A case study on the evolutionary law of water resources in Sanchuan river basin

We apply the distributed hydrological model(WEP-L model)with physical mechanism to simulate hydrological cycle under the different conditions of Sanchuanhe basin as a case study,and analyze the quantitative influence of the different factors such as precipitation,water use and underlying surface on the evolution of water resources on the basis. Eight cases are described:Case I,the precipitation data in 1956-1979,the underlying surface data in 2000 and the zero water use;case 2,the precipitation data in 1980-2000,the underlying surface data in 2000 and the zero water use;case 3,the precipitation data in 1956-2000,the underlying surface data in 2000 and the zero water use;case 4,the precipitation data in 1956-2000,the underlying surface data in 2000 and the real water use;case 5,the precipitation data in 1956-2000,the underlying surface data in 1956-2000 and the zero water use;case 6,the precipitation data in 1956-2000,the underlying surface data in 2000 and the zero water use;case 7,the precipitation data in 1956-1979,the underlying surface data in 1956-1979 and the zero water use;and Case 8,the precipitation data in 1980-2000,the underlying surface data in 2000 and the real water use. The comparison of case 1 and case 2 show that 4.5% reduction of precipitation causes the decrease in water resources in all forms:18.4% surface water resources and groundwater resources,15.8% not overlapped with surface water resources,18.3% special water resources,2.1% precipitation effective utilization and 4.6% general water resources. In case 4,the surface water resources reduce by 4.6% but the not-overlapped groundwater resources and surface water increase by 113.5%,and the special water resources decrease by 0.4% but the general water resources increase by 0.7%,and 0.9% increase of the precipitation effective utilization compared with that in case 4. Comparing with the water resources in case 5,the special water resources decrease by 4.3% with 4.3% and 2.8% decrease of not-overlapped surface water resources and groundwater resources,while the general water resources increase by 5.13% with 7.1% increase of the precipitation effective utilization in case 6. In case 8,the general water resources decrease by 25.8% with 30.6% decrease of surface water and 114.5% increase of not-overlapped the groundwater and surface water,and the precipitation effective utilization and the general water resources increase by 7.1% and 5.3% compared with that in case 7. The research achievement can be referenced in other basins.