Catchment management strongly decreases the sediment transport in rivers: a comprehensive study in May Zeg-zeg (North Ethiopian Highlands)

Abstract

An overall approach to assess the effectiveness of soil conservation measures at catchment scale is the comparison of sediment budgets before and after implementation of a catchment management programme. In the May Zeg-zeg catchment (187 ha) in Tigray, north Ethiopia, integrated catchment management has been implemented since 2004: stone bunds were built in the whole catchment, vegetation was allowed to regrow on steep slopes and other marginal land, stubble grazing partly abandoned, and check dams built in gullies. Land use and management were mapped and analysed for 2000 and 2006, whereby particular attention was given to the quantification of changes in soil loss due to the abandonment of stubble grazing. Sediment yield was also measured at the catchment‘s outlet. A combination of decreased soil loss (from 14.3 t ha-1 y-1 in 2000 to 9.0 t ha-1 y-1 in 2006) and increased sediment deposition (from 5.8 to 7.1 t ha-1 y-1) has led to strongly decreased sediment yield (from 8.5 to 1.9 t ha-1 y-1) and sediment delivery ratio (from 0.6 to 0.21). This diachronic comparison of sediment budgets revealed that integrated catchment management is most effective and efficient and is the advisable and desirable way to combat land degradation in Tigray and other tropical mountains