Surface water balance and future water demands under environmental flow requirements, Nam Xong Watershed, Laos By Phousavanh Fongkhamdeng Student ID: 2195076 Supervisor: Strategic Professor Okke Batelaan Thesis Submitted to Flinders University for the degree of Master of Science (Water Resource Management) College of Science and Engineering Adelaide, November 2019 CONTENTS LIST OF FIGURES ............................................................................................................. III LIST OF TABLES .............................................................................................................. IV ABBREVIATIONS .............................................................................................................. V SUMMARY ...................................................................................................................... VIII DECLARATION .................................................................................................................. X ACKNOWLEDGEMENTS ................................................................................................. XI 1. INTRODUCTION ........................................................................................................... 1 1.1 Background and rationale ....................................................................................... 1 1.2 Objectives ............................................................................................................... 9 1.3 Expected results ..................................................................................................... 9 1.4 Research questions ................................................................................................ 9 1.5 Scope of the study ................................................................................................ 10 1.6 Structure of the thesis ........................................................................................... 10 2. LITERATURE REVIEW .............................................................................................. 12 2.1 Water balance study ............................................................................................. 12 2.2 Environmental flow ............................................................................................... 14 2.3 Water demand and allocation ............................................................................... 15 2.4 Climate change ..................................................................................................... 16 2.5 Water resources policy and institutional framework .............................................. 18 2.5.1 Policy, strategy and action plans .................................................................... 18 2.5.2 Water and water resources law and regulations ............................................ 20 2.5.3 Institution and coordination ............................................................................ 22 2.6 WEAP model application ...................................................................................... 23 3. MATERIALS AND METHODOLOGY ......................................................................... 28 3.1 Study area ............................................................................................................ 28 3.2 Data preparation and analysis .............................................................................. 29 3.2.1 Precipitation ................................................................................................... 29 3.2.2 River flow ....................................................................................................... 30 3.2.3 Evaporation .................................................................................................... 31 3.2.4 Nam Xong Dam .............................................................................................. 32 3.2.5 Population ...................................................................................................... 33 3.2.6 Land use ........................................................................................................ 34 3.2.7 Industry .......................................................................................................... 35 3.3 Method .................................................................................................................. 36 3.3.1 Water head flow ............................................................................................. 37 3.3.2 Reservoir ........................................................................................................ 37 i 3.3.3 Water demand sites ....................................................................................... 38 3.3.4 Water use rates .............................................................................................. 39 3.3.5 Flow requirement ........................................................................................... 41 3.3.6 Calibration ...................................................................................................... 42 3.3.7 Scenario development ................................................................................... 44 4. RESULTS AND DISCUSSIONS ................................................................................. 46 4.1 Calibration process ............................................................................................... 46 4.1.1 Observed river flow ........................................................................................ 46 4.1.2 WEAP model calibration ................................................................................ 47 4.2 Current water availability ...................................................................................... 49 4.2.1 Water inflows .................................................................................................. 50 4.2.2 Water outflows ............................................................................................... 50 4.3 Current water use ................................................................................................. 51 4.3.1 Current domestic water use ........................................................................... 53 4.3.2 Current agriculture water use ......................................................................... 54 4.3.3 Current industry water use ............................................................................. 55 4.4 Environmental flow requirement ........................................................................... 56 4.5 Projection of future water demands ...................................................................... 59 4.5.1 Scenario 1: Increased irrigated agriculture areas ........................................... 62 4.5.2 Scenario 2: Increased population ................................................................... 65 4.5.3 Scenario 3: Increased industry units .............................................................. 67 5. CONCLUSION AND RECOMMENDATION ............................................................... 70 5.1 Conclusion ............................................................................................................ 70 5.2 Limitations ............................................................................................................ 72 5.3 Recommendations ................................................................................................ 73 BIBLIOGRAPHY ............................................................................................................... 75 ii LIST OF FIGURES Figure 1.1. Global water budget diagram. ............................................................................ 2 Figure 1.2. River basins atlas in Laos. ................................................................................. 4 Figure 1.3. Nam Xong watershed administration map. ........................................................ 6 Figure 2.1. Diagram of the water balance in the watershed. .............................................. 13 Figure 2.2. Diagram of the watershed planning and stakeholder coordination. ................. 23 Figure 2.3. General WEAP model feature and schematic package snapshot. ................... 24 Figure 3.1. Location of the study area. .............................................................................. 28 Figure 3.2. Average monthly precipitation at Kasy, Vangvieng and Hinheup stations. ...... 30 Figure 3.3. Annual mean river flow at the Vangvieng and Nam Xong Dam stations. ......... 31 Figure 3.4. Average monthly potential evaporation (piche) at the Vangvieng station. ....... 32 Figure 3.5. Average monthly river flow at Nam Xong Dam (at upstream, diversion canal and downstream dam stations). ......................................................................................... 33 Figure 3.6. Diagram of the main methodology of the study................................................ 37 Figure 3.7. Water reservoir zone classification and operation. .......................................... 38 Figure 3.8. Linear relationship of the observed river flow at the Vangvieng and Nam Xong Dam stations from 1997-2004. ........................................................................................... 42 Figure 4.1. Comparison of the observed river flow at the Vangvieng and Nam Xong Dam stations. ............................................................................................................................