Evaluating soil loss and sediment yield response to decadal land use and land cover changes in the Maybar watershed of the Awash Basin of Ethiopia and implications for sustainable land management

Abstract

Soil erosion and its sedimentation, mainly due to LULC alterations, are substantial environmental problems worldwide, with greater severity in developing countries, which affect the sustainability of ecosystem services and agricultural production. This study analyzed the impact of decadal LULC alterations (1990–2020) on erosion and sediment export in a highland watershed of Maybar employing the InVEST SDR, a model for the valuation of ecosystem services. A series of Landsat images (1990–2020) was categorized into LULC classes using the hybrid classification technique. The results revealed that dense forest and settlements increased by 6.5–45.5% and 7.1–42.4%, respectively, between 1990 and 2020. Between 1990 and 2020, open forest decreased by 12.5–25% and grazing land by 33–53%. Cultivated land showed fluctuations, with a decrease of up to 10.9% between 1990 and 2010 and an increase of 5.8% between 2010 and 2020. A slight decrease in soil erosion was witnessed from 29.5 t ha −1 yr −1 in 1990 to 25.4 t ha −1 yr −1 in 2000 and 22.0 t ha −1 yr −1 in 2010. An increase in soil erosion was observed to 27.1 t ha −1 yr −1 in 2020 due to the expansion of cultivation. The sediment yield decreased from 6.9 t ha −1 yr −1 in 1990 to 4.8 t ha −1 yr −1 in 2000 and 3.6 t ha −1 yr −1 in 2010, but increased slightly in 2020 to 5.2 t ha −1 yr −1 . The study informed that information on erosion and sediment export is indispensable for drawing appropriate policies for land conservation planning to sustain ecosystem services at regional as well as watershed scales.