The model GLEAMS-SWAT (GLEAMS with Subsurface drainage and WAter Table
) is a modified version of GLEAMS that accounts for shallow water tabl
e fluctuations and subsurface drainage. The modification was accomplis
hed by incorporating a subsurface drainage routine in GLEAMS-WT. Simul
ation performances of GLEAMS and GLEAMS-SWAT were evaluated by compari
ng their predictions with seven years (1981-1987) of measured data fro
m a runoff-erosion-drainage experimental plot at Baton Rouge, Louisian
a. Validations to test the accuracy of GLEAMS-SWAT predictions of surf
ace runoff volume, subsurface drainage volume, total volume (surface r
unoff + subsurface drainage), and water table depth were satisfactory.
Total predicted surface runoff volume for the seven-year period was 9
4% of the observed runoff volume, an improvement from GLEAMS underpred
iction of surface runoff volume which was 71% of the observed runoff.
Subsurface drainage volume and total drainage (runoff + subsurface dra
inage) volume predictions were, respectively, 99% and 96% of the obser
ved volumes. Water table depth prediction was deeper than the observed
depth, especially during the pregrowing and growing seasons.