Evaluation of rainfall -runoff and suspended sediment concentration in the semi-arid Ethiopian highlands, Tekeze Basin, Ethiopia

The study was carried out at Weshikayina and Megachoch rivers in Tekeze Basin Ethiopia. Agricultural intensification, deforestation, and soil erosion are currently common problems in the highlands of Ethiopia. However, this research focuses to understand the primary drivers of rainfall-runoff and sediment concentration for Planning effective landscape interventions. Precipitation, runoff, and sediment concentration were continuously assessed in two sub-watersheds during the rainy season of 2019 and 2020. The velocity is determined by the floating time needed for the float to reach the specified length. At 10-min intervals, 0.6 litters of water were sampled using bottles and then using Whitman filter papers to measure the mass of the suspended sediment concentration in a laboratory. In various land uses, the soil infiltration rate has been calculated. The outcome shows that upland and mid-slope infiltration rates in shrubs and bushlands are poor relative to cultivated lands. From all 10-min flow depths, the best fit rating curve was developed and sediment rating curves were also developed using the regression function of power and exponential form. Sediment yields were averaging 11.5-ton ha-1 year-1 and 13.8-ton ha-1 year-1 for Weshikayina and 7.1-ton ha- year-1 and 6.2-ton ha-1 year-1 for Megachoch in 2019 and 2020 respectively. Therefore, the Weshikayina watershed was highly degraded and more fragile than the Megachoch watershed in runoff and sediment yields.