Report E-Mail Version November 2006
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Electricity of Vietnam Environmental Impact Assessment on the Cambodian Side of the Srepok River due to Hydropower Development in Vietnam Final Report E-mail Version November 2006 Prepared by SWECO Grøner in association with Norwegian Institute for Water Research, EVIORO-DEV, ENS Consult Environmental Impact Assessment on the Cambodian part of the Srepok River November 2006 due to hydropower development in Vietnam ACKNOWLEDGEMENTS.....................................................................................5 EXECUTIVE SUMMARY......................................................................................6 1. INTRODUCTION AND METHODOLOGY.............................................12 1.1 OBJECTIVES OF THE PROJECT...........................................................................12 1.2 SCOPE OF WORK AND LIMITATIONS ................................................................13 1.3 STUDY AREA ...................................................................................................14 1.3.1 Landscape and Ecology...........................................................................14 1.3.2 Aquatic Ecology.......................................................................................14 1.3.3 Administrative Areas and Population ......................................................15 1.3.4 Ethnicity...................................................................................................18 1.3.5 Socio-Economic Setting...........................................................................19 1.3.6 Living and Health Standards....................................................................20 1.4 STUDY METHODS ............................................................................................21 1.4.1 Study Process...........................................................................................21 1.4.2 Study Topics............................................................................................22 1.4.3 Methodology for an Integrated Field Survey...........................................23 1.4.4 Integration of Data into Impact Assessment............................................26 2. HYDROPOWER PROJECTS ON THE VIETNAMESE PART OF SREPOK RIVER....................................................................................................28 2.1 GENERAL.........................................................................................................28 2.2 DESCRIPTION OF THE HYDROPOWER PROJECTS ...............................................29 2.2.1 Projects in Operation................................................................................29 2.2.2 Projects under Construction.....................................................................29 2.2.3 Committed Projects..................................................................................33 2.2.4 Hydropower Projects under Planning ......................................................35 2.3 HYDROPOWER PROJECTS ON CAMBODIAN SIDE OF SREPOK RIVER .................37 3. HYDROLOGY AND FLOW CHARACTERISTICS ...............................39 3.1 HYDROPOWER OPERATION SCENARIOS ...........................................................42 3.1.1 Scenario 1 – Baseline...............................................................................42 3.1.2 Scenario 2 – Srepok 3 turbine design discharge ......................................42 3.1.3 Scenario 3 – Srepok 3 flood storage ........................................................43 3.1.4 Scenario 4 – Srepok 4 high operational discharge...................................43 3.1.5 Scenario 5 – Srepok 4 mean operational discharge (Re-regulation Reservoir)..............................................................................................................43 3.2 MAIN RESULTS FROM THE HYDRODYNAMIC MODELING STUDY .....................44 3.2.1 Scenario 1 - Baseline ...............................................................................44 3.2.2 Scenario 2 – Srepok 3 Turbine Design Discharge...................................45 3.2.3 Scenario 3 – Srepok 3 Flood Storage.......................................................47 3.2.4 Scenario 4 - Srepok 4 High Operational Discharge.................................47 3.2.5 Scenario 5 – Srepok 4 Mean Operational Discharge (Re-regulation Reservoir)..............................................................................................................48 4. BASELINE CONDITIONS .........................................................................50 4.1 WATER QUALITY AND AQUATIC LIFE .............................................................50 4.1.1 Water Quality...........................................................................................50 4.1.2 Fish...........................................................................................................53 4.1.3 Fish Management.....................................................................................58 4.2 LAND USE AND TERRESTRIAL BIODIVERSITY..................................................59 4.2.1 Land: Use, Cover and Resources.............................................................59 4.2.2 Biodiversity Status and Protected Areas (PA).........................................66 SWECO Grøner in association with Final Report 2/141 NIVA, ENVIRO-DEV, and ENS Consult Environmental Impact Assessment on the Cambodian part of the Srepok River November 2006 due to hydropower development in Vietnam 4.2.3 Use of Forest and Wildlife by Local People............................................73 4.2.4 Dependency on Srepok River – Animals and Vegetation Needs ............73 4.2.5 Threats to Vegetation and Wildlife..........................................................73 4.3 SOCIO-ECONOMIC AND CULTURAL ISSUES ......................................................74 4.3.1 Livelihoods and Subsistence Economy ...................................................74 4.3.2 Water and Health .....................................................................................78 4.3.3 Cultural Significance of Natural Resources Utilization...........................80 5. IMPACT ASSESSMENT.............................................................................83 5.1 IMPACTS DURING CONSTRUCTION OF NEW HYDROELECTRIC PROJECTS..........83 5.1.1 Impacts on Water Quality, Aquatic Life, Land Use and Biodiversity.....83 5.1.2 Impacts on Socio-Economy and Culture .................................................85 5.2 IMPACTS DURING OPERATION PHASE (WITHOUT SREPOK 4 AS A RE- REGULATION RESERVOIR).........................................................................................87 5.2.1 Ecological Flow.......................................................................................87 5.2.2 Impacts on Water Quality and Aquatic Life............................................87 5.2.3 Impacts on Land Use and Biodiversity....................................................93 5.2.4 Anticipated Impacts on Socio-Economy and Culture..............................94 5.3 IMPACTS DURING OPERATION PHASE (WITH SREPOK 4 AS A RE-REGULATION RESERVOIR)...............................................................................................................97 5.4 POSITIVE IMPACTS...........................................................................................98 6. MITIGATION AND ENHANCEMENT MEASURES .............................99 6.1 MITIGATION OF IMPACTS FROM CONSTRUCTION OF NEW HYDROELECTRIC PROJECTS...................................................................................................................99 6.1.1 Measures Against Erosion .......................................................................99 6.1.2 Runoff from Tunnel Blasting and Tunnel Drilling................................100 6.1.3 Soil Deposits and Spoil Rock Deposits .................................................100 6.1.4 Sanitary Effluents from the Construction Workers Camp.....................101 6.1.5 Oil and Chemical Spill...........................................................................101 6.1.6 Measures against Accidental Water Releases........................................102 6.1.7 Measures against Dry-ups......................................................................102 6.2 MITIGATION OF IMPACTS FROM OPERATION OF HYDROPOWER PROJECTS.....102 6.2.1 Prolong the Wet Season Filling of the Reservoirs.................................102 6.2.2 Reduce the Nutrient Inputs to the Reservoirs ........................................103 6.2.3 Building Fish Bypass Systems...............................................................103 6.2.4 Fish Stocking Program...........................................................................103 6.2.5 Development Program for Aquaculture.................................................103 6.2.6 Protected Areas......................................................................................104 6.2.7 Mitigation of Socio-economic Impacts in the Downstream Area .........104 6.2.8 Planning of Social Mitigation ................................................................105 6.3 ADDITIONAL MITIGATION MEASURES WITHOUT SREPOK 4 OPERATED AS A RE- REGULATION RESERVOIR.........................................................................................106 6.3.1 Erosion ...................................................................................................107 6.3.2 Daily Water Level Fluctuations (and sudden releases of water) ...........108