COMPARISON OF EROSION PREDICTIONS WITH GLEAMS, GLEAMS-WT, AND GLEAMS-SWAT MODELS FOR ALLUVIAL SOILS

Simulation performances of GLEAMS, GLEAMS-WT, and GLEAMS-SWAT were eva luated by comparing their soil loss predictions with measured data fro m two runoff-erosion-drainage experimental plots at Baton Rouge, Louis iana. One of the experimental plots was surface drained only, and the other was both surface and subsurface drained. Although the hydrology components of GLEAMS-WT and GLEAMS-SWAT predicted surface runoff more accurately than the original GLEAMS, all three models seriously underp redicted total soil losses over a seven-year period (1981 to 1987). Tr ansport capacity limited soil loss prediction values in the models. He nce, we recommend that any changes or modifications in the erosion sub model be focused on improving transport capacity simulation; changes i n the detachment simulation routine may not be needed. A calibration p arameter was added to the erosion subroutine to adjust transport capac ity. However, even when the models were calibrated for a specific site , there were still substantial annual and monthly differences between predicted and observed soil losses.