Irrigated agriculture, particularly small-scale irrigation (SSI), is a mainstay for sustainable livelihoods in the developing world. In Ethiopia, SSI sustainability is threatened mainly due to excessive sedimentation. Stakeholders’ perceptions of the causes of sedimentation and how they sustain SSI under excessive sedimentation conditions were investigated in two SSI schemes in Ethiopia. A participatory rapid diagnosis and action planning was implemented, consisting of a literature review, participatory rural appraisal, and semi-structured interviews. Results show that farmers slightly differed in perception of excessive sedimentation drivers. Farmers reported design problems as the main cause of excessive sedimentation (64%), followed by poor operation and maintenance (O and M) practices (21%) and external factors (15%). In contrast, 62% of the interviewed engineers indicated erosion and irrigation technologies as the main causes of excessive sedimentation, while few reported poor design (13%). In addition to an intensive desilting campaign, farmers delayed the start of the irrigation season to avoid the intake of highly sedimented water. Local social capital and knowledge appeared to be more important than formal knowledge and blue-print institutions for dealing with sedimentation problems. Well-organized structure and extra time devoted by famers were vital for SSI sustainability. Integration of the farmers’ knowledge with that of the engineers could yield more effective ways to deal with sedimentation problems.

Excessive soil erosion hampers the functioning of many irrigation schemes throughout sub-Saharan Africa, increasing management difficulties and operation and maintenance costs. River water is often considered the main source of sedimentation, while overland sediment inflow is overlooked. From 2016 to 2018, participatory research was conducted to assess sediment influx in two irrigation schemes in Ethiopia. Sediment influx was simulated using the revised universal soil loss equation (RUSLE) and compared to the amount of sediment removed during desilting campaigns. The sediment deposition rate was 308 m3/km and 1087 m3/km, respectively, for the Arata-Chufa and Ketar schemes. Spatial soil losses amounts to up to 18 t/ha/yr for the Arata-Chufa scheme and 41 t/ha/yr for the Ketar scheme. Overland sediment inflow contribution was significantly high in the Ketar scheme accounting for 77% of the deposited sediment, while only 4% of the sedimentation at the Arata-Chufa scheme came from overland flow. Feeder canal length and the absence of canal banks increased the sedimentation rate, however, this was overlooked by the stakeholders. We conclude that overland sediment inflow is an often neglected component of canal sedimentation, and this is a major cause of excessive sedimentation and management problems in numerous irrigation schemes in sub-Saharan Africa.

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