Simulation Of Runoff Based On SWAT Model

This paper studies the hydrological situation changes in the basin under the influence of reservoir group storage,and obtains the topography,soil,land use and hydrological data through investigation,and builds a distributed hydrological model based on SWAT model using multi-source meteorological data.The runoff simulation and its changes are analyzed.At the same time,by adding the reservoir module and modifying the reservoir outflow scheme,the flow variation of the lower reaches of the basin under different schemes and its impact on the ecological environment are studied,which can provide some references for the water resources management considering the ecological objectives.The results of this paper are as follows:(1)The SWAT distributed hydrological model has good applicability in the research basin.The NSE coefficient and R~2 of the model simulation results driven by the Chinese Meteorological Assimilation Datasets(CMADS)are higher in the upper,middle and lower reaches.The result,especially at the watershed exit point,has an NSE coefficient of 0.84and R~2 of 0.85.The model simulation effect driven by Traditional Meteorological Station Data(TMSD)is obviously worse than that of CMADS,indicating that CMADS can be effectively applied to areas where weather stations are scarce,and it improves the accuracy of runoff simulation.(2)The sensitivity of the model parameters,ESCO(soil evaporation compensation coefficient),SOL_BD(surface soil wet bulk density),ALPHA_BNK(channel regulation coefficient),SOL_K(soil saturation conductivity)are four parameters in the sensitivity of the two models.The same level indicates that they have the greatest impact on the structure of the model and the results of the simulation.At the same time,the parameter uncertainty of the model is also one of the factors affecting the accuracy of the simulation results.The p-factor values of each hydrological station of the model driven by CMADS are smaller than those driven by TMSD,and the 95%confidence interval is also smaller than that of TMSD,indicating that the uncertainty range of simulation results of SWAT model driven by CMADS is relatively small.(3)Adding the reservoir module to the SWAT model and inputting the measured monthly outflow into the model,it is found that the runoff simulation evaluation index of the hydrological station in the lower reaches of the basin has significantly improved during the periodic and verification periods.It shows that the scheme based on the measured outflow of the reservoir can effectively improve the accuracy of the runoff simulation in the basin,especially in the dry season and the flood peak,the fitting degree between the simulated runoff and the observed runoff is greatly improved.(4)Two different schemes are input into the reservoir adjustment calculation module,and it is found that the runoff simulated at the exit point of the basin is significantly different.The results show that the monthly runoff simulated by SWAT model based on the conventional regulation calculation scheme is relatively stable in the last six years,while the monthly runoff simulated by the model based on the power generation preference regulation calculation scheme is relatively volatile.At the same time,through the use of ecological indicators to evaluate the simulation results of the SWAT model in the watershed export ecological section under the two schemes,it is found that the model simulated by the conventional scheme is more suitable for the ecological environment below the section.