Changes in land use / land cover, coupled with poor management systems, can result in a high rate of soil erosion and increased sediment transport by changing the extent and structure of runoff and sediment yield. The purpose of this study was to assess sediment yield and conservation practices in the Akaki watershed using the Soil and Water Assessment Tool (SWAT) model. The watershed has been severely degraded due to increasing urbanization, deforestation, careless use of land and water resources that have led to soil erosion. MUSLES were used to estimate sediment yield in watersheds. SWAT has been used to delineate the watershed and to analyze the slope of the watershed, soils and land uses. In addition, ground control points, interviews and field observations were conducted to collect data on the effects of soil erosion and the status of existing conservation measures. The average annual soil loss in the study area is estimated at 2.12 tonnes / ha / year due to the high erosivity of rainfall in the region. In addition, the results showed a direct relationship between precipitation and sediment yield. Spatial variability of sediment yield was performed using simulated sediment yield results for LULC generated. Also based on the spatial outcome for critical sub-watersheds, the design and development of best management practices were proposed under different scenarios. The scenarios showed that the average annual reduction in sediment yield at the sub-basins of hot spots after the application of filter belts, terraces and stone bunds was 75.6%, 68.8% and 69.6% respectively, 4% of sediment reduction. Therefore, the placement of filter strips for the Akaki catchment should be developed and encouraged for effective sediment reduction.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.