Soil erosion and sediment yield assessment using RUSLE and GIS-based approach in Anjeb watershed, Northwest Ethiopia

Abstract

Soil erosion is a serious and continuous environmental problem in Ethiopia. Lack of land use planning, environmental protection, over-cultivation, and overgrazing are prominent causes of erosion and sedimentation. This study is conducted in Anjeb watershed located in the Upper Blue Nile Basin, Ethiopia. In this study, the quantity and distribution of soil erosion, sediment delivery ratio (SDR), and sediment yield of the watershed were assessed by employing remote sensing, geographic information system (GIS), and revised universal soil loss equation analysis capabilities. Important data sets of topography, soil, conservations practices, cover management, and rainfall factors were processed and superimposed in GIS analysis, and soil loss rate, SDR, and sediment yield of the watershed were derived. Based on the result found, the watershed was categorized into six classes of erosion: slight (0–5), moderate (5–10), high (10–15), very high (15–30), severe (30–50), and very severe (> 50) t ha−1 yr−1. The estimated average annual soil loss was 17.3 t ha−1 yr−1. The soil loss rate is higher in the steeper and topographically dissected part of the watershed. The average sediment delivery capacity was about 0.122. The result showed that the average sediment yield in the watershed was grouped into classes of low (< 2.5), moderate (2.5–7.5), high (7.5–12.5), very high (12.5–22.5), severe (22.5–40), and very severe (> 40) t ha−1 yr−1. It is found that from a total of 20,125.5 t yr−1 eroded soil over the whole watershed 2254.5 t yr−1 of sediment has been brought and deposited to the channels. Sediment accumulation from the watershed threatens the storage capacity and life span of Anjeb reservoir which is the source of irrigation water downstream. The study provides an insight to planners and resource managers to design and implement practices of watershed management to reduce erosion and enhance land productivity and to minimize the reservoir sediment accumulation.

Analyzing the Benefit-Cost Ratio of Sediment Resources by Remote Sensing Data in the Ping River Basin, Thailand

“…The erodibility factor (K) expresses the effect of water flow and the soil resistance to particle movement. In previous research, the erodibility factor values varied between 0 to 1 Mg•h/MJ•mm [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. The soil properties, such as chemistry, texture, organic matter content, and calcium carbonate contents, are very important in the determination of soil erodibility [58].…”

Assessing soil erosion risk in a peri-urban catchment of the Lake Victoria basin

“…However, that data was unavailable for IMB catchment. Instead, R was estimated with an alternative equation proposed by Hurni ( 1985 ) and commonly used in studies in East Africa and the Nile basin (Tamene and Le 2015 ; Njiru et al 2018 ; Eniyew et al 2021 ; Tsegaye and Bharti 2021 ; Jothimani et al 2022 ) (Eq. 3 ).…”

Soil Erosion and Sedimentation Rate in the Blue Nile River Basin of Ethiopia

“…According to this, the estimated annual mean soil loss rate of the Blue Nile basin's Beshilo catchment was determined to be 37ton ha -1 year -1 , which is more than two times higher than the maximum tolerated soil loss value (16tonha -1 year -1 ) [36]. In the Anjeb watershed in North Western Ethiopia, annual soil loss was estimated to be 17.3tonha -1 year -1 [37].…”

“…Hurni H. [50] observed a sediment export rate of 1.1ton ha -1 year -1 in vegetation-rich catchments in South-Western Ethiopia. Similarly, the average annual sediment yield in the Anjeb watershed in north-western Ethiopia was calculated to be 2.11tons ha -1 year -1 [37]. Contrarily, the average sediment yield for 11 reservoirs in the Ethiopian Blue Nile basin was determined to be 9.89ton ha -1 year -1 [51].…”