Runoff Simulation Based On SWAT Model In The Sanshuihe Basin

Scientific understanding and grasping of water cycle process can provide references forrational use of water resources. The main findings are as follows:(1) The basin environmental database included DEM, land use, soil properties andmeteorological station were established according to the basic materials. In this study, thesub-basins and hydrological response units (HRU) basin was divided in order to realize thedistributed description of the watershed.(2) The SWAT model of Sanshuihe basin was built to simulate the monthly runoff atwatershed scale, the sensitivity of the parameters that affect the simulation results wasanalyzed and calibrated according to monthly runoff observations of the Lucunhehydrological station in Sanshuihe basin from1980to1986, and the model was validatedaccording to monthly runoff observations from1987to1990. The result showed that therelative errors of monthly runoff were-18%and12%during calibration and validation period,respectively; and the determination coefficient and Nash-Suttcliffe (Ens) were0.73,0.76and0.71,0.72, respectively. Therefore, the established SWAT model of Sanshuihe basin wasstable and could be used for simulating and predicting the basin runoff of Sanshuihe basin.(3) Both historical inversion method and extreme land use method were used forsimulating the basin runoff under land use changes. The simulation results by historicalinversion method demonstrate that the basin runoff amount based on the land use conditionsin1996increases by1.21%than1985, and the basin runoff amount in2000raises slightly by0.4%than1996; and the simulation results by extreme land use method show that the runoffamount in Sanshuihe basin shows a decrease tendency with the increase of forest andcultivated land. However, it shows an increase tendency with the increase of grassland, andthe impacts from the changes of forest and the cultivated land are basically the same asgrassland, but they are both greater than that from changes of grassland.(4) According to the25kinds of climate scenarios designed by the basic data of theChangwu and Tongchuan weather stations from1961to1998, the runoff amount of theSanshuihe Basin under different climate combinations was predicted using the predictionmodule in SWAT model. The prediction results showed that the basin runoff increasedsignificantly with the decrease of temperature and precipitation, the amplitude of variations of the basin runoff with rainfall are is significantly than that with temperate, and the basin runoffamount may be dramatically different under different climate scenarios.