Effect of Land Uses and Physical Soil and Water Conservation Practices on Runoff and Soil Loss in Western Tigray, Ethiopia

Abstract

A field experiment was conducted in three consecutive years (2014- 2016) in the western zone of Tigray, Northern Ethiopia. It was conducted with the objectives of estimating the runoff and soil loss of four different land uses. Area closure, grazing land, treated cultivated land and the untreated cultivated land was selected in a watershed. A total of 12 runoff plots with a size of 15 m X 3 m were constructed in each land use type with the same slope (8.5%). About 25 cm height corrugated iron was constructed for each plot. A runoff collection ditch with dimensions of 2 m length, 1.2 m width and 1 m depth was dug and lined with a thick plastic sheet at the bottom side of each runoff plots to collect runoff discharge and sediment yield. After each rainfall event runoff volume in the ditch was measured and subsequently, the one-liter sample was taken to laboratory from each runoff collection ditch after the runoff is mixed vigorously. Samples filtered using filter paper and oven dried at 105 oC for 24 hours for sediment concentration calculation. The highest average surface runoff 7277 m3/ha/year and the corresponding soil loss 110 t/ha/year were recorded in the grazing land. The lowest runoff 597 m3/ha/year and lowest soil loss 2 t/ha/year were also recorded in the area closure. Hence, the actual runoff and soil losses recorded were higher in untreated cultivated land and grazing land than area closure and treated cultivated land which warrants the requirement of more effective soil and water conservation measures. Therefore, area closure is the best technology for soil and water conservation and rehabilitation of degraded land. The treated cultivated land is also the best technology on cultivated land to conserve soil and water.