Discipline: Natural Sciences
The impact of rainfall regimes and crop management practices in the rainfed uplands of the Cagayan Valley region, Northern Philippines was examined. The primary goal of the study is to evaluate the performance and adaptability of the Water Erosion Prediction Project (WEPP) model in estimating the rate of soil erosion and runoff under upland rice cultivation. The research involves establishment of automatic weather station and erosion plots with three conservation management as treatments. Analysis was undertaken to characterize rainfall events in terms of amount, intensity, duration and frequency in relation to erosion data. Comparison of actual and simulated data and sensitivity analysis of scenarios for different types of rainfall, slope, and conservation practices were made. The validation results demonstrated the statistical acceptability of the WEPP model. The actual and simulated data indicated that 50 percent soil loss is reduced when contour planting with hedgerow is practiced. The rate of soil loss is linearly affected by increasing slopes and length, such that, the rate of soil removal ranges 1.2 - 48.46 t ha-1 across treatments at 10-50 percent slope and 10-40m slope length.The model can be used to develop decision support tools for conservation, optimization and utilization of farm resources in agricultural watershed units for improved productivity of upland areas in sustainable way.