59895 VIETNAM ELECTRICITY POWER ENGINEERING CONSULTING JOINT STOCK COMPANY 4 ISO 9001:2000 Project: T .02.04 D ÁN TH Y I N TRUNG S N TRUNG SON HYDROPOWER PROJECT THI T K K THU T TECHNICAL DESIGN MÔ HÌNH V N HÀNH H CH A OPERATION MODEL OF RESERVOIR Nha Trang City, July 2010 Trung Son hydropower project Technical design CONTRIBUTORS No. Full name Task Signature 1 Vuong Anh Dung Preparing chapter 3 2 Nguyen Van De Preparing chapter 1 3 Nguyen Tien Phong Preparing chapter 2 4 Truong Hoai The Tuyen Preparing chapter 4 5 Phung Ngoc Tam Preparing chapter 4 6 Tran Minh Kha Checking Contributor i Trung Son hydropower project Technical design CONTENTS The document is established in below volume "Operation model of reservoir" Contents ii Trung Son hydropower project Technical design TABLE OF CONTENTS CHAPTER 1: ANNUAL FLOW SPECIFIC CALCULATION 1 1.1 FLOW CONDITION CALCULATION ON BASIN 1 1.2 CALCULATION OF ANNUAL AVERAGE FLOW IN LONG-TERM PERIOD AT TRUNG SON HYDROLOGICAL 5 1.3 DESIGN ANNUAL FLOW DISTRIBUTION AND ANNUAL FREQUENCY 10 1.4 DAILY FLOW RANGE TO TRUNG SON HYDROPOWER DAMSITE 11 CHAPTER 2: RESERVOIR ANALYSIS AND SIMULATION 12 2.1 PLANNING HYDROPOWER PROJECTS CASCADES ON MA RIVER 12 2.2 ADDITIONAL PLANNING HYDROPOWER PROJECTS CASCADES ON MA RIVER 13 2.3 MAIN PARAMETERS OF TRUNG SON HYDROPOWER PROJECT ­ TECHNICAL DESIGN STAGE 14 2.4 DATA FOR CALCULATION 16 2.5 CALCULATION, SIMULATION OF RESERVOIR 18 2.6 WITHOUT THANH SON RESERVOIR IN DOWNSTREAM OF TRUNG SON HYDROPOWER PLANT (CASE 1) 18 2.7 DOWNSTREAM WITH THANH SON RESERVOIR (CASE 2) 37 CHAPTER 3: WATER SUPPLY DEMAND FOR DOWNSTREAM 40 3.1 WATER DEMAND AT DOWNSTREAM 40 3.2 ENVIRONMENT FLOW RELEASE MEASURES 42 3.3 DISCHARGE OF WATER DURING OPERATION PROCESS 42 3.4 DISCHARGE OF MUD AND SAND 43 3.5 RESERVOIR DEWATERING 43 3.6 CONCLUSION 43 CHAPTER 4: RESERVOIR AND DOWNSTREAM LANDSLIDE POSSIBILITY FORECAST 44 4.1 RESERVOIR BANK LANDSIDE POSSIBILITY 44 4.2 EROSION RIVER BED OF RESERVOIR DOWNSTREAM 47 4.3 SLIDING AT BANKS OF DOWNSTREAM 48 APPENDIX ..............................................................................................................48 - Appendix calculation of hydrographical - Location chart of section calculation stability - Appendix calculation of reservoir bank stability - Appendix calculation reservoir downstream stability Table of contents iii Trung Son hydropower project Technical design Chapter 1: ANNUAL FLOW SPECIFIC CALCULATION 1.1 FLOW CONDITION CALCULATION ON BASIN Trung Son Hydrological station has been built and put into operation since Oct 2004, it is located about 400m downstream of Trung Son dam site. It measures all the factors: precipitation, water level, discharge, flood.. The difference between the basin areas of the damsites and Trung Son station is not remarkable, we can consider the flow to Trung Son hydrological station is equal to the flow to the damsite. Thus, the calculation result at the Trung Son hydrological station is equal to the calculation result at the damsites. There are hydrological stations at the upstream of Ma river: Muong Lat (water level, precipitation), Xa La (precipitation, water level, temperature, discharge..); at the downstream of the river, there are hydrological stations such as:Hoi Xuan (discharge, 1965 ­ 1970, water level, 1962 ­ 2008), Cam Thuy (water level, 1957 ­ 2008; discharge 1957 ­ 1976, 1995 ­ 2008)... besides, there are other hydrological stations at the tributaries such as Nam Ty, Nam Cong, Cua Dat, Lang Chanh... Due to the non-sychronous data and lack of data continuity observed at those stations, the flow calculation of Trung Son hydrological station mainly depends on the analysis method of flow correlation, co-ordinating with precipitation distribution and flow module analysis. The method is carried out between Trung Son hydrological station and 3 other hydrological stations that measure the discharge namely Cam Thuy, Hoi Xuan, Xa La. 1.1.1. Recovering the flow data at Cam Thuy Hydrological Station Cam Thuy hydrological station measured the water level and discharge from 1957 to 1976 with the standard of Level 1 hydrological station. From 1977 to 1994, it moved some kilometers downstream and downgraded, only measured water level. From 1995 up until now (2008), it moved to the old location and continued observing according to the station of level 1 station. Now, the water level data at Cam Thuy from 1977 to 1994 has been correlatively calculated by Hydro-meteorological General Bureau and brought back to water elevation of the old Cam Thuy hydrological station (it is also the location now) to unify the elevation. The relationship curve Q=F(H) is synthetized at Cam Thuy hydrological station in 1973, 1975, 1995. Then the discharge is interpolated from the relation Q=F(H) and daily water level data in 1977÷1994 Flow data chaining advent barrage calculation 1 Trung Son hydropower project Technical design After the calculation, we have the daily flow at Cam Thuy hydrological station from 1957 to 2008, average long-term flow is Qtb=346 m3/s. Summarization of monthly observed flow and calculated flow from 1957 to 2008 at Cam Thuy hydrological station are shown in Table 1 of the Appendices. 1.1.2. Recovering data at Hoi Xuan hydrological Station Hoi Xuan hydrological station has been measuring the water level from 1962 up until now (2008), it measured the discharge from 1965 to 1970. The recovering and addition to this flow data at Hoi Xuan hydrological station is carried out through 3 methods: 1) Calculation according to monthly average discharge in correlation with Cam Thuy hydrological station: The monthly average discharge correlation between Cam Thuy and Hoi Xuan hydrological stations from 1965 to 1970 Flood season: Correlation coefficient =0.989; Correlation equation: QHoi Xuan = 0.861*QCam Thuy ­ 5.14 (m3/s) Dry season: Correlation coefficient =0.984; Correlation equation: QHoi Xuan = 0.823*QCam Thuy+ 4.864 (m3/s) From this equation and the monthly average discharge at Cam Thuy hydrological station, we can calculate the data chain at Hoi Xuan hydrological station from 1957 ­ 1964, 1971 ­ 2008. According to that, the average annual discharge in long-term period at Hoi Xuan is 295 m3/s. 2) Calculation according to daily average discharge in correlation with Cam Thuy hydrological station: The daily average discharge correlation between Cam Thuy and Hoi Xuan hydrological stations from 1965 to 1970 January: the coefficient of =0.890. Correlation equation: QHoi Xuan = 0.694*QCam Thuy + 18.79 (m3/s) February: the coefficient of =0.900. Correlation equation: QHoi Xuan= 0.625*QCam Thuy + 25.09 (m3/s) March: the coefficient of =0.933. Correlation equation: QHoi Xuan= 0.770*QCam Thuy + 9.632 (m3/s) April: the coefficient of =0.927. Correlation equation: Flow data chaining advent barrage calculation 2 Trung Son hydropower project Technical design 3 QHoi Xuan = 0.825*QCam Thuy + 7.81 (m /s) May: the coefficient of =0,895. Correlation equation: QHoi Xuan = 0.704*QCam Thuy + 19.31 (m3/s) June: the coefficient of =0.942. Correlation equation: QHoi Xuan = 0.819*QCam Thuy + 9.512 (m3/s) July: the coefficient of =0.890. Correlation equation: QHoi Xuan = 0.765*QCam Thuy + 54.43 (m3/s) August: the coefficient of =0,965. Correlation equation: QHoi Xuan = 0.755*QCam Thuy + 84.42 (m3/s) September: the coefficient of =0.952. Correlation equation: QHoi Xuan = 0.740*QCam Thuy + 55.17 (m3/s) October: the coefficient of =0.956. Correlation equation: QHoi Xuan = 0.646*QCam Thuy + 61.63 (m3/s) November: the coefficient of =0.936. Correlation equation: QHoi Xuan = 0.590*QCam Thuy + 59.62 (m3/s) December: the coefficient of =0.902. Correlation equation: QHoi Xuan = 0.936*QCam Thuy ­ 8.29 (m3/s) Based on these equations and the daily average discharge at Cam Thuy hydrological station can calculate data chain at Hoi Xuan hydrological station from 1957 ­ 1964, 1971 ­ 2008. Thence, the long-term average discharge at Hoi Xuan is 289 m3/s. 3) Calculation according to water level data and the relation Q=F(H) Water level data at Hoi Xuan hydrological station from 1957-1961 was recovered from water level data at Cam Thuy hydrological station by correlation method. Cam Thuy hydrological station measured discharge and level water from 1957 - 1976. After, it's displaced to downstream and measured level water only. In 1995, it's displaced again to return the initial location, and upgraded to measure both discharge and level water. The level water data at Cam Thuy hydrological station from 1977 - 1994 is calculated and converted. Hence, daily average level water in every month in correlation between Cam Thuy hydrological station and Hoi Xuan hydrological station is carried out from 1962 - 1976. Flow data chaining advent barrage calculation 3 Trung Son hydropower project Technical design January: the coefficient of =0.868. Correlation equation: HHoi Xuan = 1.56*HCam Thuy+ 3,386 (cm) February: the coefficient of =0.831. Correlation equation: HHoi Xuan = 1.15*HCam Thuy + 3863 (cm) March: the coefficient of =0.889. Correlation equation: HHoi Xuan = 1.55*HCam Thuy + 3407 (cm) April: the coefficient of =0.927. Correlation equation: HHoi Xuan = 1.44*HCam Thuy + 3526 (cm) May: the coefficient of =0.840. Correlation equation: HHoi Xuan = 1.06*HCam Thuy + 3972 (cm) June: the coefficient of =0.957. Correlation equation: HHoi Xuan = 1.08*HCam Thuy + 3960 (cm) July: the coefficient of =0.962. Correlation equation: HHoi Xuan = 0.922*HCam Thuy +4167 (cm) August: the coefficient of =0.936. Correlation equation: HHoi Xuan = 0.912*HCam Thuy + 4188 (cm) September: the coefficient of =0.965. Correlation equation: HHoi Xuan = 0.936*HCam Thuy + 4139 (cm) October: the coefficient of =0.954. Correlation equation: HHoi Xuan = 0.887*HCam Thuy + 4202 (cm) November: the coefficient of =0.900. Correlation equation: HHoi Xuan = 1.02*HCam Thuy + 4031 (cm) December: the coefficient of =0.808. Correlation equation: HHoi Xuan = 1.61*HCam Thuy + 3332 (cm) Based on these equations and daily average level water at Cam Thuy hydrological station can calculate data chain at Hoi Xuan hydrological station from 1957 - 1961 The relation curve Q=F(H) is synthesized from Hoi Xuan's observed data in 1965-1970. Then, the daily flow data chain at Hoi Xuan hydrological station from 1957 ­ 1964 and 1971- 2008 is calculated based on the over relation curve Q=F(H) and water level data. Hence, the long-term average discharge at Hoi Xuan is 290 m3/s Flow data chaining advent barrage calculation 4 Trung Son hydropower project Technical design Over results (calculated by three methods) are not different much. The daily average discharge correlation method with Cam Thuy hydrological station (Method 2) reflects the reality of the river flow, having high coefficient, giving values close to values calculated by water level and the relation curve Q=F(H) method, and reducing the errors due to the changes of river bed through many years. Thus, it is chosen. Hence, the long-term average flow at Hoi Xuan hydrological station is 289 m3/s. The synthesized results of monthly flow data chain at Hoi Xuan hydrological station is in Table 2 in the appendices. 1.2 CALCULATION OF ANNUAL AVERAGE FLOW IN LONG-TERM PERIOD AT TRUNG SON HYDROLOGICAL 1.2.1. Daily average water level data recovery method Create the correlation relationship of daily average water level between Trung Son and Hoi Xuan hydrological stations from 01 January 2005 to 31 December 2008, the achieved correlation coefficient is =0,949 and correlation equation is as follows: HTrung Son = 0.707*HHoi Xuan + 5131 (cm) February: the coefficient of =0.914. Correlation equation: HTrung Son = 0.328*HHoi Xuan + 7105 (cm) June: the coefficient of =0.914. Correlation equation: HTrung Son = 0.637*HHoi Xuan + 5493 (cm) July: the coefficient of =0.958. Correlation equation: HTrung Son = 0.820*HHoi Xuan + 4525 (cm) August: the coefficient of =0.947. Correlation equation: HTrung Son = 0.934*HHoi Xuan + 3919 (cm) September: the coefficient of =0.899. Correlation equation: HTrung Son = 0.883*HHoi Xuan + 4194 (cm) October: the coefficient of =0.935. Correlation equation: HTrung Son = 0.634*HHoi Xuan + 5520 (cm) November: the coefficient of =0.918. Correlation equation: HTrung Son = 0.565*HHoi Xuan + 5879 (cm) December: the coefficient of =0.928. Correlation equation: HTrung Son = 0.534*HHoi Xuan + 6038 (cm) Flow data chaining advent barrage calculation 5 Trung Son hydropower project Technical design The coefficient of Jan, Mar, Apr, May months is smaller than 0.8. Thus, correlation equation of this are taken general correlation equation: HTrung Son = 0.707*HHoi Xuan + 5131 (cm) With these equations and the water level data at Hoi Xuan can recover the water level data at Trung Son in the period of 1957-2004. The correlation curve Q=F(H) at Trung Son station is synthetized from observed data in the period 2005 ÷ 2008. Then, calculating the daily flow data chain at Trung Son station in the period of 1957÷ 2004 from the water level data and the synthetized relationship Q=F(H). Hence, the long-term average discharge is 216 m3/s. 1.2.2. Flow correlation method with Cam Thuy hydrological station - Creating the monthly average discharge correlation between Cam Thuy and Trung Son stations from January 2005 to December 2008 Flood season: Correlation coefficient is =0.954. Correlation equation: QTrung Son = 0.636*QCam Thuy - 3,27 (m3/s) Dry season: Correlation coefficient is =0.941. Correlation equation: QTrung Son = 0.506*QCam Thuy + 20,45 (m3/s) With these equations and discharge at Cam Thuy hydrological station can calculate the flow data chain at Trung Son station from 1957- 2004. Hence, the average discharge in long-term period (1957-2008) is 218 m3/s. - Creating the daily average discharge correlation between Cam Thuy and Trung Son stations from January 2005 to December 2008 Average calculation result from 01 January 2005 to 31 December 2008, correlation coefficient is =0,922. Correlation equation is as below: QTrung Son = 0.545*QCam Thuy + 30.6 (m3/s) January: the coefficient of =0.947. Correlation equation: QTrung Son = 0.654*QCam Thuy ­ 1.04 (m3/s) February: the coefficient of =0.876. Correlation equation: QTrung Son = 0.745*QCam Thuy ­ 11.69 (m3/s) March: the coefficient of =0.852. Correlation equation: QTrung Son = 0.651*QCam Thuy ­ 2.43 (m3/s) Flow data chaining advent barrage calculation 6 Trung Son hydropower project Technical design April: The coefficient of April is smaller than 0.8. Thus, the correlation equation of this is taken genera correlation equation: QTrung Son = 0.545*QCam Thuy + 30.6 (m3/s) May: The coefficient of May is smaller than 0.8. Thus, the correlation equation of this is taken genera correlation equation: QTrung Son = 0.545*QCam Thuy + 30.6 (m3/s) June: the coefficient of =0.901. Correlation equation: QTrung Son = 0.674*QCam Thuy ­ 23.08 (m3/s) July: the coefficient of =0.871. Correlation equation: QTrung Son = 0.661*QCam Thuy ­ 7.65 (m3/s) August: the coefficient of =0.899. Correlation equation: QTrung Son = 0.622*QCam Thuy + 44.74 (m3/s) September: the coefficient of =0.876. Correlation equation: QTrung Son = 0.512*QCam Thuy + 103.23 (m3/s) October: the coefficient of =0.936. Correlation equation: QTrung Son = 0.387*QCam Thuy + 112.22 (m3/s) November: the coefficient of =0.882. Correlation equation: QTrung Son = 0.341*QCam Thuy + 95.14 (m3/s) December: the coefficient of =0.971. Correlation equation: QTrung Son = 0.756*QCam Thuy ­ 11.47 (m3/s) Calculate the daily discharge data chain at Trung Son station in the period of 1957÷ 2004 based on these correlation equations and daily average discharge at Cam Thuy hydrological station. Hence, average annual discharge in long-term period is 229 m3/s. 1.2.3. Flow correlation method with Xa La station Creating the monthly average discharge correlation between Xa La and Trung Son station from January 2005 to December 2008 In flood season, the coefficient is =0.758. It is too small to calculate and recover flow data at Trung Son station. So, data in flood months is recovered and calculated by correlation relation among months in the whole year. The synthesized coefficient of Flow data chaining advent barrage calculation 7 Trung Son hydropower project Technical design months from 2005 to 2008 between Xa La and Trung Son stations is D=0.875. The correlation equation is as below: QTrung Son = 1.638*QXa La + 45.61 (m3/s) In dry season, the coefficient =0.893. The correlation equation: QTrung Son = 1.75*QXa La + 26.17 (m3/s) Based on these equations and discharge at Xa La station can calculate flow data chain at Trung Son station from 1961- 2004. Hence, average annual discharge in long- term period at Trung Son is 235 m3/s. 1.2.4. Flow correlation method with Hoi Xuan hydrological station Creating the monthly average discharge in correlation between Hoi Xuan and Trung Son station from I/2005 to XII/2008. In flood season, the coefficient =0.968. The correlation equation: QTrung Son = 0.836*QHoi Xuan ­ 34.78 (m3/s) In dry season, the coefficient ( =0.692) is too small to correspond with calculating and recovering flow data at Trung Son station. So, data in dry months is recovered by correlative relation among months in the whole year. The synthesized coefficient of months from 2005 to 2008 between Hoi Xuan and Trung Son is D=0.964. The correlation equation: QTrung Son = 0.801*QHoi Xuan ­ 20.01 (m3/s) From these equations and discharge at Hoi Xuan hydrological station, we can flow data chain at Trung Son station from 1957 to 2004. According to that, average annual discharge in long-term period at Trung Son is 213 m3/s. 1.2.5. Flow module analysis method The flow module distribution on Ma river is as follows: Table 1.1: The flow module at some stations in Ma river basin Station Area (km2) Period Qaver (m3/s) M (l/s/km2) Cam Thuy 18,879 1957÷2008 346 18.3 Hoi Xuan 16,850 1957÷2008 289 17.2 Xa La 6,430 1961÷2008 120 18.7 Flow data chaining advent barrage calculation 8 Trung Son hydropower project Technical design Trung Son station is located between Hoi Xuan and Xa La stations, the flow module of Trung Son station is M= 17.5 l/s/km2, calculated by interpolation method. Thus, can calculate the annual average discharge at Trung Son station Q= 257 m3/s. The flow data at Hoi Xuan hydrological station is recovered mainly; data at Cam Thuy and Xa La stations is more adequate. Use interpolation method to calculate flow module to Trung Son station from relation between area and flow module of Cam Thuy and Xa La stations. According to this method, the flow module to Trung Son station will be M= 18.4 l/s/km2. Thus, the long-term average discharge at Trung Son station can calculated Q= 270 m3/s. The analysis of precipitation changes in the mid-areas from Cam Thuy to Hoi Xuan and from Hoi Xuan to Trung Son shows that the average annual rainfall in long- term period from Cam Thuy to Hoi Xuan is about 1850 mm; from Hoi Xuan to Trung Son is about 1600 mm. The application of area rate method plus basin average rainfall rate method due to mid-basin from Cam Thuy to Hoi Xuan. The average annual discharge at Trung Son will be equal to the average annual discharge in long-term period at Hoi Xuan minus the mid-area. QTrung Son = 236 m3/s. 1.2.6. Analyse, choose the results of flow calculation to Trung Son dam site Table 1.2: Synthesized results of annual average flow in long-term period at Trung Son station according to different methods Method Q0 M0 1. Interpolating Water data and the relationship Q=F(H) 216 14.7 2. Monthly average discharge correlation with Cam Thuy 218 14.9 hydrological station 2. Daily average discharge correlation with Cam Thuy 229 15.6 hydrological station 3. Discharge correlation with Xa La station 235 16.0 4. Discharge correlation with Hoi Xuan hydrological station 213 14.5 5. Interpolating flow module Hoi Xuan ­ Xa La 257 17.5 6. Interpolating flow module Cam Thuy ­ Xa La 270 18.4 7. Mid-area discharge deduction from Hoi Xuan to Trung 236 16.1 Average 234 16.0 Due to the complexity of the precipitation and flow distribution on Ma river ­ the part on Laos territory has less rainfall than on Vietnam, so the calculation results by the different methods will be different as well. Each method has its own advantages and disadvantages. The water level data retrieval method at Trung Son station from Flow data chaining advent barrage calculation 9 Trung Son hydropower project Technical design Hoi Xuan hydrological station is easy to cause errors because the parallel measured water level data chain is short, the water level in serious flood years isn't measured sufficiently and the cross sections are changed after years. The data chain from 1977 ­ 1994 at Cam Thuy hydrological station is achieved through calculation and recovery from the water level and relationship Q=F(H), the parallel measured data chain between Cam Thuy and Trung Son is still short, thus the monthly average flow correlation method between Trung Son and Cam Thuy is not fully trusted. It is similar to above mention, the correlation method between Trung Son and Xa La also have a short parallel observed data chain; their correlation coefficient is not much great; Ma river, after flowing cross Laos territory where rainfall is small, flow amplitude changes a little bit, thus results achieved by this method isn't completely trusted. The method considering flow module progress based on the measured data at the hydrological stations on Ma river basin, considering the effect of rainfall distribution on the basin, can determine quite exactly the long-term average flow but determining exactly the average annual precipitation in the basin is difficult, so it is difficult to determine exactly the annual flow. The average flow value achieved from these above methods are QTrung Son = 234 3 m /s, MTrung Son = 16,0 l/s/km2, these values are equal to the discharge depreation method at mid-area with the mean rain fall (QTrung S n = 236 m3/s), nearly the same with the result of discharge correlation with Xa La station method (QTrung S n = 235 m3/s). As change a number of calculating years, the average annual runoff value at Trung Son station fluctuates around at 235 m3/s, recommend to choose this result Q0Trung Son = 235 m3/s 1.3 DESIGN ANNUAL FLOW DISTRIBUTION AND ANNUAL FREQUENCY 1.3.1. Monthy average flow range To achieve a nearly correct flow distribution at Trung Son station, the flow distribution following the daily average flow correlation wih Cam Thuy hydrological station has been used, with the modification according to the chosen average flow in the long-term period. The results are as in table 3, Appendixes. 1.3.2. Seasonal flow rate Based on the observed and calculated flow data at Trung Son station (1957 ­ 2007) carry out the seasonal flow classification according to the over-average standard, the results achieved are: flood season starts from June, ends in October; dry Flow data chaining advent barrage calculation 10 Trung Son hydropower project Technical design season starts from November, ends in next May. The results are in table 4 in the appendices. 1.4 DAILY FLOW RANGE TO TRUNG SON HYDROPOWER DAMSITE By correlation relation analysis, the flow correlation in Ma river at Trung Son with Hoi Xuan and Cam Thuy is better than with Xa La. This difference shows that the natural condition in Ma river is: heavy rain in the upstream, small rain in Laos territory and gradually heavier from Trung Son to Cam Thuy, the area difference between Trung Son and Hoi Xuan, Cam Thuy is smaller than between Trung Son and Xa La. Hoi Xuan hydrological station has an short observed daily discharge data chain (1965-1970), the data of the remaining years (1957÷ 1964, 1971÷ 2008) are achieved by recovering calculation, the old relation Q=F(H) (synthetized from 1965 - 1970) is not measured to check the changes in the following years, thus it is easily to cause errors. Cam Thuy hydrological station has a longer observed data chain (1957÷ 1976, 1995÷ 2008), the calculated recovering flow data chain (1977÷ 1994) has a close base, the relation Q= F(H) is synthetized according to the years before 1977 and after 1994. Thus, flow distribution reflects the reality, can trust well, and choose to calculate flow distribution at Trung Son hydrological station. The daily discharge chain (1957-2004) at Trung Son station is chosen according to daily average discharge correlation calculation results with Cam Thuy hydrological station, in which: using separate correlation equations for each month and calculating is in the adjustment to get average annual discharge at Trung Son, Qaver=235 m3/s. The synthetized results of daily average discharge at Trung Son station are summarized in the report of "Reservoir operation process". Flow data chaining advent barrage calculation 11 Trung Son hydropower project Technical design Chapter 2: RESERVOIR ANALYSIS AND SIMULATION 2.1 PLANNING HYDROPOWER PROJECTS CASCADES ON MA RIVER On March 31, 2005, Ministry of Industry (presently called as Ministry of Industry and Trade) issued decision No.1195/Q -NLDK, concerning "approval on planning of hydropower cascades on Ma river", main contents as below: - Exploiting scheme of hydropower cascades projects and main task of hydropower projects on Ma river: + On Ma river tributary, there are 05 multi-purposes hydropower reservoirs projects Pa Ma hydropower project, with normal water level at 455m, installed capacity of 80MW; main tasks are water supply and flood control; combined with electric power generation. Huoi Tao hydropower project: normal water level at 380m, installed capacity of 180MW; main task are water supply and flood control; combined with electric power generation. Trung Son hydropower project: normal water level at 160m, installed capacity of 280MW; main task are electric power generation and flood control. Hoi Xuan hydropower project: normal water level at 80m, installed capacity of 92MW; main task are electric power generation and water supply. Cam Ngoc hydropower project: normal water level at 50m, installed capacity of 145MW; main tasks are water supply, combined with electric power generation. + In Chu River tributary, there are 02 hydropower projects Hua Na hydropower project, normal water level at 240m, installed capacity of 180MW; main tasks are electric power generation and flood control. Cua Dat hydropower project, normal water level at 119m, installed capacity of 97MW. This project is under operation. Main tasks are water supply and flood control, combined with electric power generation. - Flood control storage capacity at respective reservoirs + Total flood control storage capacity on Ma River is estimated approximately 700 million m3 respectively at Pa Ma reservoir (about 200 million m3), Huoi Tao (about 300 million m3), Trung Son reservoir (maximum 200 million m3). It is required to substantiate presisely in details the distribution flood control storage capacity between cascades in Ma River when establishing Feasibility Study, with consideration of all actual topographical, geological condition of the project as well as in the downstream area, proposed other Analysis and simulation of reservoir 12 Trung Son hydropower project Technical design reservoirs in Ma River construction time according to water resource development program, to ensure economical and technical requirements. + Total flood control storage capacity on Chu River is estimated approximately at 400 million m3, respectively at Cua Dat hydropower reservoir at 300 million m3 and Hua Na hydropower reservoir at 100 million m3 - Priority sequence construction of projects: + Hydropower projects to be constructed in the first stage: Cua Dat and Hua Na projects on Chu River, Trung Son project in Ma River + Hydropower projects to be studied as multipurpose: Hoi Xuan, Cam Ngoc, Pa Ma, Huoi Tao projects on Ma river (detail at appendix: attachment legal documents) 2.2 ADDITIONAL PLANNING HYDROPOWER PROJECTS CASCADES ON MA RIVER On April 18, 2008, Ministry of Industry and Trade issued decision No.2383/Q -BCT converning "approval on additional planning hydropower project cascades on Ma River", with main contents, as below: - Additional planning Thanh Son hydropower project on Ma river cascades was approved by Ministry of Industry (presently called as Ministry of Industry and Trade) at decision No. 1195/Q -NLDK dated on March 31, 2005 with main contents, as below: + Construction site: On the main stream of Ma river at the Thanh Son and Trung Thanh communes, Quan Hoa district, Thanh Hoa Province, with coordinates (VN-2000 system): X= 2 277 459.6 and Y= 490 006.9 + Task and exploiting scheme of project: Project has main task is power generation. The hyro energy exploiting scheme consisting of main dam and spillway with dam-toe hydropower plant type. + Main parameters of project: Catchment basin area calculated to damsite Flv = 13.275Km2, annual average discharge Q0= 246 m3/s, normal water level = 89m, tailrace water level MNHLmin= 78.5m, rated water head Htt= 8.8m and installed capacity Nlm= 37MW - Investment of Thanh Son hydropower project must be complied with socio- economic development plans, land and water resource use plans, electric power development plan in the Thanh Hoa province; synchronously with power load development situation as well as investment of electric power transmission network in region as planned by Vietnam Electricity. - In feasibility study stage of Thanh Son hydropower project, Thanh Hoa Provincial People's Committee shall be responsible to give directives, inspection and consideration of below issues: + Additional investigation, survey on natural conditions (topographical, geological, hydrological conditions, etc,..) for project area, precisely Analysis and simulation of reservoir 13 Trung Son hydropower project Technical design calculate relation curve between water level and discharge at tailrace of powerhouse. + Precisely calculate normal water level of hydropower reservoir based on calculation of surge water level to the end of reservoir caused by flood, to ensure no influence on electric energy efficiency and safety operation of Trung Son hydropower plant at upstream. + The spillway of Thanh Son hydropower project shall be designed in such a manner to ensure release safely checked flood discharge from Trung Son hydropower project in accordance with regulation specified in design standards and codes.. + Updating parameters such as upstream and downstream water level and power generation discharge of Trung Son and Hoi Xuan hydropower cascade projects (downstream side). Analysis, comparison to make accuracy of main parameters of project, especially installed capacity to ensure effective exploitation of project as well as electric power transmission network + Investigate, survey and establish compensation and resettlement plan for project, to ensure compliance with current relevant State regulation. 2.3 MAIN PARAMETERS OF TRUNG SON HYDROPOWER PROJECT ­ TECHNICAL DESIGN STAGE In the technical design stage, the main tasks of project are defined as below: - With regards of electric power generation, installed capacity is Nlm = 260MW, annual electric energy Eo=1018.61 million kWh. - In terms of flood control, the reservoir flood control storage capacity is 150 million m3 in which regular flood control storage capacity of 112 million m3 . Flood control period is 02 consecutive months of main flood season from 15th July to 15th September annually. Table 2-1: Main parameters of Trung Son hydropower project No. Description Unit Value I Basin characteristics 1 Catchment area Km2 14660 2 Average long-term rainfalls X0 mm 1 420 3 Average long-term flow (Qo) m3/s 235 4 Total annual flow Wo 106m3 7411 II Reservoir 1 Normal water level (NWL) m 160 2 Dead water level m 150 3 Water level before flood m 150 4 Flood storage volume Wpl 106m3 112 5 Reservoir storage volume corresponding to normal 106m3 348.53 Analysis and simulation of reservoir 14 Trung Son hydropower project Technical design No. Description Unit Value water level Wbt Effective storage volume, flood storage volume 6 106m3 112.13 Wpl 7 Dead storage volume Wc 106m3 236.40 Reservoir surface area corresponding to normal 8 km2 13.13 water level 9 Flood peak discharge corresponding to frequencies - P= 0.1 % m3/s 13 400 - P= 0.5 % m3/s 10 400 - P= 1 % m3/s 9 100 - P= 5 % m3/s 6 200 III RCC dam 1 Dam crest elevation m 162.8 2 Dam crest length (Lÿ) m 513.0 3 Max. dam height m 84.5 4 Dam crest width (b) m 8 5 Upstream slope (m) 0.35 6 Downstream slope (m) 0.65 IV Spillway 1 Spillway sill elevation m 145 2 Number of spillway cells 6 3 Spillway span BxH m 14x15 4 Orifice dimension of radial gate BxH m 14x15.5 5 Design flood released discharge P=0.5% m3/s 9 900 6 Checked flood released discharge P=0.1% m3/s 12 534 7 Dissipation structure Flip bucket V Waterway A Power intake gate 1 Power intake gate sill elevation m 135 2 Orifice dimension of trash rack nxBxH m 8x5.5x11 3 Orifice dimension of maintenance stop logs nxBxH m 1x5.5x5.5 4 Orifice dimension of operation gate nxBxH m 4x5.5x5.5 B Penstock 1 Penstock diameter m 5.5 2 Total length of one penstock m 229.57 3 Gradient slope of penstock % 13.95; 46.63 4 Penstock shell thickness mm 16-18 C Powerhouse characteristics 1 Turbine type Francis 2 Number of units 4 3 Installed capacity Nlm MW 260 4 Firmed capacity Nbÿ MW 41.80 5 Max. head Hmax m 72.02 Analysis and simulation of reservoir 15 Trung Son hydropower project Technical design No. Description Unit Value 6 Min. head Hmin m 51.32 7 Average head Htb m 66.30 8 Rated head Htt m 56.50 9 Max. discharge Qmax through turbine m3/s 522 10 Average annual generated electricity E0 106 KWh 1018.61 Number of power generated hours at installed 11 hour 3918 capacity D Tailrace channel 1 Bottom width (b) m 79.7 2 Slope factor (m) 0.5 ÷ 1.5 3 Gradient slope of channel bottom (i) 0.0001 4 Tailrace channel length (L) m 80 2.4 DATA FOR CALCULATION - Reservoir regulation curve: Coordinate on regulation curves of Trung Son hydropower project are shown in below table: Table 2-2: Water level on regulation curves of Trung Son hydropower project No. Month NWL(m) CXT PPH HCCN MWL(m) 1 June 160.0 160.00 160.00 150.00 150.0 2 July 160.0 150.00 150.00 150.00 150.0 3 Aug 160.0 150.00 150.00 150.00 150.0 4 Sept 160.0 160.00 160.00 150.00 150.0 5 Oct 160.0 160.00 160.00 157.00 150.0 6 Nov 160.0 160.00 160.00 156.60 150.0 7 Dec 160.0 160.00 160.00 155.50 150.0 8 Jan 160.0 160.00 160.00 154.30 150.0 9 Feb 160.0 160.00 160.00 153.10 150.0 10 Mar 160.0 160.00 160.00 152.50 150.0 11 Apr 160.0 159.00 158.20 151.70 150.0 12 May 160.0 158.00 155.40 150.50 150.0 Remark: + NWL: Normal water level. + CXT: Redundant discharge control regulation curve + PPH: Critical reservoir water level regulation curve + HCCN: Limit water supply regulation curve + MNC: Minimum water level. - 24 hours average flow to damsite of Trung Son hydropower project: see in chapter 1 Analysis and simulation of reservoir 16 Trung Son hydropower project Technical design - Reservoir characteristic curve: reservoir characteristic curve is set up on the map of 1/10,000 scale, established in 2003 by Power Engineering Consulting Joint Stock Company 4 with aerial photograph method. The results are as below: Table 2-3: Reservoir characteristic curve of Trung Son hydropower project Elevation Area Storage volume No. Z (m) F (km2) V (106m3) Remarks 1 85.0 0.0 0.0 2 90.0 0.3 0.6 3 95.0 0.5 2.6 4 100.0 1.1 6.4 5 105.0 1.7 13.2 6 110.0 2.2 22.7 7 115.0 2.8 35.1 8 120.0 3.5 50.9 9 125.0 4.4 70.6 10 130.0 5.1 94.1 11 135.0 5.9 121.6 12 140.0 7.0 153.9 13 145.0 8.2 191.9 14 150.0 9.6 236.4 MWL 15 155.0 11.1 288.1 16 160.0 13.1 348.5 NWL 17 165.0 15.2 419.3 18 170.0 17.6 501.2 - Relation curve between discharge and tailrace water level of Trung Son hydropower plant was set up based on hydraulic calculation formulas and river cross section, river bed longitudinal profile, investigation historical flood,...The results are as below: Table 2-4:Relation curve between discharge and tailrace water level of Trung Son hydropower plant Discharge Water level Discharge Water level No. No. Q (m3/s) Z (m) Q (m3/s) Z (m) 1 0 85.90 17 300 90.51 2 10 86.71 18 350 90.76 3 20 87.27 19 400 90.98 4 30 87.82 20 500 91.39 5 40 88.37 21 600 91.78 6 50 88.67 22 700 92.14 7 60 88.81 23 800 92.48 Analysis and simulation of reservoir 17 Trung Son hydropower project Technical design Discharge Water level Discharge Water level No. No. Q (m3/s) Z (m) Q (m3/s) Z (m) 8 80 89.05 24 1000 93.12 9 100 89.25 25 1500 94.48 10 120 89.42 26 2000 95.66 11 150 89.66 27 3000 97.63 12 180 89.86 28 4000 99.41 13 200 89.98 29 5000 100.90 14 220 90.10 30 7000 103.82 15 250 90.26 31 8000 105.06 16 280 90.42 32 10000 107.38 - Efficiency of hydropower plant: Efficiency of unit at the calculation time depends on rated water head and discharge through turbine. In the calculation of daily hydro-energy operation of reservoir simulation, average efficiency of powerhouse is selected at 0.88. 2.5 CALCULATION, SIMULATION OF RESERVOIR The process of reservoir simulation calculation is executed according hydrological years, with hydrological calculation data obtaned in 50 years starting from June 1, 1975 to May 31, 2007. On the basic of the data calculation as mentioned above, calculating hydro- energy simulation in two cases: - Without Thanh Son reservoir in downstream of Trung Son hydropower plant - With Thanh Son reservoir in downstream of Trung Son hydropower plant 2.6 WITHOUT THANH SON RESERVOIR IN DOWNSTREAM OF TRUNG SON HYDROPOWER PLANT (CASE 1) 2.6.1. Electric energy (Case 1) - The results of hydro energy calculation shown that the Energy difference between daily flow and monthy flow for calculation is about -4.6%. The results of calculation reflected variation in simulation operation of reservoir according to average daily flow and average monthy flow. Trung Son reservoir has small regulation coefficient E= 0.015. Furthermore, the reservoir uses 2 months period as flood control for lowlands (from 15th July to 15th September annualy, reservoir water level at 150.0m elevation) hence regulation capacity of the reservoir in such period is not well enough. During flood control period, when natural inflow to reservoir is greater than maximum discharge for power generation, the redundant discharge will be released through the spillway (such Analysis and simulation of reservoir 18 Trung Son hydropower project Technical design redundant discharge shall not be considered as reservoir storage volume). The monthy average flow covers the average flow of incoming floods to reservoir, so, the redundant discharge through spillway of about 9% was calculated in reservoir discharge simulation. The daily average flow shown the incoming floods to the reservoir, so, the redundant discharge through spillway of 14% was calculated in reservoir discharge simulation. (greater than simulation of monthy average flow). According evaluation made by Design Consultant, the hydro energy simulation calculation results by daily average flow are more reliable than the hydro energy simulation calculation results by monthy average flow. Table 2-5: Results of hydro-energy calculation of Trung Son HPP using daily flow data, without Thanh Son reservoir in downstream of powerhouse ----------------------------------------------------------------- | No | Qs | Qtbin | Qx | Htt | N | E | ----------------------------------------------------------------- 1. 112.70 112.17 .00 65.31 63.78 558.68 2. 184.43 165.79 14.50 67.44 93.59 819.86 3. 193.34 172.10 23.60 66.49 96.13 842.10 4. 290.12 225.92 60.81 66.89 125.47 1099.11 5. 234.88 200.85 33.33 67.35 114.49 1002.94 6. 225.50 198.62 26.29 67.42 112.92 989.14 7. 285.93 232.26 53.08 67.02 130.67 1144.65 8. 265.17 222.07 42.51 67.15 125.65 1100.68 9. 196.35 188.96 7.71 67.35 107.41 940.95 10. 259.87 211.02 47.38 67.16 117.19 1026.60 11. 205.69 183.57 21.52 67.59 103.84 909.67 12. 154.83 143.59 14.07 66.23 81.86 717.09 13. 186.31 168.94 13.41 66.88 94.47 827.54 14. 232.57 212.00 19.99 67.17 118.57 1038.68 15. 253.44 200.21 52.65 67.28 111.19 974.03 16. 249.88 206.54 42.76 67.27 116.24 1018.25 17. 341.71 233.54 107.58 66.94 130.34 1141.74 18. 228.45 212.48 15.39 67.32 121.21 1061.83 19. 274.81 214.58 59.65 67.19 121.91 1067.91 20. 233.28 199.87 32.82 67.40 113.95 998.16 21. 221.72 209.59 11.55 67.37 119.18 1043.98 22. 314.56 272.84 41.13 66.71 154.54 1353.73 23. 238.89 220.43 17.92 67.31 124.91 1094.21 24. 255.04 208.25 46.16 67.35 118.06 1034.22 25. 255.54 237.42 17.54 67.05 134.30 1176.43 26. 292.48 246.29 45.60 66.94 139.44 1221.46 27. 203.34 186.93 15.83 67.61 107.85 944.77 28. 228.78 214.81 13.38 67.31 122.77 1075.48 29. 249.90 218.34 30.97 67.31 125.13 1096.15 30. 207.13 200.24 6.31 67.48 114.14 999.85 31. 175.81 161.98 13.23 67.84 93.08 815.42 32. 175.43 158.94 15.91 67.84 91.86 804.68 33. 229.75 205.65 23.51 67.37 118.08 1034.39 34. 275.91 234.00 41.32 66.99 131.43 1151.34 35. 206.27 181.01 24.68 67.58 101.18 886.35 36. 155.24 149.25 5.40 67.94 85.82 751.76 37. 172.08 164.69 6.80 67.83 94.78 830.31 38. 340.05 250.28 90.25 66.27 138.95 1217.23 39. 263.38 208.67 53.06 67.16 116.12 1017.22 40. 354.29 243.20 110.50 66.72 136.92 1199.39 41. 277.88 206.47 70.81 67.32 116.53 1020.81 42. 136.77 135.86 3.59 65.87 77.28 676.99 Analysis and simulation of reservoir 19 Trung Son hydropower project Technical design 43. 226.20 203.78 18.60 67.30 115.69 1013.43 44. 249.11 221.13 27.39 67.29 124.98 1094.86 45. 292.05 248.47 42.99 66.86 139.14 1218.85 46. 333.96 269.39 63.98 66.56 151.24 1324.91 47. 242.04 223.27 18.18 67.27 128.20 1123.05 48. 248.41 218.69 29.38 67.29 123.05 1077.94 49. 264.07 206.05 57.20 67.24 116.84 1023.55 50. 161.65 146.66 17.94 67.84 82.89 726.09 ----------------------------------------------------------------- --------------------------------------------------------------------------------------------------- |TT| NWL | MWL | Vtb | Vc | Vhi | Vplu | Q0 | Qtbin | Qxa | Qdb | Qmax | Hmax | --------------------------------------------------------------------------------------------------- 1. 160.00 150.00 348.53 236.40 112.13 112.13 237.14 203.15 33.40 66.53 504.0 71.07 --------------------------------------------------------------------------------------------------- |TT| Hmin | Htb | Nlm | Ndb | Ntb | E0 | Elu | Eki | Emua | Ekho | Hsd | Beta | --------------------------------------------------------------------------------------------------- 1. 48.05 64.85 260.00 41.75 114.91 1006.57 649.00 357.57 549.13 457.44 3871. .0150 --------------------------------------------------------------------------------------------------- In which: - Qs: Incoming discharge to Trung Son dam site (m3/s) - Qtbin: Discharge through turbine (m3/s) - Qx: Redundant discharge through spillway (m3/s) - Htt: Water head (m) - N: Capacity (MW) - E: Electric energy (million kWh) - NWL: Normal water level (m) - MWL: Minimum water level (m) - Vtb: Total storage volume (million m3) - Vc: Dead storage (million m3) - Q0: Annual average discharge to dam site (m3/s) - Qdb: Firm discharge (m3/s) - Qmax: Design discharge through turbine (m3/s) - Hmax: Maximum water head (m) - Hmin: Minimum water head(m) - Htb: Average water head (m) - Nlm: Installed capacity (MW) - Nÿb: Firm capacity (MW) - E0: Long-term average electric energy (million kWh) - Eflood season: Long-term average electric energy in flood season (million kWh) - Edry flow season: Long-term average electric energy in dry flow season (million kWh) - Ewet season: Long-term average electric energy in raining season (million kWh) - Edry season: Long-term average electric energy in dry season (million kWh) 2.6.2. Trung Son hydropower plant tailrace water level (case 1) - During the dry season days, the powerhouse is always operated with one turbine to ensure the release discharge to downstream to avoid great fluctuation in water level at downstream. The process of fluctuation in water level at downstream is considered as the most dangerous case when the power plant increases from 40% ÷ 50% capacity of one unit to installed capacity (Nlm= 260MW), equivalent to discharge increasing from minimum discharge of one unit (about 63m3/s) to powerhouse design discharge of 522m3/s. During the operating process, it is not permitted to increase discharge to level which is greater than natural increase discharge before existence of reservoir. The maximum natural increased discharge taken place in range of < 700m3/s in period from 1957 to 2007 as shown in below statistical table: Analysis and simulation of reservoir 20 Trung Son hydropower project Technical design 3 Table 2-6: Process of maximum natural increased discharge (<700 m /s) in period from 1957 to 2007 Discharge increased Time Qday & night (m3/s) Q (m3/s) Note time (hour) Nov 13, 1966 124.37 Nov 14, 1966 675.3 551.0 12 Nov 15, 1966 653.3 Oct 16, 1985 220.2 Oct 17, 1985 690.2 470.0 12 Oct 18, 1985 632.9 Sept 14, 1998 208.0 Sept 15, 1998 664.8 456.7 24 Sept 16, 1998 757.8 July 23, 1989 201.3 July 24, 1989 653.1 451.8 24 July 25, 1989 1343.6 Oct 3, 1989 201.9 Oct 4, 1989 641.1 439.2 24 Oct 5, 1989 769.4 Sept 20, 1992 252.1 Sept 21, 1992 688.1 436.0 24 Sept 22, 1992 837.5 Oct 24, 1971 186.7 Oct 25, 1971 619.5 432.7 12 Oct 26, 1971 591.9 Nov 8, 1984 182.3 Nov 9, 1984 597.1 414.8 24 Nov 10, 1984 1300.2 Oct 12, 1988 174.6 Oct 13, 1988 574.6 400.0 24 Oct 14, 1988 1396.2 July 20, 1974 236.3 July 21, 1974 634.3 398.0 24 July 22, 1974 691.0 Average 445.0 - The table above shown that the hourly average natural increased discharge was about 40 m3. So, in order to increase operating discharge from 63m3/s (50% maximum discharge of one unit) to 522 m3/s (design discharge of powerhouse), it is required at least 11 hours Analysis and simulation of reservoir 21 Trung Son hydropower project Technical design 2.6.3. Specific characteristics of flow at power plant tailrace in daily period The plant tailrace daily average water level, natural daily average water level at river across section in powerhouse area, daily average discharge at tailrace of power plant, natural daily average discharge at river cross-section in powerhouse area are shown in below figures: Analysis and simulation of reservoir 22 Trung Son hydropower project Feasibility Study Average water level and natural water level at Trung Son hydropower plant (Plant tailrace without Thanh Son reservoir) 92.50 92.00 91.50 91.00 90.50 Water level (m) 90.00 89.50 89.00 88.50 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Plant tailrace water level Natural tailrace water level Analysis and simulation of reservoir 23 Trung Son hydropower project Feasibility Study Water level in little water year with frequency P=90% and natural water level at Trung Son hydropower plant (plant tailrace without Thanh Son reservoir) 94.00 93.50 93.00 92.50 92.00 91.50 91.00 Water level(m) 90.50 90.00 89.50 89.00 88.50 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Plant tailrace water level Natural water level Analysis and simulation of reservoir 24 Trung Son hydropower project Feasibility Study Water level in much water year with frequency P=10% and natural water level at Trung Son hydropower plant (In case plant tailrace without Thanh Son reservoir) 95.00 94.00 93.00 92.00 91.00 Water level (m) 90.00 89.00 88.00 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Plant tailrace water level Natural water level Analysis and simulation of reservoir 25 Trung Son hydropower project Feasibility Study Average discharge and natural discharge at Trung Son plant tailrace (In case Plant tailrace without Thanh Son reservoir) 800.0 700.0 600.0 500.0 400.0 Discharge (m 3/s) 300.0 200.0 100.0 0.0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Discharge at plant tailrace Natural discharge at plant tailrace Analysis and simulation of reservoir 26 Trung Son hydropower project Feasibility Study Discharge in little water year with frequency P=90% and natural discharge at Trung Son plant tailrace (In case plant tailrace without Thanh Son reservoir) 1200 1000 800 600 Discharge (m 3/s) 400 200 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Discharge at plant tailrace Natural discharge at plant tailrace Analysis and simulation of reservoir 27 Trung Son hydropower project Feasibility Study Discharge in much water year with P=10% and natural discharge at Trung Son hydropower plant tailrace (In case plant tailrace without Thanh Son reservoir) 1600 1400 1200 1000 800 Discharge (m 3/s) 600 400 200 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time(day) Discharge at plant tailrace Natural discharge at plant tailrace Analysis and simulation of reservoir 28 Trung Son hydropower project Feasibility Study 2.6.4. Specific characteristics of flow at power plant tailrace in hourly period For estimation of flow specific characteristics fluctuation level (water level, discharge) in hourly period at river cross-section at powerhouse area, the Design Consultant calculated some operation cases, particularly as below: Table 2-7:Operation of Trung Son hydropower plant in case daily average discharge of 234 m3/s released to downstream 3 Discharge(m /s) Hour Unit 1 Unit 2 Unit 3 Unit 4 Total Increasing 1 63 63 2 63 63 3 63 63 4 63 63 5 63 63 6 63 63 7 63 63 8 126 126 63 9 126 126 10 126 126 11 126 63 189 63 12 126 63 63 252 63 13 126 126 63 315 63 14 126 126 126 378 63 15 126 126 126 378 16 126 126 126 378 17 126 126 126 63 441 63 18 126 126 126 126 504 63 19 126 126 126 126 504 20 126 126 126 126 504 21 126 126 126 126 504 22 126 63 63 63 315 -189 23 63 63 -252 24 63 63 Average 102 55 50 26 234 Analysis and simulation of reservoir 29 Trung Son hydropower project Feasibility Study Table 2-8: Operation of Trung Son hydropower plant in case daily average discharge of 200 m3/s released to downstream 3 Discharge(m /s) Hour Unit 1 Unit 2 Unit 3 Unit 4 Total Increasing 1 63 63 2 63 63 3 63 63 4 63 63 5 63 63 6 63 63 7 63 63 8 63 63 9 126 126 63 10 126 126 11 126 126 12 126 126 13 126 126 14 126 63 189 63 15 126 63 63 252 63 16 126 126 63 315 63 17 126 126 63 63 378 63 18 126 126 126 63 441 63 19 126 126 126 126 504 63 20 126 126 126 126 504 21 126 126 126 126 504 22 126 63 63 63 315 -189 23 63 63 63 189 -126 24 63 63 -126 Average 100 42 34 24 200 Analysis and simulation of reservoir 30 Trung Son hydropower project Feasibility Study Table 2-9: Operation of Trung Son hydropower plant in case daily average discharge of 155 m3/s released to downstream 3 Discharge(m /s) Hour Unit 1 Unit 2 Unit 3 Unit 4 Total Increasing 1 63 63 2 63 63 3 63 63 4 63 63 5 63 63 6 63 63 7 63 63 8 63 63 9 63 63 10 63 63 11 63 63 12 126 126 63 13 126 126 14 126 126 15 126 63 189 63 16 126 126 252 63 17 126 126 63 315 63 18 126 126 126 378 63 19 126 126 126 378 20 126 126 126 378 21 126 126 126 378 22 126 63 63 252 -126 23 63 63 -189 24 63 63 Average 92 37 26 155 Analysis and simulation of reservoir 31 Trung Son hydropower project Feasibility Study Table 2-10: Operation of Trung Son hydropower plant in case daily average discharge of 102 m3/s released to downstream 3 Discharge(m /s) Hour Unit 1 Unit 2 Unit 3 Unit 4 Total Increasing 1 63 63 2 63 63 3 63 63 4 63 63 5 63 63 6 63 63 7 63 63 8 63 63 9 63 63 10 63 63 11 63 63 12 63 63 13 63 63 14 126 126 63 15 126 126 16 126 126 17 126 63 189 63 18 126 126 252 63 19 126 126 252 20 126 126 252 21 63 63 126 -126 22 63 63 -63 23 63 63 24 63 63 Average 81 21 102 Analysis and simulation of reservoir 32 Trung Son hydropower project Feasibility Study 2.6.5. Trung Son hydropower reservoir water level fluctuation (case1) - Regulation on maximum water level of reservoir: from 15th July to 15th September annually, maximum water level of reservoir is regulated at minimum water level of 150.0m to control flood for lowlands (according regulation on water level of reservoir specified in Trung Son hydropower reservoir operation rules which was approved by Ministry of Industry and Trade). According stability calculation of the reservoir banks (in some areas with possibility of reservoir banks collapse and sliding), it is shown that the requirement on process of draining water level in reservoir should not be greater than 0.7m/day and night, therefore in the hydro energy calculation, the time requested for draining water level in reservoir from NWL=160.0m down MWL=150.0m should be over 15 days. In the actual reservoir operation process, depending on incoming flow discharge in initial flood season, reservoir draining to lower water level should be made suitably, to ensure minimum redundant discharge and increase electricity generation output. The actual process of draining reservoir water level can be twenty days to drain water level from 160.0m down to water level at 150.0m. - The generation discharge include natural incoming discharge to reservoir and discharge supplied from reservoir. The reservoir discharge supply potential is shown in below table: Table 2-11: Discharge supply potential from Trung Son hydropower reservoir Surface area Storage capacity Discharge supply Elevation No. of reservoir F of reservoir V from the reservoir Remarks Z (m) (km2) (106m3) Qcâp (m3/s) 1 160.0 13.13 348.5 2 159.0 12.72 336.4 140.0 3 158.0 12.31 324.3 140.0 4 157.0 11.90 312.2 140.0 5 156.0 11.49 300.2 140.0 6 155.0 11.08 288.1 140.0 7 154.0 10.78 277.7 119.6 8 153.0 10.49 267.4 119.6 9 152.0 10.19 257.1 119.6 10 151.0 9.90 246.7 119.6 11 150.0 9.60 236.4 119.6 - The process of reservoir impounding shall begin from 15th September annually. The reservoir impounding is allowable to full water level from time to time as possible because the erosion to reservoir banks shall not be taken place during process of impounding water Analysis and simulation of reservoir 33 Trung Son hydropower project Feasibility Study The water level curve process with frequency 90% of Trung Son hydropower reservoir ( Downstream without Thanh Son reservoir) 161.0 160.0 159.0 158.0 157.0 156.0 155.0 Water level (m) 154.0 153.0 152.0 151.0 150.0 149.0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Analysis and simulation of reservoir 34 Trung Son hydropower project Feasibility Study The water level curve process with frequency 10% of Trung Son hydropower reservoir ( Downstream without Thanh Son reservoir) 161.0 160.0 159.0 158.0 157.0 156.0 155.0 Water level (m) 154.0 153.0 152.0 151.0 150.0 149.0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Analysis and simulation of reservoir 35 Trung Son hydropower project Feasibility Study The avearge water level curve process of Trung Son hydropower reservoir ( Downstream without Thanh Son reservoir) 161.0 160.0 159.0 158.0 157.0 156.0 155.0 Water level (m) 154.0 153.0 152.0 151.0 150.0 149.0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Time (day) Analysis and simulation of reservoir 36 Trung Son hydropower project Technical design 2.7 DOWNSTREAM WITH THANH SON RESERVOIR (CASE 2) 2.7.1. Electric energy (case 2) - In case with Thanh Son Hydropower reservoir (Normal Water Level = 89.0m) located downstream of Trung Son hydro powerhouse, the toe of Trung Son hydro powerhouse is submerged. The hydro energy calculation results show that the energy decreases inconsiderable in compared with the case of insubmerged powerhouse toe (0.08 million KWh). See details as below: Table 2-12: Hydro energy calculation results of Trung Son ­ using daily flow data, with Thanh Son reservoir dowstream of Trung Son HPP ----------------------------------------------------------------- | No | Qs | Qtbin | Qx | Htt | N | E | ----------------------------------------------------------------- 1. 112.70 112.17 .00 65.13 63.71 558.07 2. 184.43 165.79 14.50 67.39 93.57 819.64 3. 193.34 172.10 23.59 66.44 96.11 841.90 4. 290.12 225.93 60.81 66.87 125.46 1099.06 5. 234.88 200.84 33.32 67.34 114.48 1002.84 6. 225.50 198.62 26.29 67.40 112.91 989.06 7. 285.93 232.26 53.07 67.01 130.67 1144.65 8. 265.17 222.08 42.50 67.14 125.64 1100.61 9. 196.35 188.98 7.71 67.32 107.41 940.89 10. 259.87 211.01 47.38 67.14 117.17 1026.42 11. 205.69 183.58 21.52 67.58 103.84 909.60 12. 154.83 143.59 14.06 66.19 81.84 716.88 13. 186.31 168.94 13.40 66.84 94.45 827.34 14. 232.57 212.00 19.99 67.14 118.56 1038.55 15. 253.44 200.22 52.64 67.26 111.18 973.95 16. 249.88 206.55 42.75 67.26 116.24 1018.22 17. 341.71 233.54 107.57 66.93 130.34 1141.75 18. 228.45 212.48 15.38 67.31 121.21 1061.81 19. 274.81 214.58 59.64 67.18 121.90 1067.88 20. 233.28 199.87 32.82 67.40 113.95 998.18 21. 221.72 209.59 11.55 67.36 119.18 1043.98 22. 314.56 272.85 41.13 66.71 154.54 1353.75 23. 238.89 220.43 17.92 67.29 124.90 1094.15 24. 255.04 208.25 46.15 67.33 118.05 1034.14 25. 255.54 237.42 17.54 67.04 134.29 1176.39 26. 292.48 246.30 45.59 66.94 139.44 1221.47 27. 203.34 186.93 15.82 67.60 107.85 944.73 28. 228.78 214.82 13.38 67.31 122.77 1075.49 29. 249.90 218.34 30.96 67.31 125.13 1096.15 30. 207.13 200.24 6.31 67.48 114.13 999.81 31. 175.81 161.99 13.22 67.83 93.08 815.37 32. 175.43 158.94 15.91 67.82 91.85 804.58 33. 229.75 205.66 23.51 67.36 118.08 1034.38 34. 275.91 234.01 41.31 66.99 131.43 1151.34 35. 206.27 181.01 24.68 67.56 101.17 886.29 36. 155.24 149.25 5.40 67.91 85.80 751.62 37. 172.08 164.70 6.80 67.81 94.77 830.22 38. 340.05 250.32 90.25 66.24 138.95 1217.24 39. 263.38 208.65 53.05 67.13 116.09 1016.92 40. 354.29 243.20 110.50 66.72 136.92 1199.41 41. 277.88 206.48 70.81 67.30 116.52 1020.74 42. 136.77 135.86 3.59 65.79 77.24 676.64 43. 226.20 203.79 18.60 67.29 115.68 1013.37 44. 249.11 221.14 27.39 67.29 124.98 1094.83 45. 292.05 248.48 42.98 66.85 139.14 1218.83 46. 333.96 269.40 63.97 66.56 151.25 1324.94 47. 242.04 223.27 18.18 67.27 128.20 1123.06 48. 248.41 218.70 29.38 67.27 123.04 1077.86 49. 264.07 206.06 57.19 67.22 116.83 1023.43 50. 161.65 146.67 17.93 67.80 82.87 725.91 ----------------------------------------------------------------- --------------------------------------------------------------------------------------------------- |TT| NWL | MNL | Vtb | Vc | Vhi | Vplu | Q0 | Qtbin | Qxa | Qdb | Qmax | Hmax | --------------------------------------------------------------------------------------------------- 1. 160.00 150.00 348.53 236.40 112.13 112.13 237.14 203.16 33.40 65.84 504.0 70.95 --------------------------------------------------------------------------------------------------- |TT| Hmin | Htb | Nlm | Ndb | Ntb | E0 | Elu | Eki | Emua | Ekho | Hsd | Beta | --------------------------------------------------------------------------------------------------- 1. 48.05 64.85 260.00 41.25 114.90 1006.49 649.01 357.48 549.15 457.34 3871. .0150 --------------------------------------------------------------------------------------------------- Analysis and simulation of reservoir 37 Trung Son hydropower project Technical design In which: - Qs: Discharge coming to dam site of Trung Son (m3/s) - Qtbin: Discharge through turbine (m3/s) - Qx: Redundant discharge release to spillway(m3/s) - Htt: Water head calculation (m) - N: Capacity (MW) - E: Electric energy (million kWh) - NWL: Normal water level (m) - MWL: Minimum water level (m) - Vtb: Total storage capacity (million m3) - Vc: Dead storage (million m3) - Q0: Annual average discharge to dam site(m3/s) - Qdb: Firm discharge (m3/s) - Qmax: Design discharge through powerhouse(m3/s) - Hmax: Maximum water head (m) - Hmin: Minimum water head (m) - Htb: Average water head (m) - Nlm: Installed capacity (MW) - Nÿb: Firm capacity(MW) - E0: Long-term average electric energy (million kWh) - Eflood season: Long-term average electric energy in flood season (million kWh) - Edry flow season: Long-term average electric energy in dry flow season (million kWh) - Ewet season: Long-term average electric energy in raining season (million kWh) - Edry season: Long-term average electric energy in dry season (million kWh) 2.7.2. Trung Son hydropower Plant tailrace water level (Case 2) - The catchment basin area calculate to damsite of Trung Son HPP is 14660 km2, to damsite of Thanh Son HPP is 14760 km2, middle catchment basin area is 100 km2 - Downstream of Trung Son hydropower plant is Thanh Son hydropower plant, so Trung Son Hydropower Plant tailrace water level is always higher than minimum water level of Thanh Son hydropower plant. The Thanh Son HPP is design with dam combined with spillway in Ma river and dam toe type powerhouse, so the water level fluctuation in reservoir is at small range. The Thanh Son HPP shall be operated synchronously with Trung Son HPP. As of present time, Thanh Son hydropower project is in feasibility study stage, the reservoir parameters such as NWL; MWL; Nlm...have not yet been defined presisely. In case the reservoir of Thanh Son HPP has 24 hours regulation storage volume, it is allowable to release discharge from 63m3/s up to 522m3/s in short time from Trung Son HPP (as allowable condition of equipment of powerhouse) Analysis and simulation of reservoir 38 Trung Son hydropower project Technical design 2.7.3. Trung Son HPP reservoir water level fluctuation (case 2) - In case with Thanh Son reservoir downstream of Trung Son HPP reservoir water levels fluctuation shall be same as in case without Thanh Son reservoir. The possibility of reservoir impounding to maximum water level is allowable. The reservoir water level drawn-down allowable condition should not be more than 0.7m/24 hours. In the process of operation, depending on hydrological condition (incoming flow to damsite) water draining capacity shall be calculated in such a manner to ensure minimum discharge released through spillway and maximum electric energy generation output. Analysis and simulation of reservoir 39 Trung Son hydropower project Technical design Chapter 3: WATER SUPPLY DEMAND FOR DOWNSTREAM 3.1 WATER DEMAND AT DOWNSTREAM 3.1.1. Scope of water demand Water demand at Ma River downstream was accessed in many previous plans by Ministry of Agriculture and Rural Development (MARD). According to report named "General updating Irrigation planning of cascades to develop economy at downstream of Ma river basin" which was conducted by Water Resource Planning Institute, under MARD, main purposes of projects on Ma River are electric generation and flood control. Main purposes of projects on Chu River are water supply and flood control. This does not mean downstream of Trung Son project has no water during dry season. Impounding period of Trung Son reservoir will only take place a short time (4 days in flood season). Water demand at downstream, however, of Trung Son project, from P/H to confluence of Ma River and Xia stream (20km) and from Xia stream to confluence of Ma River and Luong tributary (25km), needs to be evaluated. - River reach from P/H to confluence of Ma River and Xia stream (20km: There are villages and local people living along both two banks. Water source for living and irrigation is mainly groundwater and streams. They were not use water from Ma River. For navigation on river: Along river bank, access road was built from Co Luong to dam site. Therefore, environmental flow on this river reach mainly secures flora and fauna such as land cover along banks, buffalo, cow, etc, and aquatic life. Result of monthly flow calculation is shown in Table below: Table 3-1: Average monthly flow within area from dam route to Xia stream. Month Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Qo (m3/s) 1.74 1.52 1.45 1.60 2.63 4.04 5.14 7.28 9.9 7.84 4.16 2.23 - River reach from Xia stream to confluence of Ma River and Luong tributary (25km): There are many tributaries and large stream which has high flow supply for Ma River's flow such as Xia stream, Luong and Lung tributaries, Chu River. Xia catchment area is 249km2 with 5.21 m3/s of annual flow, 8.07 m3/s of average flood flow, and 6.5 m3/s when diversion culvert is blocked (July). Table 3-2: Average monthly flow of Xia stream. Month Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec Qo 2.20 1.92 1.83 2.02 3.33 5.10 6.50 9.20 12.5 9.91 5.25 2.82 (m3/s) Luong tributary has 970 km2 of catchment area with 23 m3/s of annual flow and 40 m3/s of average flood flow. Therefore, abundant water resource can be supplied to this river section. Moreover, National Highway No. 15 (QL15) along river bank was built so transportation does not be affected during reservoir impounding (3-5days on Appendix 40 Trung Son hydropower project Technical design July) and flood season. Environmental flow is always secured on Ma river after Luong tributary. Hence, only environmental flow within river section from downstream of dam route to confluence with Xia stream is considered. Xia Catchment Area F=249 km2 Trung Son HPP Ma River 3.1.2. Xia Stream Interstream Area F=209 km2 3.1.3. Water demand for Industry and daily uses. Water demand for Industry and daily uses is considered up to 2020. According to report named "General updating Irrigation planning of cascades to develop economy at downstream of Ma river basin", water demand for these fields as below: Table 3-3: Water demand for Industry and daily uses No Location Demand (m3/s) Note 1 Trung S n town 0.05 2 Quan Hoá town 0.05 3 Bá Th c town 0.10 4 C m Th y town 0.10 Total 0.30 Appendix 41 Trung Son hydropower project Technical design 3.1.4. Water demand to secure environmental and ecological system. In order to mitigate effects on environment of Ma river reach, time to set blocking of diversion culvert is flood season. Tentative blocking time is on July when it often rains and flow is approximate to annual value (418m3/s) on catchment from Trung Son dam route to Xia stream. Impounding time is 4 days to raise reservoir water level reach to spillway crest elevation. During impounding period, flow within river reach from dam route to confluence with Xia stream is runoff and groundwater. This 290 km2 catchment has average monthly flow in July with Qo= 5.14 m3/s, equivalent to 14.12% of natural flow of Ma River at the dam site. Minimum observed monthly flow at the dam site from 1957 to 2002 is 36.4m3/s occurred in May 1957. According to Tenant method, environmental flow to secure ecological system in flood season is about 10-30% of annual flow. Therefore, flow on Ma river reach from dam site to Xia stream which is 5.14m3/s (14.12% of minimum monthly flow) is enough to supply all demands and environment along the river reach in 04 days of diversion culvert blocking. Then, environmental flow will be supplied by discharge through spillway after these 4 days. 3.1.5. Conclusion With selected method for diversion culvert blocking and time to raise reservoir water level to spillway crest in 4 days in July, flow on 20km-Ma river reach at downstream of Trung Son dam will supply from runoff and groundwater. Hence, there is no any structure that need be built in order to release discharge to downstream during 4 days of culvert blocking. Cost of project, then, will be saved. 3.2 ENVIRONMENT FLOW RELEASE MEASURES In order to release flow discharge at 15 m3/s during reservoir impounding period, it is required to install released culvert with dimension BxH=1.2x1.2m for Trung Son HPP. The position of this released culvert is next to diversion culvert. The hydraulic cylinders operated maintenance gate and operation gate with dimensions 1.2x1.2m are arranged at upstream of this culvert. Design of environment flow released culvert are shown in drawings of appendices. 3.3 DISCHARGE OF WATER DURING OPERATION PROCESS During operation process, water will be discharged to downstream through the turbines of powerhouse. During operation of powerhouse, if there is any failure encountered or ceases operation due to different causes, water will be discharged through spillway to maintain environment flow and water supply demand for downstream without needing any other discharge structures, because the spillway weir Appendix 42 Trung Son hydropower project Technical design elevation is set at 145m and minimum water level is set at 150m (5m higher than spillway crest elevation). 3.4 DISCHARGE OF MUD AND SAND According to the calculation about sedimentation in reservoir of Trung Son HPP, after 100 years, the quantity of mud and sand still do not reach to the intake gate elevation. Mud and sand will be mainly accumulated in the end part and middle part of reservoir, so it is not necessary to install discharge outlet for mud and sand. The results of calculation in 2.2 "Subject calculation sediment backwater" Trung Son HPP, after 100 years operation, sediment elevation at section near the dam at 97.0m 3.5 RESERVOIR DEWATERING According to the ruling standards of Vietnam as well as many other countries in the world, there is no obligation for installation of drainage system for reservoir dewatering. 3.6 CONCLUSION Installation of a culvert to release water to downstream at 15m3/s discharge to maintain ecological environment during reservoir impounding period is necessary. When the reservoir impounding is up to the full supply water level, the discharge culvert ceases its role, and according to the relevant regulations, there is no need to install culvert for reservoir dewatering. Specific calculations on sedimentation confirmed that it is not required to arrange culvert for discharging mud and sand. Appendix 43 Trung Son hydropower project Technical design Chapter 4: RESERVOIR AND DOWNSTREAM LANDSLIDE POSSIBILITY FORECAST 4.1 RESERVOIR BANK LANDSIDE POSSIBILITY 4.1.1. CALCULATION DATA 4.1.1.1 Table of physical ­ mechanical properties indices stability calculation bank of reservoir Table 4-1: Physical-mechical properties indices stability calculation bank of reservoir Material layer J (T/m3) M C (KG/cm2) (natural/saturated) (natural/saturated) (natural/saturated) edQ 1.72/1.79 0.18/0.16 IA1 1.65/1.77 25/18 0.24/0.18 IA2 1.68/1.79 25 0.22 IB 2.66/2.68 29 2.00 IIA 2.77/2.79 37 2.50 4.1.1.2 Project grade: grade II Stability safe factor allowable of project: According Vietnamese construction standard TCXD V 285: 2002 with project grade II, natural slope, safety factor is calculated according to the formula as follow: k nc.kn/m In which: nc: Load combination factor. For basic load combination: nc=1, for special load combination: nc=0.9. kn: Guarantee factor calculated according to project scale and tasks. Project grade II. Guarantee factor is taken as kn=1.2. m: Operating condition factor. For natural and artificial slope m=1. with parameters as above, safety factor is calculated as follow: - Basic load combination : k = 1.20 - Special load combination : k= 1.08 4.1.1.3 Location of section calculation According topographical, geological condition at reservoir foundation area studied in technical design stage to choose reservoir bank section easy to sliding Specifically are 5 typical sections with features as below: sloping topographical, thick weak geological zone and thin covering vegetation layer to calculate and check stability See location of calculation sections in drawing "chart location of section stability calculation" see in appendix Appendix 44 Trung Son hydropower project Technical design 4.1.2. CALCULATION CASE atural slope of reservoir foundation area is stability through time when reservoir is not impounding and more stability after impounding at regular water level exploit. So that it needs to check for two danger cases as follow: - Fast drain reservoil water level frome WL=160.0m down to MWL=150.0m follow different time step . (Special load combination) - Fast drain reservoil water level frome WL=160.0m down to MWL=150.0m follow different time step and underground water level is raised to surface of slope. (Special load combination according to WB recommend) From calculation results for two cases as above to recommend reasonable time period to drain water of reservoir in operation process. 4.1.3. SOFTWARE CALCULATION The program use to calculate stability: Slope/w software of Canada. Analysis method: Bishop and Janbu, these are two methods applicable worldwide for slope stability analysis. 4.1.4. CALCULATION RESULTS Table 4-2: Calculation result table according to recommend case of Consultant Section Kmin min Case Case [K] calculation Bishop Janbu Drain water in 5 days Case 1 1.41 1.35 Section 1 Drain water in 10 days Case 2 1.50 1.45 1.08 Drain water in 15 days Case 3 1.55 1.49 Drain water in 5 days Case 1 1.04 1.01 Section 2 Drain water in 10 days Case 2 1.11 1.06 1.08 Drain water in 15 days Case 3 1.13 1.10 Drain water in 5 days Case 1 1.29 1.29 Section 3 Drain water in 10 days Case 2 1.36 1.35 1.08 Drain water in 15 days Case 3 1.39 1.38 Drain water in 5 days Case 1 1.01 0.98 Section 4 at left Case 2 Drain water in 10 days 1.09 1.08 1.08 bank Drain water in 15 days Case 3 1.11 1.09 Drain water in 5 days Case 1 1.02 0.99 Section 4 at Case 2 Drain water in 10 days 1.09 1.06 1.08 right bank Drain water in 15 days Case 3 1.12 1.09 Drain water in 5 days Case 1 1.06 1.04 Section 5 Drain water in 10 days Case 2 1.12 1.09 1.08 Drain water in 15 days Case 3 1.18 1.17 (Detail see in appendix) Appendix 45 Trung Son hydropower project Technical design Table 4-3: Calculation result table according to recommend case of WB Section Kmin min Case [K] calculation Bishop Janbu Underground water level is raised to Section1 0.80 0.79 1.08 the surface of the slope Underground water level is raised to Section2 0.40 0.37 1.08 the surface of the slope Underground water level is raised to Section3 0.70 0.68 1.08 the surface of the slope Section 4 at left Underground water level is raised to 0.44 0.42 1.08 bank the surface of the slope Section 4 at Underground water level is raised to 0.55 0.54 1.08 right bank the surface of the slope Underground water level is raised to Section5 0.40 0.37 1.08 the surface of the slope (See details in appendix) 4.1.5. CONCLUSION AND RECOMMENDATION FROM CALCULATION COMBINATION DONE BY CONSULTANT According to calculation result mentioned in Table 4-2, recommendation can be made, as follow: - The banks of reservoir shall be instable in case water level draining from WL=160m down to MWL=150m in period time 5 days for Bishop method and 10 days for Janbu method. However in practical operation reservoir, water level draining from WL=160m down to MWL=150m shall be taken place in 20 days period. - In the process of operation reservoir, the reservoir drawn-down water level in 24 hours period should not be over 0.7m to protect environment and stable reservoir banks. 4.1.6. ANALYSIS RECOMMEND CASE OF WB For Consultancy, WB has recommended a case which is a extreme case, in fact it cannot occur because of the following reasons: - The formation process of underground water level is happened in a long time and stabilized versus time. The fluctuation of underground water level is just occured at the location water level adjacent of river bank. Therefore, the case underground water level is raised to the surface of the slope which cannot occur. In fact it is checked in process exploratory drilling geologic for many. - The natural rive bank slope of Trung Son HPP area is heavy gradient (from 300 to 450). Therefore the water shall be discharged follow subsurface flow down natural water-course when it has heavy rain, only a small part of the rain-water percolation Appendix 46 Trung Son hydropower project Technical design into underground. The part of leakage water just enough to do water-saturated soil sub- grade lap on surface of the slope and it cannot raise to the slope surface. - Consultancy has checked realistic condition that: the slopes when HPP doesn't build yet which is stabilized before age-old with reputed that underground water level is raised to the surface of the slope by heavy rain, results show all the slopes in shear with safe factors are very low, that fact indicate calculation case as above never occur. (Results have shown at table 4-3 and in appendix). 4.2 EROSION RIVER BED OF RESERVOIR DOWNSTREAM The river bed erosion is a part of the process of moving sediment cause flow. This phenomena is happening continuous in the time. To estimate erode ability river bed for specific river. measurement data and study about sediment moving flow include suspended load and bed load in a necessary period time. In addition. factors effect to the sediment moving process as form of river bed. covering vegetation bed. geological structure of river bed and banks. ..etc. owadays. there are studies in the world about erosion and moving layers at river bed cause by flow for different grain component types. The method calculations usually application so much and was mention in Handbook of Hydrology. Chapter 12 of David R.Maidment author. McGraw-Hill publisher. Inc.. 1992 include: "Mayer- Peter and Muller (1948)". "Einstein (1950)". "Bagnold (1956.1966. 1973)". and "Paker (1990)". In which. Mayer-Peter method and Muller method was application for river bed has coarse grain component. grain size from 0.4mm to 30mm. The Bagnold method using for flow has much content sediment. The Einstein method is nearly complete and the most suitable. The other methods are necessary to estimation much more. Out of Mayer-Peter and Muller method as mentioned above. other methods as Acker and White (1973). England-Hansen (1967). Laursen-Copeland (1968.1989). Toffeleti (1968). Yang (1973.1984). Wilcock (2001. 2003) was introduction in HEC- RAS 4.0 (HEC-6) software to calculate moving sediment ability by flow. Downstream riverbed erosion assessment for Trung Son HPP is a complicated study which requires a lot of data, including accuracy measured and observed data, to apply for a specific erosion modeling. However, based on the current data, the consultant can give the overview about erodibility of riverbed as follows: Riverbed geological formation at downstream of the dam: the riverbed was formed mainly by medium to slightly weathered rock with medium hardness. Its compressive strength and shearing resistance are about 10 MPa and 0.36MPa respectively. The erodible velocity (critical velocity) for such kind of riverbed is found at 8 m/s. Moreover, only some location along the river was found that having deposition with small scale. Further to downstream of project, there is no officially measured or investigated data of riverbed geological formation. However, based on observed of our geological engineers' observation during the time period for site investigation, most of riverbed was found medium to slightly weathered rock (see the Figure below). In order to assess, a narrow river cross section, of which section, geological condition, and water level data are available, was selected. The consultant checked for Appendix 47 Trung Son hydropower project Technical design different discharge rate from a half of unit discharge to check flood discharge through powerhouse and spillway. Result of hydraulic calculation is shown in table below: Discharge (m3/s) Water level (m) Wet area (m2) Velocity (m/s) 63 (0.5 unit) 87.9 283.7 0.2 126 (1 unit) 88.4 322.0 0.4 252 (2 units) 89.1 378.3 0.7 378 (3 units) 89.6 429.0 0.9 504 (4 units) 90.1 463.9 1.1 10400 (design flood) 103.8 2009.4 5.2 13400 (check flood) 106.3 2328.1 5.8 The result stated that water speed is always less than the critical speed. In general, with such geology condition of the riverbed mentioned, additional study on riverbed erosion should not take account. 4.3 SLIDING AT BANKS OF DOWNSTREAM 4.3.1. CALCULATION DATA 4.3.1.1 Table of physical ­ mechanical properties indices stability calculation bank of downstream Table 4-4: Physical-mechical properties indices stability calculation bank of downstream Material layer J (T/m3) M C (KG/cm2) atural/Saturated atural/Saturated atural/Saturated edQ 1.72/1.79 0.18/0.16 IA1 1.65/1.77 25/18 0.24/0.18 IA2 1.68/1.79 25 0.22 IB 2.66/2.68 29 2.00 IIA 2.77/2.79 37 2.50 4.3.1.2 Project grade: grade II Stability safe factor allowable of project: According Vietnamese construction standard TCXD V 285: 2002 with project grade II. natural slope. safe factor is calculated according to the formula as follow: k nc.kn/m In which: nc: Load combination factor. For basic load combination: nc=1. for special load combination: nc=0.9. kn: Guarantee factor calculated according to project size and tasks. Project grade II. Guarantee factor is taken as kn=1.2. m: Operating condition factor. For natural and artificial slope m=1. with parameters as above. safe factor is calculated as follow: - Basic load combination : k = 1.20 Appendix 48 Trung Son hydropower project Technical design - Special load combination : k= 1.08 4.3.1.3 Location of section calculation Acoording topographical. geological condition at reservoir foundation area studied in technical design stage to choose reservoir bank section prone to sliding possibility. Specifically are 4 typical sections with features as below: sloping topographical, thick weak geological zone and thin covering vegetation bed layer to calculate and check stability Location of section calculation see in drawing " chart location of section stability calculation" attached to this report. 4.3.2. CALCULATION CASE atural slope at downstream reservoir after exist project. Water level is only fluctuation mainly in range from 107m elevation to 90.2m elevation. In this range belong river bed area so geological is rather good. mainly IB rock layer and IIA rock layer so fast drain water process is not effect more to slope stability of banks at downstream. In this appendix it is only checking for the most dangerous case. in the operation reservoir process water level at downstream is draining fast from 104.5m (corresponding to release design flood P=0.5%) down to 90.2m (corresponding to Q=504m3/s through powerhouse) in 5 days period of time. 4.3.3. SOFTWARE CALCULATION The program use to calculate stability: Slope/w software of Canada. Analysis method: Bishop and Janbu, these are two methods applicale worldwide for slope stability analysis. 4.3.4. RESULTS CALCULATION Table 4-3: Results calculation Kmin min Section calculation Case [K] Bishop Janbu Downstream section 1 Drain water in 5 days 1.25 1.24 1.08 Downstream section 2 Drain water in 5 days 1.09 1.08 1.08 Downstream section 3 Drain water in 5 days 1.11 1.10 1.08 Downstream section 4 Drain water in 5 days 1.28 1.27 1.08 (See details in appendix) 4.3.5. CONCLUSION According calculation results mentioned in table above, the bank of downstream will be stable in all cases of reservoir operation. Appendix 49 Trung Son hydropower project Technical design APPENDICES Appendix 50 Trung Son hydropower project Technical design APPENDIX HYDROGRAPHICAL CALCULATION Appendix 51 Trung Son hydropower project Technical design Table 1: Monthy average discharge at Cam Thuy hydrological station Unit: m3/s No I II III IV V VI VII VIII IX X XI XII TB 1957 123 114 113 101 103 318 348 211 278 207 120 88.9 177 1958 72.7 81.8 61.0 53.1 63.5 326 711 493 562 268 149 124 247 1959 126 92.1 94.6 106 110 172 268 958 825 327 189 138 284 1960 113 93.7 76.6 72.4 95.4 312 763 1460 902 522 274 193 406 1961 141 135 112 103 93.4 437 232 724 951 564 290 185 331 1962 168 162 100 107 144 576 651 529 698 452 205 163 330 1963 136 108 168 92.0 114 275 793 932 1080 561 403 235 408 1964 161 129 111 117 151 272 794 593 955 815 321 202 385 1965 150 131 105 111 197 542 625 499 513 298 263 164 300 1966 127 98.4 81.4 86.7 91.7 422 660 1070 817 294 283 149 348 1967 139 127 90.1 126 147 371 417 755 744 305 190 142 296 1968 118 106 104 121 135 247 231 721 543 291 178 119 243 1969 91.4 75.9 67.4 92.0 96.4 285 514 802 425 209 222 135 251 1970 111 82.5 71.6 118 232 374 641 769 856 430 213 169 339 1971 129 112 85.2 97.9 157 244 908 1240 571 450 225 152 364 1972 124 104 96.7 111 122 150 393 1160 975 475 262 185 347 1973 149 117 120 120 219 326 897 1300 1760 524 274 184 499 1974 145 118 110 131 169 368 383 678 658 565 340 182 321 1975 188 131 112 150 213 537 428 692 1550 409 251 190 404 1976 146 135 105 106 205 257 434 1230 461 319 252 155 317 1977 224 178 146 176 230 206 662 667 621 374 268 217 331 1978 196 154 120 122 286 567 743 1020 1014 609 370 269 456 1979 230 196 162 160 266 605 441 781 917 381 255 197 383 1980 156 133 103 111 123 220 553 896 1264 439 276 212 374 1981 165 124 105 139 225 448 580 827 673 607 342 238 373 1982 190 144 104 158 161 339 565 1390 878 587 361 259 428 1983 204 172 163 137 171 171 276 536 650 717 303 212 309 1984 185 147 114 113 212 436 657 602 411 458 364 203 325 1985 183 152 129 185 200 328 371 725 1127 487 328 226 370 1986 177 140 120 138 337 476 586 533 520 340 233 185 315 1987 155 140 118 114 130 155 277 670 610 328 220 169 257 1988 152 122 107 109 175 130 283 511 399 731 240 164 260 1989 141 118 112 98.5 173 604 493 524 459 707 261 194 324 1990 151 144 189 133 227 713 1138 752 613 464 269 198 416 1991 154 133 116 133 157 618 844 702 350 230 173 143 313 1992 146 120 115 107 132 262 609 337 384 220 170 143 229 1993 112 98.7 96.4 90.5 205 169 348 586 572 291 179 141 241 1994 122 102 116 145 223 488 1443 1307 1148 617 328 269 526 1995 133 105 88.3 76.3 98.4 449 692 1260 936 317 205 140 375 1996 128 106 113 97.2 153 262 863 1660 1230 541 523 232 492 1997 175 142 151 192 148 228 911 911 1180 540 254 184 418 1998 140 120 101 116 145 274 431 312 456 202 129 102 211 1999 86.3 67.6 59.4 78.2 152 564 441 742 749 308 234 170 304 2000 130 121 115 104 235 391 760 679 961 426 220 165 359 2001 144 120 153 111 235 640 987 983 719 451 279 184 417 2002 157 132 108 110 233 677 1280 1170 597 394 260 221 445 2003 291 249 211 203 275 278 512 660 868 359 249 212 364 2004 169 158 144 274 410 501 705 843 904 356 267 218 412 2005 145 121 116 107 107 210 380 1290 1290 548 297 202 401 2006 140 127 119 115 158 207 405 1100 424 243 157 130 277 2007 116 104 105 120 194 260 432 377 560 1040 252 179 312 2008 143 149 132 140 172 462 856 924 835 790 737 275 468 TB 146 124 113 120 174 365 603 828 783 448 263 179 346 Appendix 52 Trung Son hydropower project Technical design Table 2: Monthy average discharge at Hoi Xuan hydrological station Unit: m3/s No I II III IV V VI VII VIII IX X XI XII TB 1957 104 96.4 96.8 89.4 91.5 270 320 244 261 196 130 74.9 164 1958 69.2 76.2 56.6 46.3 64.0 277 598 457 471 235 148 107 217 1959 106 82.6 82.5 95.0 96.9 150 260 808 666 273 171 121 243 1960 96.9 83.6 68.6 58.3 86.4 265 638 1186 723 399 221 172 333 1961 116 109 96.3 86.6 85.0 367 232 631 759 426 231 165 275 1962 135 126 87.0 90.1 121 481 552 484 572 353 181 144 277 1963 113 92.6 139 75.1 99.8 235 661 788 858 424 297 211 333 1964 131 105 95.3 96.9 126 232 662 533 762 589 249 180 313 1965 125 105 88.4 95.3 138 421 499 424 458 259 231 140 249 1966 115 94.9 79.9 77.8 80.4 397 606 929 721 276 232 144 313 1967 109 97.4 79.7 116 119 322 377 678 602 260 161 119 253 1968 99.6 94.9 88.2 104 119 198 194 573 425 232 157 106 199 1969 83.2 67.3 56.9 76.0 84.1 260 418 724 327 180 184 107 214 1970 91.8 77.5 65.0 100 208 293 595 666 682 343 189 155 289 1971 108 95.0 75.3 81.2 130 209 749 1020 478 352 192 134 302 1972 105 90.3 84.1 99.4 105 133 355 959 777 369 214 165 288 1973 122 98.0 102 107 173 276 740 1065 1354 400 221 164 402 1974 119 98.7 94.4 116 138 311 347 597 542 427 260 162 268 1975 149 107 96.0 131 169 449 382 607 1199 326 208 170 333 1976 120 109 90.7 95.5 164 220 386 1015 397 268 208 136 267 1977 126 104 89.7 113 148 138 497 527 481 250 181 148 234 1978 122 102 86.2 89.8 183 434 563 861 834 458 246 195 348 1979 148 125 112 124 189 474 354 698 707 273 186 153 295 1980 116 100 90.0 96.7 104 177 517 779 1158 366 206 172 323 1981 130 104 99.2 129 182 374 488 672 541 456 242 193 301 1982 147 120 111 135 124 257 429 1135 799 455 249 209 348 1983 160 133 135 121 140 149 266 489 536 525 238 190 257 1984 147 117 97.8 101 169 366 557 539 360 357 274 182 272 1985 146 120 109 160 160 278 338 632 889 376 253 203 305 1986 141 112 102 122 256 399 503 487 440 282 197 165 267 1987 126 113 101 102 111 136 266 590 507 274 190 150 222 1988 124 101 91.7 97.8 142 116 271 470 350 534 201 146 220 1989 117 98.7 96.2 89.1 141 504 431 480 395 518 214 173 271 1990 124 115 155 117 179 593 925 652 509 361 218 177 344 1991 126 108 98.9 117 130 515 700 615 314 210 162 125 268 1992 120 100 98.2 95.9 112 224 520 339 339 204 160 125 203 1993 96.3 86.8 83.9 82.4 164 148 321 527 478 250 165 123 210 1994 103 88.8 98.7 127 176 409 1158 1071 904 461 253 243 424 1995 111 90.8 77.7 70.7 88.5 377 584 1035 748 266 181 123 313 1996 108 91.1 96.8 88.0 127 224 714 1338 969 411 368 209 395 1997 140 114 126 166 124 197 751 773 927 411 210 164 342 1998 116 100 87.0 103 122 234 384 320 393 192 136 87.3 190 1999 78.6 67.3 55.3 72.3 127 471 392 645 610 261 197 151 261 2000 109 101 98.2 93.8 184 330 636 597 767 337 190 146 299 2001 119 99.8 127 99.6 185 534 809 827 588 353 224 164 344 2002 128 108 92.9 98.9 183 563 1031 966 497 316 213 199 366 2003 220 181 172 175 213 237 446 583 697 294 206 190 301 2004 136 124 121 234 308 419 594 721 724 292 217 196 340 2005 120 101 121 310 373 181 345 1062 1013 416 235 181 371 2006 116 105 101 151 130 179 364 918 369 219 152 113 243 2007 99.1 90.1 90.5 107 156 222 385 369 470 734 208 159 258 2008 118 118 111 123 140 388 709 782 673 572 494 249 373 TB 120 103 97.2 111 147 308 516 709 635 351 214 159 289 Appendix 53 Trung Son hydropower project Technical design Table 3: Monthy average discharge at Trung Son station Unit: m3/s No I II III IV V VI VII VIII IX X XI XII TB 1957 81.2 75.3 73.1 86.7 88.7 197 228 181 252 198 140 57.2 138 1958 47.7 50.5 38.2 57.5 66.9 202 474 361 401 222 150 84.1 180 1959 83.6 58.4 60.6 90.5 93.0 95.5 174 657 540 245 164 95.0 196 1960 74.5 59.7 48.6 65.6 84.7 193 509 977 580 323 194 138 271 1961 93.3 91.1 72.6 84.8 83.6 279 150 508 606 339 199 132 220 1962 112 112 64.6 87.2 112 375 434 384 473 294 169 114 228 1963 90.1 70.6 59.9 77.0 95.3 167 530 641 676 338 239 170 263 1964 107 86.3 71.7 91.7 116 164 531 425 608 439 210 145 250 1965 99.6 88.1 67.7 93.6 141 352 416 365 376 233 190 115 211 1966 84.4 63.2 51.8 74.9 82.6 268 440 731 535 232 197 104 239 1967 92.3 84.9 57.7 102 114 233 275 528 497 236 164 98.6 207 1968 78.3 68.8 67.0 99.3 107 147 149 506 391 231 160 80.2 174 1969 60.3 46.0 42.5 79.9 85.3 173 340 558 329 198 175 93.1 182 1970 73.8 51.1 45.3 93.4 161 235 427 537 556 286 172 119 230 1971 85.6 73.6 54.4 81.1 119 145 608 837 406 294 176 106 249 1972 82.2 67.9 62.0 93.5 99.6 80.4 259 786 619 304 190 132 231 1973 98.6 77.2 77.8 98.4 154 202 600 875 1028 323 194 131 322 1974 96.3 78.1 71.0 104 126 231 251 479 452 339 217 130 215 1975 125 88.4 72.4 115 150 348 283 488 918 278 186 136 266 1976 97.2 91.0 67.8 90.8 146 154 286 833 348 242 186 108 221 1977 149 124 95.1 130 160 119 441 472 432 263 191 156 228 1978 130 106 77.4 99.3 191 369 496 697 639 357 227 197 299 1979 154 138 106 121 180 395 291 544 588 266 187 141 259 1980 104 89.7 66.1 93.7 99.9 128 367 618 771 290 194 152 248 1981 110 82.7 67.7 109 157 286 385 574 460 356 217 173 248 1982 127 97.8 67.2 120 121 211 375 934 568 348 224 189 282 1983 136 120 106 108 127 94.4 180 388 447 400 204 152 205 1984 123 101 73.9 94.6 150 278 437 430 322 297 225 146 223 1985 122 104 83.8 135 143 204 244 509 698 308 213 163 244 1986 118 94.8 77.3 109 220 306 389 386 379 250 179 132 220 1987 103 95.2 76.5 95.0 104 83.3 180 473 427 245 175 119 181 1988 101 80.9 68.7 92.4 129 66.1 184 372 316 405 182 116 176 1989 93.7 78.1 72.5 86.5 128 395 326 380 347 396 189 138 219 1990 101 97.8 124 106 158 470 763 526 428 299 192 142 284 1991 103 89.5 74.9 106 119 404 564 494 290 206 158 98.9 226 1992 97.3 79.9 74.3 91.1 105 157 405 261 308 203 157 99.0 170 1993 74.0 63.5 61.9 82.0 146 93.6 228 420 406 231 160 97.2 172 1994 80.9 65.9 74.7 112 156 314 970 881 709 360 213 197 344 1995 88.1 68.4 56.5 74.0 86.4 287 461 849 598 241 169 96.8 256 1996 84.9 68.8 73.0 85.7 117 158 577 1106 755 330 281 168 317 1997 117 96.8 98.1 138 114 134 609 739 726 330 187 131 285 1998 92.8 80.1 64.6 96.1 113 166 284 245 346 195 143 67.5 158 1999 56.9 39.7 37.1 75.1 117 367 291 520 500 237 180 120 212 2000 86.5 80.9 74.3 89.6 163 247 508 480 611 284 175 116 243 2001 95.8 79.4 99.6 93.6 163 419 661 674 484 294 195 131 282 2002 105 88.9 69.7 93.1 161 445 857 791 420 272 189 160 304 2003 194 179 138 145 185 169 339 467 562 258 185 153 248 2004 112 105 93.7 184 261 323 470 584 581 256 191 157 277 2005 91.5 75.9 73.0 76.2 62.2 122 209 874 790 365 250 156 262 2006 90.9 81.2 71.7 73.1 85.9 94.9 262 610 262 148 106 84.8 164 2007 74.5 67.5 64.4 77.6 66.2 146 253 256 342 448 154 113 172 2008 95.3 102 88.3 96.0 97.9 313 614 739 615 503 363 194 318 TB 99.5 84.7 72.6 97.2 127 231 404 576 514 293 191 130 235 Appendix 54 Trung Son hydropower project Technical design Table 4: Monthy average discharge as hydrologic year Unit: m3/s No I II III IV V VI VII VIII IX X XI XII TB 1957 197 228 181 252 198 140 57.2 47.7 50.5 38.2 57.5 66.9 126 1958 202 474 361 401 222 150 84.1 83.6 58.4 60.6 90.5 93.0 190 1959 95.5 174 657 540 245 164 95.0 74.5 59.7 48.6 65.6 84.7 192 1960 193 509 977 580 323 194 138 93.3 91.1 72.6 84.8 83.6 278 1961 279 150 508 606 339 199 132 112 112 64.6 87.2 112 225 1962 375 434 384 473 294 169 114 90.1 70.6 59.9 77.0 95.3 220 1963 167 530 641 676 338 239 170 107 86.3 71.7 91.7 116 269 1964 164 531 425 608 439 210 145 99.6 88.1 67.7 93.6 141 251 1965 352 416 365 376 233 190 115 84.4 63.2 51.8 74.9 82.6 200 1966 268 440 731 535 232 197 104 92.3 84.9 57.7 102 114 246 1967 233 275 528 497 236 164 98.6 78.3 68.8 67.0 99.3 107 204 1968 147 149 506 391 231 160 80.2 60.3 46.0 42.5 79.9 85.3 165 1969 173 340 558 329 198 175 93.1 73.8 51.1 45.3 93.4 161 191 1970 235 427 537 556 286 172 119 85.6 73.6 54.4 81.1 119 229 1971 145 608 837 406 294 176 106 82.2 67.9 62.0 93.5 99.6 248 1972 80.4 259 786 619 304 190 132 98.6 77.2 77.8 98.4 154 239 1973 202 600 875 1028 323 194 131 96.3 78.1 71.0 104 126 319 1974 231 251 479 452 339 217 130 125 88.4 72.4 115 150 221 1975 348 283 488 918 278 186 136 97.2 91.0 67.8 90.8 146 261 1976 154 286 833 348 242 186 108 149 124 95.1 130 160 235 1977 119 441 472 432 263 191 156 130 106 77.4 99.3 191 223 1978 369 496 697 639 357 227 197 154 138 106 121 180 307 1979 395 291 544 588 266 187 141 104 89.7 66.1 93.7 99.9 239 1980 128 367 618 771 290 194 152 110 82.7 67.7 109 157 254 1981 286 385 574 460 356 217 173 127 97.8 67.2 120 121 249 1982 211 375 934 568 348 224 189 136 120 106 108 127 287 1983 94.4 180 388 447 400 204 152 123 101 73.9 94.6 150 201 1984 278 437 430 322 297 225 146 122 104 83.8 135 143 227 1985 204 244 509 698 308 213 163 118 94.8 77.3 109 220 246 1986 306 389 386 379 250 179 132 103 95.2 76.5 95.0 104 208 1987 83.3 180 473 427 245 175 119 101 80.9 68.7 92.4 129 181 1988 66.1 184 372 316 405 182 116 93.7 78.1 72.5 86.5 128 175 1989 395 326 380 347 396 189 138 101 97.8 124 106 158 230 1990 470 763 526 428 299 192 142 103 89.5 74.9 106 119 276 1991 404 564 494 290 206 158 98.9 97.3 79.9 74.3 91.1 105 222 1992 157 405 261 308 203 157 99.0 74.0 63.5 61.9 82.0 146 168 1993 93.6 228 420 406 231 160 97.2 80.9 65.9 74.7 112 156 177 1994 314 970 881 709 360 213 197 88.1 68.4 56.5 74.0 86.4 335 1995 287 461 849 598 241 169 96.8 84.9 68.8 73.0 85.7 117 261 1996 158 577 1106 755 330 281 168 117 96.8 98.1 138 114 328 1997 134 609 739 726 330 187 131 92.8 80.1 64.6 96.1 113 275 1998 166 284 245 346 195 143 67.5 56.9 39.7 37.1 75.1 117 148 1999 367 291 520 500 237 180 120 86.5 80.9 74.3 89.6 163 226 2000 247 508 480 611 284 175 116 95.8 79.4 99.6 93.6 163 246 2001 419 661 674 484 294 195 131 105 88.9 69.7 93.1 161 281 2002 445 857 791 420 272 189 160 194 179 138 145 185 331 2003 169 339 467 562 258 185 153 112 105 93.7 184 261 241 2004 323 470 584 581 256 191 157 91.5 75.9 73.0 76.2 62.2 245 2005 122 209 874 790 365 250 156 90.9 81.2 71.7 73.1 85.9 264 2006 94.9 262 610 262 148 106 84.8 74.5 67.5 64.4 77.6 66.2 160 2007 146 253 256 342 448 154 113 95.3 102 88.3 96.0 97.9 183 TB 229 399 573 512 289 188 128 99.8 84.9 72.6 97.4 128 233 Appendix 55 Trung Son hydropower project Technical design APPENDIX CALCULATION OF RESERVOIR BANK SLOPE STABILITY Appendix 56 Trung Son hydropower project Technical design I. CASE ACCORDING TO RECOMMEND OF CONSULTANCY a) Section 1 Case 1: Water drain from NWL=160m down to MWL=150m in 5 days. (K=1.41) Bishop method 230 210 IA1 190 1.41 IA2 Elevation(m) 170 IB 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) 230 210 2.05 IA1 190 IA2 Elevation(m) 170 IB 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 57 Trung Son hydropower project Technical design Janbu method (K=1.35) 230 210 IA1 190 IA2 1.35 Elevation(m) 170 IB 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) 230 210 2.01 IA1 190 IA2 Elevation(m) 170 IB 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 58 Trung Son hydropower project Technical design Case 2: Water drain from NWL=160m down to MWL=150m in 10 days. (K=1.50) Bishop method 230 210 IA1 190 1.50 IA2 IB Elevation(m) 170 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) 230 210 IA1 2.13 190 IA2 IB Elevation(m) 170 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 59 Trung Son hydropower project Technical design Janbu method (K=1.45) 230 210 IA1 190 IA2 1.45 IB Elevation(m) 170 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) 230 210 IA1 2.08 190 IA2 IB Elevation(m) 170 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 60 Trung Son hydropower project Technical design Case 3: Water drain from NWL=160m down to MWL=150m in 15 days. (K=1.55) Bishop method 230 210 IA1 190 1.55 IA2 IB Elevation(m) 170 IIA 150 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) 230 210 IA1 2.11 190 IA2 IB Elevation(m) 170 IIA 150 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 61 Trung Son hydropower project Technical design Janbu method (K=1.49) 230 210 IA1 190 1.49 IA2 IB Elevation(m) 170 IIA 150 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) 230 210 IA1 2.04 190 IA2 IB Elevation(m) 170 IIA 150 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 62 Trung Son hydropower project Technical design b) Section 2 Case 1: Water drain from NWL=160m down to MWL=150m in 5 days. (K=1.04) Bishop method 260 240 220 1.04 200 IA1 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) 260 240 220 1.39 200 IA1 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 63 Trung Son hydropower project Technical design Janbu method (K=1.01) 260 240 220 200 IA1 IA2 1.01 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) 260 240 220 1.37 200 IA1 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 64 Trung Son hydropower project Technical design Case 2: Water drain from NWL=160m down to MWL=150m in 10 days. (K=1.10) Bishop method 260 240 220 IA1 1.10 200 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) 260 240 220 IA1 1.44 200 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 65 Trung Son hydropower project Technical design Janbu method (K=1.06) 260 240 220 IA1 200 IA2 1.06 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) 260 240 220 IA1 1.41 200 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 66 Trung Son hydropower project Technical design Case 3: Water drain from NWL=160m down to MWL=150m in 15 days. (K=1.13) Bishop method 260 240 IA1 220 1.13 200 IA2 180 Elevation(m) IB 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) 260 240 IA1 220 1.48 200 IA2 180 Elevation(m) IB 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 67 Trung Son hydropower project Technical design Janbu method (K=1.10) 260 240 IA1 220 200 IA2 1.10 180 Elevation(m) IB 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) 260 240 IA1 220 1.45 200 IA2 180 Elevation(m) IB 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 68 Trung Son hydropower project Technical design c) Section 3 Case 1: Water drain from NWL=160m down to MWL=150m in 5 days. (K=1.29) Bishop method 220 200 IA1 IA2 1.29 180 IB Elevation(m) 160 IIA 140 120 100 80 60 80 100 120 140 160 180 200 220 240 260 Distance(m) 220 200 IA1 IA2 1.60 180 IB Elevation(m) 160 IIA 140 120 100 80 60 80 100 120 140 160 180 200 220 240 260 Distance(m) Appendix 69 Trung Son hydropower project Technical design Janbu method (K=1.29) 220 200 IA1 IA2 1.29 180 IB Elevation(m) 160 IIA 140 120 100 80 60 80 100 120 140 160 180 200 220 240 260 Distance(m) 220 200 IA1 IA2 1.60 180 IB Elevation(m) 160 IIA 140 120 100 80 60 80 100 120 140 160 180 200 220 240 260 Distance(m) Appendix 70 Trung Son hydropower project Technical design Case 2: Water drain from NWL=160m down to MWL=150m in 10 days. (K=1.36) Bishop method 210 IA1 IA2 190 1.36 IB 170 Elevation(m) IIA 150 130 110 90 70 90 110 130 150 170 190 210 230 250 Distance(m) 210 IA1 IA2 190 1.64 IB 170 Elevation(m) IIA 150 130 110 90 70 90 110 130 150 170 190 210 230 250 Distance(m) Appendix 71 Trung Son hydropower project Technical design Janbu method (K=1.35) 210 IA1 IA2 190 1.35 IB 170 Elevation(m) IIA 150 130 110 90 70 90 110 130 150 170 190 210 230 250 Distance(m) 210 IA1 IA2 190 1.63 IB 170 Elevation(m) IIA 150 130 110 90 70 90 110 130 150 170 190 210 230 250 Distance(m) Appendix 72 Trung Son hydropower project Technical design Case 3: Water drain from NWL=160m down to MWL=150m in 15 days. (K=1.39) Bishop method 220 200 IA1 IA2 1.39 180 IB Elevation(m) IIA 160 140 120 100 80 70 90 110 130 150 170 190 210 230 250 Distance(m) 220 200 IA1 IA2 1.66 180 IB Elevation(m) IIA 160 140 120 100 80 70 90 110 130 150 170 190 210 230 250 Distance(m) Appendix 73 Trung Son hydropower project Technical design Janbu method (K=1.38) 220 200 IA1 IA2 1.38 180 IB Elevation(m) IIA 160 140 120 100 80 70 90 110 130 150 170 190 210 230 250 Distance(m) 220 200 IA1 IA2 1.65 180 IB Elevation(m) IIA 160 140 120 100 80 70 90 110 130 150 170 190 210 230 250 Distance(m) d) Section 4 at left abutment dam Case 1: Water drain from NWL=160m down to MWL=150m in 5 days. (K=1.01) Appendix 74 Trung Son hydropower project Technical design Bishop method 220 200 IA1 1.01 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) 220 200 IA1 1.30 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Janbu method (K=0.98) Appendix 75 Trung Son hydropower project Technical design 220 200 IA1 180 0.98 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) 220 200 IA1 180 1.25 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Case 2: Water drain from NWL=160m down to MWL=150m in 10 days. (K=1.09) Appendix 76 Trung Son hydropower project Technical design Bishop method 220 200 IA1 1.09 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) 220 200 1.38 IA1 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Janbu method (K=1.07) Appendix 77 Trung Son hydropower project Technical design 220 200 IA1 1.07 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) 220 200 1.30 IA1 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Case 3: Water drain from NWL=160m down to MWL=150m in 15 days. (K=1.11) Bishop method Appendix 78 Trung Son hydropower project Technical design 220 200 1.11 IA1 180 IA2 Elevation(m) IB 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) 220 200 IA1 1.27 180 IA2 IB Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Janbu method (K=1.09) Appendix 79 Trung Son hydropower project Technical design 220 200 IA1 1.09 180 IA2 IB Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) 220 200 IA1 1.29 180 IA2 IB Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) e) Section 4 at right abutment Case 1: Water drain from NWL=160m down to MWL=150m in 5 days. (K=1.02) Appendix 80 Trung Son hydropower project Technical design Bishop method 240 220 1.02 200 Elevation(m) 180 160 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) 240 220 1.17 200 Elevation(m) 180 160 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Janbu method (K=0.99) Appendix 81 Trung Son hydropower project Technical design 240 220 200 Elevation(m) 0.99 180 160 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) 240 220 1.17 200 Elevation(m) 180 160 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Case 2: Water drain from NWL=160m down to MWL=150m in 10 days. (K=1.09) Appendix 82 Trung Son hydropower project Technical design Bishop method 240 220 1.09 200 IA1 Elevation(m) 180 IA2 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) 240 220 1.22 200 IA1 Elevation(m) 180 IA2 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Appendix 83 Trung Son hydropower project Technical design Janbu method (K=1.06) 240 220 200 1.06 IA1 Elevation(m) 180 IA2 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) 240 220 1.20 200 IA1 Elevation(m) 180 IA2 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Appendix 84 Trung Son hydropower project Technical design Case 3: Water drain from NWL=160m down to MWL=150m in 15 days. (K=1.12) Bishop method 240 220 1.12 200 IA1 IA2 Elevation(m) 180 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) 240 220 1.24 200 IA1 IA2 Elevation(m) 180 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Appendix 85 Trung Son hydropower project Technical design Janbu method (K=1.09) 240 220 200 1.09 IA1 IA2 Elevation(m) 180 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) 240 220 1.23 200 IA1 IA2 Elevation(m) 180 IB 160 IIA 140 120 100 80 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) f) Section 5 Case 1: Water drain from NWL=160m down to MWL=150m in 5 days. (K=1.06) Appendix 86 Trung Son hydropower project Technical design Bishop method 250 230 IA1 210 1.06 IA2 190 Elevation(m) 170 IB 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) 250 230 1.33 IA1 210 IA2 190 Elevation(m) 170 IB 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Janbu method (K=1.04) Appendix 87 Trung Son hydropower project Technical design 250 230 IA1 210 IA2 190 1.04 Elevation(m) 170 IB 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) 250 230 IA1 210 1.30 IA2 190 Elevation(m) 170 IB 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Case 2: Water drain from NWL=160m down to MWL=150m in 10 days. (K=1.12) Appendix 88 Trung Son hydropower project Technical design Bishop method 250 230 IA1 210 IA2 190 1.12 Elevation(m) IB 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) 250 230 IA1 1.28 210 IA2 190 Elevation(m) IB 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Janbu method (K=1.09) Appendix 89 Trung Son hydropower project Technical design 250 230 IA1 210 IA2 190 1.09 Elevation(m) IB 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) 250 230 IA1 1.28 210 IA2 190 Elevation(m) IB 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Case 3: Water drain from NWL=160m down to MWL=150m in 15 days. (K=1.18) Appendix 90 Trung Son hydropower project Technical design Bishop method 230 1.18 IA1 210 IA2 190 IB Elevation(m) 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) 230 1.23 IA1 210 IA2 190 IB Elevation(m) 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Janbu method (K=1.16) Appendix 91 Trung Son hydropower project Technical design 230 IA1 210 IA2 190 1.17 Elevation(m) IB 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) 230 1.26 IA1 210 IA2 190 IB Elevation(m) 170 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Appendix 92 Trung Son hydropower project Technical design II. CALCULATION COMBINATION CASES FOR VERIFYING RECOMMENDATION GIVEN BY WB Slope without reservoir. ground water level raised to slope surface due to rain. a) Section1 Bishop method (K=0.80) 0.80 230 210 IA1 190 IA2 Elevation(m) 170 IB 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 93 Trung Son hydropower project Technical design Janbu method (K=0.79) 0.79 230 210 IA1 190 IA2 Elevation(m) 170 IB 150 IIA 130 110 90 70 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 94 Trung Son hydropower project Technical design b) Section2 Bishop method (K=0.40) 0.40 260 240 220 200 IA1 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 95 Trung Son hydropower project Technical design Janbu method (K=0.37) 0.37 260 240 220 200 IA1 IA2 180 IB Elevation(m) 160 140 120 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance(m) Appendix 96 Trung Son hydropower project Technical design c) Section3 Bishop method (K=0.70) 240 220 0.70 200 IA1 IA2 180 IB Elevation(m) 160 IIA 140 120 100 80 20 40 60 80 100 120 140 160 180 200 220 240 260 Distance(m) Janbu method (K=0.68) 240 220 0.68 200 IA1 IA2 180 IB Elevation(m) 160 IIA 140 120 100 80 20 40 60 80 100 120 140 160 180 200 220 240 260 Distance(m) Appendix 97 Trung Son hydropower project Technical design d) Section 4 at left abutment dam Bishop method (K=0.44) 0.44 220 200 IA1 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Janbu method (K=0.42) 220 0.42 200 IA1 180 IB IA2 Elevation(m) 160 IIA 140 120 100 80 50 70 90 110 130 150 170 190 Distance(m) Appendix 98 Trung Son hydropower project Technical design e) Section 4 at right abutment dam Bishop method (K=0.55) 240 0.55 220 200 Elevation(m) 180 160 140 120 100 80 20 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Janbu method (K=0.54) 240 220 200 0.54 Elevation(m) 180 160 140 120 100 80 20 40 60 80 100 120 140 160 180 200 220 240 260 280 Distance(m) Appendix 99 Trung Son hydropower project Technical design f) Section 5 Bishop method (K=0.40) 0.40 250 230 IA1 210 IA2 190 Elevation(m) 170 IB 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Janbu method (K=0.37) 0.37 250 230 IA1 210 IA2 190 Elevation(m) 170 IB 150 130 110 90 70 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance(m) Appendix 100 Trung Son hydropower project Technical design APPENDIX CALCULATION OF RESERVOIR DOWNSTREAM STABILITY Appendix 101 Trung Son hydropower project Technical design a) Downstream section 1 Water drain from downstream water level=104.5m down downstream water level=90.2m in 5 days. Bishop method (K=1.25) 240 220 1.25 200 180 IB Elevation(m) 160 IA2 IA1 140 120 IIA 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Distance(m) Janbu method (K=1.24) 240 220 200 180 1.240 IB Elevation(m) 160 IA2 IA1 140 120 IIA 100 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 Distance(m) Appendix 102 Trung Son hydropower project Technical design b) Downstream section 2 Water drain from downstream water level=104.5m down to downstream water level=90.2m in 5 days. Bishop method (K=1.09) 280 260 1.09 240 220 200 edQ IA1 Elevation(m) 180 IA2 160 140 IB 120 IIA 100 80 60 40 60 80 100 120 140 160 180 200 220 240 260 Distance(m) Janbu method (K=1.08) 280 260 1.08 240 220 200 edQ IA1 Elevation(m) 180 IA2 160 140 IB 120 IIA 100 80 60 40 60 80 100 120 140 160 180 200 220 240 260 Distance(m) Appendix 103 Trung Son hydropower project Technical design c) Downstream section 3 Water drain from downstream water level=104.5m down to downstream water level=90.2m in 5 days. Bishop method (K=1.11) 260 1.11 240 220 200 edQ 180 IA1 Elevation(m) 160 IA2 140 IB 120 100 IIA 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Janbu method (K=1.10) 260 240 220 1.10 200 edQ 180 IA1 Elevation(m) 160 IA2 140 IB 120 100 IIA 80 60 40 40 60 80 100 120 140 160 180 200 220 240 260 280 300 Distance(m) Appendix 104 Trung Son hydropower project Technical design d) Downstream section 4 Water drain from downstream water level=104.5m down to downstream water level=90.2m in 5 days. Bishop method (K=1.28) 1.28 190 170 edQ 150 IB IA1 Elevation(m) 130 IA2 110 IIA 90 70 50 100 120 140 160 180 200 220 240 260 280 300 320 Distance(m) Janbu method (K=1.27) 1.27 190 170 edQ 150 IB IA1 Elevation(m) 130 IA2 110 IIA 90 70 50 100 120 140 160 180 200 220 240 260 280 300 320 Distance(m) Appendix 105 VIETNAM ELECTRICITY POWER ENGINEERING CONSULTING JOINT STOCK COMPANY 4 ISO 9001:2000 Project: T .02.04 TRUNG SON HYDROPOWER PROJECT TECHNICAL DESIGN OPERATION MODEL OF RESERVOIR Deputy Director of Hydropower Tr ng Hoài Th Tuyên Engineering Consulting Center Project Manager V ng Anh D ng Nha trang City, July , 2010 ON BEHALF OF GENERAL DIRECTOR Tran Van Tho DEPUTY GENERAL DIRECTOR