Livestock and Small-Scale Irrigation Scheme Interactions as a Key Source for Sedimentation during the Irrigation Season: Four Case Studies from South-West Shoa, Ethiopia

Abstract

Small-scale irrigation (SSI) development can play a major role in Ethiopia’s economic development, but sedimentation is a major threat to its sustainability. The focus of the dominant discourse around the sedimentation of SSI schemes lies in upstream catchment protection during the rainy season, neglecting both protection against erosion through overland flow along the margins of the canal network and sedimentation caused by livestock disturbances. Remedies against the latter causes of sedimentation during the irrigation season have been ineffective due to erroneous assumptions regarding its cause. This study aimed to identify the sources and extent of sedimentation in SSI schemes. The accumulated sediment in the canal pre-irrigation season was measured from four SSI schemes and suspended sediment samples during irrigation season were collected from one SSI scheme. The accumulated sediment in the canal pre-irrigation season was measured from four SSI and suspended sediment samples during irrigation season were collected from one SSI scheme. The extent of sedimentation in the canals during the pre-irrigation season in relation to canal capacity was 100% of lined and unlined canals in abandoned, 68% in a lined, and 84% unlined canals in heavily sedimented and 38% in a lined and 46% of unlined canals lightly sedimented schemes. Livestock interactions with the SSI schemes were found to be the major sediment source before and during the irrigation, hence, attention should be given to integrating livestock as a part of the system.

Rainfall event‐based surface runoff and erosion in small watersheds under dairy and direct‐seeding grain production

“…This was attributed to the effect of the reduction in surface roughness in the trampled areas, promoting greater connectivity and more frequent flow (Greenwood & Meusburger, 2019). In Ethiopia, the identification of sources and the extent of sedimentation in small‐scale irrigation schemes, staggered with livestock activity, showed that channel sedimentation occurs through disturbances caused by cattle encroaching on the river banks to graze and drink water (Dessalegn et al, 2021). The results of this study corroborate our results for the watersheds with channel disturbances by cattle movement, and these channels flow into the Passo Real reservoir, which may increase its sedimentation.…”