Sediment Yield Modeling and Identification of Erosion Hotspots in Tropical Watersheds: The Case of Upper Ruvu Catchment in Tanzania

The main objective of this study was to test the sediment prediction capability of the Water Erosion Prediction Project (WEPP) model on tropical watersheds and also identify erosion hotspot areas. The maximum total discharge at the watershed outlet was 3,462m3/s. Runoff also varied with soil type in all four watersheds. The highest average annual runoff depths occurred on areas with high percentage of ferralic cambisols and humic acrisols soils. The lowest runoff depth was in areas with high percentage of rhodic ferralsols and eutric leptosols soils in Kibungo chini. The soil loss and sediment yield had the same relationship as the runoff changes. The highest and lowest total average annual soil loss rate was estimated in Mfizigo juu and Kibungo chini respectively. The cultivated land contributed to over 81% of soil loss and 86% of sediment yield in all four scenarios. The overall spatial results maps indicated WEPP model can help managers to implement necessary precaution measures to prevent sediment yield and soil erosion