Runoff Simulation In Muzhu River Basin Based On GIS And SWAT Model

Influenced by human activities and climate change, the hydrological function of MuzhuRiver basin in Wendeng in Weihai is highlighted. Water resources in the river basin changedlargely in a year, such as droughts and floods. The hydrological function in a river basin notonly affects people’s production and living, at the same time, also restricts the river basin andregional economy in Wendeng.By using measured rainfall data and measured meteorological data from1978to2008from several rainfall stations and weather stations, built a SWAT model for the Muzhu Riverbasin to simulate the runoff. Using GIS’s visualization and spatial analysis methods to analyzethe distribution characteristics of runoff in space and time in the Muzhu River basin, and gavean evaluation model. The simulation results show that the distribution of runoff in space andtime is very different. Runoff was generated mainly in July and September, especially in July.According to the results of simulation, the annual depth of runoff on average in the MuzhuRiver basin is268.35mm. Runoff mainly is distributed in the midwest and northeast Jieshi town,Mishan town and Wendengyin town. Runoff in the southern coastal plain is relatively low.Analysis and comparison in the Yinwu River, Shanma River, Zhangge River and other rivers inthe basin, the results show that their runoff modulus make a different. Wudao River andChuxian River originated from Kunyu mountain, their runoff modulus are higher, reached10.249(10-3m3/km2) and10.087(10-3m3/km2), which proves the strong runoff ability in highaltitude area.Global ocean-atmosphere coupled model predicted that China’s annual average airtemperature over the next20years will increase1.3-2.1℃and annual average precipitationwill increase by2%-3%; Over the next50years, China’s annual average air temperature andprecipitation will increase2.3-3.3℃and by5%-7%. Based on the SWAT model of MuzhuRiver basin and different precipitation and air temperature change assumptions, determined therelevance of the precipitation, air temperature and runoff and simulated the hydrologicalresponse of climate change in the future. The results show that by2020, annual average runoffin the Muzhu River basin will increase by4.26%, reach to279.78mm; in2050, annual averagerunoff will increase by9.94%, reach to295.02mm. The impact of climate change on runoff issignificant. Main factors to affect the climate including precipitation, air temperature, windspeed and solar radiation. Using theAHP(Analytic Hierarchy Process）to determine the weightof main factors. According to the input and output of sub-basin in Muzhu River basin SWATmodel, the interpolation and superimposed analysis of main factors were be done. Using GISclassification and grid computing to advoid the dimension discrepancy of main factors, and built an evaluation model and scattergram for runoff spatial distribution. According to theresults, high value area of runoff is mainly distributed in Muzhu River basin’s midwest orwhere precipitation are high and air temperature is low; Middle value area of runoff is mainlydistributed in Muzhu River basin’s middle and north area; Low runoff area is mainly distributedsouthern coastal area. The influence of wind speed and solar radiation is relatively weak.Building a SWAT hydrological model to simulate the runoff and assess the climate changeand its impact on Muzhu River basin is of great significance. At the same time, it would providetheoretical basis for water protection, seawater intrusion prevention and flood control.