A Dissipative Hydrological Model for Oasis in Arid Area

1. A Dissipative Hydrological Model for Oasisin Arid Area TANG, Qiuhong Oki/Kanae Lab. The University of Tokyo 2003-11 IHWR, Tsinghua Univ. 2003-06

2. About the model • Background • Water & Salt Balance Model • World Bank projects in Tarimu River • I developed the model by making the water cycle relations more reasonable , adding the soil water module, putting it into action.

3. About the model • A model for arid area • The key of sustainable development of arid area is water resources. A model for arid area will do favor for water resources management. • There are lots of famous conceptual hydrological model such as Standford, Sacramento, Tank… These models can work well at humid area.

4. Water cycle in river basin • A model focus on dissipative flow

5. River basin in arid area P>E P<<E watershed a mountainous area plain area RFA (Runoff flow area) DFA (Dissipative flow area ) The region, a lake or a stream，a waterway，a reservoir suppliesto water, ora lake or a stream，a waterway，a reservoir receives runoff which originates from precipitation.

6. Difference between dissipative flow model and runoff model • Research area is arid area . • Usually, a dissipative flow model need not a module to simulate runoff, but it need a dissipative flow module. • Human activities(irrigation, pumping groundwater,..) must be considered. • Evaporation should been calculated more precisely. (soil water, crop, irrigation, management level…)

7. Profile of water cycle in DFA Precipitation Naked land Lowland Non-Irrigated crop Irrigated crop River Reservoir drainage channel water Groundwater exchange River seepage Non-agriculture area Agriculture area Water surface • River is the main water supplier. • The transfer between atmospheric moisture, surface water, soil water and groundwateris very complex, and the dissipative flow is distinguished.

8. Water decentralization in DFA River inflow outflow seepage channel channel Spring/well Irrigated crop Non-Irrigated crop Reservoir drainage Groundwater flow

9. Lowland River Industry Naked Non-Irrigated Irrigated Reservoir Channel water Drainage Drainage River Industry Soil Soil Soil Soil Reservoir Spring Well GW GW GW GW Drainage Groundwater exchange River seepage Naked land Non-Irrigated Lowland Irrigated Agriculture area Non-agriculture area Water surface Framework of the model

10. Framework of the model Atmosphere Soil water Groundwater

11. Framework of the model 2 1 3

12. E Channel Seepage Note: All these parameters use water depth, unit: millimeter/ month. 1. Agriculture area module • I,P: irrigation water, precipitation • EU,EM: evaporation of Up-Soil layer and Down-Soil layer • EG:groundwater supplying soil water • FWM:seepage water to Down-Soil layer • FGW:seepage water to groundwater • IGW:groundwater from river, reservoir, … • IIG:groundwater exchange between Agriculture area and Non-agriculture area • DR: drainage E=EU+EM Up-Soil Down-Soil Groundwater

13. Ea: Evaporation Ability • Let evaporation ability be Ea, potential evaporation be Ep, crop coefficientbe Kc, then: Ea=Ep*Kc • Ep(FAO, Penman-Monteith) • Kc

14. E=EU+EM

15. Ea EG:groundwater to Down-Soil layer Phreatic water evaporation: E0: Water surface evaporation

16. DR:drainage Field Drain • We assume it is Dupuit flow, and use the Dupuit equation :

17. 2. Non-agriculture area module

18. Non-agriculture area Evaporation E0

19. 3. Groundwater Exchange System Type1 Type2 Type3 Type… • Also we assume it is Dupuit flow, and use the Dupuit equation to estimate groundwater exchange

20. Applications of Model • Based on the research on the pilot area of Akesu River basin oasis in northwest China, I will introduce the development and application of the dissipative hydrological model for arid oasis. • Both the evaporation in agriculture area and in non-agriculture area as well as groundwater exchange from Jan 1999 to Dec 2002 in Akesu River basin oasis are calculated by the model.

21. Akesu River Tarimu River Research area

22. Sketch of Research Area Xiehela Shaliguilanke Alaer Area: 12,000km2 Precipitation: 30-90mm/year Water-surface evaporation : 1100-1300mm/year

23. Sketch of riverway Legend Station Reservoir Riverway

24. simulated observed runoff simulated observed runoff simulated observed runoff Comparison of the simulated and recorded hydrograph at Xidaqiao Station Comparison of the simulated and recorded hydrograph at Yimapaxia Station Comparison of the simulated and recorded hydrograph at Alaer Station

25. simulated observed simulated observed Water table Comparison of the simulated and observed water table at Unit 3 Comparison of the simulated and observed water table at Unit 4

26. Result: main water cycle

27. Result

28. Summary • Out of the results in Akesu river basin, we can draw conclusion that the model works well in Akesu river basin which is a representative plain oasis in arid area, and more applications of the model in northwest China may be possible.

29. Further Research • The model, based on a typical DFA, focus on dissipative flow, runoff flow is simplified. How to establish a model which focus on both dissipative flow and runoff flow? • The groundwater exchange system is complex, and it is hard to distribute groundwater to land types. • It is hard to ascertain some parameters, such as drainage coefficient and channel coefficient. • A model system is required. • My colleagues are employing the model to other basin (Hetianhe river, Weiganhe river, Kai-konghe river )in Xinjiang. I will develop the model according to the applications.