Assessment of the effects of land use/cover changes on soil loss and sediment export in the Tul Watershed, Northwest Ethiopia using the RUSLE and InVEST models

Numerous studies found that the main factor contributing to the export of sediment from the Ethiopian highlands is soil erosion, which is related to the expansion of cultivated land at the expense of steep slopes of natural vegetation covers. Plantation practices on steep slopes of bare surfaces and utilizing effective water and soil conservation measures on cultivated lands, may, however, have an impact on the rate of soil loss and the sediment yield ratio. Thus, the main objective of the research was to determine how changes in land use and land cover introduced by soil conservation affected the spatiotemporal variability in soil loss and sediment delivery ratio. RUSLE, InVEST, and integrated GIS technology were used to quantify the study's results. The expansion of farmed land at the expense of natural forests, woodlands, shrubs, and grasslands between 1990 and 2000 resulted in a significant increase in soil loss and sediment yield. This was mostly seen where natural vegetation cover areas on steep slopes were turned into cultivable land. Watershed development interventions significantly decreased both the mean annual soil loss and sediment yields between 2003 and 2021. For instance, from 2010 to 2021, the mean annual soil loss in the watershed dropped by 23.5 t ha(-1) and the sediment export declined by 6.13 t ha(-1)yr(-1). To prevent soil loss and sediment export at the extensive level, it is therefore concluded that sustainable soil management on cultivated land and plantation techniques on community land should be expanded up to the adjacent watersheds.

Automated summary

Numerous studies have shown that soil erosion caused by the expansion of cultivated land is the main factor contributing to sediment export from the Ethiopian highlands. The research aimed to investigate the effects of soil conservation measures on land use changes and their impact on soil loss and sediment delivery. The results were quantified using RUSLE, InVEST, and integrated GIS technology. The expansion of farmed land at the expense of natural vegetation cover increased soil loss and sediment yield, while watershed development interventions significantly reduced these rates between 2003 and 2021. To prevent soil loss and sediment export, sustainable soil management and plantation techniques should be extended to adjacent watersheds.