Evaluation of spatial heterogeneity of watershed through HRU concept using SWAT

The accurate simulation of SWAT can assist the government in making correct decisions about water management practices, which are important for human health, agricultural management, industry development, environmental quality, flood risk assessment, and recreation. In this project, the PIs were trying to improve the simulation accuracy of the SWAT model through developing new algorithm to obtain accurate rainfall input. The PIs developed a GIS based automatic rainfall interpolation program which incorporates six interpolation methods to estimate rainfall field for the distributed hydrologic model – SWAT (Soil and Water Assessment Tool). The simulated results show that the areal mean rainfall depths estimated by different methods are similar to each other, while the spatial distribution of a rainfall field could exhibit great differences. The stream flow simulated by the SWAT model is sensitive to rainfall fields estimated by different methods, especially for the daily temporal scale, both hydrograph shape and flow volume could show big differences. The accuracy of rainfall field information is essential for distributed hydrologic modeling, and the tool developed in this study will be useful for accurately estimating rainfall fields. The tools developed in these studies are expected to be used in the HAWQS (Hydrologic and Water Quality System) project supported by the USEPA. Developing a GIS tool for Accurately Estimating rainfall field for the SWAT model