Application Comparison Of AnnAGNPS And SWAT Models In Loess Hilly-gully Region

According to the investigation,the soil erosion in the Yellow River Basin of China is still serious.The continuous occurrence of soil erosion makes the local ecological environment extremely vulnerable,even restricts the development of local social economy.Hydrology is an important carrier of sediment,which is particularly important for the monitoring and management of water in the basin.Model simulation is one of the important means of hydrologic and sediment research,among which AnnAGNPS model and SWAT Model are widely used.The two models have high applicability in simulating basin hydrology and sediment erosion,but the internal mechanism of the two models is more complex,include structure,algorithm and parameters,and little literature compare the AnnAGNPS and SWAT models in the runoff prediction of small watershed in the Loess Hilly and gully region.Therefore,this study takes Chakou basin as the research area,constructs the AnnAGNPS Model and SWAT model database which are suitable for Chakou basin,and compares the two models in structure,algorithm,input parameters and application effect by combining model construction and simulation.On this basis,this paper explore the influence of the same parameter change on runoff simulation in the two models,which lays the foundation for further study of the model.The main research results are as follows:(1)The AnnAGNPS Model and SWAT model were successfully constructed and operated by using the spatial information and related attribute information of Chakou watershed.The results show that the daily simulation accuracy of AnnAGNPS Model is high,R2 and NSE are both 0.99 in the validation period,SWAT model is based on monthly runoff simulation,and the rates of R2 and NSE are 0.74 and 0.66 respectively in the validation period,R2 and NSE are 0.72 and 0.65 respectively,indicating that the AnnAGNPS Model and SWAT model have high accuracy in Chakou watershed.(2)Combined with the construction and Simulation of AnnAGNPS and SWAT model,The results show that the two models have similarities in structure,algorithm,input parameters and other aspects,but also have their own unique parts.It is found that AnnAGNPS Model is better than SWAT Model in rainfall concentration period,SWAT model overestimates runoff in low flow period.(3)The same parameters in the hydrological sub-model were selected,and the parameters were changed by ± 5%,± 15%.The influence of the same parameter change on runoff simulation was quantitatively evaluated in the two models by factorial analysis.The research results show that in the parameter individual effect,Only CN2 in the AnnAGNPS model has a significant effect on runoff,which is as high as 0.65,the CN2 and SOL-K in the SWAT model have significant effects on runoff,which are 0.26 and 0.42,respectively.In the parameter interaction,the interaction between the parameters of the two models has no significant effect on the runoff.(4)Different levels of parameter may cause the change of correlation between parameters and runoff,when the parameters in the AnnAGNPS model change by ± 5%,± 15% respectively,the correlation between the parameter and the runoff have no change,the runoff is positively related to CN2,negatively related to SHC and FC;when the SWAT model parameters are changed by ± 5%,the runoff are positively related to the CN2,and are negatively related to the SOL-K and SOL-AWC,but when the parameters are changed by ± 15%,The correlation between the runoff and SOL-AWC changes.As the value increases,Runoff decreases and then increases.