Effects of soil data resolution on modeling results using physically based rainfall-runoff model.

Abstract

Spatially based data representing soil hydraulic properties are available from the United States Natural Resources Conservation Service (NRCS) at several spatial resolutions. These databases can be used in physically based rainfall runoff models to predict watershed runoff. The advantages of using either a higher or lower resolution database have yet to be determined. In this study, using data from the Walnut Gulch Experimental Watershed in Southeast Arizona, the hydraulic properties from two NRCS databases are compared as well as their effects on the simulated runoff from the physically based rainfall runoff model KINEROS (Kinematic Runoff and Erosion). The two soils databases used in this study were the State Soil Geographic Data Base (STATSGO), and the Soil Survey Geographic Database (SSURGO) from Cochise County, Arizona. It was determined that the STATSGO did not represent a spatial averaging of the higher resolution SSURGO when the hydraulic parameters of the databases were compared. The difference between runoff predictions produced from the two databases did not increase with increasing watershed size. KINEROS was able to simulate observed runoff on 3 of 4 watersheds using the SSURGO database while it was unable to simulated observed runoff on any watershed using the STATSGO database.