Assessment of gully erosion using conventional field measurements: A case study from northern Ethiopia

Abstract

I n Ethiopia, one of the poorest countries in the world, soil erosion by water contributes significantly to food insecurity of rural households and represents a real threat to sustainability of the existing subsistence agriculture (Hurni 1993; Sutcliffe 1993; Sonneveld 2002). Ethiopia has a total surface area of 111.8 million ha (276.3 million ac); 24% of the land area, and 45% of the area used for agriculture, is significantly affected by erosion. Studies by Fikru (1990) and Sertsu (2000) estimate an annual total soil loss of 2 billion m3 (71 billion ft3), which corresponds to an overall mean annual soil loss of 18 t ha−1 (8.0 tn ac−1). Other studies suggest erosion rates ranging from 16 to 300 t ha−1 y−1 (7.1 to 133.8 tn ac−1 yr−1) (Hurni 1993; Hawando 1989, 1995). In the Ethiopian highlands, annual soil loss reaches rates up to 200 to 300 t ha−1 (89.2 to 133.8 tn ac−1), while global soil loss can reach up to 23,400 million t y−1 (25,787 million tn yr−1) (FAO 1986). Compared to rill and interrill erosion rates measured in Europe (Cerdan et al. 2010), these soil losses are much higher. Occurrence of wide and deep gullies is a common observation…