Long-Term River Basin Planning: GA-LP Approach

1. Long-Term River Basin Planning: GA-LP Approach Daene McKinney Center for Research in Water Resources University of Texas at Austin Ximing Cai International Food Policy Research Institute Leon LasdonDepartment of Management Science University of Texas at Austin

2. Outline • Sustainability in River Basin Planning • Modeling Framework • Solution Approach (GA-LP) • Application • Conclusions & Next steps

3. Sustainability in River Basin Planning • Concepts of sustainable development • Demand management, supply reliability and flexibility, environmental impact control, technology adaptation, economic efficiency, etc • Broad guidelines • Provide guidance to planners, but • Not translated into operational concepts that can be applied to specific systems

4. Modeling Framework • Incorporate quantified sustainability criteria into long-term water resource systems models • Relations between water uses and their long-term consequences • Tradeoffs in benefits received over many generations

5. Application • Water resources management in river basins with (semi) arid climate • Large diversions to irrigated agriculture • Potential for environmental degradation from water and soil salinity • Sustainability (one might define it as) • Ensuring long-term, stable and flexible water supply capacity • Meeting irrigation and growing M&I demands, • Mitigating negative environmental consequences

6. Modeling Framework • Basic Premise • Short-term decisions should be controlled by long-term sustainability criteria • Long-term (Multi-year) Control • Inter-Year Control Program (IYCP) • Long-term model controlling short-term decisions to approach sustainability • Short-term (Annual) Control • Sequencing of Yearly Models (YMs) • Short-term models optimizing benefits for a year

7. Solve by GA Inter-Year Control Program (IYCP) Each is NLP or LP Inter-Year Control Variables (IYCV) ws End of year water storage A Available area of a crop 1 Water distribution efficiency  2 Water application efficiency  3 Water drainage efficiency tax Salt discharge tax rate Sustainability Criteria RELi Reliability criterion, i = a or e REVi Reversibility criterion, i = a or e VULi Vulnerability criterion, i = a or e ENV Environment criterion SEQ Spatial equity criterion TEQ Temporal equity criterion EA Economic acceptability criterion YM 1 YM 2 YM Y Yearly models Modeling Framework

8. Crop (c) Field (f) Area (a) Demand site (d) ER RF P Groundwater Yearly Model • Constraints • Flow balances • Salinity balances • Policy constraints • Objective • Irrigation benefit • Hydropower benefit • Environmental benefit

9. IYCP IYCV(y) IYCV(y+1) YM(y+1) YM(y) Stored water Stored water FM(y) FM(y+1) Flows Soil salinity, Salt discharge SM(y) SM(y+1) Water salinity, Soil salinity, Salt discharge Water salinity, Soil salinity, Salt discharge solution for year y+1 solution for year y IYCP Solving the Yearly Model • YM  FM + SM • Decompose • Linearize • LPs for each year

10. IYCP Objective Function • Weighted sum of sustainability criteria: • Risk criteria (expressed in terms of agricultural and ecological water use) • Reliability (frequency of system failure) • Reversibility (time to return from system failure) • Vulnerability (severity of system failure) • Environmental criteria • Max allowable water and soil salinities • Equity criteria • Temporal (equitable access to benefits over time) • Spatial (equitable geographic access to water) • Economic acceptability criteria (impact of investment benefits)

11. Generation g=1,…,G Individual i=1,…,I Year y=1,…,Y Inter-Year Control Variables (IYCV) ws Water storage A Area for crop 1 Distribution efficiency  2 Application efficiency  3 Drainage efficiency tax Salt discharge tax rate Performance for year y YM(y) Performance of individual i: F(IYCVg,i)=F(Risk, Env, Equity, Econ) Performance of generation g: Fi = F(IYCVg,i) , i=1,…,I Solving the IYCP

12. Syr Darya Amu Darya Application – Syr Darya Basin

13. Aral Sea Basin XX Cent.

14. Amount being used for Irrigation Aral Sea Basin (1989 – 2000) • Question: Can irrigated agriculture be sustained while minimizing environmental impacts?

15. ASB RiverSystem

16. Irrigation Profit • Scenarios • Baseline: No change • Master: Area & efficiencies are DV’s • Low Irrigation: reduced area

17. Crop Areas(Master Scenario)

18. Distribution Efficiency Application Efficiency Efficiencies(Master Scenario)

19. Salt Discharge Soil Salinity Salt

20. Sustainability criteria Sustainability Criteria Scenario REL REV VUL ENV TEQ SEQ EA Baseline 4 4 4 3 3 3 NA Master 2 2 1 2 2 1 1 Low Irrigation 1 1 2 1 1 2 2 High Irrigation 3 3 3 4 4 4 3

21. Conclusions • Modeling framework developed • short-term decisions combined with long-term decisions to find sustainable patterns in irrigation-dominated river basins • Results • Both soil and water salinity sensitive to changes in irrigated area over the long-term • Small increases in irrigated area without accompanying infrastructure improvements places the environment at risk

22. Conclusions • Next Steps • Linking water and salt to energy • WB GEF project has incorporated sustainability criteria into their project and are beginning to use the models • Agricultural policy in the region • Both basins together (linked by energy) • Water allocation agreements

23. X2 H2 Tajikistan G2 Kyrgyzstan Turkmenistan G1 A2 H1 G3 H3 X1 X3 Amu Darya Syr Darya X – Small H – Thermal G – Hydro A – User O – Pool O2 O1 A1 O3 A3 O5 O4 CAEP A4 A5 Uzbekistan Kazakhstan G4 G5 X4 H4 X5 H5 CAR Energy System

24. Water Results Display

25. Energy Results Display