Author(s): Motuma Shiferaw Regasa; Michael Nones

Linked Author(s): Michael Nones

Keywords: Fincha watershed; Land use land cover; Sediment yield; Soil erosion; SWAT model

Abstract: In the last decades, soil erosion is affecting arid and semi-arid regions significantly. Ethiopia does not differ, and the country is losing soil mainly due to the increasing human pressure, with the consequent conversion of natural vegetation cover into cultivated land. Moreover, soil erosion is also affecting surface waterbodies, and dam reservoirs in particular, which are threatened by an increase in sediment yield entering the lake. Besides decreasing the status of the waterbody, sediments contribute to reducing the dam's lifespan, eventually affecting the local economy. Using the Ethiopian Fincha watershed as a case study, and applying the Soil & Water Assessment Tool (SWAT) model, the present research investigates how Land Use Land Cover (LULC) changes impact soil erosion and sediment yield entering the Fincha Dam. SWAT was calibrated and validated using time series data of stream flow and sediment discharge covering the period 1986-2008. After validation, the model was applied to derive sediment yield for the future thirty years, based on forecasted land use land cover conditions. The results show that the mean annual soil loss rate in 2019 reached around 41 tons per hectare, increasing to more than 53 tons per hectare by 2050. This soil erosion means that sediments entering the Fincha Dam are planned to increase from 2.75 mil tons in 2019 to 4.42 mil tons by 2050, therefore highly affecting the Fincha reservoir services in terms of reduction of water volume available for irrigation and hydroelectric power generation.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0535-cd

Year: 2023