Modeling of watershed intervention techniques to rehabilitate sediment yield hotspot areas in Hare watershed, rift valley basin, Ethiopia

Soil erosion and sedimentation are broadly recognized as one of the major earth and environmental problems. Increase of agricultural activities, poor farming system, deforestation and overgrazing causing serious soil erosion and sediment yield in the watershed. Modeling watershed management practices play significant role on soil erosion reduction, increase soil moisture content and decrease sediment production. Thus, the main objective of this study was modeling of watershed intervention practices to rehabilitate the soil erosion and sediment hotspot areas. Twenty four suspended sediment samples were collected from Hare River and its concentration was determined in laboratory. The sediment concentration was then converted into sediment load in ton per day and sediment-rating curve was developed. Eighteen years sediment data was generated using developed sediment rating curve. Monthly flow and sediment data calibrated and validated in Soil and Water Assessment Tool-Calibration and Uncertainty Program (SWAT-CUP). Model performance was checked and found very well. Spatial variability map of the sediment yield in the watershed was developed. Twelve sediment hotspots sub-watersheds which produce sediment from high to severe (20.38 to 61.99ton/ha/year) were identified. For those twelve sediment hotspot sub-watersheds, four watershed intervention techniques were applied. After application of strip cropping, residue management, contouring and terracing, sediment production was reduced by 47.42%, 5.54%, 69.22%, and 84.88%, respectively. Among the intervention techniques terracing found to be the most watershed treatment approach in this study. The research finding is vital to environmental protection authority, decision makers and scientific community to undertake intervention techniques for soil erosion hotspot sub-watersheds.