Study On Runoff Simulation And Prediction Based On SWAT Model

Based on xiangjiang river basin as study area,this paper according to the xiangjiang river basin 7 meteorological stations daily precipitation data from 1960 to 2012,as extreme precipitation index selection of maximum daily precipitation,generalized pareto distribution model is used to study the xiangjiang river basin extreme precipitation return period,discusses the xiangjiang river watershed spatial and temporal variations of maximum daily rainfall return period,at the same time,using the SWAT model,using DEM data,soil data,seven meteorological site observation data,the three hydrological station measured data to establish the SWAT model database,using the SWAT-CPU software analysis parameter sensitivity and calculate the optimal parameters,using Nash coefficient,The correlation coefficient and relative error measure the simulation accuracy of the SWAT model,and the final utilization of the SWAT model is used to study the impact of precipitation change and temperature change on runoff,and the following conclusions are drawn:(1)In xiangjiang river basin occur once in ten and twenty years before and after the return period of the maximum precipitation in mutation change is small,almost no change,return period for fifty years and a once-in-a-century worst rainfall change is bigger,50 years with a maximum daily precipitation in 1980 than previously increased by 4.5%,after a once-in-a-century maximum daily precipitation increased by 5%,after 1980 than before that in the 80 s may increase the risk of flooding disasters occurring after that extreme precipitation exists difference before and after 1980.(2)Use DEM data,land use data,meteorological data and soil data to construct research area database,divide the study area into 67 sub-basins and 302 hydrological response units.(3)Using the SWAT-CUP sensitivity analysis of parameters,found that the greatest influence on xiangjiang river basin runoff simulation parameters is SCS runoff curve number,main channel manning coefficient,base flow back coefficient,coefficient of soil evaporation,groundwater delay compensation coefficient.(4)The Nsah-Sutcliffe deterministic coefficient,correlation coefficient R ^ 2,and the relative error R_e three methods to evaluate the applicability of the SWAT model of the xiangjiang river basin.The relative error of three hydrological site R_e range is 5%11%,determination coefficient R ^ 2 were greater than 0.86,Nash coefficients were greater than 0.83,meet the requirement of accuracy evaluation,and explain the SWAT in xiangjiang river basin runoff simulation has good applicability.Precipitation unchanged(5)The assumption that each rise by 0.5 ? temperature,runoff was reduced by 2.43%,the temperature and negatively correlated with the relationship between the runoff,runoff decreases with the increase of temperature;It is assumed that when the temperature remains constant,the amount of precipitation increases by 10%and the runoff increases by 23.63%,and the runoff increases with the increase of precipitation.According to the increase of runoff,precipitation is the most important factor affecting runoff.