Annual Journal of Hydraulic Engineering, JSCE, Vol.54, 2010, February
POTENTIAL IMPACT OF SAMBOR DAM PROJECT ON INTERACTION BETWEEN MEKONG RIVER AND TONLE SAP LAKE
Sushu WU1, Hiroshi ISHIDAIRA2 and Wenchao SUN3
1Student member of JSCE, Ph. D. Student, Dept. of Civil and Environmental Engineering, University of Yamanashi (Takeda 4-4-37, Kofu, Yamanashi 400-8511, Japan) 2Member of JSCE, Associate Professor, Dept. of Civil & Environment Engineering, University of Yamanashi (Takeda 4-4-37, Kofu, Yamanashi 400-8511, Japan) 3Student member of JSCE, Ph. D. Student, Dept. of Civil and Environmental Engineering, University of Yamanashi (Takeda 4-4-37, Kofu, Yamanashi 400-8511, Japan)
Tonle Sap Lake (TSL), an integral part of the Mekong River (MR) Basin, is an important region for social-environmental development of Cambodia. The water flow exchange between TSL and the MR Basin is a vital hydrological process that influences the ecosystem of TSL. Cambodia plan to build a dam for hydropower generation in mainstream of the Mekong River at Sambor which is located in the upstream of the confluence between TSL system and the MR. The objective of this study is to analyze the potential impact of Sambor Dam on interaction between the MR and TSL. The River Lake Water Exchange (RLWE) model was developed to describe this interaction. Then by giving a designed operation rule for the dam, the possible impact was explored through RLWE model. The results show that minimum water level in dry season would rise by 1.2m and peak flood water level would decrease by 1.0m after the installation of Sambor Dam, which would cause damage to ecosystem of TSL.
Key Words : Mekong River, Tonle Sap Lake, impact, RLEW model
1. INTRODUCTION reservoirs, and huge amount of water intake for irrigation result in an increase in dry-season water Tonle Sap Lake (TSL) has abundant resources levels and a decrease in flood peak level. For the 5) such as forests, fisheries, wetlands, agricultural land, period of 1997-2005, Kummu pointed out that and others. It is an important region for socio- water levels in the dry-season increased by 0.15– economic development of Cambodia1), 2), 3). In dry 0.60 m in TSL, which would, in particular, be season, the water surface area is about 3,000km2. harmful to the present lake ecosystem. And during the rainy season, it expands to about In November 2006, on the request of Kingdom 15,000 km2, largely due to flow discharge from the of Cambodia, China Southern Power Grid, Mekong River through Tonle Sap River (TSR). This conducted a feasibility study for the Sambor creates an enormous fish breeding, nursing and hydropower project, which is planned to be installed feeding. About 280 fish species utilize the inundated in the Mekong River mainstream at Sambor district, 6), 7), 8) forests for at least 6 months for their breeding and Kratie province, Cambodia . The site locates to feeding during the monsoon4). approximately 174km north of Phnom Penh Port, Due to the huge water volume exchange the confluence of the Mekong River and TSR. between the Mekong River and TSL, the River-Lake According to a report of Mekong Secretariat in 9) interaction is of great importance for understanding 1994 , Sambor Dam will be designed as a “Run-off hydrological characteristics of TSL. However, it has river dam”. However, it will be nearest hydropower already been changed in recent years because of project to TSL, and have largest hydropower human activities in upstream area of the Mekong generation capacity among dam projects along the River. Construction of hydropower dams and mainstream of the Mekong.
Several researchers point out possible negative impact of this dam construction on ecosystem. Some researchers thought that the dam would destroy the natural situation for deep pool refuge habitats, migration corridors, and larval drift system, which will influence migratory fish species in the Mekong River. Chan et al.10) consider that any dam on the Mekong mainstream in this part of Cambodia could Fig.2 Extract water surface of TSL on March 11, 2000 be disastrous for fisheries, but this site, Sambor, is water surface area the worst possible location from this perspective. A (103km2) water level of TSL H(m) TERRA7) even use a subheading “protecting or 10 damning the Mekong?” to protest the project. Most 10 of these researches are from the point of river 5 ecology. Few researches discussed about 5 hydrological changes and consequent impact on 0 0 environment by Sambor Dam, especially for TSL. Date Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb The objective of this study is to investigate the potential impact of Sambor Dam on TSL. Firstly, a Fig.3 TSL area variation from March 2000 to March 2001 River Lake Water Exchange (RLWE) model was developed to simulate interaction between the available. As the human activity increase in the Mekong River and TSL. Then the impact of Sambor surrounding area of TSL and the Mekong River , the Dam on volume and water level of TSL was WL-V relation of TSL have been changed in the explored by RWLE model. past decades. Therefore, it is desired to renew the relation based on information from recent years. 2. STUDY AREA AND METHODOLOGY Thirty MODIS images for the period of March 2000 to March 2001 were collected to extract water (1) Study Area surface area of TSL. Since the reflectance of water Tonle Sap Lake (Fig.1) is the largest freshwater is very low in the reflective infrared bands, and the lake in Southeast Asia. It is located in the northwest majority of land covers are of higher reflectance, it part of Cambodia, which is an integral part of the is very efficiency to distinguish water surface and Mekong River. Mekong River is among the largest land area by MODIS. Unsupervised classification rivers in the world. It originates from Tibaetan method was used to identify water area in every Plateau in China, flows along the border between image. An example is demonstrated in Fig.2: Left Thailand and Laos, and then into Cambodia. The image is the original MODIS image; the blue part in confluence of Mekong River and Tonle Sap River is the right image is the water surface area of TSL area at Phnom Penh Port8). being extracted. The extracted water surface area (2) Water Level-Volume relationship time series is showed in Fig.3. By sorting the The relation between Water Level (WL) and derived water surface area in ascending order, Volume (V) is essential for have a better volume of water between two adjacent water surface understanding of hydrological cycle of TSL system. areas in the area sequence is computed as follow: 1 Currently, only the WL-V relationship of TSL ∆푉 = ∆퐻 × 퐴 + 퐴 (1) 2 1 2 9 3 where V(10 m ) is the water volume, A1 and A2 are N the two water surface areas (103 km2), ΔH is the difference between gauged stages at TSL on the Mekong River dates when the two images were captured. By sum this volume for each two adjacent water surface area, Tonle Sap Lake the corresponding total water surface volume of Sambor TSL for each images is obtained. Then the 3rd order polynomial was applied to describe WL-V relation between water level at Kompong Luong station and Thailand Tonle Sap River water volume of TSL: Mekong 3 2 Cambodia 푉 = 0.0626퐻퐾퐿 − 0.6209퐻퐾퐿 +
4.6267퐻퐾퐿 − 3.7625 (2) 50 KM 9 3 Vietnam Phnom Penh Port where V is water volume of TSL (10 m ), HKL is gauged stage at Kompong Luong station. A good 2 Fig.1 MODIS image of Tonle Sap Lake on January 17, 2005 statistical fit exist for the WL-V relation (R =0.99).
(3) RLWE MODEL Input Output a) Basic concept RLWE model can be used to simulate the Option Ⅰ Without dam balanced system of the interaction hydrologic HPK, HKL, HKC, (HCC) factors in the circumference of TSL (Fig.4). H Q Option Ⅱ PK Submodel for QPK PK The balanced system can be described as the H V H , H , (H ) KL H-V relationship following equation: PK KC CC Q Submodel for Q FP 푡𝑖 푡𝑖 푡𝑖 Hi Qi , Qi HKC FP 푄𝑖 + 푄퐹푃 + 푃푡 − 퐸푡 ± 푄푃퐾 KL PK FP 𝑖 𝑖 (HCC) = (푉푡 − 푉푡 )/∆푡 (3) V V 𝑖+1 𝑖 0 i i=0, 1, 2…n Eq.(3) 푡𝑖 where 푄 is the discharge from the tributaries at ti, P , E , Q H i+1 𝑖 i i i Eq.(3) Vi+1 KL 푡𝑖 δ 푄푃퐾 is the discharge in Prek Kdam station at ti, With dam i when normal flow (MR to TSL) in TSR “±” is “+” QPPP* H -Q H 푡𝑖 PPP PPP PPP and reverse flow (TSL to MR) is “-”, 푄퐹푃 is the inflow from floodplain at ti, 푃푡 is the precipitation i HPK Submodel for Q Q 𝑖 HPPP-HKC H KC PK PK V of TSL at ti, 퐸푡𝑖 is the evaporation of TSL at ti, 푉푡𝑖 is HKL H-V relationship HPPP-HPK-HKL QFP the water volume of TSL at time ti, Δt is the Submodel for Q HKC FP i calculate time interval. One variable “훿i” is used in H PK (HCC) RLEW model, which can be derived from the i V0 Vi H KL i i following equation: Q PK, Q FP, Vi i=0, 1, 2…n Eq.(3) 훿 = 푄푡𝑖 + 푃 − 퐸 (4) Vi+1 𝑖 𝑖 푡𝑖 푡𝑖 This study make an assumption: 훿 would not be Fig. 5 RLEW model structure changed after the dam operation. Based on Eq.(3), after input 푄푡𝑖 , 푄푡𝑖 and 푉 , 훿 can be obtained. By discipline of discharge flow through TSR is of 퐹푃 푃퐾 푡𝑖 𝑖 paramount importance. This study set Prek Kdam input 훿 and Q *(discharge of Phnom Penh Port 𝑖 PPP gauging station as the control station of TSR. In wet be changed by human activity such as dam season, water flow from river to lake, the lake serves operation) to RLEW model, water volume of TSL as an efficient flood reservoir, and in dry season, after dam operation can be calculated (Fig.5). reversed flow exists in TSR, support water to Any items of this system changed would lead a downstream for regional agriculture. The water level new water volume of TSL. The interaction between difference between river and lake is the key point, water levels along TSR and the Mekong River need this study use the water level in Phnom Penh Port to be discussed: (1) H -H -H ; (2) H -H . PPP PK KL PPP KC and Kompong Luong represent the water level of Any change on these water levels would cause a river and lake, respectively. variation on Q and Q . The balanced system and PK FP The equations11) for discharge in open channels volume of TSL also will be changed. In case of can be generally expressed as: QPPP* be put into RLWE model, the H-Q 훼 훽 relationship of Phnom Penh Port need to be obtained. 푄 = 퐾 × 퐴 × 푅 × 푆 (5) where Q is discharge (m3/s), K is a coefficient, A is b) RLWE model structure 2 The output and input data of RLWE Model are cross-sectional area (m ), R is hydraulic radius (L), showed in Fig.5. RLEW model structure can be α and β are exponents. S is friction slope, which can described as follow: be derived from the following equation: b.1) Discharge in Tonle Sap River 푆 = ∆퐻 퐿 (6) Among the River-Lake interaction, the ΔH here is water level difference between Prek Q Kdam and Kompong Luong station, L is the i Qi distance between Prek Kdam and Kompong Luong Tonle Sap Lake Mekong River station.By input S into Eq.(5), discharge can be Qi expressed as: Qi 훽 Sambor 푄 = 푓(퐻) × ∆퐻 (7) Observed discharge and water level at Prek Qi Kompong Luong QFP Kdam station in 2005 were used to get the following Tonle Sap River equation for QPK: Kompong Cham 푁표푟푚푎푙 퐹푙표푤 ∶ QPK Prek Kdam 푄 = 486.84 ∙ 퐻1.4545 ∙ (퐻 − 퐻 )0.5 Chroui Changvar 푃퐾 푃퐾 푃퐾 퐾퐿 (8) Phnom Penh Port 푅푒푣푒푟푠푒 퐹푙표푤: 2.3842 0.78 Fig. 4 Balanced system of RLWE model 푄푃퐾 = 74.453 ∙ 퐻푃퐾 ∙ (퐻퐾퐿 − 퐻푃퐾)
3 푄푃퐾 is discharge in Prek Kdam station (m /s), 퐻푃퐾 − 퐻퐾퐿 = HPK (m)and HKL (m)is water level in Prek Kdam and 0.7361 × 퐻푃푃푃 − 퐻퐾퐿 + 0.1573 (13) Kompong Luong station, respectively. Daily observed water level data in Phnom Penh b.2) Flood plain discharge Port and Kompong Cham station in 1993-2004 were Based on Inomata et al. 12), discharge from used to generate a regression equation for the floodplain flow into TSL uses the following relationship of these two stations. 2 equation: 푢푝: 퐻퐾퐶 − 퐻푃푃푃 = −0.078 × 퐻푃푃푃 𝑖 𝑖−1 𝑖−1 푄퐹푃 = 0.6612 푄퐾퐶 − 푄퐶퐶 − 2625.4 (9) +1.3237 × 퐻푃푃푃 + 0.2065 (14a) 𝑖 3 3 where i is time step on a daily basis, 푄퐹푃(m /s) is 푑표푤푛: 퐻퐾퐶 − 퐻푃푃푃 = 0.018 × 퐻푃푃푃 − 0.2075 𝑖−1 3 × 퐻2 + 0.6329 × 퐻 + 1.0522 (14b) discharge from flood plain on the date i, 푄퐾퐶 (m /s) 푃푃푃 푃푃푃 𝑖−1 3 where “up” and “down” is the discharge increase and 푄퐶퐶 (m /s) are discharges at Kompong Cham and Chroui Changvar on the date i-1. In case where and decrease period respectively, the correlation the water level data for Kompong Cham are coefficient of the up equation is 0.92 and the down available while the water level data for Chroui equation is 0.94. Changvar are not available, the equation based on the Kompong Cham water level data collected two 3. RESAULTS AND DISCUSSION days earlier was used as the follow equation: 푄𝑖 =1196.2(퐻𝑖−2 − 12.0) (10) (1) Validation for RLWE model 퐹푃 퐾퐶 There are insufficient observed discharge data in where 퐻𝑖−2(m) is water level in Kompong Cham on 퐾퐶 TSL for validating RLWE model. Only observed the date i-2. discharge data in 2005 are available. Fig.6 shows b.3) H-Q relationship of Phnom Penh Port the observed discharge and simulated discharge by There are insufficient hydrological data in TSL Eq.(8) for 2005. The flows larger than zero are and its surrounding area, especially the observed normal flow and lower than zero are reverse flow. discharge data. This paper uses the relationship The mean error is 9%. By input daily observed between H and H -H published by Mekong PPP KC PPP water level data at Prek Kdam and Kompong Luong River Commission in 197013) to calculate Q . PPP station from 1996 to 2004, the water volume of TSL After regression analysis, the discharge in Phnom and discharge at Prek Kdam are obtained as shown Penh Port station (Q (m3/s)) is given as: PPP in Fig.7, the discharge above the abscissa axis is 푄 = (11.0869 × 퐻 + 37.4245)2 × 푃푃푃 푃푃푃 normal flow, the others is reverse flow. (퐻 − 퐻 )0.4569 (11) 퐾퐶 푃푃푃 1 푁 푄표푏푠 −푄푐푎푙 푚푒푎푛 푒푟푟표푟 = 𝑖=1 (15) where 퐻푃푃푃 (m) and 퐻퐾퐶 (m) are water levels at 푁 푄표푏푠 Phnom Penh Port and Kompong Cham station respectively. By putting the observed daily 퐻 푃푃푃 (2) Impact analysis of Sambor Dam project and 퐻 from 1991 to 2002, calculate the discharge 푘푐 a) Restoration of historical discharge data of at Phnom Penh Port station in these 12 years. Use Sambor site the discharge and the water level at Phnom Penh Due to no observed data at Sambor site, a simple Port gauge to fitting the H-Q curve: way used to roughly estimate the discharge based on 푢푝 −14 3 −9 2 푄푃푃푃 = 8 × 10 × 퐻푃푃푃 − 8 × 10 × 퐻푃푃푃 the catchment area: +0.0004 × 퐻푃푃푃 − 0.1985 (12a) 10 3 3 푑표푤푛 QPK (10 m /s) 푄푃푃푃 = 3.1413 푙푛 퐻푝푝푝 − 24.074 (12b) The discharge was divided into two period: No. 푢푝 0 푄푃푃푃 is discharge in the period from minimum to 푑표푤푛 observed discharge peak discharge, 푄푃푃푃 is in the discharge decrease calculated discharge period after the peak discharge, the correlation -10 coefficient are 0.997 and 0.988 during up and down Fig.6 Calculated and observed discharge of Prek Kdam in 2005 period, respectively. 3 3 Q (10 m /s) Qpk 9 3 b.4) H -H -H and H -H relationship 15 PK V (10 m ) 50 PPP PK KL PPP KC V As TSR is the link of TSL and the Mekong 40 River, Phnom Penh Port, Prek Kdam and Kompong 30 0 Luong stations are used as the representative date 20 stations to connect the river and lake. Observed 96-1 97-1 98-1 99-1 00-1 01-1 02-1 03-1 04-1 daily water level data of these three gauges from 10 -15 0 1996 to 2004 were used to get a regression equation, with a correlation coefficient of 0.96. Fig.7 Water volume of TSL and discharge at Prek Kdam calculated by RLWE mode
𝑖 𝑖 퐴푆퐴푀 40 3 푄푆퐴푀 = 푄푃푃푃 × (16) Q(10 m3/s) 퐴푃푃푃 without dam 𝑖 𝑖 where 푄푆퐴푀 is daily discharge at Sambor, 푄푃푃푃 is 20 with dam the discharge at Phnom Penh Port, 퐴푆퐴푀 and 퐴푃푃푃 are the catchment areas (km2) of Sambor and Phnom 0 9) month Penh Port respectively. Based on initial design , 1 2 3 4 5 6 7 8 9 10 11 12 Sambor Dam site have a catchment area of Fig. 8 Discharge in Sambor with and without dam in 1985 2 646,000km . According the Lower Mekong 60 V (109m3) without dam Hydrology Yearbook, catchment area of Phnom 40 Penh Port is 663,000 km2. with dam 20 b) Scenario setting The theoretical power derived from the water 0 month 1 2 3 4 5 6 7 8 9 10 11 12 fall depends upon the height and the rate of flow. The available hydropower is calculated from the Fig.9 Water volume of TSL with and without dam in 2000 following formula:14),15) are available12) in 1985-2004. The data sets are used 푃 = 9.8 × 푟 × 푞 × ℎ (17) to analyze flood frequency in this region. Based on where P is theoretical output power (kW), q is water derived flood frequency curve of Kompong Cham, flow rate (m3/s), h is water head (m), and r is overall year 2000 and 1998 were selected as typical 1-20 power generation efficiency, which is set to 90% wet year and typical 1-20 dry respectively, for here. According to the report “Mekong Mainstream which the impact of Sambor Dam on interaction Run-of-River Hydropower” published by Mekong between TSL and the Mekong River was analyzed. Secretariat in 19949), the water head is roughly equal c) Potential impact on natural environment to 40m and one of designed hydropower capacity is According to the calculated discharge of Sambor, 2500MW. Based on Eq.(17), the designed discharge discharge in Phnom Penh Port station can be derived 3 （ QD=q ） is 7102m /s, for which the possible from the following equation: ∗ ∗ impact is analyzed. 푄푃푃푃 = 푄푆퐴푀 + (푄푃푃푃 − 푄푆퐴푀 ) (19) ∗ One simple hypothetical hydropower dam where 푄푃푃푃 and 푄푃푃푃 are discharge in Phnom Penh operation rule was designed: In wet season, when Port station with and without dam operation, 3 ∗ inflow is larger than 7102m /s, appropriate part of respectively. 푄푆퐴푀 and 푄푆퐴푀 are discharge in daily excessive inflow will be kept in the reservoir, Sambor site with and without dam operation, ∗ which will be release in dry season to maintain the respectively. By putting 푄푃푃푃 to RLWE model, discharge at the level of 7102 m3/s. The discharge in water volume was calculated. Fig.9 shows the daily Sambor Dam site after dam operation can be derived water volume variation of TSL in 2000 with Sambor from the following equation: Dam working or not. Obvious water volume 𝑖 increase in dry season and decrease in flood season 푄퐷, 푄푆퐴푀 < 푄퐷 ∗𝑖 푄푆퐴푀 = 𝑖 푉2 𝑖 𝑖 can be found in this figure. 푄푆퐴푀 − 푄푆퐴푀 − 푄퐷 , 푄푆퐴푀 ≥ 푄퐷 푉1 For the typical wet year 2000 and typical dry 푉 = 푞𝑖 푑푡 푉 = 푞𝑖 푑푡 year 1998, the maximum and minimum stage at 1 1 푦푒푎푟 푒 2 1 푦푒푎푟 푟 Kompong Luong, the period for TSL within 𝑖 𝑖 0 , 푄푆퐴푀 < 푄퐷 different water volume level and the period of flood 푞푒 = 𝑖 𝑖 푄푆퐴푀 − 푄퐷 , 푄푆퐴푀 ≥ 푄퐷 plain exist with and without dam installation are 𝑖 shown in Table 1. The extent of hydrological 𝑖 0 , 푄푆퐴푀 ≥ 푄퐷 푞푟 = 𝑖 𝑖 variation will decrease if the dam exists. The time (푄퐷 − 푄푆퐴푀 ) , 푄푆퐴푀 < 푄퐷 (18) 9 3 ∗𝑖 𝑖 3 period for high water level (V>40×10 m ) and low where 푄 and 푄 are discharge (m /s) in 9 3 푆퐴푀 푆퐴푀 water level (V<10×10 m ) is shorter than natural Sambor site with and without dam operation 𝑖 𝑖 situation. The water level would change from the respectively. 푞푒 and 푞푟 are excessive and recruitment 3 lowest water level in typical dry year 1.2m to the discharge (m /s) respectively. V1 and V2 are water highest water level in typical wet year 10.4m under 3 𝑖 𝑖 volume (m ) integral of 푞푒 and 푞푟 respectively. natural situation. However, after dam operation, the The impact of Sambor Dam operation on range of variation would change to 2.4m-9.4m. discharge in 1985 is shown in Fig.8. In this case, Minimum water level of TSL in dry season 22% of the daily excessive inflow was kept in the would rise by 1.2m (2.4m-1.2m), which would reservoir to maintain the hydrology power. cause permanently inundated large areas, rendering Observed data in TSL system is scarce, it inaccessible to floodplain vegetation and eroding especially continuity data series. Only daily the productivity basis of the ecosystem, the lake observed water level data sets in Kompong Cham extension would destroy considerable areas of
Table 1 Influence of TSL volume characteristic of TSL need to be further discussed. Integration of 1998 1998 2000 2000 RLWE model with basin-scale hydrological Nature With dam Nature With Dam model would also be in the future work for the Max H 6.9m 6.3m 10.4m 9.4m impact analysis of other potential human Min H 1.2m 2.4m 1.7m 3.3m activities on hydrological cycle in this region. V<10 217 days 252 days 142 days 145 days 10
(RR2002). gallery forest stripe surrounding the lake in the 16) floodplain . REFERENCES Maximum TSL water volume in wet season 9 3 1) Bonheur, N. : Tonle Sap Ecosystem and Value. Technical would decrease (10.7 × 10 m ) and peak flood water Coordination Unit for Tonle Sap, Ministry of Environment, level would have 1.0m lower(10.4m-9.4m). The Phnom Penh, Cambodia, 2001. relationship between the maximum flood level in 2) Keskinen, M. : The lake with floating villages: socio- wet season and the fish catch shows that a economic analysis of the Tonle Sap Lake, Int. J. Water Resource., Dev. 22, pp. 463–480, 2006. permanent lowering of the average peak flood levels 3) Kummu, M. and Nikula, J. : Ecosystem management of would result in a proportionally lower fish catch. Tonle Sap Lake: An integrated modelling approach. Int. J. Because of the primary reason for the enormous Water Resource., Vol. 22, pp.497–519, 2006. quantity of fish in TSL is the monsoon which 4) Sverdrup-Jensen, S. : Fisheries in the Lower Mekong Basin: Status and perspectives. MRC Technical Paper No. annually swells the lake area and the temporary 6. Mekong River Commission, 2002. access to enormous quantities of food drives the 5) Kummu, M. and Sarkkula, K. : Impact of the Mekong huge production of fish17). River Flow Alteration on the Tonle Sap Flood Pulse, J. The period that flood plain exists does not show Royal Swedish Academy of Sciences, pp. 185-192, 2008. a signification change. In flood season, natural 6) Sambor dam, Kratie province, Cambodia, Bangkok, TERRA., September 2007. inflow into reservoir is enough to generate the 7) Background to the Mekong mainstream dams, Bangkok, electric power, for that reason, the discharge in peak TERRA., September 2007. time would not change a lot. Also, discharge and 8) Press Briefing: MRC silent as mainstream dams move water level in Kompong Cham station would not forward, Bangkok, TERRA., 8 November 2007. 9) Acres International Limited and Compaigne Nationale du have a large alteration, which decide the flood plain Rhone, Mekong Mainstream Run-of-River Hydropower, exist duration time(when HKC≥12). Therefore, most Mekong Secretariat, Bangkok, 1994. of the water exchange between river and lake is 10) Chan, S., Putrea, S., Sean, K., and Hortle, K.G. : Using through TSR, nevertheless, the dam would still local knowledge to inventory deep pools, important fish habitats in Cambodia, Proceedings of the 6th Technical bring impact on TSL area. Symposium on Mekong Fisheries, pp.65, 2003. 11) López, R. and Barragán, J. : Flow resistance equations 4. CONCLUSION without explicit estimation of the resistance coefficient for coarse-grained rivers, J. Journal of Hydrology, Vol. 338, Issues 1-2, pp. 113-121, 2007. In this study, the potential impact of Sambor 12) Inomata, H. and Fukami, K. : Restoration of historical data Dam on interaction between TSL and the Mekong of Tonle Sap Lake and its surrounding areas, J. River was analyzed. RLWE model was developed to Hydrological Processes, 22, pp.1337-1350, 2008. simulate the interaction. By applying RLEW model, 13) Mekong River Commission: Lower Mekong Hydrologic Yearbook, 1970. the hydrological characteristics of TSL under 14) Rajput, R.K. : A Textbook of Power Plant Engineering, scenarios with and without Sambor Dam were pp.585, 2005. analyzed for one typical dry and wet year. The 15) Gevorkian, P. : Sustainable energy systems engineering: results show that if the dam is installed, the extent of the complete green building design resource, pp.313, 2006. 16) Lamberts, D. : Little impact, much damage: The hydrological variation in TSL will decrease. consequences of Mekong River flow alterations for the Especially, minimum water level would increase Tonle Sap ecosystem. Modern Myths of the Mekong, pp. 1.2m in dry season and peak flood water level 3–18, 2008. would decrease by 1.0m. This paper is only focused 17) Zalinge, N.P. : Mekong fisheries network newsletter, on the potential influence of hydrological interacting Mekong Fish Catch and Culture, Vol.8, No.2, 2002. variables on TSL and the Mekong River by Sambor Dam, the impact of ecosystem and fish production (Received September 30, 2009)