GLEAMS HYDROLOGY SUBMODEL MODIFIED FOR SHALLOW-WATER TABLE CONDITIONS

GLEAMS-Water Table (GLEAMS-WT) is a modified version of GLEAMS that ac counts for shallow water table fluctuations. The modification was acco mplished by replacing the evapotranspiration and percolation algorithm s in GLEAMS with evapotranspiration and percolation routines that are affected by shallow water table. Furthermore, routines to account for depression storage, steady state upward flux from the water table, and water table depth predictions were added. The simulation performances of GLEAMS and GLEAMS-WT were evaluated by comparing their predictions with seven years (1981 through 1987) of measured data from a runoff-e rosion-drainage experimental plot at Baton Rouge, Louisiana. The GLEAM S-WT predictions of surface runoff volume were very satisfactory. Tota l predicted surface runoff volume for seven years was only 0.6 cm (0%) greater than the observed runoff volume, a significant improvement fr om GLEAMS underprediction of surface runoff volume by 54%. GLEAMS-WT p redictions of water table depth were satisfactory.