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Abstract:

Soil erosion is an important form of land degradation. Erosion modeling is valuable tool for predicting soil degradation and runoff under different agricultural practices and was used in this study to evaluate different tillage practices with the The Water Erosion Prediction Project (WEPP) hillslope model. Previously measured runoff and sediment delivery data were collected from fallow and cropped plots with a wheat, lentil and tobacco rotation. On the fallow plots, two cultivation methods were used, parallel and perpendicular to the slope. The fallow plots were used to estimate the soil erodibility parameter values for the WEPP model for interrill erodibility, rill erodibility, critical shear, and saturated hydraulic conductivity. Individual events variability in model performance was evaluated with a long term set of data that contained both for wet and dry years. A sensitivity analysis was also conducted for the model parameters. On the up and down the hill tillage plot, average runoff and soil loss for individual events for observed and estimated values were 2.40 and 4.98 mm, and 0.09 and 0.28 kg /m². Similarly, on the contour-till plot, event-based runoff and soil loss data from actual and estimated values were 3.05 and 7.26 mm, and 0.1 and 0.26 kg/m² sediment delivery. In the same manner, on the rotation cropping plot, event-based runoff and soil loss data from observed and estimated values were 1.67 and 3.97 mm, and 0.06 and 0.18 kg/m² sediment delivery.