A FINITE-ELEMENT MODEL FOR SIMULATING RUNOFF AND SOIL-EROSION FROM MECHANICALLY TREATED AGRICULTURAL LANDS .2. FIELD VALIDATION AND APPLICATIONS

The finite element model for simulation of runoff and soil erosion as developed by Sharda and Singh (this issue) is evaluated using data col lected from agricultural land treated with major mechanical soil and w ater conservation measures, namely, contour bunding, graded bunding, b ench terracing, and conservation bench terracing. The simulated and ex perimentally realized hydrographs and soil loss values are in reasonab ly good agreement for various measures. Probable reasons for discrepan cies between the predicted and observed values are discussed. The mode l has the potential of being used on a single storm or a continuous ba sis provided the soil, crop, and climatic parameters are precisely kno wn or estimated for a given location and for the period under consider ation. The model logically simulates the effects of flow, topographic, soil, and crop parameters such as antecedent moisture level, roughnes s coefficient, saturated hydraulic conductivity, slope, depth of impou ndment, size of outlet, longitudinal slope of the channel, vertical in terval, and cropping management factor. The model is found to be quite sensitive to changes in roughness coefficient, rainfall excess rate, and cover management factor, and hence these parameters need to be ass essed carefully in the field. The general applicability of the model a s a planning tool for soil conservation measures and the scope for fut ure development are also discussed.