Distributive analysis of soil loss in the Abbay River Basin in Ethiopia after watershed management interventions

For many decades, there was inadequate research in estimating soil loss from lands and the associated sediment concentrations in stream due to changes in land use, watershed management, or soil conservation interventions. Recently, an immense concern by researchers and policy makers has been registered on the potential impacts of water and land management on sediment behavior. This research paper analyzed spatial distributive data including soil and hydrological features, changes in cropland, grassland, and soil bunds using geographic information system tools. A simple spreadsheets water and sediment load balance model was developed and used to determine the impacts of implementing watershed management interventions in the Abbay Basin in Ethiopia on soil loss, sediment loads, and sediment delivery ratio (SDR) in the Abbay River. The mathematical computations were carried out on a sub-basin level where watershed management interventions were applied and evolved from Year 2010 till Year 2018. Focusing on changes during that period, the results of the distributive analysis indicated that the overall annual soil loss within the Abbay Basin were estimated about 322 and 291 million tons, in Year 2010 and Year 2018, respectively. The watershed management interventions implemented during that period caused a positive soil conservation leading to reduction in soil loss in the Abbay Basin by about 10%. The average annual SDR at El-Diem site in the Abbay River was estimated about 43% as a result of implementing the watershed management interventions in the Abbay Basin. The overall annual sediment load at El-Diem site on the Abbay River was then estimated about 125 million tons with a reduction of about 11% from the long-term average annual measured value.