Date of Award

1992

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Engineering Science (Interdepartmental Program)

First Advisor

Richard L. Bengtson

Abstract

DRAINMOD-CREAMS model was used to simulate surface runoff and sediment loss from subsurface drained plot and non-subsurface drained plot in southern Louisiana. Seven years (1981-1987) of recorded data were used in this study. In general, the performance of the model in simulating surface runoff and sediment loss from subsurface drained plot is satisfactory. However, the DRAINMOD-CREAMS model did not simulate surface runoff and sediment loss accurately from non-subsurface drained plot. The CREAMS nutrient submodel was also tested on both plots. The CREAMS model seriously overestimates the nitrogen loss from non-subsurface drained plot. The sensitivity of the DRAINMOD-CREAMS model on erodibility value and erosivity was tested. Results showed that the model was not sensitive to the erodibility value and only moderately sensitive to erosivity. The CREAMS nutrient submodel was modified to account for high soil moisture conditions by incorporating a water function in denitrification algorithm. The modified submodel was incorporated into the DRAINMOD-CREAMS model. The resulting model is called the Modified DRAINMOD-CREAMS model. The modified model can be used to simulate surface runoff, sediment loss, and nitrogen loss from subsurface drained plot. Evaluating the performance of the Modified DRAINMOD-CREAMS model showed that the model significantly improves the prediction of the nitrogen loss from non-subsurface drained plot.

Pages

267

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