Assessing the Effect of Soil and Water Conservation Practices on Runoff and Sediment Yield on Hunde Lafto watershed of Upper Wabi Shebelle Basin

Abstract

A study was carried out at Hunde Lafto watershed to assess effect of Soil and Water Conservation practices on runoff and sediment yield. Soil and Water Assessment Tool (SWAT) model was used to assess the effectiveness of different Soil and Water Conservation (SWC) practices implemented in the watershed based on different scenarios (base line, stone bunds and crop residue management scenarios). The simulated sediment yield shows that soil loss rate range from 0-76.9 t/ha/yr with annual weighted average rate of 45.4 t/ha/yr. Parallel terrace (stone bunds) scenario reduced the total sediment yield from 10,978.7 t/yr to 3,734.26 t/yr relative to base simulation, which is equivalent to 65.9% decrease and reduces the surface runoff by 27% from 410.4 mm to 299.5 mm, increase base flow by 23% and lateral flow by 22.6% at outlet of watershed. While simulation of crop residue management scenario reduced total sediment yield to 4,299.84 t/yr from base simulation, which is equivalent to 60.8% reduction and the surface runoff by 23.5% from 410.4 mm to 313.6 mm, increase base flow by 18.6% and lateral flow by 19.9% at outlet. the benefits of crop residue management practices were more important in the watershed and recommended for farmers.

Keywords: Soil and water conservation, Calibration and validation, simulation, Hunde Lafto catchment, Baseline scenario, runoff, sediment yield, watershed management