Gully erosion and its impacts on soil loss and crop yield in three decades, northwest Ethiopia

This paper investigated the rate of gully formation and development, and its impacts on land competition and crop yield reduction in Genbo Wonze watershed, northwest highlands of Ethiopia. Geometrical gully dimension measurements, field observations and satellite imagery assessment have been performed selecting 22 gullies. The result shows that road construction and design problem of soil and water conservation practices (SWCPs) were found as important causes of gully formation and development. The total volume of soil lost from 22 gullies in three decades was ~ 340,957 t and ~ 10 ha productive agricultural land was changed to unproductive land. The annual rate of gully erosion was found to be 62 t ha−1 with an average gully density of 16.4 m ha−1. Gully erosion also results a loss of 24 t year−1 Teff grain yield (Eragrostis teff, E. abyssinica) and 14 t year−1 animals forage. In general, gully erosion is found to be a serious problem causing soil loss and crop yield reduction, and in shrinking the size of agricultural land. To arrest the problem, proper design of SWCPs within farmlands, proper runoff discharge mechanisms along roads, and controlled grazing systems within the grazing lands ought to be executed.