Modeling Soil Loss and Its Association to Site Physical Characteristics in Majang Watershed, Baro Abobo River Basin

Abstract

One of Ethiopia’s threatening environmental problems is soil erosion. Minimizing soil erosion to the tolerable level needs evidence-based sustainable land management. This study aimed to investigate the soil erosion rate and its relation with site physical characteristics (slope, land use/cover, and soil properties) using the GIS-based RUSLE model in the Majang watershed. Climate data, DEM, Landsat image, and soil map were used to model soil erosion by applying the RUSLE model. The results showed that cultivated land is the most vulnerable type of land use to soil loss (35.1·t ha−1 year−1) followed by grasslands (19.6·t ha−1 year−1) in the watershed. Conversely, forest land is the least vulnerable land use and generates a very low amount of soil loss (12·t ha−1 year−1). Similarly, the average soil loss of the watershed is strongly related to the slope gradient. The model result indicated that a high amount of soil loss was observed in very steep slope land (62.8·t ha−1 year−1) but lower in the gentle slope (13.6·t ha−1 year−1). Soil types and their characteristics have greater roles in generating a high amount of soil loss. Acrisols, which lack organic matter content, have experienced a high soil loss rate (20·t ha−1 year−1). This implies soil loss is highly associated with site-specific characteristics such as slope gradient, land cover/use, and soil condition. The greatest share of the soil loss was estimated from steep slopes, bare and cultivated land, and less fertile soils. Therefore, building an integrated participatory approach needs immediate attention, and all farmers and stakeholders need to focus on on-site prioritization and invest more in conserving vulnerable areas.