Review of Soil Erosion and Sediment Transport, and Management Status in the Blue Nile River Basin: The Case of Ethiopia

Abstract

Soil erosion and sedimentation have a serious effect on the water abstraction structures and sustainable agriculture and that may be managed through appropriate watershed management practices. To make it, information between researchers and government or non-governmental organizations on soil erosion, sediment transport, and watershed management status at the river basin is very important. Therefore, this paper review was conducted to know the updated information about soil erosion potential, sedimentation rate, and status of watershed management practices in the Blue Nile River Basin.  Approximately, 22.5% of the Blue Nile basin fell under very high to extreme areas of soil erosion potential and it needs effective watershed management implementation along the basin. The average annual soil loss and sedimentation rates of the Blue Nile river basin were 41.7 and 11.2 tons ha^-1 year^-1, respectively. The mean annual soil loss in Blue Nile River Basin along the different stations in Ethiopia was 5395.57 ton-km^-2 and it shows a large amount of sediment transported to the Grand Ethiopian Renaissance Dam (GERD) that will reduce dam storage capacity. Aswan high dam and Roseires reservoir received 100 and 30 million tons of sediment per year, respectively from Blue Nile River Basin in Ethiopia and the filling of GERD will raise the life span of Aswan dam from 365 years to 593 years. Around 42% of the Jemma watersheds were covered by terracing and other water management structures up to 2016 and reforestation combined with vegetative strips was the most effective for soil erosion control (87.8% reduction in the case of Jemma watershed). Therefore, cooperative watershed management practice at the basin level is very important to increase the sustainability of GERD and to protect the sedimentation of Sudan and Egypt's water storage structures.