Determining Sediment Load of Awash River entering into Metehara Sugarcane Irrigation Scheme in Ethiopia

Abstract

A study was undertaken to estimate the sediment concentration that enters into irrigation system of Metehara sugar estate from Awash River. Sediment samples were taken from Awash River and irrigation canals. The samples were analyzed for sediment concentration and particle size distribution. Measurements of suspended sediment transport in Awash River have shown that very high sediment concentrations occur during flood flows. Suspended sediment loads, estimated over one year period (Nov. 2013 – Oct. 2014), showed seasonal variations reflecting the seasonal rainfall distribution. Average annual sediment yields that enter the irrigation system through Merti and Abadir intake structures were 106,352.59 tons and 90472.54 tons, respectively. Average annual sediment yields in Awash River at Merti Bridge were 658,120 ton and increasing during rainy season. Capacity of the canal system and night storage reservoirs is reduced by sediment deposits and the estate cost huge amount of money for annual reservoirs and canals maintenance. There should be effective maintenance and monitoring of the canals and the reservoirs through regular de-silting and cleaning of the canals. Therefore, it is recommended to construct settling basins at the intake structures on the bases of the criterion that no sedimentation would occurred.

Keywords: Sediment, Discharge, Awash, Canal, Reservoir, Metehara