The Surface Runoff Simulation Of Different Resolution Data Based On SWAT Model In Dawen River Basin

With the increasingly serious problems of water resource management,it is an effective way to solve the problem of water resource management by using hydrological model to simulate the process of water cycle such as watershed.Based on the SWAT model and the Dawen River Basin as the research area,the SUFI-2 method is used to determine the parameters.Nash-Sutcliffe is used as the objective function,and the “image preprocessing system” which facilitates the input data preprocessing is developed.In this paper,16 iterations of 8 different resolution combinations(DEM data and land use data)in the Dawen River Basin were simulated in 2008-2009 and 300 times per iteration.Finally,this study validates the runoff data for 2010-2011(the DEM data and the land use data are both 30 m resolution).The main results include the following:(1)In this study,six parameters with the strongest sensitivity of six groups were analyzed,and the six parameters with the strongest sensitivity were the same,which were SCS Runoff Curve Number(CN2),soil moisture and bulk density(SOL_BD),soil saturated infiltration coefficient(SOL_K),average slope(SLSUBBSN),the average gradient ratio(HRU_SLP),bank storage base flow factor(ALPHA_BNK),indicated that the sensitivity of the different resolution combinations had little effect on the sensitivity of the model simulation parameters.The optimal values of the six parameters were different under different resolution combinations,which indicated that different resolution combinations had a great influence on the optimal value of parameters.(2)In this study,the elevation,drainage area,river network structure,sub basin characteristics,HRU number and runoff characteristics of the eight groups with different resolution combinations were analyzed.The results showed that three features were extracted from DEM data.Under the same precision and the same data source,the simulation of different resolution combinations had little effect on the three watershed characteristics,but the sub basin characteristics,HRU the number,length,river runoff ha d some effects.In the resolution matching combination,with the decrease of the combined resolution,the number of sub-watersheds,HRU number,river length and runoff showed a decreasing trend,among which the average length of the river and annual runoff was the closest to the measured data under the 30 m resolution combination.The channel length deviation was only-1.07%;In the resolution mismatch combination,More the number of combinations of HRU with higher resolution land use.HRU is the basic unit of SWAT hydrological model in hydrology calculation,it also affected the runoff,but sub basin characteristics and river length did not change with the combination of resolution and change.This experimental result showed that the influence of sub basin characteristics and channel length were affect by the resolution of DEM which was not affect by the land use data resolution.(3)The results of simulation of surface runoff with different resolution combinations and simulated surface runoff at 30 m resolution DEM and land use data combination period had been satisfactorily simulated.This study simulated the combination of two sets of resolution mismatches,and found that the SWAT model automatically unifies the data with the highest resolution data,but the model input spatial data,even if the data resolution did not match.But resolution mismatch simulated annual runoff and resolution matching simulation results were somewhat different.This indicated that it was necessary to unify the resolution of the input spatial data before the model is simulated.