28: Comparison water level at Chau Doc 33 Figure 29: Comparison water level at Vam Nao 34 Figure 30: Comparison water level at Cao Lanh 34 Figure 31: Comparison water level at Can Tho 34 Figure 32: Comparison water level at My Thuan 35 Figure 33: Location of verification points/stations for numerical model 36 Figure 34:Comparison water level at Tan Chau station during 2000 flood 36 Figure 35: Comparison water level at Chau Doc station during 2000 flood 36 Figure 36: Comparison water level at Vam Nao station during 2000 flood 37 Southern Institute of Water resources research v Contract No. 7182300 Main report Figure 37: Comparison water level at Long Xuyen station during 2000 flood 37 Figure 38: Comparison water level at My Thuan station during 2000 flood 37 Figure 39: Comparison water level at Tuyen Nhon station during 2000 flood 37 Figure 40: Comparison water level at Tan An station during 2000 flood 38 Figure 41: Comparison water level at Cao Lanh station during 2000 flood 38 Figure 42: Comparison water level at Ben Luc station during 2000 flood 38 Figure 43: Water level on Chin Te canal in case of with and without SUUP 41 Figure 44: Water level on 30-4 canal in case of with and without SUUP 42 Figure 45: Proposed bridge the gap between two channel sections 43 Figure 46: Proposed location of supplement one way gravity gates 43 Figure 47: Maximum water level on Tan Binh 1 canal in case of with and without SUUP intervention 45 Figure 48: Tidal control gates location in Vinh Long City 46 Figure 49: Water level on Tra Kha Canal in case of with and without SUUP intervention 47 Figure 50: Maximum water level on Tra Kha Canal after intervention 48 Figure 51: Water level on Thong Nhat 1 canal in case of with and without SUUP intervention 49 Figure 52: Water level on Ba Bau Canal in case of with and without SUUP 51 Figure 53: Location of proposed sewers on Ong Manh and Ba Bau canal 52 Figure 54: Water level on Rach Rot in case of with and without SUUP 53 Figure 55: Water level on Cau Tre Canal in case of with and without SUUP 53 Figure 56: Location of proposed sewers on Cau tre and Rach Rot canal 54 Figure 57: Water level on Tra Men in case of with and without SUUP 55 Figure 58: Water level on Hitech canal in different simulation 56 Figure 59: Salinity control gate proposed in Bac Ben Tre project 79 Figure 60: Locations of water resourses controlling gates proposed in Ben Tre 80 Figure 61: Proposed control infrastructures in Vinh Long City 81 Figure 62: Locations of control gate proposed for Bac Lieu 81 Figure 63: Locations of flooding control gate in Long Xuyen city 82 Figure 64: Proposed controlling gates for Soc Trang City 83 Figure 65: Digital elevation map of Vinh Long city A-1 Figure 66: Digital elevation map of Ben Tre City A-1 Figure 67: Digital elevation map of Vi Thanh City A-2 Figure 68: Digital elevation map of Soc Trang City A-2 Figure 69: Digital elevation map of Bac Lieu City A-3 Figure 70: Digital elevation map of Tan An City A-3 Figure 71: Digital elevation map of Soc Trang City A-4 Figure 72: Existing land use map in Long Xuyen City B-1 Figure 73: Existing land use map in Vi Thanh City B-1 Figure 74: Existing land use map in Bac Lieu City B-2 Southern Institute of Water resources research vi Contract No. 7182300 Main report Figure 75: Existing land use map in Tan An City B-2 Figure 76: Existing land use map in Ben Tre City B-3 Figure 77: Existing land use map in Vinh Long City B-3 Figure 78: Existing land use map in Soc Trang City B-4 Figure 79: Land use planning to 2025 in Long Xuyen City C-1 Figure 80: Land use planning to 2025 in Vi Thanh City C-1 Figure 81: Land use planning to 2025 in Bac Lieu City C-2 Figure 82: Land use planning to 2025 in Tan An City C-2 Figure 83: Land use planning to 2025 in Ben Tre City C-3 Figure 84: Land use planning to 2025 in Vinh Long City C-3 Figure 85: Land use planning to 2025 in Soc Trang City C-4 Figure 86: BL3 scenario flood map in Ben Tre City D-1 Figure 87: BL3 scenario flood map in Vinh Long City D-1 Figure 88: BL3 scenario flood map in Bac Lieu City D-2 Figure 89: BL3 scenario flood map in Vi Thanh City D-2 Figure 90: BL3 scenario flood map in Long Xuyen D-3 Figure 91: BL3 scenario flood map in Tan An City D-3 Figure 92: BL3 scenario flood map in Soc Trang City D-4 Figure 93: SU3 scenario flood map in Ben Tre City D-5 Figure 94: SU3 scenario flood map in Vinh Long City D-5 Figure 95: SU3 scenario flood map in Bac Lieu City D-6 Figure 96: SU3 scenario flood map in Vi Thanh City D-6 Figure 97: SU3 scenario flood map in Long Xuyen City D-7 Figure 98: SU3 scenario flood map in Tan An City D-7 Figure 99: SU3 scenario flood map in Soc Trang City D-8 Figure 100: SP3 scenario flood map in Ben Tre City D-9 Figure 101: SP3 scenario flood map in Vinh Long City D-9 Figure 102: SP3 scenario flood map in Bac Lieu City D-10 Figure 103: SP3 scenario flood map in Vi Thanh City D-10 Figure 104: SP3 scenario flood map in Long Xuyen City D-11 Figure 105: SP3 scenario flood map in Tan An City D-11 Figure 106: SP3 scenario flood map in Soc Trang City D-12 Figure 107: CC3 scenario flood map in Ben Tre D-13 Figure 108: CC3 scenario flood map in Vinh Long D-13 Figure 109: CC3 scenario flood map in Bac Lieu D-14 Figure 110: CC3 scenario flood map in Vi Thanh D-14 Figure 111: CC3 scenario flood map in Long Xuyen D-15 Figure 112: CC3 scenario flood map in Tan An D-15 Figure 113: CC3 scenario flood map in Soc Trang D-16 Figure 114: Flood map for existing siotuation in Ben Tre G-1 Southern Institute of Water resources research vii Contract No. 7182300 Main report Figure 115: Flood map for existing situation WITH SUUP interventions in Ben Tre G-1 Figure 116: Flood map for planed urban (2025) WITH SUUP in Ben Tre G-2 Figure 117: Flood map with climate change scenario in Ben Tre G-2 Figure 118: Flood map for existing siotuation in Vinh Long G-3 Figure 119: Flood map for existing situation WITH SUUP interventions in Vinh Long G-3 Figure 120: Flood map for planed urban (2025) WITH SUUP in Vinh Long G-4 Figure 121: Flood map with climate change scenario in Vinh Long G-4 Figure 122: Flood map for existing siotuation in Bac Lieu G-5 Figure 123: Flood map for existing situation WITH SUUP interventions in Bac Lieu G-5 Figure 124: Flood map for planed urban (2025) WITH SUUP in Bac Lieu G-6 Figure 125: Flood map with climate change scenario in Bac Lieu G-6 Figure 126: Flood map for existing siotuation in Vi Thanh G-7 Figure 127: Flood map for existing situation WITH SUUP interventions in Vi Thanh G-7 Figure 128: Flood map for planed urban (2025) WITH SUUP in Vi Thanh G-8 Figure 129: Flood map with climate change scenario in Vi Thanh G-8 Figure 130: Flood map for existing siotuation in Long Xuyen G-9 Figure 131: Flood map for existing situation WITH SUUP interventions in Long Xuyen G-10 Figure 132: Flood map for planed urban (2025) WITH SUUP in Long Xuyen G-11 Figure 133: Flood map with climate change scenario in Long Xuyen G-12 Figure 134: Flood map for existing siotuation in Tan An G-13 Figure 135: Flood map for existing situation WITH SUUP interventions in Tan An G-13 Figure 136: Flood map for planed urban (2025) WITH SUUP in Tan An G-14 Figure 137: Flood map with climate change scenario in Tan An G-14 Figure 138: Flood map for existing siotuation in Soc Trang G-15 Figure 139: Flood map for existing situation WITH SUUP interventions in Soc Trang G-16 Figure 140: Flood map for planed urban (2025) WITH SUUP in Soc Trang G-17 Figure 141: Flood map with climate change scenario in Soc Trang G-18 Figure 142: General layout of investment in Ben Tre City H-1 Figure 143: Existing layout of Chin Te channel H-2 Figure 144: Existing layout of 30/4 channel H-3 Figure 145: General layout of investment proposal in Vinh Long City H-3 Figure 146: Restoration layout plan within LIA 1 H-5 Figure 147: Canal renovation layout in LIA 3 H-6 Figure 148: Restoration channels layout within LIA 3 H-7 Figure 149: Restoration general layout of LIA 4 H-10 Figure 150: Restoration channels layout in Vinh Long City H-10 Figure 151: Investment location layout at Bac Lieu City H-11 Figure 152: LIA 6 channel locations H-12 Figure 153: LIA 6 Existing siotuationof drainage system H-12 Southern Institute of Water resources research viii Contract No. 7182300 Main report Figure 154: Kenh Xang channel existing status H-13 Figure 155: General layout of investment proposal for Vi Thanh City H-14 Figure 156: General layout of canal renovation in Vi Thanh City H-15 Figure 157: Renovation canals layout within LIA 3 H-16 Figure 158: Renovation layout within LIA 7 H-17 Figure 159: General layout of investment index at Long Xuyen city H-18 Figure 160: Renovation canal layout in Long Xuyen city H-18 Figure 161: Ong Manh canal and Ba Bau canal current condition H-19 Figure 162: General layout of investment index at Tan An City H-20 Figure 163: Plan view and current conditions of Rach Rot Canal in Tan An City H-21 Figure 164: Plan view and current conditions of Cau Tre Canal in Tan An City H-21 Figure 165: General layout of working package for Soc Trang city H-22 Figure 166: Plan view of concerned canals in Soc Trang H-22 Figure 167: Plan view of existing sluice at Tra Men canal H-23 Figure 168: Plan view of existing sluice at Hitech canal H-24 Southern Institute of Water resources research ix Contract No. 7182300 Main report 1. OVERVIEW 1.1. Introduction The proposed SUUP Project is meant to improve accessibility of basic infrastructures located in low-income regions. The outcome are expected to enhance connectivity of primary infrastructure system and the ability to integrate urban planning with city resilience. Broader urban development agenda will serve via primary and secondary infrastructure investments with a vision to improve connectivity of infrastructure network. This project will promote the growing of climate change adaptation and eco-friendly infrastructures which lead to increase accessibility of public spaces and enhance urban planning quality, land management and city resilience. These proposed investment consist of five components which are: (i) Tertiary Infrastructure Upgrading in Low Income Areas; (ii) Priority Primary and Secondary Infrastructures; (iii) Resettlement Sites; and (iv) Implementation Support and Capacity Building. Within the seven cities, a preliminary list of LIAs with deficient basic infrastructure and services has been drawn up. This list has been further refined to prioritize a sub-set of LIAs for investments under this project. In each LIA, a single multi-sectoral package of tertiary infrastructure improvements and services will be provided, an approach which has been tested and refined in VUUP and MDR UUP. These packages are likely to include: (a) construction, rehabilitation, and upgrading of roads and lanes; (b) construction and rehabilitation of drains; (c) improvements to environmental sanitation by rehabilitating or constructing public sewers, constructing septic tanks, providing access to septic management services, and house connections to public sewers; (d) improvement of water supply including the installation of metered domestic connections; (e) provision of metered domestic connections for electricity and public lighting in residential lanes and streets; and (f) construction and rehabilitation of social infrastructure facilities such as schools, markets, community halls, public places and green spaces. The investments will utilize disaster and climate resilient technical and engineering standards. Component 2 provides support to improve priority infrastructure in line with the broader city development agenda, and with a vision to increase connectivity with tertiary infrastructure in LIAs. It is likely to include: (a) roads improving the connectivity among different parts of the city; (b) water supply lines; (c) drains and sewers; (d) electrical power lines; and (e) River and canal embankments. The investments will utilize disaster and climate change resilient technical and engineering standards. Unfortunately, there are no initial hydraulic model developed for the catchment areas of the upgrading sites and integrated with existing urban plans for flood and salinity intrusion control, drainage, and waterways development. We consider all of above issues should be the final resolve for this consultancy assignment. Southern Institute of Water resources research 2 Contract No. 7182300 Main report Figure 1: Locations of seven cities include in SUUP project (Source: TOR) The infrastructure investment proposal to be made by the 7 cities would be screened to verify that the investments are not exposed to the flooding risk while even contributing to flood risk reduction where possible. Furthermore, the numerical hydraulic model would allow a rapid screening of the existing urban development plan and other sector plans to the flood hazard. Consultant is requested to establish a simple hydraulic model for 7 target Mekong Delta secondary cities to support SUUP in its decision making process for section of the investments, as well as for supporting long term integrated urban planning. 1.2. Objectives of Assignments The overall objective of the consultancy which is specified in TOR, is to construct a tool to support the cities in sustainable urban management with natural risk integration including river discharge and tidal inundation. Southern Institute of Water resources research 3 Contract No. 7182300 Main report Therefore following specific objectives of consultancy are identified: Review the use of the Downscale existing hydraulic model while integrating with numerical hydraulic available regional and local data provided by the cities for models in the Mekong flooding simulation purposes in Mekong Delta region and the delta and available seven cities which are marked in above Figure : Long Xuyen, information in all 7 target Vinh Long, Tan An, Ben Tre, Soc Trang, Bac Lieu and Vi cities; Thanh; Simulate historical flood situation for the seven cities in case Provide hands-on training of with and without SUUP interventions. This model would to enhance capacity of the be a support tool for project investment making decisions as authority staffs for well as further development scenarios including climate maintaining services change and sea level rise impact for long term urban related to utilizing integrated management of the cities, and; hydraulic modeling. 1.3. Major activities Task 1: Preparation with an inventory of Task 2: Adapt the existing hydrological and flood hazards and available models and hydraulic models for the seven cities; data; Major activities Task 3: Flood hazard mapping and Task 4: Training assigned staffs of the seven additional recommendations for the seven cities. cities; 2. INPUT DATA - COLLECTING AND VERIFICATION Input data completeness and accuracy are crucial to any hydraulic simulation. Data and information collecting should always be carried on at the early stage of consultant assignment. In our assignment, we have been investigating and collection all related information and data e.g. geographic data, land use planning, development planning and current controlling structures locations. 2.1. Geographic data Geographic data is foundation material for hydraulic simulation as well as flood mapping projection. Aside from already achieved geographic data for river and streamline network in low Mekong Delta, we pay a great attention in update latest data and information on rivers and canals located in 7 cities which consist with: All of newly updated canal profiles in seven cities which was provided by Structural design consultants. Digital elevation data and geographic information with very high resolution (5x5)m for each city (refer to Appendix A - Ground elevation maps). Those maps are result from aerial survey on 2012 for whole Mekong Delta which are provided by MONRE. They play a very important role in construction of flood mapping. Southern Institute of Water resources research 4 Contract No. 7182300 Main report 2.2. Meteorology 2.2.1. Precipitation Daily precipitation data are collected from following national meteo-stations: Hung Thanh, Moc Hoa, Tuyen Nhon, Kien Binh, Ben Luc and Tan An (in study area); Tan Chau, Long Xuyen, Chau Doc, Cho Moi and Ha Tien, Rach Gia, Can Tho, Soc Trang, My Tho, Cang Long, Tan Son Hoa and Vung Tau. Extracted maximum daily precipitation values from long-term rainfall data series are used to analyze maximum probability distribution which are shown in table below: Figure 2: Hydro-meteorological stations locations Source: Hydro-meteorological Observatory Southern region Southern Institute of Water resources research 5 Contract No. 7182300 Main report Table 1: Maximum daily rainfall (mm) at different hydro-station corresponding to probability Daily rainfall (P %) Station 0.5 1 1,5 2 3 4 5 10 20 25 50 Bien Hoa 208.1 192.3 183 176.4 167.1 161.2 155.2 138.8 121.3 118.6 93.4 Ben Luc 224.3 204.4 192.7 184.4 172.7 165.3 157.8 137.2 120.9 118.1 92.9 Moc Hoa 248 226.2 213.4 204.4 191.5 183.4 175.2 152.7 129.5 124.2 94.1 Nha Be 206.9 189.5 179.3 172.1 161.8 155.3 148.8 130.8 103.8 120.3 99.2 Tan An 312.9 281.5 263 249.9 231.4 219.7 207.9 175.4 132.6 124.5 86.2 Tan Son Hoa 189.8 176.6 168.9 163.5 155.7 150.8 145.9 132.3 105.4 101.2 84.1 Tay Ninh 216.5 200.3 190.8 184 174.5 168.4 162.3 145.6 129.4 122.1 100.3 Vung Tau 276.3 251.8 237.5 227.2 212.8 203.6 194.4 169.1 141.8 135.6 103.2 Tuyen Nhon 191.0 181.8 176.3 172.2 166.4 162.5 158.7 147.5 134.9 130.4 113.7 My Tho 138.1 132.0 128.3 125.5 121.6 118.9 116.2 108.3 99.2 95.9 83.2 Ba Tri 213.1 199.7 191.7 185.7 177.2 171.5 165.8 149.1 130.2 123.5 97.9 Cang Long 156.4 149.8 145.7 142.6 138.1 135.0 131.9 122.4 111.0 106.7 89.3 Can Tho 160.4 151.7 146.5 142.6 137.0 133.3 129.6 118.9 106.9 102.6 86.6 Cao Lanh 170.8 160.3 154.0 149.3 142.6 138.2 133.8 121.0 106.8 101.8 83.0 Soc Trang 179.1 166.9 159.9 154.6 147.3 142.5 137.8 124.5 110.5 105.9 89.6 Bac Lieu 207.2 193.5 185.5 179.4 171.0 165.4 159.9 144.1 126.8 120.9 99.4 Ca Mau 189.1 180.0 174.5 170.4 164.5 160.5 156.5 144.6 131.0 126.0 106.7 Rach Gia 301.4 278.7 265.2 255.2 241.0 231.8 222.5 196.0 167.0 157.1 120.6 Ha Tien 269.8 241.4 225.3 213.2 197.2 186.9 176.7 149.8 123.8 116.2 92.6 Chau Doc 210.6 192.4 181.9 174.0 163.1 156.0 148.8 129.0 108.0 101.1 76.6 Also base on above result, scale up daily rainfall corresponding to year 2000 distribution. A demonstration of precipitation of 50 years return period (2% probability) is shown in below graph. Figure 3: rainfall corresponding to 2% probability at different meteo-stations Southern Institute of Water resources research 6 Contract No. 7182300 Main report In regard of occasional rains which are used as boundary conditions in verifying urban drainage capacity, data are collected from local meteo-stations. For those cities does not have its own meteo-station, neighbor station would be utilized. Detail data sources are described as below: Table 2: Local stations used in urban drainage simulations No City Station Note 1 Ben Tre My Tho Neighbor 2 Tan An My Tho Neighbor 3 Vinh Long Cang Long Neighbor 4 Bac Lieu Bac Lieu In the city 5 Soc Trang Soc Trang In the city 6 Vi Thanh Can Tho Neighbor 7 Long Xuyen Chau Doc Neighbor According to occasional rain data from above stations, annual maximum 180 minutes rainfall at each of seven cities are shown as below: Table 3: Annual maximum 180 minutes rainfall at each station 1 Year My Tho Cang Long Bac Lieu Soc Trang Chau Doc Can Tho 1995 61.5 70.0 99.5 68.9 52.7 106.4 1996 75.0 85.6 66.6 69.5 63.6 101.8 1997 92.0 114.6 90.5 74.3 75.8 62.5 1998 65.0 108.1 73.7 69.3 44.8 76.9 1999 82.4 69.3 65.3 119.1 103.5 75.9 2000 60.5 106.0 73.6 88.7 76.8 85.4 2001 74.5 93.2 47.1 65.9 46.7 117.4 2002 42.4 76.3 67.1 71 40.8 51.0 2003 50.6 95.8 89.8 67 64.9 52.7 2004 149.6 89.3 110.2 46 86.9 50.8 2005 108.0 76.3 75.5 107.6 77.1 85.4 2006 69.4 136.1 112.1 84.1 39.8 74.9 2007 99.0 73.4 138.4 89 93.8 96.8 2008 72.2 90.9 76.3 82.4 90.6 62.1 2009 92.5 97.8 103.2 82.9 54.9 82.3 2010 61.4 68.0 122.7 130.4 97.9 53.9 2011 57.0 81.6 72.4 197.3 79.1 93.8 2012 65.9 57.9 82.9 111.1 52.2 86.0 2013 81.6 57.7 73 98 49.2 92.0 2014 106.4 70.7 147.4 69 64.7 97.4 1 Source: SOUTHERN REGIONAL HYDROMETEOROLOGICAL CENTER Southern Institute of Water resources research 7 Contract No. 7182300 Main report 150.00 Total Rainfall (mm) 100.00 50.00 My Tho .00 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year Figure 4: Annual maximum 180 minutes rainfall at My Tho 140.00 120.00 Total Rainfall (mm) 100.00 80.00 60.00 Cang Long 40.00 20.00 .00 2003 1995 1996 1997 1998 1999 2000 2001 2002 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year Figure 5: Annual maximum 180 minutes rainfall at Can Long 160 140 120 Total Rainfall (mm) 100 80 60 Bac Lieu 40 20 0 2003 2012 1995 1996 1997 1998 1999 2000 2001 2002 2004 2005 2006 2007 2008 2009 2010 2011 2013 2014 Year Figure 6: Annual maximum 180 minutes rainfall at Bac Lieu Southern Institute of Water resources research 8 Contract No. 7182300 Main report 200 150 Total Rainfall (mm) 100 Soc Trang 50 0 2001 1995 1996 1997 1998 1999 2000 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year Figure 7: Annual maximum 180 minutes rainfall at Soc Trang 120 100 Total Rainfall (mm) 80 60 40 Chau Doc 20 0 2010 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2011 2012 2013 2014 Year Figure 8: Annual maximum 180 minutes rainfall at Chau Doc 120.00 100.00 Total Rainfall (mm) 80.00 60.00 40.00 Can Tho 20.00 .00 1996 1995 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Year Figure 9: Annual maximum 180 minutes rainfall at Can Tho Southern Institute of Water resources research 9 Contract No. 7182300 Main report According to [TCVN 7957:2008, Category Return period (year) clause 4.2.2], required return period Primary canals and sluices 10 used in design calculation in urban areas are: Level 1 culverts 5 Secondary culverts 2 Precipitation data series must acquire at least 20 years for occasional 150-180 mins rainfall. Besides that, it is worth to mention that low Mekong Delta is driven by semi-diurnal regime which mean there are 2 peaks and 2 trough. An average tidal rising duration is 6 hours. If heavy rains occur during high tide period, water drainage capacity will be excessively reduced. Therefore, we included 180 mins occasional rains in our simulations to evaluate urban drainage capacity in each city. Base on occasional rainfall data from 1995-2014, we have estimated the rainfall corresponding to probability as shown in below table. Table 4: Total 180mins rainfall at each city in corresponding to probability Ben Vinh Bac Soc Vi Long Tan P (%) Tre Long Lieu Trang Thanh Xuyen An 0.2 187 162 190 261 144 131 187 0.5 170 152 176 231 136 124 170 1.0 157 143 165 208 130 118 157 2.0 144 135 153 185 123 111 144 4.0 130 126 141 162 116 104 130 5.0 126 123 137 155 113 102 126 10.0 111 113 124 132 105 94 111 20.0 96 102 110 109 95 84 96 50.0 73 83 86 79 78 67 73 Base on rainfall distribution at each stations, we project occasional 180mins rainfall accordingly. Southern Institute of Water resources research 10 Contract No. 7182300 Main report Table 5: 10% probability occasional rainfall distribution Ben Tre Vinh Long Bac Lieu Soc Trang Vi Thanh Long Xuyen Tan An Rainfall distribution corresponding to different probabilities were also analyzed to provide input data for hydrodynamic computation. Southern Institute of Water resources research 11 Contract No. 7182300 Main report 2.2.2. Water level stations Water level data is collected from: Tan Chau, Chau Doc, Cao Lanh, My Thuan, Long Xuyen, Can Tho, Ben Luc, Cau Noi, Moc Hoa, Tuyen Nhon, Tan An, Kien Binh, Vam Kenh, An Thuan, Tra Vinh, Ben Trei, Vam Nao, Can Tho, Dai Ngai, Vung Tau, Binh Dai, Vi Thanh, My Thanh (Figure 10) Figure 10: Mainstream hydro-stations locations in low Mekong Delta Source: Hydrometeorology observatory Southern region Figure 11: Hourly water level data at Vung Tau Station Figure 12: Hourly water level data at Rach Gia Station Southern Institute of Water resources research 12 Contract No. 7182300 Main report Extracted annual maximum water level from record data at: Vung Tau, Vam Kenh, My Thanh, Ganh Hao, Song Doc and Rach Gia, they are used as input for probability analysis for each of stations. Analysis result have been shown in below table: Table 6: Maximum water level probability at different stations along the coast for sea level boundary preparation P% Vung Tau Vam Kenh My Thanh Ganh Hao Song Doc Rach Gia 0.5 1.54 1.83 2.52 2.29 0.99 1.15 1 1.52 1.80 2.47 2.26 0.98 1.11 1.5 1.50 1.79 2.43 2.24 0.97 1.09 2 1.49 1.77 2.40 2.23 0.96 1.08 3 1.48 1.76 2.36 2.20 0.95 1.06 4 1.47 1.75 2.34 2.19 0.95 1.05 5 1.46 1.73 2.31 2.17 0.94 1.03 10 1.43 1.70 2.23 2.12 0.91 0.99 20 1.39 1.66 2.14 2.05 0.88 0.94 25 1.37 1.64 2.10 2.03 0.87 0.92 50 1.31 1.59 1.96 1.92 0.82 0.86 75 1.25 1.54 1.83 1.80 0.77 0.81 80 1.24 1.53 1.80 1.77 0.75 0.79 85 1.22 1.52 1.76 1.73 0.74 0.78 90 1.20 1.51 1.71 1.68 0.72 0.76 95 1.17 1.49 1.64 1.61 0.69 0.74 99 1.10 1.45 1.52 1.47 0.63 0.7 Base on above analysis we scale up hourly water level corresponding to year of 2000 hydrograph. Tidal water level distribution (HTP) were constructed base on correlation between maximum water level corresponding to probabilities and maximum tidal water level in 2000 (Hmax2000) and water level record of year 2000 (H2000) (HTP) = HP/ Hmax2000 x H2000 Below graph represent a 50 years return period (2%) water level at My Thanh station to demonstrate the input in the boundary. Southern Institute of Water resources research 13 Contract No. 7182300 Main report Figure 13: Water level hydrograph of 2% probability at My Thanh station 2.2.3. Upstream discharge Upstream discharge is collected from Kratie data record as numerical upstream boundary (Figure 14). Source: Hydrometeorology observatory Southern region Figure 14: Kratie location in Mekong basin Table 7:Design flood discharge at Kratie (base on water discharge distribution of 2000) 2 Probability (%) 1% 2% 4% 5% 10% 20% 50% Qmax (m3/s) 59.500 56.500 53.600 52.400 48.800 46.200 44.500 Discharge distribution according to flood of year 2000: 2 Flooding master plan for LMD – Southern Institute of Water resources planning, 2014 Southern Institute of Water resources research 14 Contract No. 7182300 Main report Figure 15: Kratie discharge corresponding to probability 2.2.4. Climate change scenarios guidelines In 2016, MONRE has published the most recent climate change scenarios. According to this report, RPC4.5 (most likely scenario) is highly recommended to adapt for calculation which consider climate change effect. RPC4.5 scenario has shown that precipitation increasing for all of regions. Rainfall in 2050 could increase by 12.4% - 33.3% in comparison to current conditions. Table 8: Rainfall evolution according to RPC4.5 (%)3 RPC4.5 also indicate that sea water level increasing in 2050 on East coast is 22cm, while it is 23cm on the West coast. 3 2016 climate change scenario, MONRE Southern Institute of Water resources research 15 Contract No. 7182300 Main report Table 9: Water level rise according to RPC4.5 (cm) Table 10: Water level rise according to RPC8.5 (cm) Those information if climate change have been updated in our simulation rainfall input as below table has shown: Table 11: 180mins rainfall corresponding to probability projected with CC at 2050 P (%) My Tho Can Long Bac Lieu Soc Trang Can Tho Chau Doc 1.0 206.5 184.4 199.9 248.1 150.1 159.1 2.0 189.0 173.2 186.1 220.9 141.9 150.8 4.0 171.0 161.6 171.6 193.7 133.0 142.1 10.0 146.3 144.8 150.9 157.8 119.5 128.4 20.0 126.3 130.6 133.3 130.6 107.4 116.6 50.0 96.3 107.2 104.4 94.9 85.3 95.7 2.2.5. Evaluation of input data quality Beside from our available cross profile of Mekong downstream network which we constantly verify and update during the last couple years. As series of newly investigated Southern Institute of Water resources research 16 Contract No. 7182300 Main report current conditions of canals network in each city have recently collected. Especially data of those canals covered within SUUP projects have been provided by structural design consultants (a section in appendix is going to describe further detail of these data). High resolution of DEM for each of seven cities are exceptional for flood mapping construction task. Hydrological data series is long enough (at least 20 years) and update up to 2014 for both the whole Mekong Delta and each of seven cities. In overall, collected input data is satisfied our assignment requirement which are capable of represent physical characteristics of Downstream Mekong Delta. Verification procedure would further confirm our choice of numerical model before it is ready for simulation tasks. 2.3. Reference projects Climate change scenario issued on 2016 by MOST. Flooding master plan for LMD up to 2020, in extending to 2030 which is established on 2014. Mekong delta development plan, 2013. General Master planning for LMD in respect to climate change and sea level rise which established on 2012. Project “Survey existing status of dike and under toe dike structures in flood plan of LMD”, established on 2011. Water resources master plan for flood prevent in Vinh Long City, 2014. Water resources master plan for flood prevent in Can Tho City, 2012. Flooding prevent master plan for cities of Ben Tre, Long Xuyen, Soc Trang, Bac Lieu (on-going project by Water Resources Planning Institute) 2.4. Other related documents Water resources data in Mekong basin. Data at Feasibility phase of seven cities project. Southern Institute of Water resources research 17 Contract No. 7182300 Main report 3. NUMERICAL MODEL SETUP AND FLOODING SCENARIOS 3.1. Hydrology model 3.1.1. Basins classification and partitions Hydrological simulation for whole Mekong system is carried on by NAM model with total of 915 basins. Input data for this model is daily rainfall. NAM has been utilized for number of projects Mekong delta. Figure 16: Basin partitions in NAM model In regard to cities, in order to represent rainfall for runoff in urban area, MIKE URBAN is used for computation. Each canal will be assigned to specific basin. Southern Institute of Water resources research 18 Contract No. 7182300 Main report Table 12: Basin area for concerned canal in this project City Basin Area (ha) Area (km2) Ba Bau canal 67.72 0.68 Long Cai Son canal 117.47 1.17 Xuyen Ong Manh canal 241.04 2.41 Chin Te canal 238.60 2.39 Ben Tre 30/4 canal 24.56 0.25 Mui Tau canal 2.27 0.02 Tan An Rot canal 76.80 0.77 Cau Tre canal 76.01 0.76 Canal Tra Men 85.85 0.86 Soc Trang Hitech canal 151.81 1.52 Tra Kha canal 597.88 5.98 Bac Lieu Cut canal 151.82 1.52 Tan Binh secondary branch 1 14.00 0.14 Tan Binh secondary branch 2 6.00 0.06 Secondary branches of Tan Binh secondary branch 1 0.20 0.00 Ong Dia canal 10.09 0.10 Song Cau Lo 1 canal 17.04 0.17 Song Cau Lo 2 canal 3.01 0.03 Ngo Quyen canal 3.39 0.03 Canal Ong Dia canal 1.78 0.02 Vinh Long Canal Ngo Quyen 1.80 0.02 Sau Van 1 canal 15.00 0.15 Sau Van 2 canal 11.00 0.11 Kinh Cut secondary branch 1 2.00 0.02 Kinh Cut secondary branch 2 4.50 0.05 Sau Van secondary branch 1 1.00 0.01 Sau Van secondary branch 2+ Kinh Cut secondary branch 3 2.00 0.02 canal Cut 7.57 0.08 Cao Lau 307.16 3.07 Thong Nhat 4 canal 3.06 0.03 Vi Thuy canal 13.02 0.13 Canal Ngang 5.54 0.06 Canal 62 296.10 2.96 Canal Xang Hau 6.47 0.06 Thong Nhat 3 canal 2.44 0.02 Thong Nhat 1 canal 8.61 0.09 Thong Nhat 2 canal b 4.23 0.04 Vi Thanh Thong Nhat 2 canal a 7.84 0.08 Canal 3 5.95 0.06 Canal Lo 2a 7.13 0.07 Phan Lo canal 13.50 0.14 Canal 2 3.40 0.03 Phan Lo canal 2b 2.95 0.03 Canal 1 2.35 0.02 Canal Cai Nhuc Nho 17.39 0.17 Canal Cai Nhuc Lon 44.27 0.44 Southern Institute of Water resources research 19 Contract No. 7182300 Main report 3.1.2. Model setup parameters The concept of Urban Runoff Model A is founded on the so-called "Time-Area" method. The runoff amount is controlled by the initial loss, size of the contributing area and by a continuous hydrological loss. The shape of the runoff hydrograph is controlled by the concentration time and by the time- area (T-A) curve 3.1.3. Time of Concentration Defines the time, required for the flow of water from the most distant part of the catchment to the point of outflow. (sec) In which: n –Manning (s/m1/3) L – Canal length (m) Z – Coverage coefficient, refer to below table I – Rainfall (mm/min) i – Slope of the land surface (100%) Manning coefficient is separated into 2 categories: (i) structures like road, houses, and buildings assigned to 0.025; (ii) Botanical covered regions assigned to 0.1 which is average value of following specification. Southern Institute of Water resources research 20 Contract No. 7182300 Main report Table 13: Manning coefficient in flooding area Flooding areas Grass 0.025 0.05 Bush 0.035 0.16 Dense willow 0.11 0.20 Scattered bush 0.03 0.05 Stem trees 0.08 0.12 Canals length are defined as measured on field. Coverage coefficient is also classified into 2 categories: (i) hard surface e.g. roads, houses, buildings are assigned to 0.15; (ii) Botanical surfaces are assigned to 0.02. Land cover are determined based on Land use maps provided by cities. Table 14: Coverage coefficient Type of surface Z coefficient - House roof 0.24 - Gravel road 0.224 - Graded material road 0.145 - Stone assembled road 0.125 - Earth road 0.084 - Park 0.038 - Trees area 0.020 - Grass 0.015 Rainfall calculated for each city has shown as below: Table 15: Calculated rainfall for each city corresponding to 10% Ben Vinh Bac Soc Vi City Tan An Long Xuyen Tre Long Lieu Trang Thanh I (mm/15 21.7 21.7 24.7 24.5 23.2 27.1 20.8 mins) I (mm/min) 1.45 1.45 1.64 1.63 1.55 1.81 1.39 Surface gradient in those cities are relative small, therefore we assume they satisfied water drainage standard which is 0.02 (2%). With all of above input, Time of concentration for each canal has shown as below: Southern Institute of Water resources research 21 Contract No. 7182300 Main report Table 16: Current water resistance area and Time of concentration Time Land use of City Coverag Canal rainfall proportion Mannin Gradie Concentra Basin e Coef.. length (mm/ g (n) nt (i) tion (Z) (L) min) Botanical Urban Min Sec cover Ba Bau canal 0.82 0.18 0.039 0.13 900 1.39 0.02 150 8993 Long Cai Son canal 0.79 0.21 0.041 0.12 1800 1.39 0.02 237 14237 Xuyen Ong Manh canal 0.63 0.37 0.053 0.10 2504 1.39 0.02 357 21423 Chin Te canal 0.12 0.88 0.091 0.04 2800 1.45 0.02 722 43290 Ben Tre 30/4 canal 0.17 0.83 0.088 0.04 770 1.45 0.02 308 18507 Mui Tau canal 0.74 0.26 0.045 0.12 188 1.45 0.02 65 3884 Tan An Rot canal 0.82 0.18 0.039 0.13 1046 1.45 0.02 162 9718 Cau Tre canal 0.74 0.26 0.045 0.12 1240 1.45 0.02 201 12045 Soc Canal Tra Men 0.52 0.48 0.061 0.09 2640 1.55 0.02 407 24436 Trang Hitech canal 0.26 0.74 0.081 0.05 3100 1.55 0.02 613 36786 Bac Tra Kha canal 0.55 0.45 0.059 0.09 4650 1.63 0.02 544 32623 Lieu Cut canal 0.36 0.64 0.073 0.07 540 1.63 0.02 187 11222 Tan Binh secondary 0.38 0.62 0.072 0.07 383 1.64 0.02 149 8952 branch 1 Tan Binh secondary 0.38 0.62 0.072 0.07 176 1.64 0.02 94 5614 branch 2 Channel, Tan Binh 0.38 0.62 0.072 0.07 423 1.64 0.02 158 9494 secondary branch 1 Ong Dia canal 0.86 0.14 0.036 0.13 196 1.64 0.02 54 3228 Song Cau Lo 1 canal 0.38 0.62 0.072 0.07 222 1.64 0.02 107 6424 Song Cau Lo 2 canal 0.39 0.61 0.071 0.07 364 1.64 0.02 142 8526 Ngo Quyen canal 0.78 0.22 0.042 0.12 157 1.64 0.02 53 3185 Canal Muong Ong Dia 0.81 0.19 0.039 0.13 387 1.64 0.02 87 5231 canal Vinh Canal Muong Ngo 0.81 0.19 0.039 0.13 156 1.64 0.02 50 3030 Long Quyen Sau Van 1 canal 0.61 0.39 0.054 0.10 603 1.64 0.02 148 8895 Sau Van 2 canal 0.61 0.39 0.054 0.10 433 1.64 0.02 122 7294 Kinh Cut secondary 0.73 0.27 0.045 0.11 233 1.64 0.02 72 4311 branch 1 Kinh Cut secondary 0.71 0.29 0.047 0.11 94 1.64 0.02 43 2567 branch 2 Sau Van secondary 0.81 0.19 0.039 0.13 141 1.64 0.02 48 2851 branch 1 Sau Van secondary 0.78 0.22 0.041 0.12 163 1.64 0.02 54 3250 branch 2 Canal Cut 0.83 0.17 0.038 0.13 540 1.64 0.02 103 6206 Cao Lau 0.77 0.23 0.042 0.12 860 1.64 0.02 149 8946 Vi Thong Nhat 4 canal 0.77 0.23 0.042 0.12 243 1.81 0.02 68 4065 Thanh Vi Thuy canal 0.37 0.63 0.072 0.07 900 1.81 0.02 243 14596 Southern Institute of Water resources research 22 Contract No. 7182300 Main report Time Land use of City Coverag Canal rainfall proportion Mannin Gradie Concentra Basin e Coef.. length (mm/ g (n) nt (i) tion (Z) (L) min) Botanical Urban Min Sec cover Canal Ngang 0.48 0.52 0.064 0.08 907 1.81 0.02 216 12943 Canal 62 0.33 0.67 0.075 0.06 2200 1.81 0.02 437 26193 Canal Xang Hau 0.42 0.58 0.069 0.07 905 1.81 0.02 230 13804 Thong Nhat 3 canal 0.73 0.27 0.045 0.11 275 1.81 0.02 77 4629 Thong Nhat 1 canal 0.51 0.49 0.062 0.09 595 1.81 0.02 161 9650 Thong Nhat 2 canalb 0.88 0.12 0.034 0.13 226 1.81 0.02 55 3302 Thong Nhat 2 canala 0.34 0.66 0.075 0.06 200 1.81 0.02 102 6139 Canal 3 0.44 0.56 0.067 0.08 294 1.81 0.02 114 6862 Canal Lô 2a 0.18 0.82 0.087 0.04 387 1.81 0.02 187 11222 Phan Lo canal 0.43 0.57 0.068 0.08 904 1.81 0.02 227 13629 Canal 2 0.45 0.55 0.066 0.08 239 1.81 0.02 100 5995 Phan Lo canal 2b 0.38 0.62 0.072 0.07 200 1.81 0.02 98 5851 Canal 1 0.37 0.63 0.072 0.07 296 1.81 0.02 125 7497 Cai Nhuc Nho canal 0.32 0.68 0.076 0.06 907 1.81 0.02 260 15580 Cai Nhuc Lon canal 0.46 0.54 0.066 0.08 1906 1.81 0.02 343 20589 Table 17: Current water resistance area and Time of concentration conform land use planning Time of City Land use proportion Mann Canal rainfall Coverage Gradie Concentrat Basin ing length (mm/ Coef. (Z) nt (i) ion (n) (L) min) Botanical Urban Min Sec cover Ba Bau canal 0.87 0.13 0.034 0.13 900 1.39 0.02 138 8268 Long Cai Son canal 0.91 0.09 0.032 0.14 1800 1.39 0.02 197 11825 Xuyen Ong Manh canal 0.78 0.22 0.042 0.12 2504 1.39 0.02 293 17602 Ben Chin Te canal 0.27 0.73 0.080 0.06 2800 1.45 0.02 581 34858 Tre 30/4 canal 0.62 0.38 0.054 0.10 770 1.45 0.02 176 10555 Mui Tau canal 0.89 0.11 0.033 0.14 188 1.45 0.02 52 3113 Tan An Rot canal 0.88 0.12 0.034 0.13 1046 1.45 0.02 148 8859 Cau Tre canal 0.82 0.18 0.039 0.13 1240 1.45 0.02 179 10763 Soc Canal Tra Men 0.75 0.25 0.044 0.12 2640 1.55 0.02 306 18330 Trang Hitech canal 0.46 0.54 0.066 0.08 3100 1.55 0.02 481 28879 Bac Tra Kha canal 0.64 0.36 0.052 0.10 4650 1.63 0.02 487 29244 Lieu Cut canal 0.42 0.58 0.069 0.07 540 1.63 0.02 174 10450 Tan Binh secondary 0.74 0.26 0.045 0.12 383 1.64 0.02 96 5738 Vinh branch 1 Long Tan Binh secondary 0.88 0.12 0.034 0.13 176 1.64 0.02 49 2931 branch 2 Southern Institute of Water resources research 23 Contract No. 7182300 Main report Time of City Land use proportion Mann Canal rainfall Coverage Gradie Concentrat Basin ing length (mm/ Coef. (Z) nt (i) ion (n) (L) min) Botanical Urban Min Sec cover Channel, Tan Binh 0.74 0.26 0.045 0.12 423 1.64 0.02 101 6084 secondary branch 1 Ong Dia canal 0.88 0.12 0.034 0.13 196 1.64 0.02 52 3127 Song Cau Lo 1 canal 0.64 0.36 0.052 0.10 222 1.64 0.02 79 4711 Song Cau Lo 2 canal 0.68 0.32 0.049 0.11 364 1.64 0.02 100 6016 Ngo Quyen canal 0.82 0.18 0.039 0.13 157 1.64 0.02 50 3010 Canal Muong Ong 0.88 0.12 0.034 0.13 387 1.64 0.02 78 4700 Dia canal Canal Muong Ngo 0.83 0.17 0.038 0.13 156 1.64 0.02 49 2942 Quyen Sau Van 1 canal 0.74 0.26 0.045 0.12 603 1.64 0.02 126 7534 Sau Van 2 canal 0.73 0.27 0.045 0.11 433 1.64 0.02 104 6262 Kinh Cut secondary 0.78 0.22 0.042 0.12 233 1.64 0.02 67 4026 branch 1 Kinh Cut secondary 0.81 0.19 0.039 0.13 94 1.64 0.02 37 2237 branch 2 Sau Van secondary 0.82 0.18 0.039 0.13 141 1.64 0.02 47 2809 branch 1 Sau Van secondary 0.79 0.21 0.041 0.12 163 1.64 0.02 53 3209 branch 2 Canal Cut 0.88 0.12 0.034 0.13 540 1.64 0.02 96 5736 Cao Lau 0.85 0.15 0.036 0.13 860 1.64 0.02 133 7959 Thong Nhat 4 canal 0.82 0.18 0.039 0.13 243 1.81 0.02 63 3784 Vi Thuy canal 0.73 0.27 0.046 0.11 900 1.81 0.02 158 9485 Canal Ngang 0.88 0.12 0.034 0.13 907 1.81 0.02 126 7560 Canal 62 0.36 0.64 0.073 0.07 2200 1.81 0.02 421 25260 Canal Xang Hau 0.80 0.20 0.040 0.12 905 1.81 0.02 143 8580 Thong Nhat 3 canal 0.78 0.22 0.042 0.12 275 1.81 0.02 72 4322 Thong Nhat 1 canal 0.68 0.32 0.049 0.11 595 1.81 0.02 131 7844 Thong Nhat 2 canalb 0.89 0.11 0.033 0.14 226 1.81 0.02 54 3249 Vi Thong Nhat 2 canala 0.42 0.58 0.069 0.07 200 1.81 0.02 93 5580 Thanh Canal 3 0.95 0.05 0.028 0.14 294 1.81 0.02 57 3399 Canal Lô 2a 0.95 0.05 0.029 0.14 387 1.81 0.02 67 4046 Phan Lo canal 0.79 0.21 0.041 0.12 904 1.81 0.02 144 8660 Canal 2 0.96 0.04 0.028 0.15 239 1.81 0.02 49 2964 Phan Lo canal 2b 0.95 0.05 0.029 0.14 200 1.81 0.02 46 2735 Canal 1 0.94 0.06 0.029 0.14 296 1.81 0.02 58 3509 Cai Nhuc Nho canal 0.91 0.09 0.031 0.14 907 1.81 0.02 120 7192 Cai Nhuc Lon canal 0.52 0.48 0.061 0.09 1906 1.81 0.02 320 19184 Southern Institute of Water resources research 24 Contract No. 7182300 Main report 3.1.4. Initial Loss Defines the precipitation depth, required to start the surface runoff. This is a one-off loss, comprising the wetting and filling of catchment depressions. For each rainfall, precipitation initial loss is assign as 0.6mm as much. 3.1.5. Reduction factor Runoff reduction factor, accounts for water losses caused by e.g. evaporate-transpiration, imperfect imperviousness, etc. on the contributing area. According to National criteria for drainage computation TCVN-7957:2008 Runoff reduction factor as follow: Table 18: L Runoff reduction factor Catchment area (ha) 300 500 1000 2000 3000 4000 Reduction factor 0.96 0.94 0.91 0.87 0.83 0.80 3.1.6. Time/Area Curve Accounts for the shape of the catchment lay-out, determines the choice of the available T/A curve to be used in the computations. Three pre-defined types of the T/A curves are available: (i) Rectangular catchment; (ii) Divergent catchment; (iii) Convergent catchment. 3.1.7. Hydrologiocal simulation output Current is simulated with different scenarios. On following table, maximum discharge for each basin corresponding to 10% probability base on existing land use map, projected land use planning, together with climate change on 2050. Specific conditions for above scenarios were defined as below: Existing: simulation rainfall on current geographic condition; Planning: simulation rainfall on 2025 land use planning; Climate change: simulation rainfall on 2025 land use planning including climate change to 2050. Southern Institute of Water resources research 25 Contract No. 7182300 Main report Table 19: Water discharge for each basins Area Qmax Qmax Qmax Climate City Basin (ha) Existing Planning change Ba Bau canal 67.72 5.79 7.31 9.29 Long Xuyen Cai Son canal 117.47 8.40 10.94 13.91 Ong Manh canal 241.04 10.28 14.74 18.72 Chin Te canal 238.60 1.26 3.40 4.51 Ben Tre 30/4 canal 24.56 0.36 1.86 2.45 Mui Tau canal 2.27 0.32 0.40 0.53 Tan An Rot canal 76.80 8.10 9.14 12.01 Cau Tre canal 76.01 6.38 9.35 12.28 Canal Tra Men 85.85 3.81 6.85 8.16 Soc Trang Hitech canal 151.81 2.36 5.15 6.12 Tra Kha canal 597.88 20.35 26.00 31.47 Bac Lieu Cut canal 151.82 7.50 9.12 11.06 Tan Binh secondary branch 1 14.00 0.70 1.67 2.15 Tan Binh secondary branch 2 6.00 0.37 1.06 1.36 Drainage, Tan Binh secondary 0.20 0.01 0.02 0.03 branch 1 Ong Dia canal 10.09 1.71 1.75 2.25 Song Cau Lo 1 canal 17.04 0.88 1.69 2.17 Song Cau Lo 2 canal 3.01 0.26 0.54 0.69 Ngo Quyen canal 3.39 0.53 0.56 0.72 Canal Muong Ong Dia 1.78 0.24 0.28 0.36 Vinh Long Canal Muong Ngo Quyen 1.80 0.29 0.30 0.39 Sau Van 1 canal 15.00 1.21 1.58 2.03 Sau Van 2 canal 11.00 0.97 1.25 1.60 Kinh Cut secondary branch 1 2.00 0.27 0.29 0.38 Kinh Cut secondary branch 2 4.50 0.67 0.80 1.03 Sau Van secondary branch 1 1.00 0.16 0.17 0.21 Sau Van secondary branch 2 2.00 0.31 0.31 0.40 canal Cut 7.57 0.99 1.08 1.39 Cao Lau 307.16 31.17 36.18 46.41 Thong Nhat 4 canal 3.06 0.51 0.56 0.69 Vi Thuy canal 13.02 0.50 1.34 1.63 Canal Ngang 5.54 0.30 0.79 0.96 Canal 62 296.10 6.47 7.26 8.85 Canal Xang Hau 6.47 0.29 0.77 0.94 Thong Nhat 3 canal 2.44 0.36 0.40 0.49 Thong Nhat 1 canal 8.61 0.61 0.93 1.13 Thong Nhat 2 canalb 4.23 0.88 0.89 1.09 Vi Thanh Thong Nhat 2 canala 7.84 0.49 0.63 0.77 Canal 3 5.95 0.45 1.32 1.61 Canal Lô 2a 7.13 0.16 1.48 1.80 Phan Lo canal 13.50 0.64 1.59 1.93 Canal 2 3.40 0.28 0.79 0.97 Phan Lo canal 2b 2.95 0.21 0.69 0.84 Canal 1 2.35 0.14 0.51 0.62 Canal Cai Nhuc Nho 17.39 0.55 2.65 3.23 Canal Cai Nhuc Lon 44.27 1.65 1.99 2.43 Those flow result would later be used as input for hydraulic model. Southern Institute of Water resources research 26 Contract No. 7182300 Main report Figure 17: Calculating water discharge at Cai Son canal in Long Xuyen city In regard to water current in project area, impermeable areas (urbanized areas) would affect significantly on water discharge on canals. 3.2. Hydraulic model 3.2.1. Hydraulic network Due to natural condition of study region which is located within Mekong Delta basin, it is necessary to cover the whole Mekong delta from Kratie down to East Sea, in order to fully describe hydrological regime of the system during Flooding and dry seasons. This hydraulic model network has been used and tested through many different water resources project in Mekong Delta which receive good evaluation for its efficiency and accuracy from many experts. Southern Institute of Water resources research 27 Contract No. 7182300 Main report Figure 18: Hydraulic model network for Low Mekong Delta and South East Vietnam region A region model of Mekong River network which initiate from Kratie, water level is controlled by hydro-station at river mouth. At local scale of each city, higher resolution networks are constructed within the original regional model. All of 7 cities would be simulated parallel at the same time with the regional model. As we have mentioned, investigation data of recent canals and their connection status have been update in our model. Demonstrations of newly updated streamline have been shown as below Figures. Southern Institute of Water resources research 28 Contract No. 7182300 Main report Figure 19: Detail hydraulic network in Vi Thanh City Figure 20: Detail hydraulic network in Bac Lieu City Southern Institute of Water resources research 29 Contract No. 7182300 Main report Figure 21: Detail hydraulic network in Long Xuyen City Figure 22: Detail hydraulic network in Vinh Long City Southern Institute of Water resources research 30 Contract No. 7182300 Main report Figure 23: Detail hydraulic network in Soc Trang City Figure 24: Detail hydraulic network in Ben Tre City Southern Institute of Water resources research 31 Contract No. 7182300 Main report Figure 25: Detail hydraulic network in Tan An City Floodplain areas are integrated to our 1D hydraulic model via water level – storage area correlation which attached to channel cross profiles. As the result, low-lying areas would be flood whenever water level exceeds their elevations. Figure 26: Storage area in the low land of the model Southern Institute of Water resources research 32 Contract No. 7182300 Main report 3.2.2. Boundary condition for hydraulic model Discharge data at Kratie. Water level boundary control total 35 points which stretch from Thi Vai river mouth to Vinh Ke canal outlet. Internal current on field computed by NAM model for all of Mekong Downstream basin. 3.2.3. Hydraulic model calibration Base on recorded water level on main rivers and from some stations on field during period of 1/7/2011 to 30/11/2011, we have setup and adjusted model parameters. Adjusting process result has shown relative match with on-field record data for major hydro-stations. Though there are some minor differences for a few regions, they are not significant which make our model qualified for this assignment. Figure 27: Comparison water level at Tan Chau Figure 28: Comparison water level at Chau Doc Southern Institute of Water resources research 33 Contract No. 7182300 Main report Figure 29: Comparison water level at Vam Nao Figure 30: Comparison water level at Cao Lanh Figure 31: Comparison water level at Can Tho Southern Institute of Water resources research 34 Contract No. 7182300 Main report Figure 32: Comparison water level at My Thuan Percent of standard deviation explained (R2) at control points range around 0.935-0.995. Table 20: Percent of standard deviation explained (R2) at control points Percent of standard No Station deviation explained (R2) 1 Can Tho 0.953 2 Cao Lanh 0.965 3 Cau Noi 0.985 4 Chau Doc 0.989 5 Duc Hue 0.935 6 Kien Binh 0.978 7 Long Xuyen 0.968 8 My Thuan 0.967 9 Tan Chau 0,985 10 Vam Nao 0.965 11 Xom Luy 0.995 3.2.4. Hydraulic model validation Flood in 2000 is one of historical event in Mekong delta on when water discharge at Kratie reach to exceptional values consist of 2 peaks: first on 21/7/2000 with 58,400 m3/s, later come up back on 17/9/2000 with 64,500 m3/s. We have utilized this event to verify our hydraulic model to ensure it is capable to describe and calculate for extreme events. On-site recorded data during this event have been use for verification process. Locations of verification points/stations has shown as below: Southern Institute of Water resources research 35 Contract No. 7182300 Main report Figure 33: Location of verification points/stations for numerical model After adjusting model in previous section, a second run was carried to verify with record data in 2000 flooding. Figure 34:Comparison water level at Tan Chau station during 2000 flood Figure 35: Comparison water level at Chau Doc station during 2000 flood Southern Institute of Water resources research 36 Contract No. 7182300 Main report Figure 36: Comparison water level at Vam Nao station during 2000 flood Figure 37: Comparison water level at Long Xuyen station during 2000 flood Figure 38: Comparison water level at My Thuan station during 2000 flood Figure 39: Comparison water level at Tuyen Nhon station during 2000 flood Southern Institute of Water resources research 37 Contract No. 7182300 Main report Figure 40: Comparison water level at Tan An station during 2000 flood Figure 41: Comparison water level at Cao Lanh station during 2000 flood Figure 42: Comparison water level at Ben Luc station during 2000 flood Percent of standard deviation explained (R2) at control points range around 0.945-0.965. Table 21: Percent of standard deviation explained (R2) at control points No Stations Percent of standard deviation explained (R2) 1 Ben Luc 0.965 2 Cao Lanh 0,953 3 Chau Doc 0,965 4 Kien Binh 0.945 5 Long Xuyen 0,957 6 My Thuan 0,935 7 Tan Chau 0,98 8 Tuyen Nhon 0,932 9 Vam Nao 0,976 Southern Institute of Water resources research 38 Contract No. 7182300 Main report 3.3. Flood mapping 3.3.1. Map construction methodologies Flood maps are constructed according to hydraulic model result and LiDAR data from Defense mapping agency of Vietnam surveyed on 2012. Those two data sources will be overplayed via tool MIKE 11GIS. 3.3.2. Flood maps In our assignment, following flood mapping have been constructed: - Flood mapping for restoration canals basin at 7 cities. Those maps would be used for computing flooding area as a criteria for investment efficiency evaluation. A total of 168 runs for all 7 cities have been issued as the result of our simulations (6 flooding scenarios x 4 land use and SUUP intervention x 7 cities). Demonstration of flooding on canals in case of with and without canal restoration are shown in Appendix D - Flood maps on channels. - Also from those 168 simulation scenarios, flood mapping for the whole 7 cities have been obtained. Demonstration for scenarios of with and without intervention are shown in Appendix G -. Digital resolution of those maps are equal to input DEM which is (5x5)m. These maps are ready to transfer to Cities administration for future utilizations. 4. SIMULATION SCENARIOS 4.1. Simulation expect outcome and scenarios construction principals As the major requirement of this assignment, numerical model which is constructed throughout our tasks would later be utilized for following targets: 4.1.1. Structural scale specification In order to define structural scale, scope of SUUP simulation would be run with hydrological probability of 10%. Simulation procedures would consist of: (i) Define current flooding conditions: (ii) Define flooding condition after intervention and (iii) Define flooding condition in 2025 as modification in land use proportion (vastly depend on Urbanization process) By comparing above scenarios, we could withdraw recommendations for further improvement e.g.: rising ground elevation; supplement sluice or pumping stations. 4.1.2. Flooding simulation in different scenario conditions Evaluate flood risk for different control conditions which consist of: current condition; after intervention and consider of climate change effect. Southern Institute of Water resources research 39 Contract No. 7182300 Main report 4.2. Simulation scenarios 4.2.1. Structural scale specification Simulation scenarios used for structural scale definition is based on 10 years return period for both river water level and precipitation. Existing Existing Planed urban situation situation Planed urban (2025) Scenarios WITHOUT WITH (2025) WITH WITHOUT SUUP SUUP SUUP SUUP interventions interventions 10 year flood + 10 year rainfall BL3 SU3 PL3 SP3 Specific boundary conditions for above scenarios were defined as below: BL3 (Based line): simulation rainfall for existing situation; current canals, channels profiles. SU3: simulation rainfall for existing situation; enhances and restored canals. PL3: simulation rainfall for planed urban to 2025; current canals, channels profiles. SP3: simulation rainfall on 2025 for planed urban to 2025; enhances and restored canals. 4.2.2. Flooding simulation in different control conditions Simulations will be carried out with river flood of 2 years, 5 years, 10 years, 25 years, 50 years and 100 years return period in combination with equivalent rainfall probability. Table 22: Simulation scenarios combination Planed Existing Existing Planed urban situation situation urban (2025) No Scenarios WITHOUT WITH (2025) WITH SUUP SUUP WITH SUUP and interventions interventions SUUP CC in 2050 1 2 year flood + 2 year rainfall BL1 SU1 SP1 CC1 2 5 year flood + 5 year rainfall BL2 SU2 SP2 CC2 3 10 year flood + 10 year rainfall BL3 SU3 SP3 CC3 4 25 year flood + 25 year rainfall BL4 SU4 SP4 CC4 5 50 year flood + 50 year rainfall BL5 SU5 SP5 CC5 6 100 flood year + 100 year rainfall BL6 SU6 SP6 CC6 A total of 24 scenarios take into account the current state of the project, and takes into account climate change. Southern Institute of Water resources research 40 Contract No. 7182300 Main report 5. STRUCTURAL DIMENSION SPECIFICATIONS 5.1. Ben Tre City Due to congested condition of canal in the city, in addition with defective or unsatisfactory controlling structures on the stream which lead to poor connection among watersheds. At Chin Te canal, current maximum water level (10%) is (+1.89m) which flood an area of 107Ha. Our calculation shown that by expand canal width to 4m and dredging bottom level to (-1.0m) could satisfy drainage discharge required. However, high tidal amplitude still flood low lying areas. Therefore, at culvert through national route 60, on canal Chin Te, it is necessary to install an one-way gravity gate to prevent tidal current form Cai Ca canal. At the end node of Chin Te Canal connect to Ca Loc Canal, another one way gravity gate should also be installed. Those gate would help to prevent tidal flood in the same time maintain rainy water in the canal. By adapting these measures, maximum water level (10%) on canals would lower to (+0.92m), flooding area reduce by 93%, down to 7 ha. Figure 43: Water level on Chin Te canal in case of with and without SUUP Southern Institute of Water resources research 41 Contract No. 7182300 Main report On 30-4 canal, maximum water level (10% probability) could reach to (+1.92m) which flood about 7ha. 30-4 canal is excessively deposit, it therefore should be dredged to level of (-0.5m) to improve discharge. Other than that, the section named “30-4 extension” should also be cleared down to level of (-0.5m) in order to freely connect to Cai Ca channel which is currently (-0.5m) at bottom level. In addition, these two channel “30-4” and “30-4 extension” should be bridged as an one straight channel to discharge to both ends. The gap between two channels is 100m long. New open channel should be at least 3m wide and bottom lay at (- 0.5m) as the original channels. And by adapting all of those measures, maximum water level (10%) is expected lower down to (+0.64m), this basin is completely free from flooding. Figure 44: Water level on 30-4 canal in case of with and without SUUP Table 23: Comparison water level in different scenarios of land use and SUUP intervention Existing Existing situation Planed urban Planed urban situation WITH STT Work packages WITHOUT (2025) WITHOUT (2025) WITH SUUP SUUP SUUP SUUP interventions interventions 1 Restore Chin Te 1.89 0.92 1.92 1.39 2 Restore 30-4 1.92 0.64 2.01 1.40 SUUP intervention has shown by our calculation that is very effective. Flooding condition reduce significantly after canals be restored. Refer to Appendix E -0. Chin Te channel in Ben Tre is obstructed by trash, especially at the North of Nguyen Thi Dinh street which severely narrow down the channel. Garbage clearing should be doing together with channel restoration activity. Besides that, it is necessary to educate the issue and convince community stop dumping trash in the streamline. Southern Institute of Water resources research 42 Contract No. 7182300 Main report Figure 45: Proposed bridge the gap between two channel sections Figure 46: Proposed location of supplement one way gravity gates Table 24: Proposed canal restoration and supplement structures in Ben Tre City Existing Existing Proposed Proposed N Work Length surface bed level surface bed level Structures o package (m) width (m) width (m) (m) (m) Install new one way gravity gates at sluice Restoration under National route 60; 1 Chin Te 2800 3 +0.31 4 -1.0 and the new one at the Canal junction with Ca Loc canal Open new channel which is 3m wide, bottom level is at (- Restoration 2 770 2 +0.65 3 -0.5 0.5m), install one way 30-4 Canal sluice 2D1000 before discharge to Cai Ca canal. Southern Institute of Water resources research 43 Contract No. 7182300 Main report 5.2. Vinh Long City In Vinh Long City, most of channels are blocked from smooth flow by sediment deposit. Bottom level of most of canals in LIA region is higher than (+0.3m). Calculation has shown that maximum water level corresponding to 10% probability on LIA canals vary from (+1.93m) to (+1.97m). On the other hand, high water level on main river contribute to make flooding worse. That explain for the use of tidal gate have already constructed on small channels. Base on our calculation, we suggest that beside from dredging channels, one way gravity gates should be installed at the outlet from canals into main river. By doing so, 10% maximum water level reduce to the level of (+0.90m) – (+1.35m). Flooding is put under well control. The reduction of flooding area could be up to 82% in LIA 1, 80% in LIA 3, 26% in LIA 4. Except for the basins of Kenh Cut Canal and Cau Lau canal, the flooding area is not reducing due to lacking of controlling structures. When adapt land use planning in our simulation, water level on those canals will increase up to (+1.4m). However, current ground level of Vinh Long is about (+1.8m) to (+2.0m); while it is (+2.2m) to (+2.3m) for roads. It shown that the intervention activities are sustainable for long term period. Southern Institute of Water resources research 44 Contract No. 7182300 Main report Figure 47: Maximum water level on Tan Binh 1 canal in case of with and without SUUP intervention Table 25: Maximum water level in different scenarios of land use and SUUP intervention (10% hydrological condition) Existing Planed Existing Planed urban situation urban situation (2025) No Work packages WITHOUT (2025) WITH SUUP WITHOUT SUUP WITH interventions SUUP interventions SUUP LIA1 Tan Binh secondary branch 1 1.96 0.90 2.02 1.39 Tan Binh secondary branch 2 1.96 0.90 1.99 1.39 LIA3 Ong Dia canal 1.97 1.37 2.02 1.39 Cau Lo river secondary branch 1 1.93 0.99 1.97 1.37 Cau Lo river secondary branch 2 1.93 0.99 1.98 1.37 Ngo Quyen Canal 1.94 1.35 1.96 1.39 LIA4 Sau Van secondary branch 1 1.97 1.22 1.99 1.38 Sau Van secondary branch 2 1.97 1.22 1.99 1.38 Kinh Cut secondary branch 1 1.95 1.31 1.98 1.37 Kinh Cut secondary branch 2 1.95 1.31 1.98 1.37 Sau Van secondary branch 1 1.97 1.22 1.96 1.38 Sau Van secondary branch 2+ Kinh Cut 1.31 secondary branch 3 1.95 1.97 1.37 1 Kinh Cut river renovation 1.93 1.62 1.94 1.67 2 Cau Lau river renovation 1.94 1.63 1.95 1.68 According to our calculation, it is recommended that Vinh Long city aside from dredging to restore canals, tidal control gates should also be constructed along side with sluice. Specific gate dimensions are described in below table: Southern Institute of Water resources research 45 Contract No. 7182300 Main report Table 26: Proposed canal restoration and supplement structures in Vinh Long Existing Proposed Existing Proposed Length surface surface Structur No Work package bed level bed level (m) width width es (m) (m) (m) (m) Secondary branch 1 Tan 383.12 6 +0.6 6 -1 2D=1000 Binh LIA Secondary branch 2 Tan 176.02 4 +0.6 4 -1 1 Binh Secondary branches 1 Tan 422.5 5 +0.6 5 -1 Binh Channel Ong Dia 196.13 5 +0.7 5 -1 2D=1000 Channel Song Cau Lo 1 222.49 7.5 +0.3 7.5 -1 2D=1000 LIA Channel Song Cau Lo 2 363.69 6 +0.3 6 -1 D=1000 3 Channel Ngo Quyen 157.41 3.5 +0.2 3.5 -1 D=1000 Channel Ong Dia 386.69 5 +0.7 5 -1 Channel Ngo Quyen 155.61 2.5 +0.2 2.5 -1 Channel Sau Van 1 603.26 5 +0.4 5 -1 Channel Sau Van 2 433.44 7.5 +0.25 7.5 -1 2D=1000 Secondary branch Kinh Cut 232.69 4.5 +0.4 4.5 -1 D=1000 1 LIA Secondary branch Kinh Cut 4 93.84 3.5 +0.4 3.5 -1 D=1000 2 Secondary branch Sau Van 1 140.57 6.5 +0.25 6.5 -1 3D=1000 Secondary branch Sau Van 2+ Secondary branch Kinh 163.19 3.5 +0.25 3.5 -1 Cut 3 1 River Kinh Cut 540 14 -0.46 15 -2.0 2 River Cau Lau 860 18 -1.75 20 -2.0 Figure 48: Tidal control gates location in Vinh Long City Southern Institute of Water resources research 46 Contract No. 7182300 Main report 5.3. Bac Lieu City Most of channels in Bac Lieu city are quite large, sufficient for current drainage requirement. Only for a section of Tra Kha Canal from Tran Phu Street to Cau Xang culvert, due to severe damage of two sewers gate, 10% probability maximum water level could reach to (1.86m) which is causing flooding an area of 505Ha. In contrast with the section from Tran Phu Street to Tra Kha culvert which has lower water level due to it is easily to discharge into Northern canal. These two sewers therefore need to be restored or even enhanced to maintain good discharge into Bac Lieu River. Base on our calculation, we suggest that dredging channels and restore damaged two sewer gates will help on one hand reduce water level on channel on the other hand better control tidal. The simulation has shown that by adapting mentioned measures, 10% water level will lower to (+1.34m), 92% of current flooding area will be diminished. Figure 49: Water level on Tra Kha Canal in case of with and without SUUP intervention It is not necessary to improve sewers under Tran Phu Street and Nguyen Van Linh Street, due to narrow stream and ability to discharge to both ends of the canal. Southern Institute of Water resources research 47 Contract No. 7182300 Main report Figure 50: Maximum water level on Tra Kha Canal after intervention When consider land use planning, water level would reach about (+1.36m) to (+1.40m). Compare to current ground level of this area [+1.8m to +2.0m] and (+2.0m) of average level of Bac Lieu City, the water level is still vary with safe threshold which ensure good drainage capability. Table 27: 10% maximum water level in different scenarios of land use and intervention Existing Existing Planed Planed urban situation situation urban (2025) No Work package WITHOUT WITH (2025) WITHOUT SUUP SUUP WITH SUUP interventions interventions SUUP Kenh Xang canal to Tra Kha, Tra 1 1.86 2.02 Khua 1.34 1.40 2 LIA 6 – canal restoration 1.86 1.34 2.01 1.36 We propose channel restoration dimension and controlling structures as below: Table 28: Proposed canal restoration and supplement structures in Bac Lieu Existing Existing Length surface Proposed Proposed Work bed level No width surface width bed level Structures package (m) (m) (m) (m) (m) Replace damage Kenh Xang gates at sewers on 1 4650 8 -0.75 10 -1.0 Canal Kenh Xang and Tra Kha LIA 6 – 2 Canal 540 5 0.25 6 -1.0 restoration Southern Institute of Water resources research 48 Contract No. 7182300 Main report 5.4. Vi Thanh City Wide channels in Vi Thanh city allow smoothly water discharge, together with high ground elevation, flooding area in this city is relatively small. Our simulation has shown that comparison between current and future land use does not show any change in water level. Even with SUUP intervention, the change is quite small, refer to Appendix E -0. Thus, channel dredging only serve as maintaining and environment enhancing. Only when consider urbanization scenario up to 2025 which cause reduction in free water surface, could lead to increasing in water level. Though before that, Vi Thanh city will be safe from flooding. Figure 51: Water level on Thong Nhat 1 canal in case of with and without SUUP intervention Southern Institute of Water resources research 49 Contract No. 7182300 Main report Table 29: 10% maximum water level in different scenarios Existing Existing Planed urban situation situation Planed urban (2025) STT Work packages WITHOUT WITH (2025) WITH WITHOUT SUUP SUUP SUUP SUUP interventions interventions LIA3 Thong Nhat 1 canal 0.83 0.83 0.87 0.87 Thong Nhat 2 canal 0.83 0.83 0.87 0.87 Thong Nhat 3 canal 0.32 0.32 0.34 0.34 Thong Nhat 4 canal 0.32 0.32 0.34 0.34 LIA7 Cai Nhuc Nho canal 0.83 0.83 0.87 0.87 Phan Lo canal 0.83 0.83 0.87 0.87 Lo 2 canal 0.83 0.83 0.87 0.87 Canal 1 0.83 0.83 0.87 0.87 Canal 2 0.83 0.83 0.87 0.87 Canal 3 0.83 0.83 0.87 0.87 1 Cai Nhuc canal renovation 0.83 0.83 0.87 0.87 2 Canal 62 renovation 0.32 0.32 0.34 0.34 Base on our calculation, proposed restoration dimension is shown as below: Table 30: Proposed canal restoration and supplement structures in Vi Thanh City Existing Length surface Existing bed level Proposed Proposed bed No Work package width surface width (m) (m) level (m) (m) (m) Thong Nhat 1 canal 594.532 11 -0.84 11 -1.0 Thong Nhat 2 canal 425.59 8 -0.63 8 -1.0 LIA3 Thong Nhat 3 canal 275.155 7.5 -0.98 7.5 -1.0 Thong Nhat 4 canal 242.615 6.5 -0.76 6.5 -1.0 Cai Nhuc Nho canal 906.839 9 -1.23 9 -1.0 Phan Lo canal 903.586 9.5 -0.81 9.5 -1.0 Lo 2 canal 587.073 7 -0.52 7 -1.0 LIA7 Canal 1 296.37 4.5 -0.65 4.5 -1.0 Canal 2 239.06 4.5 -0.65 4.5 -1.0 Canal 3 293.64 5.5 -0.65 5.5 -1.0 Cai Nhuc canal 1 1906 22 22 -2.0 renovation -1.31 2 Canal 62 renovation 2200 20 -1.23 20 -2.0 Southern Institute of Water resources research 50 Contract No. 7182300 Main report 5.5. Long Xuyen City Ba Bau Canal is narrow and shallow and very difficult for water discharge. In addition, two controlling gates currently located on this canal is insufficient which lead to high difference in water level before and after gate up to 20-30cm during drainage. Our calculation also shown that 2 current round sewers on Ba Bau Canal are not satisfied for water discharge requirement. Therefore, we suggest to replace those with rectangular culvert under Bui Van Danh Street (B=2.5m, H=2.0m, Z=-0.5m). Besides that, it is also recommended to upgrade sewer under Route 943 up to (B=2.0m, H=1.6m, Z=-0.5m). By doing all of that, we expect to see 10% max water level will reduce to (+2.50m), and diminish about 92% of current flooding area. Figure 52: Water level on Ba Bau Canal in case of with and without SUUP In regard to Ong Manh canal, due to small sewer under Ha Hoang Ho Street, water mostly escape via two ends of the canal. We suggest to supplement another D1000 sewer next to current D1000 sewer, while dredging to restore original state of the channel, will help to decrease water level down to (+2.68m), and also cut down 34% of flooding area. Southern Institute of Water resources research 51 Contract No. 7182300 Main report The situation is totally different for Cai Son Canal, due to wide streamline, its drainage capacity is very sufficient. Dredging therefore will only serves as maintaining. Table 31:10% maximum water level in different scenarios of land use and intervention Existing Existing Planed urban situation Planed urban situation (2025) STT Work packages WITHOUT (2025) WITH WITH SUUP WITHOUT SUUP SUUP interventions SUUP interventions 1 Ong Manh canal restoration 2.83 2.66 2.88 2.68 2 Ba Bau canal restoration 2.90 2.50 2.93 2.56 3 Cai Son canal restoration 2.63 2.63 2.66 2.66 Table 32: Proposed canal restoration and supplement structures in Long Xuyen City Existing Existing Proposed Work Length surface Proposed bed No bed level surface width Structures package (m) width level (m) (m) (m) (m) Supplement 1 Ong Manh D1000 with 1 1 canal 1400 6 -0.05 8 -0.50 current D1000 restoration sewer Upgrade 2 Ba Bau sewers under 2 canal 900 4 +0.83 6 -0.50 road up to restoration B=2.5, Z=-0.5 B=2.0, Z=-0.5 Cai Son 3 canal 1800 12 +0.19 15 -0.50 restoration Figure 53: Location of proposed sewers on Ong Manh and Ba Bau canal Southern Institute of Water resources research 52 Contract No. 7182300 Main report 5.6. Tan An City At Rach Rot and Cau Tre Canal, their width are quite limited which obstruct water discharge. On the other hand, these canals are relatively shallow and outlet culvert dimensions are not sufficient. It is recommended to improve those outlet for better drainage capacity. Figure 54: Water level on Rach Rot in case of with and without SUUP Figure 55: Water level on Cau Tre Canal in case of with and without SUUP Southern Institute of Water resources research 53 Contract No. 7182300 Main report Table 33: 10% probability maximum water level in different scenarios Existing Planed urban situation Existing situation Planed urban (2025) STT Work packages WITHOUT WITH SUUP (2025) WITH WITHOUT SUUP interventions SUUP SUUP interventions 1 Cau Tre canal 1.76 1.34 1.88 1.39 2 Rot Canal 1.82 1.28 2.00 1.35 Canals restoration has shown in our calculation to reduce flooding area in Rach Rot basin by 59%, and 37% in Cau Tre basin. Detail proposed restoration and intervention are described in below table: Table 34: Proposed canal restoration and supplement structures in Tan An Existing Existing Proposed Proposed Work Length surface No bed level surface bed level Structures package (m) width (m) width (m) (m) (m) Remove sewers and directly connect to 1 Cau Tre Canal 1240 5 -1.3 8 -1.5 Bao Dinh water resources system. Rach Rot B=3 m 2 1211 6 -1.20 8 -1.5 Canal Z=-1.0 Those canals’ width fluctuate remarkably from one end to the other. We suggest that they should be expand to at least 8m wide. However, the final dredging area should only be confirmed by FS consultants to appropriate with current condition. Figure 56: Location of proposed sewers on Cau tre and Rach Rot canal Southern Institute of Water resources research 54 Contract No. 7182300 Main report 5.7. Soc Trang City Maximum water level on Tra Men canal in existing siotuation scenario is (+1.90m). It is worth to mention that sluice gate dimension at outlet of Tra Men into Maspero is not sufficient which obstruct flow from escaping smoothly, and water level increase accordingly. Base on our calculation, in order to improve water discharge, it is recommended to expand range and scope of canal restoration as below: At Tra Men outlet into Maspero, it should be installed 4 round sewers equipped with one way gravity gates; At Tra Men outlet into 30/4 canal, it should construct a culvert with ready slot for closing sheet in future if outer water level exceed the outlet threshold. Figure 57: Water level on Tra Men in case of with and without SUUP For Hitech canal, which is very sufficient for drainage, our simulation have shown that the different is small between with and without SUUP intervention. In order to reduce water level Southern Institute of Water resources research 55 Contract No. 7182300 Main report in case of heavy rain and high tide which cause flood in low lying areas, it is recommended to properly operate tidal controlling gate. Figure 58: Water level on Hitech canal in different simulation Table 35: 10% probability water level in different scenarios of land use and SUUP intervention Existing Existing Planed urban situation Planed urban situation (2025) STT Work packages WITHOUT (2025) WITH WITH SUUP WITHOUT SUUP SUUP interventions SUUP interventions 1 Tra Men restoration 1.90 1.19 1.94 1.23 2 Hitech canal restoration 1.77 1.25 1.79 1.31 Our calculation have shown that by adapting above intervention, flooding area in Tra Men basin reduce by 66%, and 31% for Hitech canal. We recommend to upgrade regulation structures and restore channel in Soc Trang City as follow specifications: Table 36: Proposed canal restoration and supplement structures in Soc Trang Existing Existing Proposed Work Length Proposed bed No surface width bed level surface Structures package (m) level (m) (m) (m) width (m) At outlet into Maspero install Tra Men 4D1000 1 2640 6 -0.20 8 -1.0 restoration At outlet into 30/4 install 2D1000 Hitech canal 2 3100 10 -0.07 12 -1.0 restoration Southern Institute of Water resources research 56 Contract No. 7182300 Main report 5.8. Summary table of canal restoration and supplement structures Recommendations of canal restoration and supplement structures as folowing table: Table 37: Proposed canal restoration and supplement structures in 07 cities Existing Existing Proposed Proposed N Work Length surface bed level surface bed level Structures o package (m) width (m) width (m) (m) (m) Ben Tre Install new one way gravity gates at sluice Restoration under National route 60; 1 Chin Te 2800 3 +0.31 4 -1.0 and the new one at the Canal junction with Ca Loc canal Open new channel which is 3m wide, bottom level is at (- Restoration 2 770 2 +0.65 3 -0.5 0.5m), install one way 30-4 Canal sluice 2D1000 before discharge to Cai Ca canal. Vinh Long Secondary branch 1 383.12 6 +0.6 6 -1 2D=1000 Tan Binh L Secondary I branch 2 176.02 4 +0.6 4 -1 A Tan Binh 1 Secondary branches 1 422.5 5 +0.6 5 -1 Tan Binh Channel 196.13 5 +0.7 5 -1 2D=1000 Ong Dia Channel Song Cau 222.49 7.5 +0.3 7.5 -1 2D=1000 Lo 1 L Channel I Song Cau 363.69 6 +0.3 6 -1 D=1000 A Lo 2 3 Channel 157.41 3.5 +0.2 3.5 -1 D=1000 Ngo Quyen Channel 386.69 5 +0.7 5 -1 Ong Dia Channel 155.61 2.5 +0.2 2.5 -1 Ngo Quyen Channel 603.26 5 +0.4 5 -1 Sau Van 1 Channel 433.44 7.5 +0.25 7.5 -1 2D=1000 Sau Van 2 Secondary L branch 232.69 4.5 +0.4 4.5 -1 D=1000 I Kinh Cut 1 A Secondary 4 branch 93.84 3.5 +0.4 3.5 -1 D=1000 Kinh Cut 2 Secondary branch Sau 140.57 6.5 +0.25 6.5 -1 3D=1000 Van 1 Southern Institute of Water resources research 57 Contract No. 7182300 Main report Existing Existing Proposed Proposed N Work Length surface bed level surface bed level Structures o package (m) width (m) width (m) (m) (m) Secondary branch Sau Van 2+ 163.19 3.5 +0.25 3.5 -1 Secondary branch Kinh Cut 3 River Kinh 1 540 14 -0.46 15 -2.0 Cut River Cau 2 860 18 -1.75 20 -2.0 Lau Bac Lieu Replace damage gates at Kenh Xang 1 4650 8 -0.75 10 -1.0 sewers on Kenh Xang Canal and Tra Kha LIA 6 – 2 Canal 540 5 0.25 6 -1.0 restoration Vi Thanh Thong Nhat 594.532 11 -0.84 11 -1.0 1 canal L Thong Nhat 425.59 8 8 -1.0 I 2 canal -0.63 A Thong Nhat 275.155 7.5 7.5 -1.0 3 3 canal -0.98 Thong Nhat 242.615 6.5 6.5 -1.0 4 canal -0.76 Cai Nhuc 906.839 9 9 -1.0 Nho canal -1.23 L Phan Lo 903.586 9.5 9.5 -1.0 I canal -0.81 A Lo 2 canal 587.073 7 -0.52 7 -1.0 7 Canal 1 296.37 4.5 -0.65 4.5 -1.0 Canal 2 239.06 4.5 -0.65 4.5 -1.0 Canal 3 293.64 5.5 -0.65 5.5 -1.0 Cai Nhuc 1 canal 1906 22 22 -2.0 renovation -1.31 Canal 62 2 2200 20 20 -2.0 renovation -1.23 Long Xuyen Ong Manh Supplement 1 D1000 1 canal 1400 6 8 -0.50 with 1 current D1000 restoration -0.05 sewer Upgrade 2 sewers under Ba Bau road up to 2 canal 900 4 6 -0.50 B=2.5, Z=-0.5 restoration +0.83 B=2.0, Z=-0.5 Cai Son 3 canal 1800 12 15 -0.50 restoration +0.19 Tan An Remove sewers and Cau Tre directly connect to Bao 1 1240 5 8 -1.5 Canal Dinh water resources -1.3 system. 2 Rach Rot 1211 6 -1.20 8 -1.5 B=3 m Southern Institute of Water resources research 58 Contract No. 7182300 Main report Existing Existing Proposed Proposed N Work Length surface bed level surface bed level Structures o package (m) width (m) width (m) (m) (m) Canal Z=-1.0 Soc Trang At outlet into Maspero Tra Men install 4D1000 1 2640 6 8 -1.0 restoration At outlet into 30/4 -0.20 install 2D1000 Hitech 2 canal 3100 10 12 -1.0 restoration -0.07 6. DESIGN WATER LEVELS 6.1. Simulation purpose In this section, we are going to cover hydraulic parameters in relation with structural design aspect. Structures type could be: sluice, revetment, roads, bridge. These hydraulic parameter would be considered as input conditions for structural design. Design water level is extracted base on long-term data series water level at hydro-stations which is located close to cities. Except for Bac Lieu which is lack of hydro-stations, design water level is calculated by utilizing numerical model. These would serve as guideline for structural design. 6.2. Design standards and regulations 6.2.1. Maximum water level for water defense structures Design water level for protection structures e.g. revetment, dikes, roads, sluice gates which meant for prevent flooding from rivers, must be taken for 1% possibility. Several different water levels are also utilized for design activities. 6.2.2. Minimum water level for design structural stability analysis According to National building code QCVN 04-05:2011/BNNPTNT, National standard for Hydraulic structures – Major design criteria issued on 2011, structural rank for this project would be III (over 2000 ha). Revetment, sluice gate would be design in respect with minimum water level of 95% possibility for those structural stability analysis, foundation calculations. 6.2.3. Inland navigation water level According to inland navigation regulation, water level used for navigation would be defined as 5% chance base on accumulation hourly water level possibility distribution. Minimum water level which utilized for determine culvert threshold, dredging level would be 98% possibility. Southern Institute of Water resources research 59 Contract No. 7182300 Main report 6.2.4. Construction water level According to National building code QCVN 04-05:2011/BNNPTNT, National standard for Hydraulic structures – Major design criteria issued on 2011, building classification in this project’s regions is grade III (over 2,000Ha area). Water discharge return period, maximum water level for temporary structures during construction period is 10%. 6.3. Design specifications calculation result 6.3.1. Maximum water level for water defense structures Maximum water level statistical analysis according to water level series has been shown as following: Table 38: Maximum water level for water defense structures Prob. Tan An Ben Tre Vinh Long Soc Trang Bac Lieu Vi Thanh Long Xuyen 1% 1.85 1.97 2.07 1.86 1.96 0.95 2.93 1.5% 1.81 1.96 2.05 1.85 1.90 0.93 2.89 2% 1.79 1.94 2.03 1.84 1.83 0.92 2.86 3% 1.75 1.93 2.01 1.83 1.77 0.90 2.82 4% 1.73 1.91 1.99 1.82 1.73 0.89 2.79 5% 1.71 1.90 1.98 1.82 1.70 0.88 2.76 6.3.2. Minimum water level for design structural stability analysis Minimum water level for designing protection structure has been shown as below: Table 39: Minimum water level for design structural stability analysis Tan An Ben Tre Vinh Long Soc Trang Bac Lieu Vi Thanh Long Xuyen -2.03 -1.76 -1.35 -1.29 -1.80 -0.58 -1.00 6.3.3. Inland navigation water level Inland navigation water level has been calculated as below: Table 40: Water level for inland navigation base on accumulation hourly water level P% Bac Lieu Ben Tre Vi Thanh Long Xuyen Vinh Long Soc Trang Tan An 5 1.31 1.43 0.57 2.44 1.40 1.34 1.14 10 1.18 1.28 0.54 2.32 1.26 1.21 1.00 50 0.44 0.56 0.24 0.87 0.66 0.75 0.39 90 -0.74 -0.56 0.02 -0.07 -0.20 0.04 -0.75 95 -0.98 -0.82 -0.04 -0.29 -0.44 -0.14 -1.01 98 -1.19 -1.07 -0.10 -0.50 -0.68 -0.30 -1.24 6.3.4. Construction water level Recommended water level for temporary structures design during construction period has been calculated as below: Southern Institute of Water resources research 60 Contract No. 7182300 Main report Table 41: Maximum water level for construction period Tan An Ben Tre Vinh Long Soc Trang Bac Lieu Vi Thanh Long Xuyen 1.63 1.87 1.93 1.79 1.67 0.84 2.67 7. BUILDING FLOOD MAPS FOR 7 CITIES 7.1. Building flood maps principal Base on updated and calibrated numerical hydraulic model for Downstream Mekong river, multiple scenarios have been simulated to create different flooding conditions. Flood mapping, later have been constructed by overlaying simulated water level over high resolution DEM (5x5)m [MONRE, 2012] each of seven cities. 7.2. Simulated scenarios used for flood mapping Scenarios used for flood mapping construction are similar to calculation scenarios while screening efficiency of channel renovation in seven cities. In total there are 3 simulation scenarios which cover both of current states and climate change impact. Those scenarios were interpreted base on combination of river water level and precipitation homogeneous return periods: 2 years, 5 years, 10 years, 25 years, 50 years and 100 years. Table 42: Simulation scenarios combination for flood mapping Planed Existing Existing Planed urban situation situation urban (2025) No Scenarios WITHOUT WITH (2025) WITH SUUP SUUP WITH SUUP and interventions interventions SUUP CC in 2050 1 2 year flood + 2 year rainfall BL1 SU1 SP1 CC1 2 5 year flood + 5 year rainfall BL2 SU2 SP2 CC2 3 10 year flood + 10 year rainfall BL3 SU3 SP3 CC3 4 25 year flood + 25 year rainfall BL4 SU4 SP4 CC4 5 50 year flood + 50 year rainfall BL5 SU5 SP5 CC5 6 100 flood year + 100 year rainfall BL6 SU6 SP6 CC6 Total of 168 scenarios take into account the existing situation, existing situation WITH SUUP planed urban (2025, and takes into account climate change. 7.3. Flood mapping results There are 126 flood mapping constructed for seven cities, 18 maps for each city. These maps represent for different conditions e.g. current states; land use modified; and even climate change projections in 2050. Digital versions of flood mapping would be transferred to local administrators as a guideline in support for authority management and future master planning studies [Appendix G -]. Southern Institute of Water resources research 61 Contract No. 7182300 Main report 7.4. Flood area results for 7 cities 7.4.1. Ben Tre City According to the calculation of the flood area of this city, total flood area in the existing situation from 1615 ha to 3750 ha (based on the flood year) accounting from 23.9% to 55.6% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 1527 to 3625 ha, reduced from 88 ha to 125 ha compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 1751 ha to 4070 ha, increasing from 224 ha to 445 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 3666 ha to 5647 ha, increase of from 1177 ha to 1915 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 43: Flood area for each scenarios in Ben Tre city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 721 1064 1147 1250 1369 1480 0.4-0.6 201 415 549 859 932 1059 0.6-0.8 153 129 157 238 327 423 0.8-1 59 138 140 131 151 129 1-1.2 41 68 63 79 91 138 1.2-1.4 13 22 32 58 62 68 1.4-1.6 5 6 10 14 19 22 > 1.6 422 425 426 428 429 430 Total flood area 1615 2265 2523 3058 3379 3750 Flood area rate 23.9% 33.6% 37.4% 45.3% 50.1% 55.6% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 662 1004 1105 1210 1333 1457 0.4-0.6 178 383 494 802 873 1005 0.6-0.8 149 124 148 216 299 383 0.8-1 58 136 139 129 147 124 1-1.2 41 68 63 78 90 136 1.2-1.4 13 22 31 58 62 68 1.4-1.6 5 5 10 14 19 22 > 1.6 422 425 426 428 429 430 Total flood area 1527 2166 2417 2933 3251 3625 Flood area rate 22.6% 32.1% 35.8% 43.5% 48.2% 53.7% Flood area compared to BL -88 -99 -106 -124 -128 -125 Flood area rate compared to BL -1.3% -1.5% -1.6% -1.8% -1.9% -1.9% Southern Institute of Water resources research 62 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 825 1160 1192 1368 1474 1520 0.4-0.6 222 524 715 932 1051 1146 0.6-0.8 127 153 195 329 435 552 0.8-1 78 140 150 151 144 176 1-1.2 57 63 59 91 138 144 1.2-1.4 14 31 41 62 68 64 1.4-1.6 5 10 13 19 22 32 > 1.6 422 426 427 429 430 436 Total flood area 1751 2507 2791 3382 3763 4070 Flood area rate 26.0% 37.2% 41.4% 50.1% 55.8% 60.3% Flood area compared to SU 224 341 374 449 512 445 Flood area rate compared to SU 3.3% 5.1% 5.5% 6.7% 7.6% 6.6% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 1459 1452 1536 1177 1042 919 0.4-0.6 1031 1017 1210 1523 1533 1485 0.6-0.8 399 422 734 1148 1205 1288 0.8-1 123 137 244 550 736 884 1-1.2 137 137 158 163 244 276 1.2-1.4 66 67 60 140 168 193 1.4-1.6 21 21 42 64 60 97 > 1.6 430 430 440 468 483 505 Total flood area 3666 3684 4424 5232 5471 5647 Flood area rate 54.3% 54.6% 65.6% 77.6% 81.1% 83.7% Flood area compared to SP 1915 1177 1632 1850 1708 1577 Flood area rate compared to SP 28.4% 17.4% 24.2% 27.4% 25.3% 23.4% Southern Institute of Water resources research 63 Contract No. 7182300 Main report 7.4.2. Vinh Long City According to the calculation of the flood area of this city, total flood area in the existing situation from 2057 ha to 2867 ha (based on the flood year) accounting from 43.1% to 60.1% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 2052 to 2854 ha, reduced from 5 ha to 13 ha compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 2207 ha to 2996 ha, increasing from 88 ha to 162 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 2607 ha to 3500 ha, increase of from 374 ha to 574 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 44: Flood area for each scenarios in Vinh Long city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 512 552 474 469 514 546 0.4-0.6 525 420 481 538 558 510 0.6-0.8 331 570 560 473 438 448 0.8-1 56 84 238 411 516 594 1-1.2 99 38 49 60 74 113 1.2-1.4 527 406 229 88 43 39 1.4-1.6 5 207 393 540 425 339 > 1.6 1 2 3 8 179 279 Total flood area 2057 2278 2427 2586 2747 2867 Flood area rate 43.1% 47.8% 50.9% 54.2% 57.6% 60.1% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 510 551 473 465 509 539 0.4-0.6 524 418 479 536 556 508 0.6-0.8 331 569 558 472 437 447 0.8-1 56 83 238 410 515 593 1-1.2 99 37 49 60 74 112 1.2-1.4 527 406 229 88 43 39 1.4-1.6 5 206 393 539 425 339 > 1.6 1 2 3 8 178 279 Total flood area 2052 2272 2422 2578 2738 2854 Flood area rate 43.0% 47.6% 50.8% 54.1% 57.4% 59.8% Flood area compared to BL -5 -6 -5 -8 -9 -13 Flood area rate compared to BL -0.1% -0.1% -0.1% -0.2% -0.2% -0.3% Southern Institute of Water resources research 64 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 555 490 475 510 546 571 0.4-0.6 448 467 518 557 493 474 0.6-0.8 490 598 487 437 463 481 0.8-1 70 141 382 515 598 559 1-1.2 61 44 58 74 125 238 1.2-1.4 455 308 92 43 42 49 1.4-1.6 126 309 535 425 324 229 > 1.6 1 2 7 178 295 396 Total flood area 2207 2360 2553 2741 2885 2996 Flood area rate 46.3% 49.5% 53.5% 57.5% 60.5% 62.8% Flood area compared to SU 154 88 131 162 147 142 Flood area rate compared to SU 3.2% 1.8% 2.7% 3.4% 3.1% 3.0% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 468 552 563 563 601 545 0.4-0.6 544 490 475 475 541 518 0.6-0.8 468 467 518 518 509 465 0.8-1 427 598 487 487 447 485 1-1.2 63 141 382 382 593 547 1.2-1.4 83 44 58 58 113 266 1.4-1.6 543 308 91 91 39 50 > 1.6 9 312 541 541 617 625 Total flood area 2607 2912 3115 3115 3459 3500 Flood area rate 54.7% 61.1% 65.3% 65.3% 72.5% 73.4% Flood area compared to SP 400 553 562 374 574 503 Flood area rate compared to SP 8.4% 11.6% 11.8% 7.8% 12.0% 10.6% Southern Institute of Water resources research 65 Contract No. 7182300 Main report 7.4.3. Bac Lieu City According to the calculation of the flood area of this city, total flood area in the existing situation from 10226 ha to 13266 ha (based on the flood year) accounting from 69.5% to 90.2% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 9987 to 13029 ha, reduced from 220 ha to 239 ha compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 10369 ha to 13222 ha, increasing from 192 ha to 382 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 11893 ha to 13861 ha, increase of from 639 ha to 1524 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 45: Flood area for each scenarios in Bac Lieu city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 3014 2631 2206 2004 1126 1064 0.4-0.6 3820 3880 3568 3372 1914 1739 0.6-0.8 1646 2223 3071 3389 3204 2950 0.8-1 1230 1407 1438 1457 3603 3855 1-1.2 376 594 957 1131 1518 1660 1.2-1.4 112 162 253 391 1229 1313 1.4-1.6 18 28 51 79 380 518 > 1.6 9 12 20 23 122 167 Total flood area 10226 10938 11563 11846 13095 13266 Flood area rate 69.5% 74.3% 78.6% 80.5% 89.0% 90.2% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 3088 2688 2247 2034 1125 1065 0.4-0.6 3751 3908 3631 3424 1954 1767 0.6-0.8 1503 2102 2997 3434 3264 3010 0.8-1 1137 1260 1295 1367 3602 3890 1-1.2 369 553 853 987 1404 1586 1.2-1.4 112 160 244 287 1079 1168 1.4-1.6 18 28 51 71 315 395 > 1.6 9 12 20 23 118 149 Total flood area 9987 10712 11337 11626 12861 13029 Flood area rate 67.9% 72.8% 77.1% 79.0% 87.4% 88.6% Flood area compared to BL -239 -226 -226 -220 -234 -236 Flood area rate compared to BL -1.6% -1.5% -1.5% -1.5% -1.6% -1.6% Southern Institute of Water resources research 66 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 2868 2511 2071 1861 1044 1001 0.4-0.6 3911 3820 3421 3164 1718 1538 0.6-0.8 1749 2493 3373 3768 2940 2748 0.8-1 1219 1280 1354 1483 3920 3963 1-1.2 455 669 987 1114 1663 2009 1.2-1.4 134 190 287 338 1196 1256 1.4-1.6 23 33 71 103 425 517 > 1.6 10 15 23 26 157 189 Total flood area 10369 11011 11587 11856 13063 13222 Flood area rate 70.5% 74.8% 78.8% 80.6% 88.8% 89.9% Flood area compared to SU 382 299 250 230 202 192 Flood area rate compared to SU 2.6% 2.0% 1.7% 1.6% 1.4% 1.3% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 1816 1500 1263 1162 817 767 0.4-0.6 2996 2625 2197 1994 1073 1021 0.6-0.8 3798 3855 3546 3346 1868 1672 0.8-1 1571 2230 3097 3526 3084 2870 1-1.2 1168 1266 1314 1379 3754 3937 1.2-1.4 395 589 896 1035 1504 1752 1.4-1.6 119 169 259 301 1137 1219 > 1.6 30 43 77 104 508 622 Total flood area 11893 12277 12649 12847 13744 13861 Flood area rate 80.8% 83.4% 86.0% 87.3% 93.4% 94.2% Flood area compared to SP 1524 1267 1062 991 680 639 Flood area rate compared to SP 10.4% 8.6% 7.2% 6.7% 4.6% 4.3% Southern Institute of Water resources research 67 Contract No. 7182300 Main report 7.4.4. Vi Thanh City According to the calculation of the flood area of this city, total flood area in the existing situation from 1493 ha to 8721 ha (based on the flood year) accounting from 16.0% to 93.3% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 1493 to 8721 ha, the flood area not change compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 1758 ha to 8837 ha, increasing from 84 ha to 266 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 8555 ha to 9026 ha, increase of from 185 ha to 6796 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 46: Flood area for each scenarios in Vi Thanh city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 1473 2949 1530 816 563 516 0.4-0.6 20 3639 3785 3087 2063 1845 0.6-0.8 0 1219 2697 3549 4134 4054 0.8-1 0 9 301 1112 1917 2306 1-1.2 0 0 0 0 0 0 1.2-1.4 0 0 0 0 0 0 1.4-1.6 0 0 0 0 0 0 > 1.6 0 0 0 0 0 0 Total flood area 1493 7816 8313 8564 8677 8721 Flood area rate 16.0% 83.6% 88.9% 91.6% 92.8% 93.3% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 1473 2949 1530 816 563 516 0.4-0.6 20 3639 3785 3087 2063 1845 0.6-0.8 0 1219 2697 3549 4134 4054 0.8-1 0 9 301 1112 1917 2306 1-1.2 0 0 0 0 0 0 1.2-1.4 0 0 0 0 0 0 1.4-1.6 0 0 0 0 0 0 > 1.6 0 0 0 0 0 0 Total flood area 1493 7816 8313 8564 8677 8721 Flood area rate 16.0% 83.6% 88.9% 91.6% 92.8% 93.3% Flood area compared to BL 0 0 0 0 0 0 Flood area rate compared to BL 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% Southern Institute of Water resources research 68 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 1727 2210 1146 632 484 455 0.4-0.6 32 4098 3482 2377 1642 1325 0.6-0.8 0 1727 3221 4013 3875 3615 0.8-1 0 32 598 1598 2508 3028 1-1.2 0 0 0 23 253 414 1.2-1.4 0 0 0 0 0 0 1.4-1.6 0 0 0 0 0 0 > 1.6 0 0 0 0 0 0 Total flood area 1758 8067 8447 8643 8761 8837 Flood area rate 18.8% 86.3% 90.4% 92.5% 93.7% 94.5% Flood area compared to SU 266 250 134 79 84 116 Flood area rate compared to SU 2.8% 2.7% 1.4% 0.8% 0.9% 1.2% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 807 426 329 259 178 143 0.4-0.6 3087 1228 709 503 438 387 0.6-0.8 3549 3548 2768 1845 1325 986 0.8-1 1112 3137 3750 4054 3615 3347 1-1.2 0 500 1354 2167 3027 3390 1.2-1.4 0 0 12 0 414 771 1.4-1.6 0 0 0 0 0 0 > 1.6 0 0 0 0 0 0 Total flood area 8555 8840 8921 8828 8997 9026 Flood area rate 91.5% 94.6% 95.4% 94.5% 96.3% 96.6% Flood area compared to SP 6796 773 474 185 236 189 Flood area rate compared to SP 72.7% 8.3% 5.1% 2.0% 2.5% 2.0% Southern Institute of Water resources research 69 Contract No. 7182300 Main report 7.4.5. Long Xuyen City According to the calculation of the flood area of this city, total flood area in the existing situation from 8337 ha to 9791 ha (based on the flood year) accounting from 72.9% to 85.6% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 8111 to 9740 ha, reduced from 14 ha to 227 ha compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 8235 ha to 10095 ha, increasing from 124 ha to 355 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 8412 ha to 10465 ha, increase of from 177 ha to 371 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 47: Flood area for each scenarios in Long Xuyen city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 331 334 477 575 699 707 0.4-0.6 160 161 376 419 499 519 0.6-0.8 263 262 190 285 391 398 0.8-1 734 733 220 169 218 241 1-1.2 2945 2946 502 288 205 197 1.2-1.4 2467 2468 2035 952 417 356 1.4-1.6 537 538 3343 3461 1599 1384 > 1.6 900 901 1791 3100 5691 5990 Total flood area 8337 8343 8935 9248 9719 9791 Flood area rate 72.9% 73.0% 78.1% 80.9% 85.0% 85.6% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 207 327 469 548 665 676 0.4-0.6 210 159 372 414 490 506 0.6-0.8 452 260 189 284 387 393 0.8-1 1722 726 220 168 217 240 1-1.2 3569 2916 502 290 205 197 1.2-1.4 898 2443 2035 951 418 356 1.4-1.6 427 532 3343 3460 1599 1384 > 1.6 625 891 1789 3099 5690 5990 Total flood area 8111 8254 8920 9213 9671 9740 Flood area rate 70.9% 72.2% 78.0% 80.6% 84.6% 85.2% Flood area compared to BL -227 -89 -14 -35 -48 -50 Flood area rate compared to BL -2.0% -0.8% -0.1% -0.3% -0.4% -0.4% Southern Institute of Water resources research 70 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 275 382 418 644 705 705 0.4-0.6 177 207 222 469 592 602 0.6-0.8 292 209 228 372 424 432 0.8-1 1034 450 459 189 331 338 1-1.2 3551 1723 1843 221 161 163 1.2-1.4 1654 3571 3885 503 263 254 1.4-1.6 445 898 996 2034 733 688 > 1.6 807 1052 1138 5131 6850 6911 Total flood area 8235 8493 9190 9564 10057 10095 Flood area rate 72.0% 74.3% 80.4% 83.6% 88.0% 88.3% Flood area compared to SU 124 239 269 350 386 355 Flood area rate compared to SU 1.1% 2.1% 2.4% 3.1% 3.4% 3.1% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 359 416 643 688 686 707 0.4-0.6 178 294 468 545 666 687 0.6-0.8 230 164 372 413 504 510 0.8-1 563 284 189 284 393 393 1-1.2 2369 885 221 168 240 239 1.2-1.4 3057 3355 506 301 199 199 1.4-1.6 682 1963 2032 946 368 342 > 1.6 974 1327 5129 6551 7356 7389 Total flood area 8412 8688 9561 9897 10412 10465 Flood area rate 73.6% 76.0% 83.6% 86.6% 91.1% 91.5% Flood area compared to SP 177 195 371 333 355 371 Flood area rate compared to SP 1.6% 1.7% 3.2% 2.9% 3.1% 3.2% Southern Institute of Water resources research 71 Contract No. 7182300 Main report 7.4.6. Tan An City According to the calculation of the flood area of this city, total flood area in the existing situation from 2391 ha to 5027 ha (based on the flood year) accounting from 29.3% to 61.7% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 1480 to 5005 ha, reduced from 22 ha to 911 ha compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 1868 ha to 5455 ha, increasing from 383 ha to 786 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 3320 ha to 6788 ha, increase of from 1332 ha to 2612 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 48: Flood area for each scenarios in Tan An city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 1445 1445 1809 1911 2097 2391 0.4-0.6 497 512 567 707 1056 1562 0.6-0.8 254 284 383 398 527 519 0.8-1 114 148 147 158 170 297 1-1.2 54 71 102 96 142 150 1.2-1.4 13 16 20 39 56 72 1.4-1.6 7 10 12 12 13 16 > 1.6 6 10 12 14 16 21 Total flood area 2391 2496 3051 3335 4078 5027 Flood area rate 29.3% 30.6% 37.4% 40.9% 50.0% 61.7% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 775 1445 1833 1924 2109 2401 0.4-0.6 446 497 581 734 1077 1582 0.6-0.8 135 254 372 399 537 535 0.8-1 65 114 116 129 147 281 1-1.2 39 54 76 67 115 118 1.2-1.4 8 13 16 35 46 59 1.4-1.6 5 7 9 10 10 14 > 1.6 5 6 8 9 12 16 Total flood area 1480 2391 3011 3306 4053 5005 Flood area rate 18.2% 29.3% 36.9% 40.6% 49.7% 61.4% Flood area compared to BL -911 -105 -40 -29 -26 -22 Flood area rate compared to BL -11.2% -1.3% -0.5% -0.4% -0.3% -0.3% Southern Institute of Water resources research 72 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 1052 1724 1980 2129 2374 2350 0.4-0.6 507 532 732 889 1464 1854 0.6-0.8 134 353 428 493 527 620 0.8-1 111 109 131 127 270 397 1-1.2 44 73 69 90 118 121 1.2-1.4 9 15 35 41 57 66 1.4-1.6 5 8 9 9 14 29 > 1.6 5 7 10 12 15 18 Total flood area 1868 2821 3394 3791 4838 5455 Flood area rate 22.9% 34.6% 41.6% 46.5% 59.4% 66.9% Flood area compared to SU 388 430 383 485 786 451 Flood area rate compared to SU 4.8% 5.3% 4.7% 5.9% 9.6% 5.5% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 1965 2339 2070 1249 1024 782 0.4-0.6 699 1833 2165 2378 2288 2045 0.6-0.8 410 555 925 1702 1935 2116 0.8-1 128 361 494 551 731 1013 1-1.2 67 113 110 312 387 518 1.2-1.4 33 74 108 109 127 137 1.4-1.6 7 15 43 73 65 111 > 1.6 10 16 19 29 53 66 Total flood area 3320 5307 5935 6403 6610 6788 Flood area rate 40.7% 65.1% 72.8% 78.6% 81.1% 83.3% Flood area compared to SP 1452 2486 2540 2612 1772 1332 Flood area rate compared to SP 17.8% 30.5% 31.2% 32.0% 21.7% 16.3% Southern Institute of Water resources research 73 Contract No. 7182300 Main report 7.4.7. Soc Trang city According to the calculation of the flood area of this city, total flood area in the existing situation from 5515 ha to 6544 ha (based on the flood year) accounting from 71.9% to 85.3% of total natural area, these flood areas are mainly in the low land, agricultural production. With SUUP, total flood area from 5061 to 6525 ha, reduced from 16 ha to 454 ha compared with the existing situation. When considering planed urban to 2025, total flood area of the city from 5140 ha to 6607 ha, increasing from 75 ha to 148 ha compared with the With SUUP. When considering climate change, total flooded area of the city from 6033 ha to 7170 ha, increase of from 563 ha to 893 ha compared with planed urban to 2025. Summarize the flooded area of the scenarios in the following table: Table 49: Flood area for each scenarios in Soc Trang city Water Depth BL1 BL2 BL3 BL4 BL5 BL6 0.2-0.4 1117 1172 932 867 852 697 0.4-0.6 2951 2994 2646 1692 1566 969 0.6-0.8 1069 1073 1845 2856 2960 2827 0.8-1 279 289 384 565 630 1594 1-1.2 71 72 86 228 237 339 1.2-1.4 10 10 23 45 50 86 1.4-1.6 4 4 5 7 8 15 > 1.6 13 13 14 16 17 19 Total flood area 5515 5627 5936 6277 6319 6544 Flood area rate 71.9% 73.3% 77.3% 81.8% 82.3% 85.3% Water Depth SU1 SU2 SU3 SU4 SU5 SU6 0.2-0.4 2242 1117 937 857 861 703 0.4-0.6 2229 2951 2594 1668 1551 971 0.6-0.8 404 1069 1844 2846 2952 2804 0.8-1 133 279 379 565 630 1592 1-1.2 32 71 82 222 238 340 1.2-1.4 6 10 23 44 47 84 1.4-1.6 4 4 5 7 8 13 > 1.6 12 13 14 16 17 19 Total flood area 5061 5515 5879 6226 6303 6525 Flood area rate 65.9% 71.9% 76.6% 81.1% 82.1% 85.0% Flood area compared to BL -454 -112 -57 -51 -16 -19 Flood area rate compared to BL -5.9% -1.5% -0.7% -0.7% -0.2% -0.2% Southern Institute of Water resources research 74 Contract No. 7182300 Main report Water Depth SP1 SP2 SP3 SP4 SP5 SP6 0.2-0.4 2037 954 909 840 811 616 0.4-0.6 2453 2824 2528 1320 1228 912 0.6-0.8 431 1460 1974 3048 3040 2516 0.8-1 161 314 405 824 953 2015 1-1.2 35 80 92 248 281 402 1.2-1.4 7 12 25 61 70 101 1.4-1.6 4 4 5 9 9 25 > 1.6 12 14 15 17 17 20 Total flood area 5140 5663 5954 6366 6410 6607 Flood area rate 67.0% 73.8% 77.6% 82.9% 83.5% 86.1% Flood area compared to SU 79 148 75 140 106 82 Flood area rate compared to SU 1.0% 1.9% 1.0% 1.8% 1.4% 1.1% Water Depth CC1 CC2 CC3 CC4 CC5 CC6 0.2-0.4 915 764 591 438 380 377 0.4-0.6 2140 1060 906 697 505 501 0.6-0.8 2355 2883 2301 970 870 859 0.8-1 430 1343 2237 2813 1666 1664 1-1.2 139 309 416 1596 2879 2900 1.2-1.4 34 77 134 337 564 567 1.4-1.6 6 12 32 89 230 231 > 1.6 15 18 21 32 68 71 Total flood area 6033 6466 6637 6971 7161 7170 Flood area rate 78.6% 84.3% 86.5% 90.8% 93.3% 93.4% Flood area compared to SP 893 803 682 605 751 563 Flood area rate compared to SP 11.6% 10.5% 8.9% 7.9% 9.8% 7.3% Analytical assessments of future conditions see Section 8 7.5. Conclusions In general, aside from Vi Thanh which is high ground level, canal restoration and proposed supplement structures contribute positively in flooding prevention effort for both current conditions and climate change impact. However, effective intervention area is very small when compare to the total area of cities. Flooding reduction in city scale is relative small, especially when including climate change impact. Therefore, it is required integrated counter- measures to be able to reduce flooding area in larger scale. Southern Institute of Water resources research 75 Contract No. 7182300 Main report Table 50: Flood area for each scenarios of the current investments in 07 cities Scenarios City BL1 BL2 BL3 BL4 BL5 BL6 Ben Tre 87.98 100.21 113.65 132.52 141.52 151.33 Vinh Long 14.56 16.70 19.72 41.60 63.12 81.19 Existing situation Bac Lieu 426.00 480.98 530.04 590.41 644.23 689.38 WITHOUT Vi Thanh 12.63 32.14 49.50 65.03 79.54 88.55 SUUP Long Xuyen 105.88 114.72 136.47 164.15 197.90 204.56 interventions Tan An 132.74 135.88 139.36 142.48 145.52 147.86 Soc Trang 29.98 49.16 141.51 165.33 177.09 190.85 Scenarios City SU1 SU2 SU3 SU4 SU5 SU6 Ben Tre 0.37 1.33 7.38 7.73 13.56 25.84 Vinh Long 9.65 10.88 13.50 33.72 53.60 69.99 Existing Bac Lieu 188.11 255.75 304.97 372.44 413.16 455.53 situation Vi Thanh 12.63 32.14 49.50 65.03 79.54 88.55 WITH SUUP interventions Long Xuyen 48.95 67.59 83.99 109.10 132.42 143.81 Tan An 17.77 30.38 74.60 90.50 100.10 110.20 Soc Trang 9.06 18.59 82.33 108.11 127.85 141.91 Scenarios City CC1 CC2 CC3 CC4 CC5 CC6 Ben Tre 41.17 47.77 57.52 67.12 74.54 85.59 Vinh Long 12.38 15.01 18.22 41.67 65.20 85.02 Planed urban Bac Lieu 304.05 365.36 414.50 478.43 525.69 569.45 (2025) WITH Vi Thanh 56.22 121.97 146.81 161.31 169.64 179.71 SUUP and CC in 2050 Long Xuyen 111.60 116.76 137.71 148.73 175.18 201.52 Tan An 48.76 59.48 95.55 108.89 117.18 125.73 Soc Trang 15.10 26.93 99.62 124.61 142.01 155.81 Table 51: Flood area for each scenarios in 07 cities Scenarios City BL1 BL2 BL3 BL4 BL5 BL6 Ben Tre 1615 2265 2523 3058 3379 3750 Vinh Long 2057 2278 2427 2586 2747 2867 Existing situation Bac Lieu 10226 10938 11563 11846 13095 13266 WITHOUT Vi Thanh 1493 7816 8313 8564 8677 8721 SUUP Long Xuyen 8337 8343 8935 9248 9719 9791 interventions Tan An 2391 2496 3051 3335 4078 5027 Soc Trang 5515 5627 5936 6277 6319 6544 Scenarios City SU1 SU2 SU3 SU4 SU5 SU6 Ben Tre 1527 2166 2417 2933 3251 3625 Existing Vinh Long 2052 2272 2422 2578 2738 2854 situation WITH SUUP Bac Lieu 9987 10712 11337 11626 12861 13029 interventions Vi Thanh 1493 7816 8313 8564 8677 8721 Long Xuyen 8111 8254 8920 9213 9671 9740 Southern Institute of Water resources research 76 Contract No. 7182300 Main report Tan An 1480 2391 3011 3306 4053 5005 Soc Trang 5061 5515 5879 6226 6303 6525 Scenarios City SP1 SP2 SP3 SP4 SP5 SP6 Ben Tre 1751 2507 2791 3382 3763 4070 Vinh Long 2207 2360 2553 2741 2885 2996 Planed urban Bac Lieu 10369 11011 11587 11856 13063 13222 (2025) WITH Vi Thanh 1758 8067 8447 8643 8761 8837 SUUP Long Xuyen 8235 8493 9190 9564 10057 10095 Tan An 1868 2821 3394 3791 4838 5455 Soc Trang 5140 5663 5954 6366 6410 6607 Scenarios City CC1 CC2 CC3 CC4 CC5 CC6 Ben Tre 3666 3684 4424 5232 5471 5647 Vinh Long 2607 2912 3115 3115 3459 3500 Planed urban Bac Lieu 11893 12277 12649 12847 13744 13861 (2025) WITH Vi Thanh 8555 8840 8921 8828 8997 9026 SUUP and CC in 2050 Long Xuyen 8412 8688 9561 9897 10412 10465 Tan An 3320 5307 5935 6403 6610 6788 Soc Trang 6033 6466 6637 6971 7161 7170 Southern Institute of Water resources research 77 Contract No. 7182300 Main report 8. LONG-TERM VISION 8.1. Urbanization impact According to land use planning up to 2025, most of the seven cities would witness significant change in surface classification. Low lying areas which currently play as storage for rain water, will be occupied by constructions. As the result, water storage will depend vastly on area of channels. Water discharge on those channels would increase correspondingly. Fully aware of this matter, we have already covered surface in our simulation. 8.2. Climate change impact By applying climate change scenario for 2050, water level on canals and channels could rise up by 12-35cm which drag down drainage capacity. Therefore, adaptation measures for each of every building would need: (i) Keeping aligned with integrated measures for whole Mekong delta which could dramatically impact on water level at canals; (ii) Keeping aligned with integrated measures for whole city; (iii) Supplement pumps at canal outlets if necessary; (iv) Ground elevation upgrading might be tricky for areas with complete construction, though it should be considered with other situations. Table 52: Maximum water level on channels in cases of current conditions, land use planning and CC 2050 City Canal SU3 SP3 CC3 SP3-SU3 CC3-SP3 Chin Te canal 0.92 1.39 1.63 0.47 0.24 Ben Tre 30-4 canal 0.64 1.40 1.64 0.76 0.24 Tan Binh secondary branch 1 0.90 1.39 1.43 0.49 0.04 Tan Binh secondary branch 2 0.90 1.39 1.43 0.49 0.04 Ong Dia canal 1.37 1.39 1.45 0.02 0.05 Cau Lo river secondary branch 1 0.99 1.37 1.41 0.38 0.04 Cau Lo river secondary branch 2 0.99 1.37 1.41 0.38 0.04 Ngo Quyen Canal 1.35 1.39 1.50 0.03 0.11 Sau Van secondary branch 1 1.22 1.38 1.40 0.15 0.03 Sau Van secondary branch 2 1.22 1.38 1.40 0.15 0.03 Kinh Cut secondary branch 1 1.31 1.37 1.42 0.07 0.04 Kinh Cut secondary branch 2 1.31 1.37 1.42 0.07 0.04 Sau Van secondary branch 1 1.22 1.38 1.37 0.15 0.00 Sau Van secondary branch 2+ Kinh Cut secondary branch 3 1.31 1.37 1.42 0.07 0.04 Kinh Cut river renovation 1.62 1.67 1.88 0.05 0.21 Vinh Long Cau Lau river renovation 1.63 1.68 1.88 0.05 0.21 Kenh Xang Canal 1.50 1.53 1.82 0.03 0.29 Bac Lieu LIA 6 1.50 1.53 1.83 0.03 0.31 Thong Nhat 1 canal 0.92 0.96 1.16 0.04 0.20 Thong Nhat 2 canal 0.92 0.96 1.16 0.04 0.20 Thong Nhat 3 canal 0.32 0.34 0.47 0.01 0.13 Vi Thanh Thong Nhat 4 canal 0.32 0.34 0.47 0.01 0.13 Cai Nhuc Nho canal 0.92 0.96 1.16 0.04 0.20 Phan Lo canal 0.92 0.96 1.16 0.04 0.20 Southern Institute of Water resources research 78 Contract No. 7182300 Main report City Canal SU3 SP3 CC3 SP3-SU3 CC3-SP3 Lo 2 canal 0.92 0.96 1.16 0.04 0.20 Canal 1 0.92 0.96 1.16 0.04 0.20 Canal 2 0.92 0.96 1.16 0.04 0.20 Canal 3 0.92 0.96 1.16 0.04 0.20 Cai Nhuc canal renovation 0.92 0.96 1.16 0.04 0.20 Canal 62 renovation 0.32 0.34 0.47 0.01 0.13 Ong Manh canal 2.45 2.54 2.65 0.10 0.10 Long Ba Bau canal 1.98 2.04 2.12 0.06 0.08 Xuyen Cai Son canal 2.43 2.53 2.63 0.10 0.10 Cau Tre canal 1.34 1.39 1.53 0.05 0.14 Tan An Rach Rot Canal 1.28 1.35 1.48 0.06 0.13 Tra Men canal 1.19 1.23 1.53 0.04 0.30 Soc Trang Hitech canal 1.01 1.15 1.35 0.14 0.21 Water level calculation and flooding area refer to Appendix E -Maximum water level simulation results and 0 Southern Institute of Water resources research 79 Contract No. 7182300 Main report 5 year flood + 5 year rainfall City Canal BL2 SU2 SP2 CC2 Chin Te canal 1.84 0.59 1.30 1.53 Ben Tre 30/4 canal 1.87 0.35 1.32 1.55 Tan Binh secondary branch 1 1.89 0.57 1.05 1.32 Tan Binh secondary branch 2 1.89 0.57 1.05 1.32 Ong Dia canal 1.90 1.15 1.17 1.36 Song Cau Lo 1 canal 1.87 0.66 1.03 1.30 Song Cau Lo 2 canal 1.87 0.66 1.03 1.30 Ngo Quyen canal 1.88 1.14 1.17 1.40 Sau Van 1 canal 1.89 0.85 1.00 1.28 Vinh Long Sau Van 2 canal 1.89 0.85 1.00 1.28 Kinh Cut secondary branch 1 1.88 0.96 1.02 1.29 Kinh Cut secondary branch 2 1.88 0.96 1.02 1.29 Sau Van secondary branch 1 1.89 0.85 1.00 1.25 Sau Van secondary branch 2 1.88 0.96 1.02 1.29 Kinh Cut river 1.86 1.86 1.92 2.10 Cau Lau river 1.87 1.87 1.92 2.10 Kenh Xang canal 1.76 1.26 1.32 1.43 Bac Lieu LIA 6 canal 1.76 1.26 1.28 1.40 Thong Nhat 1 canal 0.71 0.71 0.73 0.91 Thong Nhat 2 canal 0.71 0.71 0.73 0.91 Thong Nhat 3 canal 0.16 0.16 0.17 0.28 Thong Nhat 4 canal 0.16 0.16 0.17 0.28 Cai Nhuc Nho canal 0.71 0.71 0.73 0.91 Phan Lo canal 0.71 0.71 0.73 0.91 Vi Thanh Lo 2 canal 0.71 0.71 0.73 0.91 Canal 1 0.71 0.71 0.73 0.91 Canal 2 0.71 0.71 0.73 0.91 Canal 3 0.71 0.71 0.73 0.91 Cai Nhuc canal 0.71 0.71 0.73 0.91 Canal 62 0.16 0.16 0.17 0.28 Ong Manh canal 2.50 2.34 2.36 2.46 Long Ba Bau canal 2.56 2.16 2.21 2.30 Xuyen Cai Son canal 2.32 2.32 2.34 2.43 Cau Tre canal 1.70 1.10 1.14 1.26 Tan An Rot canal 1.76 0.76 0.80 0.88 Tra Men canal 1.84 1.05 1.08 1.34 Soc Trang Hitech canal 1.74 1.18 1.23 1.46 Southern Institute of Water resources research 80 Contract No. 7182300 Main report 10 year flood + 10 year rainfall City Canal BL3 SU3 SP3 CC3 Chin Te canal 1.89 0.92 1.39 1.63 Ben Tre 30/4 canal 1.92 0.64 1.40 1.64 Tan Binh secondary branch 1 1.96 0.90 1.39 1.43 Tan Binh secondary branch 2 1.96 0.90 1.39 1.43 Ong Dia canal 1.97 1.37 1.39 1.45 Song Cau Lo 1 canal 1.93 0.99 1.37 1.41 Song Cau Lo 2 canal 1.93 0.99 1.37 1.41 Ngo Quyen canal 1.94 1.35 1.39 1.50 Sau Van 1 canal 1.97 1.22 1.38 1.40 Vinh Long Sau Van 2 canal 1.97 1.22 1.38 1.40 Kinh Cut secondary branch 1 1.95 1.31 1.37 1.42 Kinh Cut secondary branch 2 1.95 1.31 1.37 1.42 Sau Van secondary branch 1 1.97 1.22 1.38 1.37 Sau Van secondary branch 2 1.95 1.31 1.37 1.42 Kinh Cut river 1.93 1.93 1.99 2.17 Cau Lau river 1.94 1.94 2.00 2.18 Kenh Xang canal 1.86 1.34 1.40 1.51 Bac Lieu LIA 6 canal 1.86 1.34 1.36 1.47 Thong Nhat 1 canal 0.83 0.83 0.87 1.05 Thong Nhat 2 canal 0.83 0.83 0.87 1.05 Thong Nhat 3 canal 0.32 0.32 0.34 0.47 Thong Nhat 4 canal 0.32 0.32 0.34 0.47 Cai Nhuc Nho canal 0.83 0.83 0.87 1.05 Phan Lo canal 0.83 0.83 0.87 1.05 Vi Thanh Lo 2 canal 0.83 0.83 0.87 1.05 Canal 1 0.83 0.83 0.87 1.05 Canal 2 0.83 0.83 0.87 1.05 Canal 3 0.83 0.83 0.87 1.05 Cai Nhuc canal 0.83 0.83 0.87 1.05 Canal 62 0.32 0.32 0.34 0.47 Ong Manh canal 2.83 2.66 2.68 2.79 Long Ba Bau canal 2.90 2.50 2.56 2.66 Xuyen Cai Son canal 2.63 2.63 2.66 2.76 Cau Tre canal 1.76 1.34 1.39 1.53 Tan An Rot canal 1.82 1.28 1.35 1.48 Tra Men canal 1.90 1.19 1.23 1.53 Soc Trang Hitech canal 1.77 1.25 1.31 1.55 Southern Institute of Water resources research 81 Contract No. 7182300 Main report 25 year flood +25 year rainfall City Canal BL4 SU4 SP4 CC4 Chin Te canal 1.97 0.93 1.50 1.75 Ben Tre 30/4 canal 2.00 0.66 1.52 1.77 Tan Binh secondary branch 1 2.02 0.96 1.45 1.56 Tan Binh secondary branch 2 2.02 0.96 1.45 1.56 Ong Dia canal 2.05 1.45 1.46 1.55 Song Cau Lo 1 canal 2.00 1.06 1.43 1.54 Song Cau Lo 2 canal 2.00 1.06 1.43 1.54 Ngo Quyen canal 2.01 1.43 1.46 1.62 Sau Van 1 canal 2.03 1.30 1.45 1.53 Vinh Long Sau Van 2 canal 2.03 1.30 1.45 1.53 Kinh Cut secondary branch 1 2.02 1.39 1.44 1.56 Kinh Cut secondary branch 2 2.02 1.39 1.44 1.56 Sau Van secondary branch 1 2.03 1.30 1.45 1.50 Sau Van secondary branch 2 2.02 1.39 1.44 1.56 Kinh Cut river 1.98 1.98 2.04 2.22 Cau Lau river 1.98 1.98 2.04 2.22 Kenh Xang canal 2.06 1.50 1.57 1.67 Bac Lieu LIA 6 canal 2.06 1.50 1.53 1.63 Thong Nhat 1 canal 0.87 0.87 0.91 1.10 Thong Nhat 2 canal 0.87 0.87 0.91 1.10 Thong Nhat 3 canal 0.36 0.36 0.37 0.51 Thong Nhat 4 canal 0.36 0.36 0.37 0.51 Cai Nhuc Nho canal 0.87 0.87 0.91 1.10 Phan Lo canal 0.87 0.87 0.91 1.10 Vi Thanh Lo 2 canal 0.87 0.87 0.91 1.10 Canal 1 0.87 0.87 0.91 1.10 Canal 2 0.87 0.87 0.91 1.10 Canal 3 0.87 0.87 0.91 1.10 Cai Nhuc canal 0.87 0.87 0.91 1.10 Canal 62 0.36 0.36 0.37 0.51 Ong Manh canal 2.92 2.75 2.77 2.88 Long Ba Bau canal 2.99 2.61 2.67 2.78 Xuyen Cai Son canal 2.72 2.72 2.75 2.86 Cau Tre canal 1.81 1.45 1.50 1.65 Tan An Rot canal 1.86 1.40 1.47 1.61 Tra Men canal 1.93 1.32 1.40 1.74 Soc Trang Hitech canal 1.79 1.30 1.36 1.61 Southern Institute of Water resources research 82 Contract No. 7182300 Main report 50 year flood + 50 year rainfall City Canal BL5 SU5 SP5 CC5 Chin Te canal 2.01 0.97 1.61 1.87 Ben Tre 30/4 canal 2.06 0.69 1.63 1.89 Tan Binh secondary branch 1 2.07 1.01 1.52 1.64 Tan Binh secondary branch 2 2.07 1.01 1.52 1.64 Ong Dia canal 2.15 1.50 1.53 1.61 Song Cau Lo 1 canal 2.05 1.11 1.50 1.63 Song Cau Lo 2 canal 2.05 1.11 1.50 1.63 Ngo Quyen canal 2.06 1.50 1.53 1.70 Sau Van 1 canal 2.08 1.37 1.52 1.63 Vinh Long Sau Van 2 canal 2.08 1.37 1.52 1.63 Kinh Cut secondary branch 1 2.07 1.47 1.51 1.66 Kinh Cut secondary branch 2 2.07 1.47 1.51 1.66 Sau Van secondary branch 1 2.08 1.37 1.52 1.60 Sau Van secondary branch 2 2.07 1.47 1.51 1.66 Kinh Cut river 2.03 2.03 2.09 2.27 Cau Lau river 2.03 2.03 2.09 2.27 Kenh Xang canal 2.20 1.61 1.69 1.78 Bac Lieu LIA 6 canal 2.20 1.61 1.64 1.74 Thong Nhat 1 canal 0.91 0.91 0.95 1.14 Thong Nhat 2 canal 0.91 0.91 0.95 1.14 Thong Nhat 3 canal 0.40 0.40 0.41 0.55 Thong Nhat 4 canal 0.40 0.40 0.41 0.55 Cai Nhuc Nho canal 0.91 0.91 0.95 1.14 Phan Lo canal 0.91 0.91 0.95 1.14 Vi Thanh Lo 2 canal 0.91 0.91 0.95 1.14 Canal 1 0.91 0.91 0.95 1.14 Canal 2 0.91 0.91 0.95 1.14 Canal 3 0.91 0.91 0.95 1.14 Cai Nhuc canal 0.91 0.91 0.95 1.14 Canal 62 0.40 0.40 0.41 0.55 Ong Manh canal 3.03 2.85 2.87 2.99 Long Ba Bau canal 3.10 2.73 2.79 2.90 Xuyen Cai Son canal 2.82 2.82 2.85 2.96 Cau Tre canal 1.87 1.51 1.57 1.73 Tan An Rot canal 1.89 1.48 1.55 1.70 Tra Men canal 1.97 1.41 1.50 1.86 Soc Trang Hitech canal 1.81 1.34 1.41 1.66 Southern Institute of Water resources research 83 Contract No. 7182300 Main report 100 year flood + 100 year rainfall City Canal BL6 SU6 SP6 CC6 Chin Te canal 2.06 1.03 1.68 1.95 Ben Tre 30/4 canal 2.10 0.76 1.71 1.98 Tan Binh secondary branch 1 2.11 1.05 1.59 1.72 Tan Binh secondary branch 2 2.10 1.05 1.59 1.72 Ong Dia canal 2.20 1.56 1.60 1.68 Song Cau Lo 1 canal 2.08 1.17 1.58 1.71 Song Cau Lo 2 canal 2.08 1.17 1.58 1.71 Ngo Quyen canal 2.09 1.56 1.60 1.77 Sau Van 1 canal 2.11 1.44 1.58 1.71 Vinh Long Sau Van 2 canal 2.11 1.44 1.58 1.71 Kinh Cut secondary branch 1 2.10 1.54 1.56 1.76 Kinh Cut secondary branch 2 2.10 1.54 1.56 1.76 Sau Van secondary branch 1 2.11 1.44 1.58 1.68 Sau Van secondary branch 2 2.10 1.54 1.56 1.76 Kinh Cut river 2.05 2.05 2.11 2.29 Cau Lau river 2.05 2.05 2.11 2.29 Kenh Xang canal 2.31 1.70 1.78 1.87 Bac Lieu LIA 6 canal 2.31 1.70 1.73 1.82 Thong Nhat 1 canal 0.94 0.94 0.98 1.18 Thong Nhat 2 canal 0.94 0.94 0.98 1.18 Thong Nhat 3 canal 0.43 0.43 0.45 0.59 Thong Nhat 4 canal 0.43 0.43 0.45 0.59 Cai Nhuc Nho canal 0.94 0.94 0.98 1.18 Phan Lo canal 0.94 0.94 0.98 1.18 Vi Thanh Lo 2 canal 0.94 0.94 0.98 1.18 Canal 1 0.94 0.94 0.98 1.18 Canal 2 0.94 0.94 0.98 1.18 Canal 3 0.94 0.94 0.98 1.18 Cai Nhuc canal 0.94 0.94 0.98 1.18 Canal 62 0.43 0.43 0.45 0.59 Ong Manh canal 3.10 2.92 2.94 3.06 Long Ba Bau canal 3.17 2.82 2.88 3.00 Xuyen Cai Son canal 2.89 2.89 2.92 3.03 Cau Tre canal 1.92 1.57 1.68 1.85 Tan An Rot canal 1.93 1.55 1.63 1.79 Tra Men canal 2.00 1.48 1.59 1.97 Soc Trang Hitech canal 1.82 1.42 1.50 1.76 Southern Institute of Water resources research 84 Contract No. 7182300 Main report Maximum flooding area simulation results. Specific condition and recommend for each of seven city: 8.2.1. Ben Tre City According to Bac Ben Tre project information, Ben Tre province would construct Ben Tre culvert for salinity control in support for Bai Lai project. However, Ben Tre city located outside of regulated region. Therefore, these construction would not contribute to flooding control effort for Ben Tre city. Figure 59: Salinity control gate proposed in Bac Ben Tre project According to water resources planning in Ben Tre province, there will be several controlling gates constructed. However, this planning is still in preliminary study stage but not yet officially confirmed. Figure 60: Locations of water resourses controlling gates proposed in Ben Tre It could be appropriate to assume that those proposed water resources controlling gates which are located along side of Ben Tre River and Ham Luong River, flooding condition in urban Southern Institute of Water resources research 85 Contract No. 7182300 Main report area would be better controlled. However, if this is not the case, then adaptation measures for climate change could consist of: (i) Supplement pumping stations: two pumping stations should be constructed at the end of Chin Te Canal and 30-4 Canal. (ii) Expand free space for water storage at two basins of Chin Te Canal and 30-4 Canal. Table 53: Adaptation for climate change up to 2050 Canal Pumping station Water storage space 3 Chin Te Canal 0.8 m /s at outlet into Ca Loc Construct reservoir with capacity of 1194 m2 30-4 Canal 0.5 m3/s at outlet into Cai Ca Construct reservoir with capacity of 823 m2 8.2.2. Vinh Long City According Vinh Long city flooding prevent planning to 2020, this city will construct a system of infrastructures in effort of protecting the urban area from flooding. Proposed constructions consist of: 19 sluices; dikes system work double as flood prevent and urban scenery enhancement; primary canals restoration (Cai Doi, Cai Da, Chua, Nha Dai, Tham, Ba Dieu, Duong Chua, Nga Tac, Dia Chuoi, Ong Me Lon, Cai Son and Tieu Nuoc); 74km of dike-road route; 8 pumping stations in total of 226,800 m3/hrs; and upgrade current dike system, canals; utilize low land, river, channels as rain water storages. By adapting all of proposed measures, flooding in Vinh Long will obviously be very well controlled. Otherwise, water level within LIA does not exceed (+1.46m) either which is quite safe in term of flooding control. Even when consider effect of climate change, there is no addition actions required for LIA region. On the other hand, water level on Kenh Cut and Cau Lau Canals could reach to (+1.99m) if consider climate change impact. This relatively high water level could block water from escape through sluice. Only when proposed measures are constructed, then water level on these could be reduce to safe value. Figure 61: Proposed control infrastructures in Vinh Long City Southern Institute of Water resources research 86 Contract No. 7182300 Main report 8.2.3. Bac Lieu City River network in Bac Lieu closely connected to East Sea. Therefore, climate change would present it impact on this city hydrological regime directly and immediately. Water level with climate change effect as we estimated will be (+2.00m) which will endanger the whole city. A flooding prevention planning is under study but rather officially approved. Storage capacity in channels is sufficient due wide canals. In additionally, MARD is investing on a flooding prevention project for Bac Lieu. This project will construct series of control gates along coast line; while there will be two flood gates located on Ca Mau-Bac Lieu canal in effort to completely control flooding condition. As the result, it is not necessary to supplement any other measures rather than restore two sluices Kenh Xang and Tra Kha. Figure 62: Locations of control gate proposed for Bac Lieu 8.2.4. Vi Thanh City Water level in Vi Thanh City is relatively low in comparing to ground level which is mostly affected by upstream floods. For those canals are regulated by flood gates, water level hardly surpass (+0.47m). While those canals are free flowing, even in case of climate change water level will reach (+1.60m) which is still lower than ground level. There is no need for expand channels width for that reason. 8.2.5. Long Xuyen City Water level in Long Xuyen is dominated strongly by upstream flood. In our simulation scenario of [10% flood + climate change], water level on Ong Manh and Cai Son reach to (+2.79m). While on Ba Ba Canal which is regulated, water level is lower at (+2.66m). So at the average of (+3.00m), Long Xuyen will stand strong versus climate change. However, for those big floods (lower than 10% possibility), it is recommended to construct control gates along Hau river bank to safely protect the city in particular and the whole West Hau River region in general. Southern Institute of Water resources research 87 Contract No. 7182300 Main report Fortunately, MARD is planning to carry out flooding prevention project for this city. From which, equip for city series of control gate to protect 29 urban polders. Furthermore, two pumping stations will also be fitted at end points of Ong Manh and Cai Son Canal. SUUP interventions has shown very appropriate for long-term planning in this city. Figure 63: Locations of flooding control gate in Long Xuyen city 8.2.6. Tan An City Tan An City has already protected under a system of salinity control system. Water level inside is normally lower than on the main river. Even when frequently heavy rain due to climate change, this city is still in its safe zone. Our simulations have shown that in case of climate change, water level on Cau Tre Canal could reach to (+1.53m) increase by 14cm, while in Rach Rot it will climb up to (+1.48m). Those levels are still lower than average ground level which is (+2.0m) 8.2.7. Soc Trang city In case of climate change, water level on Hitech canal will be (+1.55m) and on Tra Men will be (+1.53m). Current ground level of this city is (+1.80m) might not be an ideal threshold. Fortunately for Soc Trang, MARD’s ongoing flood prevent project will separate the city center from the agricultural regions in order to protect the city. By utilizing Boundary route 2, QL60 and Route 933, in combination with flooding control infrastructures, MARD expect to Southern Institute of Water resources research 88 Contract No. 7182300 Main report completely isolate the urban area from outside flood. This project will also provide both solutions of pumping and water storages to reduce water level. This plan match perfectly with what SUUP intervention. Figure 64: Proposed controlling gates for Soc Trang City 9. CONCLUSION AND RECOMMENDATION 9.1. Conclusion A massive yet very detail numerical hydraulic model has been utilized for this assignment. Channels network cover the whole Downstream Mekong Delta (DMD), from Kratie- Cambodia reach to river mouths. This could be only possible since SIWRR is leading hydraulic scientific institute in DMD region throughout over 40 years. While adapting our existing model, we also update input data e.g. recently survey channel profiles in all of seven cities (Long Xuyen, Vinh Long, Tan An, Ben Tre, Soc Trang, Bac Lieu and Vi Thanh). This newly updated model has been carefully calibrated multiple times with long-term measurement records to ensure for its capability. Southern Institute of Water resources research 89 Contract No. 7182300 Main report Hydrological data are collected from national stations which has been in service for over 22 years. They are fully capable for our statistical analysis while constructing simulation scenarios. On the other hand, rainfall of 15 minutes interval records are also provided from 20 meteo-stations evenly located over Mekong Delta region. They are used to represent for the both of whole region precipitation and local rainfall in each of seven cities. This hydraulic model has been used to simulate in different conditions of existing land use, future land use and climate change projections up to 2050. In regard to climate change projection, RPC4.5 has been adapted for this assignment as it is the most realistic scenario according to MONRE recommendation [MONRE, 2016]. Hydrological boundaries were defined according to TOR and updated correspondingly to experts and cities’ authorities feedbacks. River discharge of year 2000 has been chosen as the framework to further develop other scenarios which are return period of 2, 5, 10, 25, 50, 100 years. Each of seven cities will be compared in case of with and without SUUP interventions; current and future land use master plans; and climate change impact projection for 2050. Flood maps for all of scenarios in each of seven cities have also been created base on high resolution DEM [MONRE, 2012]. These maps would be transferred to local administration as scientific reference for their future planning studies. By looking at the differences between scenarios, SUUP interventions have been evaluated for medium to long term development. Many of improvements have been found base on our results. Proposed structural solutions of the FS consultants have been recommended as below: - Ben Tre City: Chin Te canal is recommended to be renovated at least 4m wide, (- 1.0m) bottom level. Both ends of this canal should be controlled by tidal gates to prevent high tide and preserver water when need. Renovate 30/4 canal to at least 3m wide, (+0.5m) bottom level. Though extend renovation might be needed to smoothly connect 30/4 canal and Cai Ca Canal. In regard to climate change, pumping stations would be required, 0.8m3/s on Chin Te Canal and 0.5m3/s on 30/4 Canal. - Vinh Long City: it is recommended to renovate to at least 20m wide on Kenh Cut Canal and 15m wide on Cau Lau Canal, (-2.0m) bottom level for both. For those canals located within LIA regions, it is required to dredging to level of (-1.0m) beside of implement tidal control gates at each canal inlet. According to flooding master plan of Vinh Long City, until 2020, there will be 19 gates, pumping stations and flood dikes would be constructed. Those measures allow to maintain water level at safe threshold even in climate change impact. - Bac Lieu City: It is recommended to restore Kenh Xang Canal to at least 10m wide, (- 1.0m) bottom level while upgrading closure gates. For those canals in LIA 6, they should be at least 6m wide, (-1.0m) bottom level. While the city has large free surface, MARD has already approved for execution of flooding prevention project in Bac Lieu which consist of new construction of tidal gates in coastal and on CaMau-BacLieu Southern Institute of Water resources research 90 Contract No. 7182300 Main report Canal, Bac Lieu City would be safe even in situation of climate change. Therefore, during this stage, renovation canals and upgrading gates for Kenh Xang and Tra Kha would be sufficient. - Vi Thanh City: Thanks to its large canals, water discharge has not been a problem in Vi Thanh. We only recommend to dredge 10 LIA’s canals to level of ( -1.0m). Cai Nhuc and 62 canal should be dredged to (-2.0m). Even in case of climate change projected for 2050, water level might reach to (+1.16m) which still lower than city average ground elevation. - Long Xuyen City: Ong Manh Canal need to be restored to at least 8m wide, (-0.5m) bottom level; upgrade connection culvert to improve discharge capacity. Ba Bau canal should be at least 6m wide, (-0.5m) bottom level, upgrade existing culvert for higher capacity. Cai Son Canal should be at least 15m wide, (-0.5m) bottom level. On the other hand, MARD has already agreed to improve this city flooding prevention in vision of climate change with system of dikes, tidal gates and pumping stations. SUUP activities have been shown to be greatly suitable for this city long term development. - Tan An City: it is recommended to improve Cau Tre Canal to at least 8m wide, (- 1.5m) bottom level, remove existing culvert at its outlet to improve discharge capacity to Bao Dinh water resources network. Rach Rot canal should be at least 8m wide, (- 1.5m) bottom level; upgrade existing tidal gate with 3.0, width, (-1.0m) bottom level. In case of climate change, water level on Cau Tre and Rot Canals would reach to (+1.48m) and (+1.53m) respectively. Those water levels are still lower than city average elevation which is (+2.0m). - Soc Trang City: we propose to restore Tra Men Canal to at least 8.0m wide, (+1.0m) bottom level, upgrade culvert at outlet to Maspero river to (4xD1000), and construction new (2xD1000) with control gates at outlet to 30/4 canals. Hitech canal should be at least 12m wide, (-1.0m) bottom level. In MARD project of flooding planning for this city, Vanh Dai 2 route and route 60 would be used to divide urban and rural areas in order to apply appropriate flooding measures. In addition, pumping stations and reservoirs would also be constructed. SUUP activities are perfectly match with this city overall flooding prevention planning. Our calculations have shown that, local flooding reduction is very efficient. In Ben Tre, average flooding reduction is 92.3%; in Vinh Long, average reduction percentage is 19.2%; while it is 40.8% in Bac Lieu; 36.6% in Long Xuyen, 49.8% in Tan An; 35.3% in Soc Trang On the other hand, flooding reduction area in Vi Thanh does not change due to high ground level. The reduction remain significant even is case of climate change impact. According to hydraulic model has been developed for the area and scenario calculation, flood maps of 7 cities are established nad tranferred to the cities for future research, management Southern Institute of Water resources research 91 Contract No. 7182300 Main report and exploitation. In general, canal renovation projects are in line with present needs as well as future plannings, especially flooding control projects mentioned in the report. In the course of the project, SIWRR works closely with the design consultant teams to collect documents and recommendations on canal and other hydraulic structures dimensions. Input data as well as calculation results are regularly updated, exchanged, verified and compared among consultants. This has not only helped to speed up the implementation but also improve the quality of the consulting product. These results have been discussed and reported to local authorities, provincial departments, experts in the field of hydraulic modeling as well as WB experts to consultation. In particular, the results were presented for local comments in August 2017 prior to final edits. In general, the project results have been agreed by the design consultants, and local departments in accordance with the conditions of each city, the plannings of urban space development, flood control and land use. The objectives and the tasks of the TOR are successfully fulfilled. 9.2. Recommendation Channel width in calculation is the breadth of the surface taking into account the roof coefficients of each case when it comes to the design of the FS. After working with the cities, due to the particular terrain of the area, the expansion of canals depends on soil characteristics along the canals. When designing the FS, it is possible to change channel width, but in order to ensure water storage in the canals, the FS consultant should notify that the design total water surface area of the canals is not less than the total value proposed in this project. Regarding new constructed sewers size, the proposed shape of culverts is round or rectangle. For each specific area, the FS consultant may change the shape of the sewer but notify that the design cross section is not less than the proposed value in this project. Southern Institute of Water resources research 92 Contract No. 7182300 Appendix A -Ground elevation maps APPENDIX A - GROUND ELEVATION MAPS In this section, up-to-date ground elevation map would be shown. Digital form are available in maximum resolution up to (5x5) m. These maps would be uses in constructing flood risk and hazard maps. Figure 65: Digital elevation map of Vinh Long city Figure 66: Digital elevation map of Ben Tre City Southern Institute of Water resources research A-1 Contract No. 7182300 Appendix A -Ground elevation maps Figure 67: Digital elevation map of Vi Thanh City Figure 68: Digital elevation map of Soc Trang City Southern Institute of Water resources research A-2 Contract No. 7182300 Appendix A -Ground elevation maps Figure 69: Digital elevation map of Bac Lieu City Figure 70: Digital elevation map of Tan An City Southern Institute of Water resources research A-3 Contract No. 7182300 Appendix A -Ground elevation maps 7 Figure 71: Digital elevation map of Soc Trang City Southern Institute of Water resources research A-4 Contract No. 7182300 Appendix B -EXISting land use map APPENDIX B - EXISTING LAND USE MAP Figure 72: Existing land use map in Long Xuyen City Figure 73: Existing land use map in Vi Thanh City Southern Institute of Water resources research B-1 Contract No. 7182300 Appendix B -EXISting land use map Figure 74: Existing land use map in Bac Lieu City Figure 75: Existing land use map in Tan An City Southern Institute of Water resources research B-2 Contract No. 7182300 Appendix B -EXISting land use map Figure 76: Existing land use map in Ben Tre City Figure 77: Existing land use map in Vinh Long City Southern Institute of Water resources research B-3 Contract No. 7182300 Appendix B -EXISting land use map Figure 78: Existing land use map in Soc Trang City Symbol Annotation Symbol Annotation I AGRICULTURAL AREAS Rice and farm product, 2-3 crops 2 crops rice - aquaculture Rice and farm product, 2 crops Salt production 1 crop rice field (Winter-spring) Other agricultural area Farm and industrial crops II RESIDENT AND SPECIALIZED AREA Fruit Rural resident Other long-term crops Urban resident, construction, industrical area Industrial forest Other specialized area Presevation forest III UNUSED AREAS Specialized forest Unused areas Aquacultural area Water area Aquacultural on alluvial area Coastal alluvial area Southern Institute of Water resources research B-4 Contract No. 7182300 Appendix C -Land use planning maps APPENDIX C - LAND USE PLANNING MAPS Figure 79: Land use planning to 2025 in Long Xuyen City Figure 80: Land use planning to 2025 in Vi Thanh City Southern Institute of Water resources research C-1 Contract No. 7182300 Appendix C -Land use planning maps Figure 81: Land use planning to 2025 in Bac Lieu City Figure 82: Land use planning to 2025 in Tan An City Southern Institute of Water resources research C-2 Contract No. 7182300 Appendix C -Land use planning maps Figure 83: Land use planning to 2025 in Ben Tre City Figure 84: Land use planning to 2025 in Vinh Long City Southern Institute of Water resources research C-3 Contract No. 7182300 Appendix C -Land use planning maps Figure 85: Land use planning to 2025 in Soc Trang City Symbol Annotation Symbol Annotation I AGRICULTURAL AREAS Rice and farm product, 2-3 crops 2 crops rice - aquaculture Rice and farm product, 2 crops Salt production 1 crop rice field (Winter-spring) Other agricultural area Farm and industrial crops II RESIDENT AND SPECIALIZED AREA Fruit Rural resident Other long-term crops Urban resident, construction, industrical area Industrial forest Other specialized area Presevation forest III UNUSED AREAS Specialized forest Unused areas Aquacultural area Water area Aquacultural on alluvial area Coastal alluvial area Southern Institute of Water resources research C-4 Contract No. 7182300 Appendix D -Flood maps on channels APPENDIX D - FLOOD MAPS ON CHANNELS BL3 SCENARIO - WITHOUT SUUP INTERVENTION AND 10% HYDROLOGICAL PROBABILITY Figure 86: BL3 scenario flood map in Ben Tre City Figure 87: BL3 scenario flood map in Vinh Long City Southern Institute of Water resources research D-1 Contract No. 7182300 Appendix D -Flood maps on channels Figure 88: BL3 scenario flood map in Bac Lieu City Figure 89: BL3 scenario flood map in Vi Thanh City Southern Institute of Water resources research D-2 Contract No. 7182300 Appendix D -Flood maps on channels Figure 90: BL3 scenario flood map in Long Xuyen Figure 91: BL3 scenario flood map in Tan An City Southern Institute of Water resources research D-3 Contract No. 7182300 Appendix D -Flood maps on channels Figure 92: BL3 scenario flood map in Soc Trang City Southern Institute of Water resources research D-4 Contract No. 7182300 Appendix D -Flood maps on channels SU3 SCENARIO - WITH SUUP INTERVENTION AND 10% HYDROLOGICAL PROBABILITY Figure 93: SU3 scenario flood map in Ben Tre City Figure 94: SU3 scenario flood map in Vinh Long City Southern Institute of Water resources research D-5 Contract No. 7182300 Appendix D -Flood maps on channels Figure 95: SU3 scenario flood map in Bac Lieu City Figure 96: SU3 scenario flood map in Vi Thanh City Southern Institute of Water resources research D-6 Contract No. 7182300 Appendix D -Flood maps on channels Figure 97: SU3 scenario flood map in Long Xuyen City Figure 98: SU3 scenario flood map in Tan An City Southern Institute of Water resources research D-7 Contract No. 7182300 Appendix D -Flood maps on channels Figure 99: SU3 scenario flood map in Soc Trang City Southern Institute of Water resources research D-8 Contract No. 7182300 Appendix D -Flood maps on channels SP3 SCENARIO - SUUP INTERVENTION + 10% HYDROLOGICA PROBABILITY + FUTURE LAND USE PLANNING Figure 100: SP3 scenario flood map in Ben Tre City Figure 101: SP3 scenario flood map in Vinh Long City Southern Institute of Water resources research D-9 Contract No. 7182300 Appendix D -Flood maps on channels Figure 102: SP3 scenario flood map in Bac Lieu City Figure 103: SP3 scenario flood map in Vi Thanh City Southern Institute of Water resources research D-10 Contract No. 7182300 Appendix D -Flood maps on channels Figure 104: SP3 scenario flood map in Long Xuyen City Figure 105: SP3 scenario flood map in Tan An City Southern Institute of Water resources research D-11 Contract No. 7182300 Appendix D -Flood maps on channels Figure 106: SP3 scenario flood map in Soc Trang City Southern Institute of Water resources research D-12 Contract No. 7182300 Appendix D -Flood maps on channels CC3 SCENARIO - CLIMATE CHANGE + 10% PROBABILITY OF HYDROLOGICAL CONDITION Figure 107: CC3 scenario flood map in Ben Tre Figure 108: CC3 scenario flood map in Vinh Long Southern Institute of Water resources research D-13 Contract No. 7182300 Appendix D -Flood maps on channels Figure 109: CC3 scenario flood map in Bac Lieu Figure 110: CC3 scenario flood map in Vi Thanh Southern Institute of Water resources research D-14 Contract No. 7182300 Appendix D -Flood maps on channels Figure 111: CC3 scenario flood map in Long Xuyen Figure 112: CC3 scenario flood map in Tan An Southern Institute of Water resources research D-15 Contract No. 7182300 Appendix D -Flood maps on channels Figure 113: CC3 scenario flood map in Soc Trang Southern Institute of Water resources research D-16 Contract No. 7182300 Appendix E - Maximum water level simulation results APPENDIX E - MAXIMUM WATER LEVEL SIMULATION RESULTS Planed Existing Existing Planed urban situation situation urban (2025) No Scenarios WITHOUT WITH (2025) WITH SUUP SUUP WITH SUUP and interventions interventions SUUP CC in 2050 1 2 year flood + 2 year rainfall BL1 SU1 SP1 CC1 2 5 year flood + 5 year rainfall BL2 SU2 SP2 CC2 3 10 year flood + 10 year rainfall BL3 SU3 SP3 CC3 4 25 year flood + 25 year rainfall BL4 SU4 SP4 CC4 5 50 year flood + 50 year rainfall BL5 SU5 SP5 CC5 6 100 flood year + 100 year rainfall BL6 SU6 SP6 CC6 Southern Institute of Water resources research E-1 Contract No. 7182300 Appendix E - Maximum water level simulation results 2 year flood + 2 year rainfall City Canal BL1 SU1 SP1 CC1 Chin Te canal 1.78 0.34 1.19 1.41 Ben Tre 30/4 canal 1.81 0.20 1.25 1.48 Tan Binh secondary branch 1 1.81 0.46 0.88 1.13 Tan Binh secondary branch 2 1.81 0.46 0.88 1.13 Ong Dia canal 1.80 1.02 1.04 1.21 Song Cau Lo 1 canal 1.78 0.54 0.86 1.11 Song Cau Lo 2 canal 1.78 0.54 0.86 1.11 Ngo Quyen canal 1.79 0.99 1.02 1.22 Sau Van 1 canal 1.81 0.70 0.82 1.08 Vinh Long Sau Van 2 canal 1.81 0.70 0.82 1.08 Kinh Cut secondary branch 1 1.80 0.79 0.84 1.07 Kinh Cut secondary branch 2 1.80 0.79 0.84 1.07 Sau Van secondary branch 1 1.81 0.70 0.82 1.05 Sau Van secondary branch 2 1.80 0.79 0.84 1.07 Kinh Cut river 1.78 1.78 1.83 2.01 Cau Lau river 1.78 1.78 1.84 2.02 Kenh Xang canal 1.64 1.16 1.22 1.34 Bac Lieu LIA 6 canal 1.64 1.16 1.19 1.31 Thong Nhat 1 canal 0.58 0.58 0.60 0.76 Thong Nhat 2 canal 0.58 0.58 0.60 0.76 Thong Nhat 3 canal 0.07 0.07 0.07 0.18 Thong Nhat 4 canal 0.07 0.07 0.07 0.18 Cai Nhuc Nho canal 0.58 0.58 0.60 0.76 Phan Lo canal 0.58 0.58 0.60 0.76 Vi Thanh Lo 2 canal 0.58 0.58 0.60 0.76 Canal 1 0.58 0.58 0.60 0.76 Canal 2 0.58 0.58 0.60 0.76 Canal 3 0.58 0.58 0.60 0.76 Cai Nhuc canal 0.58 0.58 0.60 0.76 Canal 62 0.07 0.07 0.07 0.18 Ong Manh canal 2.36 2.21 2.23 2.32 Long Ba Bau canal 2.42 2.05 2.10 2.18 Xuyen Cai Son canal 2.19 2.19 2.21 2.30 Cau Tre canal 1.66 0.95 0.99 1.09 Tan An Rot canal 1.68 0.60 0.63 0.70 Tra Men canal 1.79 0.78 0.80 0.99 Soc Trang Hitech canal 1.70 1.05 1.11 1.31 Southern Institute of Water resources research E-2 Contract No. 7182300 Appendix E - Maximum water level simulation results 5 year flood + 5 year rainfall City Canal BL2 SU2 SP2 CC2 Chin Te canal 1.84 0.59 1.30 1.53 Ben Tre 30/4 canal 1.87 0.35 1.32 1.55 Tan Binh secondary branch 1 1.89 0.57 1.05 1.32 Tan Binh secondary branch 2 1.89 0.57 1.05 1.32 Ong Dia canal 1.90 1.15 1.17 1.36 Song Cau Lo 1 canal 1.87 0.66 1.03 1.30 Song Cau Lo 2 canal 1.87 0.66 1.03 1.30 Ngo Quyen canal 1.88 1.14 1.17 1.40 Sau Van 1 canal 1.89 0.85 1.00 1.28 Vinh Long Sau Van 2 canal 1.89 0.85 1.00 1.28 Kinh Cut secondary branch 1 1.88 0.96 1.02 1.29 Kinh Cut secondary branch 2 1.88 0.96 1.02 1.29 Sau Van secondary branch 1 1.89 0.85 1.00 1.25 Sau Van secondary branch 2 1.88 0.96 1.02 1.29 Kinh Cut river 1.86 1.86 1.92 2.10 Cau Lau river 1.87 1.87 1.92 2.10 Kenh Xang canal 1.76 1.26 1.32 1.43 Bac Lieu LIA 6 canal 1.76 1.26 1.28 1.40 Thong Nhat 1 canal 0.71 0.71 0.73 0.91 Thong Nhat 2 canal 0.71 0.71 0.73 0.91 Thong Nhat 3 canal 0.16 0.16 0.17 0.28 Thong Nhat 4 canal 0.16 0.16 0.17 0.28 Cai Nhuc Nho canal 0.71 0.71 0.73 0.91 Phan Lo canal 0.71 0.71 0.73 0.91 Vi Thanh Lo 2 canal 0.71 0.71 0.73 0.91 Canal 1 0.71 0.71 0.73 0.91 Canal 2 0.71 0.71 0.73 0.91 Canal 3 0.71 0.71 0.73 0.91 Cai Nhuc canal 0.71 0.71 0.73 0.91 Canal 62 0.16 0.16 0.17 0.28 Ong Manh canal 2.50 2.34 2.36 2.46 Long Ba Bau canal 2.56 2.16 2.21 2.30 Xuyen Cai Son canal 2.32 2.32 2.34 2.43 Cau Tre canal 1.70 1.10 1.14 1.26 Tan An Rot canal 1.76 0.76 0.80 0.88 Tra Men canal 1.84 1.05 1.08 1.34 Soc Trang Hitech canal 1.74 1.18 1.23 1.46 Southern Institute of Water resources research E-3 Contract No. 7182300 Appendix E - Maximum water level simulation results 10 year flood + 10 year rainfall City Canal BL3 SU3 SP3 CC3 Chin Te canal 1.89 0.92 1.39 1.63 Ben Tre 30/4 canal 1.92 0.64 1.40 1.64 Tan Binh secondary branch 1 1.96 0.90 1.39 1.43 Tan Binh secondary branch 2 1.96 0.90 1.39 1.43 Ong Dia canal 1.97 1.37 1.39 1.45 Song Cau Lo 1 canal 1.93 0.99 1.37 1.41 Song Cau Lo 2 canal 1.93 0.99 1.37 1.41 Ngo Quyen canal 1.94 1.35 1.39 1.50 Sau Van 1 canal 1.97 1.22 1.38 1.40 Vinh Long Sau Van 2 canal 1.97 1.22 1.38 1.40 Kinh Cut secondary branch 1 1.95 1.31 1.37 1.42 Kinh Cut secondary branch 2 1.95 1.31 1.37 1.42 Sau Van secondary branch 1 1.97 1.22 1.38 1.37 Sau Van secondary branch 2 1.95 1.31 1.37 1.42 Kinh Cut river 1.93 1.93 1.99 2.17 Cau Lau river 1.94 1.94 2.00 2.18 Kenh Xang canal 1.86 1.34 1.40 1.51 Bac Lieu LIA 6 canal 1.86 1.34 1.36 1.47 Thong Nhat 1 canal 0.83 0.83 0.87 1.05 Thong Nhat 2 canal 0.83 0.83 0.87 1.05 Thong Nhat 3 canal 0.32 0.32 0.34 0.47 Thong Nhat 4 canal 0.32 0.32 0.34 0.47 Cai Nhuc Nho canal 0.83 0.83 0.87 1.05 Phan Lo canal 0.83 0.83 0.87 1.05 Vi Thanh Lo 2 canal 0.83 0.83 0.87 1.05 Canal 1 0.83 0.83 0.87 1.05 Canal 2 0.83 0.83 0.87 1.05 Canal 3 0.83 0.83 0.87 1.05 Cai Nhuc canal 0.83 0.83 0.87 1.05 Canal 62 0.32 0.32 0.34 0.47 Ong Manh canal 2.83 2.66 2.68 2.79 Long Ba Bau canal 2.90 2.50 2.56 2.66 Xuyen Cai Son canal 2.63 2.63 2.66 2.76 Cau Tre canal 1.76 1.34 1.39 1.53 Tan An Rot canal 1.82 1.28 1.35 1.48 Tra Men canal 1.90 1.19 1.23 1.53 Soc Trang Hitech canal 1.77 1.25 1.31 1.55 Southern Institute of Water resources research E-4 Contract No. 7182300 Appendix E - Maximum water level simulation results 25 year flood +25 year rainfall City Canal BL4 SU4 SP4 CC4 Chin Te canal 1.97 0.93 1.50 1.75 Ben Tre 30/4 canal 2.00 0.66 1.52 1.77 Tan Binh secondary branch 1 2.02 0.96 1.45 1.56 Tan Binh secondary branch 2 2.02 0.96 1.45 1.56 Ong Dia canal 2.05 1.45 1.46 1.55 Song Cau Lo 1 canal 2.00 1.06 1.43 1.54 Song Cau Lo 2 canal 2.00 1.06 1.43 1.54 Ngo Quyen canal 2.01 1.43 1.46 1.62 Sau Van 1 canal 2.03 1.30 1.45 1.53 Vinh Long Sau Van 2 canal 2.03 1.30 1.45 1.53 Kinh Cut secondary branch 1 2.02 1.39 1.44 1.56 Kinh Cut secondary branch 2 2.02 1.39 1.44 1.56 Sau Van secondary branch 1 2.03 1.30 1.45 1.50 Sau Van secondary branch 2 2.02 1.39 1.44 1.56 Kinh Cut river 1.98 1.98 2.04 2.22 Cau Lau river 1.98 1.98 2.04 2.22 Kenh Xang canal 2.06 1.50 1.57 1.67 Bac Lieu LIA 6 canal 2.06 1.50 1.53 1.63 Thong Nhat 1 canal 0.87 0.87 0.91 1.10 Thong Nhat 2 canal 0.87 0.87 0.91 1.10 Thong Nhat 3 canal 0.36 0.36 0.37 0.51 Thong Nhat 4 canal 0.36 0.36 0.37 0.51 Cai Nhuc Nho canal 0.87 0.87 0.91 1.10 Phan Lo canal 0.87 0.87 0.91 1.10 Vi Thanh Lo 2 canal 0.87 0.87 0.91 1.10 Canal 1 0.87 0.87 0.91 1.10 Canal 2 0.87 0.87 0.91 1.10 Canal 3 0.87 0.87 0.91 1.10 Cai Nhuc canal 0.87 0.87 0.91 1.10 Canal 62 0.36 0.36 0.37 0.51 Ong Manh canal 2.92 2.75 2.77 2.88 Long Ba Bau canal 2.99 2.61 2.67 2.78 Xuyen Cai Son canal 2.72 2.72 2.75 2.86 Cau Tre canal 1.81 1.45 1.50 1.65 Tan An Rot canal 1.86 1.40 1.47 1.61 Tra Men canal 1.93 1.32 1.40 1.74 Soc Trang Hitech canal 1.79 1.30 1.36 1.61 Southern Institute of Water resources research E-5 Contract No. 7182300 Appendix E - Maximum water level simulation results 50 year flood + 50 year rainfall City Canal BL5 SU5 SP5 CC5 Chin Te canal 2.01 0.97 1.61 1.87 Ben Tre 30/4 canal 2.06 0.69 1.63 1.89 Tan Binh secondary branch 1 2.07 1.01 1.52 1.64 Tan Binh secondary branch 2 2.07 1.01 1.52 1.64 Ong Dia canal 2.15 1.50 1.53 1.61 Song Cau Lo 1 canal 2.05 1.11 1.50 1.63 Song Cau Lo 2 canal 2.05 1.11 1.50 1.63 Ngo Quyen canal 2.06 1.50 1.53 1.70 Sau Van 1 canal 2.08 1.37 1.52 1.63 Vinh Long Sau Van 2 canal 2.08 1.37 1.52 1.63 Kinh Cut secondary branch 1 2.07 1.47 1.51 1.66 Kinh Cut secondary branch 2 2.07 1.47 1.51 1.66 Sau Van secondary branch 1 2.08 1.37 1.52 1.60 Sau Van secondary branch 2 2.07 1.47 1.51 1.66 Kinh Cut river 2.03 2.03 2.09 2.27 Cau Lau river 2.03 2.03 2.09 2.27 Kenh Xang canal 2.20 1.61 1.69 1.78 Bac Lieu LIA 6 canal 2.20 1.61 1.64 1.74 Thong Nhat 1 canal 0.91 0.91 0.95 1.14 Thong Nhat 2 canal 0.91 0.91 0.95 1.14 Thong Nhat 3 canal 0.40 0.40 0.41 0.55 Thong Nhat 4 canal 0.40 0.40 0.41 0.55 Cai Nhuc Nho canal 0.91 0.91 0.95 1.14 Phan Lo canal 0.91 0.91 0.95 1.14 Vi Thanh Lo 2 canal 0.91 0.91 0.95 1.14 Canal 1 0.91 0.91 0.95 1.14 Canal 2 0.91 0.91 0.95 1.14 Canal 3 0.91 0.91 0.95 1.14 Cai Nhuc canal 0.91 0.91 0.95 1.14 Canal 62 0.40 0.40 0.41 0.55 Ong Manh canal 3.03 2.85 2.87 2.99 Long Ba Bau canal 3.10 2.73 2.79 2.90 Xuyen Cai Son canal 2.82 2.82 2.85 2.96 Cau Tre canal 1.87 1.51 1.57 1.73 Tan An Rot canal 1.89 1.48 1.55 1.70 Tra Men canal 1.97 1.41 1.50 1.86 Soc Trang Hitech canal 1.81 1.34 1.41 1.66 Southern Institute of Water resources research E-6 Contract No. 7182300 Appendix E - Maximum water level simulation results 100 year flood + 100 year rainfall City Canal BL6 SU6 SP6 CC6 Chin Te canal 2.06 1.03 1.68 1.95 Ben Tre 30/4 canal 2.10 0.76 1.71 1.98 Tan Binh secondary branch 1 2.11 1.05 1.59 1.72 Tan Binh secondary branch 2 2.10 1.05 1.59 1.72 Ong Dia canal 2.20 1.56 1.60 1.68 Song Cau Lo 1 canal 2.08 1.17 1.58 1.71 Song Cau Lo 2 canal 2.08 1.17 1.58 1.71 Ngo Quyen canal 2.09 1.56 1.60 1.77 Sau Van 1 canal 2.11 1.44 1.58 1.71 Vinh Long Sau Van 2 canal 2.11 1.44 1.58 1.71 Kinh Cut secondary branch 1 2.10 1.54 1.56 1.76 Kinh Cut secondary branch 2 2.10 1.54 1.56 1.76 Sau Van secondary branch 1 2.11 1.44 1.58 1.68 Sau Van secondary branch 2 2.10 1.54 1.56 1.76 Kinh Cut river 2.05 2.05 2.11 2.29 Cau Lau river 2.05 2.05 2.11 2.29 Kenh Xang canal 2.31 1.70 1.78 1.87 Bac Lieu LIA 6 canal 2.31 1.70 1.73 1.82 Thong Nhat 1 canal 0.94 0.94 0.98 1.18 Thong Nhat 2 canal 0.94 0.94 0.98 1.18 Thong Nhat 3 canal 0.43 0.43 0.45 0.59 Thong Nhat 4 canal 0.43 0.43 0.45 0.59 Cai Nhuc Nho canal 0.94 0.94 0.98 1.18 Phan Lo canal 0.94 0.94 0.98 1.18 Vi Thanh Lo 2 canal 0.94 0.94 0.98 1.18 Canal 1 0.94 0.94 0.98 1.18 Canal 2 0.94 0.94 0.98 1.18 Canal 3 0.94 0.94 0.98 1.18 Cai Nhuc canal 0.94 0.94 0.98 1.18 Canal 62 0.43 0.43 0.45 0.59 Ong Manh canal 3.10 2.92 2.94 3.06 Long Ba Bau canal 3.17 2.82 2.88 3.00 Xuyen Cai Son canal 2.89 2.89 2.92 3.03 Cau Tre canal 1.92 1.57 1.68 1.85 Tan An Rot canal 1.93 1.55 1.63 1.79 Tra Men canal 2.00 1.48 1.59 1.97 Soc Trang Hitech canal 1.82 1.42 1.50 1.76 Southern Institute of Water resources research E-7 Contract No. 7182300 Appendix F - Maximum flooding area simulation results APPENDIX F - MAXIMUM FLOODING AREA SIMULATION RESULTS BEN TRE CITY Canal Scenarios 1 2 3 4 5 6 BL 85.33 95.32 106.83 122.63 129.80 138.46 SU 0.37 1.33 7.38 7.73 13.56 25.84 BL-SU 84.96 93.99 99.44 114.90 116.24 112.62 9TE BL-SU (%) 100% 99% 93% 94% 90% 81% CC 40.85 46.32 55.10 63.18 69.68 80.15 BL-CC 44.48 49.00 51.72 59.45 60.12 58.31 BL-CC (%) 52% 51% 48% 48% 46% 42% BL 2.65 4.89 6.83 9.89 11.72 12.87 SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU 2.65 4.89 6.83 9.89 11.72 12.87 30/4 BL-SU (%) 100% 100% 100% 100% 100% 100% CC 0.33 1.45 2.41 3.94 4.86 5.44 BL-CC 2.33 3.45 4.41 5.94 6.86 7.44 BL-CC (%) 88% 70% 65% 60% 59% 58% BAC LIEU CITY Canal Scenarios 1 2 3 4 5 6 BL 182.78 229.34 396.71 446.21 494.98 538.56 SU 3.66 11.47 32.50 58.01 103.95 188.50 BL-SU 179.12 217.88 364.21 388.20 391.03 350.06 TRAKHA BL-SU (%) 98% 95% 92% 87% 79% 65% CC 49.48 65.04 115.34 145.65 192.15 268.51 BL-CC 133.30 164.30 281.37 300.56 302.83 270.05 BL-CC (%) 73% 72% 71% 67% 61% 50% BL 91.48 98.83 109.02 119.26 123.83 125.81 SU 1.83 3.95 7.96 14.31 24.77 41.52 BL-SU 89.65 94.88 101.06 104.94 99.06 84.29 KENH CUT BL-SU (%) 98% 96% 93% 88% 80% 67% CC 23.76 26.93 32.17 39.30 48.58 62.37 BL-CC 67.72 71.90 76.85 79.96 75.25 63.43 BL-CC (%) 74% 73% 70% 67% 61% 50% VINH LONG CITY Canal Scenarios 1 2 3 4 5 6 BL 3.15 3.57 4.03 5.04 5.74 6.65 TANBINH_VL SU 0.23 0.31 0.71 0.76 0.81 0.92 BL-SU 2.93 3.26 3.32 4.28 4.93 5.73 Southern Institute of Water resources research F-8 Contract No. 7182300 Appendix F - Maximum flooding area simulation results BL-SU (%) 93% 91% 82% 85% 86% 86% CC 1.25 2.23 2.87 3.57 4.19 5.45 BL-CC 1.91 1.35 1.16 1.47 1.55 1.20 BL-CC (%) 61% 38% 29% 29% 27% 18% BL 1.46 2.07 2.66 3.60 4.56 5.23 SU 0.00 0.00 0.09 0.28 0.42 0.55 BL-SU 1.46 2.07 2.57 3.32 4.14 4.68 MUONGLO_VL BL-SU (%) 100% 100% 97% 92% 91% 90% CC 0.42 0.90 1.24 2.07 3.03 4.36 BL-CC 1.04 1.18 1.42 1.53 1.53 0.87 BL-CC (%) 71% 57% 53% 43% 34% 17% BL 0.37 0.38 0.40 0.41 0.42 0.44 SU 0.21 0.25 0.31 0.34 0.38 0.38 BL-SU 0.15 0.13 0.08 0.07 0.04 0.06 ONGDIA_VL BL-SU (%) 42% 34% 21% 16% 11% 14% CC 0.27 0.31 0.37 0.39 0.39 0.41 BL-CC 0.09 0.07 0.03 0.02 0.03 0.03 BL-CC (%) 25% 18% 7% 5% 7% 7% BL 0.21 0.22 0.23 0.23 0.24 0.24 SU 0.18 0.19 0.20 0.21 0.22 0.22 BL-SU 0.03 0.03 0.03 0.03 0.02 0.02 NGOQUYEN_V BL-SU (%) 14% 14% 12% 11% 9% 7% CC 0.19 0.20 0.22 0.23 0.23 0.24 BL-CC 0.02 0.02 0.01 0.01 0.01 0.00 BL-CC (%) 9% 8% 4% 2% 3% 0% BL 0.09 0.10 0.10 0.11 0.12 0.12 SU 0.06 0.07 0.08 0.09 0.09 0.10 BL-SU 0.04 0.04 0.02 0.02 0.03 0.02 MUONG1_VL BL-SU (%) 38% 35% 22% 19% 22% 15% CC 0.08 0.09 0.09 0.10 0.11 0.12 BL-CC 0.02 0.01 0.01 0.01 0.01 0.00 BL-CC (%) 19% 13% 10% 7% 7% 0% BL 0.67 0.72 0.75 0.78 0.99 1.35 SU 0.36 0.43 0.56 0.61 0.64 0.66 BL-SU 0.32 0.30 0.19 0.17 0.36 0.70 SAUVAN_VL BL-SU (%) 47% 41% 26% 22% 36% 51% CC 0.49 0.58 0.66 0.72 0.76 0.86 BL-CC 0.18 0.15 0.10 0.05 0.23 0.49 BL-CC (%) 27% 20% 13% 7% 23% 36% KENHCUT_VL BL 0.83 0.86 0.89 0.92 0.94 0.95 Southern Institute of Water resources research F-9 Contract No. 7182300 Appendix F - Maximum flooding area simulation results SU 0.83 0.86 0.89 0.92 0.94 0.95 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.93 0.96 0.99 1.02 1.03 1.05 BL-CC -0.10 -0.09 -0.10 -0.10 -0.08 -0.09 BL-CC (%) -11% -11% -11% -10% -9% -10% BL 7.78 8.78 10.67 30.52 50.12 66.22 SU 7.78 8.78 10.67 30.52 50.12 66.22 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 CAULAU_VL BL-SU (%) 0% 0% 0% 0% 0% 0% CC 8.76 9.76 11.79 33.58 55.46 72.56 BL-CC -0.98 -0.98 -1.13 -3.07 -5.34 -6.34 BL-CC (%) -13% -11% -11% -10% -11% -10% VI THANH CITY Canal Kịch bản 1 2 3 4 5 6 BL 0.00 0.00 0.00 0.00 0.00 0.00 SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 THONGNHAT4 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.00 0.00 0.00 0.17 0.24 0.30 CC-SU 0.00 0.00 0.00 0.17 0.24 0.30 BL 2.49 3.53 3.86 4.11 5.19 6.17 SU 2.49 3.53 3.86 4.11 5.19 6.17 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHVITHUY BL-SU (%) 0% 0% 0% 0% 0% 0% CC 4.11 9.76 10.77 10.99 11.30 11.45 CC-SU 1.62 6.23 6.91 6.89 6.11 5.28 BL 0.56 1.14 1.31 1.49 2.90 3.03 SU 0.56 1.14 1.31 1.49 2.90 3.03 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHNGANG_ BL-SU (%) 0% 0% 0% 0% 0% 0% CC 1.49 3.59 4.51 4.58 4.67 5.01 CC-SU 0.94 2.45 3.20 3.08 1.76 1.99 BL 0.00 0.00 1.95 8.87 11.13 13.51 SU 0.00 0.00 1.95 8.87 11.13 13.51 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENH62_VT BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.07 3.28 11.71 23.71 30.72 39.65 CC-SU 0.07 3.28 9.76 14.85 19.59 26.15 XANGHAU_VT BL 0.03 0.08 0.11 0.13 0.16 0.63 Southern Institute of Water resources research F-10 Contract No. 7182300 Appendix F - Maximum flooding area simulation results SU 0.03 0.08 0.11 0.13 0.16 0.63 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.13 4.37 5.45 5.72 5.96 6.11 CC-SU 0.10 4.29 5.34 5.59 5.80 5.48 BL 0.00 0.00 0.00 0.00 0.00 0.00 SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU 0.00 0.00 0.56 0.61 0.64 0.66 THONGNHAT3 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.00 0.00 0.00 0.15 0.20 0.24 CC-SU 0.00 0.00 0.00 0.15 0.20 0.24 BL 0.45 1.88 2.56 4.47 6.06 6.70 SU 0.45 1.88 2.56 4.47 6.06 6.70 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 THONGNHAT1 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 4.47 7.87 8.54 8.55 8.55 8.56 CC-SU 4.01 5.99 5.98 4.08 2.49 1.86 BL 0.22 0.82 5.53 7.21 8.36 8.61 SU 0.22 0.82 5.53 7.21 8.36 8.61 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 THONGNHAT2 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 7.20 9.56 11.24 11.88 11.95 11.95 CC-SU 6.98 8.73 5.72 4.67 3.59 3.35 BL 0.03 0.07 0.09 0.18 1.71 2.48 SU 0.03 0.07 0.09 0.18 1.71 2.48 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 RACH3_VT BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.18 5.49 5.95 5.95 5.95 5.95 CC-SU 0.15 5.41 5.87 5.78 4.24 3.48 BL 0.33 0.87 1.00 1.15 1.54 2.00 SU 0.33 0.87 1.00 1.15 1.54 2.00 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHLO2A_V BL-SU (%) 0% 0% 0% 0% 0% 0% CC 1.15 6.49 7.14 7.14 7.14 7.14 CC-SU 0.83 5.62 6.13 5.98 5.59 5.14 BL 0.82 2.50 2.97 3.49 4.67 5.27 SU 0.82 2.50 2.97 3.49 4.67 5.27 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHPHANLO BL-SU (%) 0% 0% 0% 0% 0% 0% CC 3.49 11.63 13.52 13.52 13.52 13.52 CC-SU 2.67 9.13 10.55 10.03 8.85 8.25 Southern Institute of Water resources research F-11 Contract No. 7182300 Appendix F - Maximum flooding area simulation results BL 0.01 0.06 0.06 0.08 0.09 0.09 SU 0.01 0.06 0.06 0.08 0.09 0.09 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 RACH2_VT BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.08 3.31 3.40 3.40 3.40 3.40 CC-SU 0.08 3.25 3.34 3.32 3.31 3.31 BL 0.21 0.57 0.67 0.78 1.23 1.55 SU 0.21 0.57 0.67 0.78 1.23 1.55 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHPHANLO BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.78 2.79 2.95 2.95 2.95 2.95 CC-SU 0.57 2.22 2.27 2.17 1.72 1.40 BL 0.00 0.00 0.00 0.00 0.00 0.00 SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 RACH1_VT BL-SU (%) 0% 0% 0% 0% 0% 0% CC 0.00 0.93 1.79 2.17 2.27 2.35 CC-SU 0.00 0.93 1.79 2.17 2.27 2.35 BL 1.15 3.07 3.56 4.08 4.44 4.74 SU 1.15 3.07 3.56 4.08 4.44 4.74 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHCAINHU BL-SU (%) 0% 0% 0% 0% 0% 0% CC 4.08 11.86 17.30 17.36 17.38 17.38 CC-SU 2.94 8.79 13.74 13.28 12.94 12.65 BL 6.35 17.56 25.83 29.01 32.07 33.80 SU 6.35 17.56 25.83 29.01 32.07 33.80 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 KENHCAINHU BL-SU (%) 0% 0% 0% 0% 0% 0% CC 29.01 41.07 42.57 43.08 43.48 43.78 CC-SU 22.66 23.51 16.74 14.07 11.41 9.97 LONG XUYEN CITY Canal Scenarios 1 2 3 4 5 6 BL 2.08 5.93 15.71 35.45 49.90 51.73 SU 1.15 1.16 1.23 1.37 1.42 1.49 BL-SU 0.93 4.77 14.48 34.09 48.48 50.25 Ba Bau Canal BL-SU (%) 45% 80% 92% 96% 97% 97% CC 1.23 1.35 1.83 1.43 1.62 1.78 BL-CC 0.85 4.58 13.88 34.02 48.27 49.95 BL-CC (%) 41% 77% 88% 96% 97% 97% Cai Son Canal BL 8.44 8.77 10.02 11.30 14.87 16.91 Southern Institute of Water resources research F-12 Contract No. 7182300 Appendix F - Maximum flooding area simulation results SU 8.44 8.77 10.02 11.30 14.87 16.91 BL-SU 0.00 0.00 0.00 0.00 0.00 0.00 BL-SU (%) 0% 0% 0% 0% 0% 0% CC 8.88 9.24 10.42 12.83 17.60 21.12 BL-CC -0.44 -0.47 -0.40 -1.53 -2.73 -4.21 BL-CC (%) -5% -5% -4% -14% -18% -25% BL 95.36 100.03 110.74 117.40 133.13 135.92 SU 39.36 57.66 72.74 96.43 116.13 125.42 BL-SU 56.00 42.37 38.00 20.97 17.00 10.50 Ong Manh Canal BL-SU (%) 59% 42% 34% 18% 13% 8% CC 101.49 106.18 125.46 134.48 155.96 178.62 BL-CC -6.13 -6.15 -14.71 -17.08 -22.83 -42.71 BL-CC (%) -6% -6% -13% -15% -17% -31% TAN AN CITY Canal Scenarios 1 2 3 4 5 6 BL 56.69 58.24 59.60 61.32 62.97 64.27 SU 3.92 5.46 24.34 28.55 33.17 38.82 BL-SU 52.78 52.78 35.27 32.77 29.80 25.45 Rach Rot BL-SU (%) 93% 91% 59% 53% 47% 40% CC 19.47 21.01 36.39 40.10 44.13 48.91 BL-CC 37.22 37.22 23.21 21.22 18.84 15.36 BL-CC (%) 66% 64% 39% 35% 30% 24% BL 76.05 77.64 79.76 81.16 82.56 83.59 SU 13.85 24.92 50.26 61.95 66.93 71.38 BL-SU 62.20 52.73 29.50 19.21 15.62 12.21 Cau Tre BL-SU (%) 82% 68% 37% 24% 19% 15% CC 29.29 38.46 59.16 68.79 73.06 76.82 BL-CC 46.76 39.18 20.60 12.37 9.50 6.77 BL-CC (%) 61% 50% 26% 15% 12% 8% SOC TRANG CITY Canal Scenarios 1 2 3 4 5 6 BL 15.02 30.98 44.08 51.50 58.65 65.07 SU 3.87 8.80 14.80 20.68 31.71 36.12 BL-SU 11.14 22.18 29.28 30.82 26.94 28.95 Tra Men BL-SU (%) 74% 72% 66% 60% 46% 44% CC 6.66 14.35 22.12 28.38 38.45 43.36 BL-CC 8.36 16.64 21.96 23.11 20.21 21.71 BL-CC (%) 56% 54% 50% 45% 34% 33% Hitech BL 14.96 18.18 97.43 113.83 118.44 125.79 Southern Institute of Water resources research F-13 Contract No. 7182300 Appendix F - Maximum flooding area simulation results SU 5.19 9.79 67.53 87.43 96.14 105.79 BL-SU 9.77 8.39 29.90 26.40 22.30 20.00 BL-SU (%) 65% 46% 31% 23% 19% 16% CC 8.45 12.59 77.50 96.23 103.57 112.45 BL-CC 6.51 5.59 19.93 17.60 14.87 13.33 BL-CC (%) 44% 31% 20% 15% 13% 11% Southern Institute of Water resources research F-14 Contract No. 7182300 Appendix G - Flood maps for whole cities region APPENDIX G - FLOOD MAPS FOR WHOLE CITIES REGION FLOOD MAPS OF BEN TRE CITY – 10% HYDROLOGICAL PROBABILITY Figure 114: Flood map for existing siotuation in Ben Tre Figure 115: Flood map for existing situation WITH SUUP interventions in Ben Tre Southern Institute of Water resources research G-1 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 116: Flood map for planed urban (2025) WITH SUUP in Ben Tre Figure 117: Flood map with climate change scenario in Ben Tre Southern Institute of Water resources research G-2 Contract No. 7182300 Appendix G - Flood maps for whole cities region FLOOD MAPS OF VINH LONG CITY – 10% HYDROLOGICAL PROBABILITY Figure 118: Flood map for existing siotuation in Vinh Long Figure 119: Flood map for existing situation WITH SUUP interventions in Vinh Long Southern Institute of Water resources research G-3 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 120: Flood map for planed urban (2025) WITH SUUP in Vinh Long Figure 121: Flood map with climate change scenario in Vinh Long FLOOD MAPS OF BAC LIEU CITY – 10% HYDROLOGICAL PROBABILITY Southern Institute of Water resources research G-4 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 122: Flood map for existing siotuation in Bac Lieu Figure 123: Flood map for existing situation WITH SUUP interventions in Bac Lieu Southern Institute of Water resources research G-5 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 124: Flood map for planed urban (2025) WITH SUUP in Bac Lieu Figure 125: Flood map with climate change scenario in Bac Lieu FLOOD MAPS OF VI THANH CITY – 10% HYDROLOGICAL PROBABILITY Southern Institute of Water resources research G-6 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 126: Flood map for existing siotuation in Vi Thanh Figure 127: Flood map for existing situation WITH SUUP interventions in Vi Thanh Southern Institute of Water resources research G-7 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 128: Flood map for planed urban (2025) WITH SUUP in Vi Thanh Figure 129: Flood map with climate change scenario in Vi Thanh Southern Institute of Water resources research G-8 Contract No. 7182300 Appendix G - Flood maps for whole cities region FLOOD MAPS OF LONG XUYEN CITY – 10% HYDROLOGICAL PROBABILITY Figure 130: Flood map for existing siotuation in Long Xuyen Southern Institute of Water resources research G-9 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 131: Flood map for existing situation WITH SUUP interventions in Long Xuyen Southern Institute of Water resources research G-10 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 132: Flood map for planed urban (2025) WITH SUUP in Long Xuyen Southern Institute of Water resources research G-11 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 133: Flood map with climate change scenario in Long Xuyen Southern Institute of Water resources research G-12 Contract No. 7182300 Appendix G - Flood maps for whole cities region FLOOD MAPS OF TAN AN CITY – 10% HYDROLOGICAL PROBABILITY Figure 134: Flood map for existing siotuation in Tan An Figure 135: Flood map for existing situation WITH SUUP interventions in Tan An Southern Institute of Water resources research G-13 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 136: Flood map for planed urban (2025) WITH SUUP in Tan An Figure 137: Flood map with climate change scenario in Tan An Southern Institute of Water resources research G-14 Contract No. 7182300 Appendix G - Flood maps for whole cities region FLOOD MAPS OF SOC TRANG CITY – 10% HYDROLOGICAL PROBABILITY Figure 138: Flood map for existing siotuation in Soc Trang Southern Institute of Water resources research G-15 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 139: Flood map for existing situation WITH SUUP interventions in Soc Trang Southern Institute of Water resources research G-16 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 140: Flood map for planed urban (2025) WITH SUUP in Soc Trang Southern Institute of Water resources research G-17 Contract No. 7182300 Appendix G - Flood maps for whole cities region Figure 141: Flood map with climate change scenario in Soc Trang Southern Institute of Water resources research G-18 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities APPENDIX H - OVERVIEW OF FEASIBILITY STUDIES INFORMATION IN SEVEN CITIES H.1. Ben Tre FS project In Ben Tre, enhancement project section 9 LIA 1. Restoring 2 channels consist of Chin Te channel, 30/4 channel, construction extending of Ngo Quyen street, construction of urban internal connection roads, West-East boulevard, construction of street N5. Figure 142: General layout of investment in Ben Tre City In that project, a geographic campaign was carried in support for channels restoration. Table 54: Existing status of concerned channels in Ben Tre City Length Current width Current depth No Items (m) (m) (m) 1 Chin Te channel restoration 3100 3 +0.31 2 30/4 channel restoration 770 2 +0.65 Southern Institute of Water resources research H-1 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Chin Te channel freely connected at both ends into Ca Loc canal. Channel geographic data is shallow which need to be dredged. However, there are several structures on this channel which block water from flowing e.g. gate, sewer. Figure 143: Existing layout of Chin Te channel 30/4 channel is poor on water discharge due to deposit material from construction sites within 100m radius. If restored, this channel should be connected to the main system. Southern Institute of Water resources research H-2 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 144: Existing layout of 30/4 channel H.2. Vinh Long FS project In Vinh Long, investments 03 LIAs: 1, LIA 3 and and LIA 4; Improving Kinh Cut river, L = 0.54km; Improving Cau Lau river, L=0,76km; Building boundary road of ward 2 and ward 9; Building the Bo Kenh road of Ward 3; Building Vo Van Kiet road, 1.1km. Figure 145: General layout of investment proposal in Vinh Long City Southern Institute of Water resources research H-3 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities 15 small channels within 3 LIA region and 2 large channels have been measured geographic data for restoration process. Table 55: Existing situation of concerned channels in Vinh Long City Lengt Curren Current No Name h t width depth (m) (m) (m) Secondary branch 1 Tan Binh 383.12 6 +0.6 LIA Secondary branch 2 Tan Binh 176.02 4 +0.6 1 Secondary branches 1 Tan Binh 422.5 5 +0.6 Channel Ong Dia 196.13 5 +0.7 Channel Song Cau Lo 1 222.49 7.5 +0.3 LIA Channel Song Cau Lo 2 363.69 6 +0.3 3 Channel Ngo Quyen 157.41 3.5 +0.2 Channel Ong Dia 386.69 5 +0.7 Channel Ngo Quyen 155.61 2.5 +0.2 Channel Sau Van 1 603.26 5 +0.4 Channel Sau Van 2 433.44 7.5 +0.25 Secondary branch Kinh Cut 1 232.69 4.5 +0.4 LIA 4 Secondary branch Kinh Cut 2 93.84 3.5 +0.4 Secondary branch Sau Van 1 140.57 6.5 +0.25 Secondary branch Sau Van 2+ Secondary branch Kinh 163.19 3.5 +0.25 Cut 3 1 River Kinh Cut 540 14 -0.46 2 River Cau Lau 860 18 -1.75 LIA 1: consist of 2 branches of Tan Binh channel, both of these 2 branches are dead end channel which initiated from commune area discharge in to Tien River. Secondary branch Tan Binh 1 at entrance is 383m long, 6m wide in average and bottom located at level of -0.2m. However its width narrow down as moving along while its bottom could reach to +0.6m level. Secondary branch Tan Binh 2 bridge between resident area into main channel Tan Binh 1 is 176m long, 4m wide and bottom at +0.6m level. This channel has 1 gate to regulate during high tide which is 80cm width span. Noticeable information in this area is local people have constructed a controlling gate on channel Tan Binh 2. Southern Institute of Water resources research H-4 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 146: Restoration layout plan within LIA 1 LIA 3: consist of channels connect resident communes to Cau Lo River. 196m Ong Dia channel discharge in to Cau Lo River is 5m wide and 0.6m average depth. There are several secondary branches discharge into Ong Dia channel which are about 386m long, 5m wide and bottom ranging at +0.7m level. Ngo Quyen channel is 157m long is a dead end stream which is also as narrow as 3m wide. Its depth is about 0.2m. Cau Lo 1 River is 222m long, 8m wide, and bottom place at level of -0.03m. However as moving along this channel its width being narrow down and its depth is only 0.3m. Southern Institute of Water resources research H-5 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities For this LIA, there are tidal controlling gates at 2 ends of Cau Lo 2 Channel, Ong Dia channel and Ngo Quyen Channel. Therefore, while estimate channel dimension, it is necessary to consider those two gates as well. Figure 147: Canal renovation layout in LIA 3 Southern Institute of Water resources research H-6 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 148: Restoration channels layout within LIA 3 LIA 4: consist of several dead end channel in this area Sau Van 1 Channel which is 600m long, runs from resident area into Cut channel. It is 5.5m wide with bottom at level of +0.4m. Sau Van 2 channel initiates from resident area pour into Cau Lo River which is 433m long, about 10m wide and average depth is about 0.25m. Secondary branches Kenh Cut 2 channel is blocked at one end, after 90m long the channel run into Cut channel which is 4m wide and 0.25 average of depth. Secondary branches of Cut channel there are total of 230m long connect to Cut channel, they are 5.5m wide and 0.4m depth. In this LIA area, there are already tidal gates at entrance of Kenh Muong channel. Therefore it should be considered while estimate channel dimensions. Southern Institute of Water resources research H-7 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Southern Institute of Water resources research H-8 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Southern Institute of Water resources research H-9 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 149: Restoration general layout of LIA 4 Figure 150: Restoration channels layout in Vinh Long City H.3. Bac Lieu FS project In Bac Lieu, there are 5 LIA area which are LIA 1, LIA 2, LIA 3, LIA 5, LIA 6. They cover a 70.33 Ha area within urban wards of Bac Lieu City. Other than that we have revetment, 0.4km extending of Nguyen Tat Thanh street, 6.1 km of De Lo Ren street, 6.0km of Lo Bo Tay street, enhance Huong Lo 6 street – section from Cau Xang channel to Hung Thanh which is 1km long, internal connection route (Nguyen Dinh Chieu, Hai Ba Trung) 0.7km long. Southern Institute of Water resources research H-10 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 151: Investment location layout at Bac Lieu City In this project, 2 channels have been survey for preparing restored. Table 56: Exisiting condition of restoration channel in Bac Lieu City Current Length Current depth No Name width (m) (m) (m) 1 Kenh Xang Canal 4650 8 -0.75 2 LIA 6 – channel restoration 540 5 0.25 LIA 6: restoration channel is 540m long in total, connect to earth canal, with average width of 3-10m. Bottom level is quite high at +0.25m which are covered with trees on both banks. Southern Institute of Water resources research H-11 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 152: LIA 6 channel locations At this channel, west end of channel has been expanded up to 10m wide. There is 1 open sewer through street which is 2.5m high, at (-0.5m) level. Figure 153: LIA 6 Existing siotuationof drainage system Kenh Xang channel which is 4,650m long, connect both ends to Bac Lieu River, has been shrunk down around 4-8m, and (+0.25m) bottom level. However, by reaching middle section, Southern Institute of Water resources research H-12 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities its bottom could lower down to (-0.25m) – (-1.5m) while its width reach to 15m. This canal has been struggling from being blocked by excessively aquatic development. Figure 154: Kenh Xang channel existing status There are 2 sluice gate at intersection with Tran Phu road and Nguyen Van Linh Road. Those sections are seriously deposit. The canal is regulated from both ends by 2 salinity controlling gate. By the east is Cau Xang gate which is 7.5m wide (3 panels, 2.5m each, bottom level at (- 1.0m)); Tra Kha A is located on the west which is 3.6m wide (2 panels, 1.8m each, bottom at level of (-1.0m)). Those gates are all damaged; Cau Xang on 2011; Tra Kha A on 2008. Therefore they are non-function structures, and while they stay close all the time they block the flow as well. H.4. Vi Thanh FS project In Vi Thanh, investment proposal consist of 2 LIAs which are LIA 3 and LIA 7. Covered in the packages are 62 channel restoration; length of 3.0km; Cai Nhuc channel restoration, length of 2.0km; green parks, and scenery lake = 3.0Ha Triangle lake; construction of Nguyen Hue street extension which is 4.3km long consist of 3 sections; enlarge First of May (1 tháng 5) street section from Quan Mieu to QL61C – 2.6km long. Southern Institute of Water resources research H-13 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 155: General layout of investment proposal for Vi Thanh City Geographic data of 12 channels have been investigated in support for restoration activities. Table 57: Existing condition of concerned channels in Vi Thanh Cities Length Current width Current depth No Names (m) (m) (m) Thong Nhat 1 canal 594.532 11 -0.84 Thong Nhat 2 canal 425.59 8 -0.63 LIA3 Thong Nhat 3 canal 275.155 7.5 -0.98 Thong Nhat 4 canal 242.615 6.5 -0.76 Cai Nhuc Nho canal 906.839 9 -1.23 Phan Lo canal 903.586 9.5 -0.81 Lo 2 canal 587.073 7 -0.52 LIA7 Canal 1 296.37 4.5 -0.65 Canal 2 239.06 4.5 -0.65 Canal 3 293.64 5.5 -0.65 1 Cai Nhuc canal renovation 1906 22 -1.31 2 Canal 62 renovation 2200 20 -1.23 LIA 3: Thong Nhat canal: 600m long, one-end channel start close at Hau Giang people committee which later pour into canal 62. On average, it is 11m wide and bottom at level (-0.84m). Southern Institute of Water resources research H-14 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Thong Nhat 2 canal runs perpendicularly to Thong Nhat Canal, 425m long, 8m wide on average while bed located at (-0.63m). At present, this canal only crossing Thong Nhat canal, Thong Nhat 3 canal and Thong Nhat 4 canal while both of its end are almost blocked Thong Nhat 3 canal is bridge connection between Thong Nhat 2 and canal 62 which is 275m long, 7.5 wide, and bottom at level of (-0.98m). Thong Nhat 4 is bridge between Thong Nhat 2 and canal 62 which is 242. Long, 6.5m wide, and bottom level at (-0.76m). Drainage capacity is currently in good condition for LIA 3. However, LIA 3 is divided in to 2 major basins which are O Mon Xa No basin (consist of Thong Nhat 3 canal and Thong Nhat 4 canal which drain into canal 62 via sluice gate); and basin of outside O Mon Xa No (consist of Thong Nhat 1 and Thong Nhat 2 which drain into canal 62 not through sluice gate). On canal 62 have been already regulated by sluice gate which is 10m wide and threshold at (- 2.5m) level. This gate functions are control salinity and flooding for O Mon Xa No system. Figure 156: General layout of canal renovation in Vi Thanh City Southern Institute of Water resources research H-15 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 157: Renovation canals layout within LIA 3 LIA 7 Phan Lo canal connect directly from Quan De Mieu canal to Mieu Than Hoang which is 900m, average width is 9.5m and bottom level at (-0.81m). Small Cai Nhuc canal which is paralle to Phan Lo canal also connect from Quan De Mieu to Mieu Than Hoang which is 900m, 9m wide and bottom located at level of (-1.23m). “One” canal runs perpendicularly to Phan Lo canal and Cai Nhuc Canal, though not connect to Trung Doan canal which is 829m, 4.5m wide and bottom level at (-0.65m). Phan Lo 2 canal runs along Cai Nhuc canal and later flow into Trung Doan canal which is 587m long, 7m wide and bottom level at (-0.52m). Those canals are artificial channels which are straight and almost perpendicular to each other. However due to deposition, water is struggling from flowing freely. Southern Institute of Water resources research H-16 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 158: Renovation layout within LIA 7 H.5. Long Xuyen FS project In Long Xuyen, investments 04 LIAs: LIA1, LIA 3, LIA 5 and LIA 6; Extended Hung Vuong street; Tran Quang Dieu road; Embankment of Long Xuyen canal; Dredging, improving and constructing embankment and road for Cai Son canal; Dredging, improving and constructing embankment and road for Ba Bau canal; Dredging, improving and constructing embankment and road for Ong Manh canal. Southern Institute of Water resources research H-17 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 159: General layout of investment index at Long Xuyen city 3 canals have been geographic investigate to provide data for restoration. Figure 160: Renovation canal layout in Long Xuyen city Southern Institute of Water resources research H-18 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Table 58: Present condition of canal in Long Xuyen City Length Current No Name Current bottom level (m) (m) width (m) 1 Ong Manh canal renovation 1400 6 -0.05 2 Ba Bau canal renovation 900 4 +0.83 2 Cai Son canal renovation 1800 12 +0.19 Cai Son canal: is bridge connect from Tam Bot canal to Hau River, run through 91 interstate which is 1.8km long, ranging from 10-25m wide, bottom vary around (-0.05m) to (+1.4m). By going further inward the bottom is rising up, therefore needed to be dredged to promote flow discharge. On this canal there is no sluice gates but only bridges. Ba Bau canal: flow from nearby Ba Co Pagoda to Long Xuyen canal, crossing 943 interstate which is 900m long, 5-14m wide, bottom vary between (+0.83m) to (+1.65m). There is currently 1 controlling gate which located under 943 interstate and Bui Van Danh Street which is 1m wide. Figure 161: Ong Manh canal and Ba Bau canal current condition Ong Manh Canal initiates from Route 943, flow around resident region, under Route 943 again before merge to Long Xuyen Canal in total of 1.4km long. Its width varies from 4m to 15m and bottom level is around (+0.19m) to (+1.56m). Ong Manh Canal escape to both ends into Long Xuyen Canal. There is currently 1 underground culvert through Route 943 which is 3m wide and 1 other 1m wide culvert in resident region. Southern Institute of Water resources research H-19 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities H.6. Tan An FS project In Tan An, investments 04 LIAs: LIA1, LIA 2, LIA 3 and LIA 4 Lia 1 is located on Ward 1 and Ward 4 which cover total 7.8ha area which border within Nguyen Dinh Chieu, Thu Khoa Huan, and Nguyen Thong streets. Lia 2 is located on Ward 2 which is 2.7Ha limited within Hoang Hoa Tham and 1A interstate. Lia 3 is located on Ward 4 which is 20.1 ha, limited within 1A interstate and Luu Van Te and Nguyen Van Tao streets. Lia 4 is located on Ward 6 which is 21.4ha, limited within Nguyen Thi Bay, Le Van Kiet, Nguyen Thi Hang streets. Figure 162: General layout of investment index at Tan An City Three canals have been surveyed in supporting canal renovation. Table 59: Existing siotuationif canal in Tan An city Length Current No Name Current bottom level (m) (m) width (m) 1 Cau Tre Canal 1240 5 -1.3 2 Rach Rot Canal 1211 6 -1.20 3 Mui Tau canal 168 2 0.50 Southern Institute of Water resources research H-20 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Cau Tre canal is 1,240m long, initiate from Nguyen Cuu Van to 1 interstate which is 3-8m wide, bottom ranging around (+0.2m), bank crest level is (+1.7m). In the end of this canal, there is 1 crossing street sluice gate under Nguyen Cuu Van Street which is 1m wide. Rot canal is also regulated by 1m sluice gates under Nguyen Thi Hanh Street and local roads. The sluice gate under Nguyen Thi Hanh Street is equipped with lifting valve for tidal controlling and rainfall drainage. Figure 163: Plan view and current Figure 164: Plan view and current conditions of Rach Rot Canal in Tan An conditions of Cau Tre Canal in Tan An City City H.7. Soc Trang FS project For Soc Trang city, there are 2 working packages have been proposed which are: Restore and enhance Tra Men A canal capacity; Enhance Hitech canal, construct Nguyen Van Linh bridge; Bordering route 2 bridges and roads; restore and enhance Dien Bien Phu street; enhance drainage system at Ward 2 – city center. Southern Institute of Water resources research H-21 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 165: General layout of working package for Soc Trang city 2 canals have been geographic investigated for restoration and enhancement. Table 60: Existing siotuationof canal in Soc Trang city Current width No Name Length (m) Current bottom level (m) (m) 1 Tra Men canal renovation 2640 6 -0.20 2 Hitech canal renovation 3100 10 -0.07 Figure 166: Plan view of concerned canals in Soc Trang Southern Institute of Water resources research H-22 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Tra Men canal: located on Ward 6, Soc Trang City which is 2.64km long. Initiate from junction with Maspero canal, about 150m long, flow toward Xang canal and reach its end at 30/4 canal. Average width is about 12m, while bottom vary around (-0.2m). There are several controlling gates on this canal which are located under Dien Bien Phu street, Hung Vuong Street, and Huynh Phan Ho street. In our hydraulic calculation, we will cover drainage capacity of those gates. Figure 167: Plan view of existing sluice at Tra Men canal Hitech canal: located on Ward 9, 3.1km long, initiate from junction of Le Duan street and 30/4 street, runs all the way to west bank of Dinh river and 400m from Cay Diep bridge. Its average width is 10m, bottom ranging around (-0.07m) level. There is one water disposal located on upstream of this canal. On the other end is salinity controlling gate which consist of 2 panels, 1.4m wide each, bottom elevation at (-1.0m). The gate operating during flooding season, if upstream water level is too high it have to be opened for drainage, during drying season it stay closed for salinity controlling. Southern Institute of Water resources research H-23 Contract No. 7182300 Appendix H - Overview of feasibility studies information in seven cities Figure 168: Plan view of existing sluice at Hitech canal Southern Institute of Water resources research H-24