Runoff Simulation Based On SWAT Model In The Miyun Reservoir Basin

Water is a matter that any human activity can not lack. Nowadays, the surfaceinflow reduces gradually, the groundwater level goes down continuously, and thedemand of social water is far more than the precipitation, so that the conflict betweenwater provision and water demand becomes more and more serious in North China.Therefore, we should research the change characteristics of runoff and the rules of thewater cycle and water environment evolution in the Miyun Reservoir basin. There areextremely important theoretical and practical significance for the rational use andoptimal allocation of water resources and solving relational nature ecological andsocio-economic problems.This paper analyzed the50years’ long-term historical trend change of theprecipitation, temperature and runoff by the method of the linear regression in MiyunReservoir basin; then, the paper simulated the surface runoff by a distributedhydrological model ArcSWAT, and proved this model had very good application inthe research area; Finally, the paper changed the land use/cover and climate, andcompared the different runoff under the various situations.The main conclusionsinclude the following aspects:(1) The paper adopt the method of the linear regression to analyze and study thetrend change of the historical precipitation, temperature and runoff from1961to2010of the Miyun Reservoir basin. The study results showed that: the annual historicaltemperature was going up; the annual historical precipitation and runoff weredeclining; the temperature, precipitation and runoff in every month all reached thehighest in summer and the lowest in winter.(2) Using the basic data of the Miyun Reservoir basin,it was built successfullythat the ArcSWAT model, and it simulated the monthly runoff of the research area.The paper chose the Xiahui hydrological station in Chaohe River basin and the ZhangJiafen hydrological station in Baihe River basin to calibrate the parameters from1990to1996and validate the parameters from1997to2001.The research results provedthat: in the Xiahui hydrological station, the relative error Re was3.98%and12.97%, the correlation coefficient R2was0.84and0.77, and the Nash-suttcliffes coefficientEns was0.69and0.70; in Zhang Jiafen hydrological station, the relative error Re was2.2%and10.17%, the correlation coefficient R2was0.79and0.80, and theNash-suttcliffes coefficient Ens was0.71and0.70. The two hydrological stations allmet the three model assessment indexes, and it proved that the model was veryapplicable for the Miyun Reservoir basin.(3) Comparing the annual runoff under the two kinds of land use/coverbetween1980and2000,it was found the latter was bigger. Then,the paper set24kinds of future climate scenarios with the method of the assumed climatescenarios,and researched the different runoff contributed to various climatesituations.The study results proved that: the increase of the precipitation and thedecrease of the temperature both contributed to the increase of the runoff, and theprecipitation changes had greater impact on the runoff than the temperature changesin the Miyun Reservoir basin.