Water Resources Management in Ba River Basin under Future Development and Climate Scenarios

1. Water Resources Management in Ba River Basin under Future Development and Climate Scenarios Presented by: Nguyen Thi Thu Ha Bangkok, May 2009 Examination Committee:Dr. Mukand S. Babel (Chairperson) Dr. Roberto S. Clemente Dr. Sylvain Perret Dr. Sutat Weesakul

2. 1 Statement of the Problem 3 Methodology 4 5 Results Conclusions and Recommendations Presentation Outline 2 Objectives and Scope of the Study

3. Statement of the Problem Rationale • A proper water planning and management will be a major step in achieving sustainable development (Bonn, 2001). • System analysis tools are powerful to evaluate and propose the best water management strategies. • Good water resources management should be based on an understanding of current demand/ supply and an awareness of possible future trends. Ba River Basin: Why? • The largest river basin in the southern region of Central Vietnam • Planning and management of water resources are currently done based on sectoral approaches and administrative boundaries • Future basin development, global warming and its impacts will put pressure on water and land resources Future and Scenarios: Why? • Scenarios: a systematic way of thinking about the future • To get a better understanding of the possible implications of decisions • To support decision-making process

4. Objectives of the Study To develop a comprehensive simulation model to assess impacts of current and future basin development, as well as climate change on runoff, demand/ supply for Ba River Basin, Vietnam. To simulate and assess climate change impacts on river runoff, water supply and demand under current and future basin development aiding for long-term WRM&P Objective 3 To simulate and assess impacts of current and future basin development on water demand/supply under different water type years aiding for short-term WRM&P. Objective 2 To calibrate and validate a comprehensive simulation model of the Ba River Basin System. Objective 1

5. Scope of the Study Study area: Ba River Basin Data collection: Hydro-meteorological data, water uses, river network, water infrastructure and their operations. The Ba river basin system model is developed by coupling NAM and WEAP Future basin development is based on the regional and sectoral plans towards 2020 Different water years based on frequency analysis are applied for scenarios of future basin development and water supply priorities for short-term WRM&P Daily CCCma-CGCM2 rainfall and evaporation SRES-A2 and B2 up to 2100 (from Canadian Centre for Climate Modeling and Analysis) is used for study of climate change impacts for long-term WRM&P

6. Study Area 13,094 Km2

7. Methodology Data on water uses for all sectors Irrigation Livestock Domestic Industry Environment Meteorological data and calibration parameters Watershed and Stream Delineation Rainfall-Runoff Model (NAM) Runoff for sub-basins Water infrastructures and their operation; river network (connectivity) Demand Estimations Water allocation and planning model (WEAP) Calibration Validation Ba River Basin System Model Different water patterns Short-term Water Planning Scenarios Current and future basin developments Long-term Water Planning Scenarios Climate change scenarios - River flow - Water Shortages or coverage (user satisfaction) - Energy production, Reservoir storages - Environmental flow… The bias corrected CCCma-CGCM2, daily evaporation and rainfall Frequency analysis of inflow record

8. Methodology (cont’d) Rainfall – Runoff Model (NAM) To translate rainfall into flow in a river via a set of linked mathematical statements River Basin Planning Model (WEAP) • Current and future water demand/ supply, water infrastructures’ operations • Water development and management options by means of scenario analyses • WEAP software: water balance accounting; a linear programming (LP) for water allocation optimization based on supply priorities.

9. System ConfigurationCalibration and Validation

10. Scenario Definition

11. S1: Reference Scenario (Current Situation)Unmet demand

12. S1: Reference Scenario (Current Situation)Reservoir Storage and Hydropower

13. S2 and S3: Impact of future basin development Without (S2) and with (S3)introduction of water supply priorities Impact on water unmet demand for all sectors and irrigation sites

14. S2 and S3: Impact of future basin development Without (S2) and With (S3)introduction of water supply priorities Impact on inter-basin transfer link and instream flow requirement

15. S2 and S3: Impact of future basin development Without (S2) and With (S3)introduction of water supply priorities (cont’d) Impact on hydropower production and reservoir storage

16. S3 and S4: Impact of future basin development No improvement (S3) and increase of irrigation efficiency (S4) Impact on water unmet demand for all sectors and irrigation sites

17. S3 and S4: Impact of future basin development No improvement (S3) and increase of irrigation efficiency (S4) Impact on inter-basin transfer link and instream flow requirement

18. S3 and S4: Impact of future basin development No improvement (S3) and increase of irrigation efficiency (S4) Impact on hydropower production and reservoir storage

19. Assessment of Climate Change ImpactsFuture evaporation and rainfall projections Canadian Centre for Climate Modeling and Analysis Future precipitation projections Future evaporation projections CCCma-CGCM2 SRES-A2 and B2 Multiplicative shift method Local time series of daily weather up to 2100 Climate Change Impacts on river flow, water deficits, etc.??? Ba River Basin System Model

20. Bias correction and validation of predicted daily CGM evap. & rainfall

21. S5 and S6: CC impact on stream flow (water availability)current (S5) and future (S6) basin development

22. S6: CC impact on water deficitsFuture basin development and introduction of water supply priorities

23. S6: CC impact on inter-basin transfer and environmental flowFuture basin development and introduction of water supply priorities

24. S6: CC impact on hydropower and reservoir storage future basin development and introduction of water supply priorities

25. Conclusions • A comprehensive system simulation model for Ba River Basin was developed by coupling a rainfall- runoff model (NAM) and a water planning model (WEAP), it is a powerful tool to aid in decision-making in ST and LT water resources planning and management. • Future water infrastructures developed in the basin are very sensitive to water deficits and environmental flows. • Introduction of water supply priorities is useful to assure the equitable allocation proportions between upstream and downstream water users and meet fully for prior water demand sectors (domestic and industrial) in case of water shortages. • Improvement of irrigation efficiency can partially help in reducing water deficits for all water use sectors including environmental flow requirements. • Climate change impacts: • An increasing trend in annual evaporation • Dry seasonal rainfall anomalies are close to or below the equilibrium line • A decrease of runoff in the dry season; an increase of the wet season flow. • More water deficits; reduction in storages of reservoirs and decreases in hydropower productions at hydropower schemes

26. Recommendations • Operation rule curves of new reservoirs should be achieved • Feasibility of inter-basin transfer links should be considered in terms of no violations of water demands within basin but also economic, environmental aspects and other benefits for the received basins. • More experiments of GCMs’ outputs should be applied to justify the results • More complex and sophisticated methods should be studied to correct biases and to downscale the GCMs’ outputs into smaller resolutions

27. Thank You ! Bangkok, May 2009