Date of Award

1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Engineering Science (Interdepartmental Program)

First Advisor

Richard L. Bengtson

Abstract

The main purpose of this research is to enable EPIC to simulate the effect of subsurface drainage systems on water budget components, sediment loss and the crop yield. To accomplish the stated purpose, four steps were taken: (1) the accuracy of the original EPIC in simulating sediment loss, crop yield and surface runoff volume for a non-subsurface drained plot was determined, (2) the hydrology section time step simulation was changed from daily to hourly and a subsurface drainage subprogram was incorporated into the model, (3) the accuracy of the modified model in simulating surface runoff volume, sediment loss, crop yield and water table fluctuations for a non-subsurface drained plot was determined, and (4) the accuracy of the model in predicting surface runoff volume, subsurface drained volume, water table fluctuations, sediment loss and crop yield for a subsurface drained plot was determined. Evaluating the performance of the original EPIC and the modified EPIC (EPIC-WT) on a non-subsurface drained plot showed that the accuracy of the EPIC-WT in simulating surface runoff volume, sediment loss and crop yield was good and comparable to the accuracy of the original EPIC. Also, EPIC-WT was tested on subsurface drained plot, and the values of surface runoff volume, subsurface drained volume, sediment loss and water table fluctuations predicted by the model were quite satisfactory.

Pages

263

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