Stakeholder Roles and Perspectives on Sedimentation Management in Small-Scale Irrigation Schemes in Ethiopia

Abstract

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.

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

“…The second discourse around causes of sediment problems in irrigation highlights the poor design of small-scale irrigation schemes without considering adequate baseline data [13,24]; faulty design and location of the intake; mild longitudinal slopes; poor layout of the main canal; and poor operation and maintenance [6]. One of the causes of sedimentation is the soil erosion of the unlined canals due to the erosive potential of the irrigation water flowing through thecanal [12].…”

“…Upstream soil erosion is another sediment source caused by sediment-laden water from the upper catchment entering the canal system through the intake structure at the beginning of the irrigation season [12]. To reduce sediment entering through the intake gate, irrigators delay the canal opening by 2-3 weeks, delaying the growing season [6] (p. 9).…”

“…In Ethiopia, most irrigation schemes do not operate at full capacity and many of the schemes fail to serve the purpose for which they are intended [3][4][5]. In Oromia Regional State alone, 109 (18%) of the modern irrigation schemes and 8508 (13%) of the pumped irrigation schemes were reported to be inoperative or semi-functional in 2017 [6]. In the Tigray region, most of the reservoirs that feed the small-scale irrigation schemes are filled with sediment within less than 50% of their intended service time [7].…”

“…Most of the existing studies point to the soil erosion in the upper and middle river catchment as a prime cause of sedimentation, whereby high sediment loads pass through the intake structure of irrigation schemes and accumulate in the (unlined) canal network, thus resulting in excessive sedimentation [12][13][14][15]. Other studies have documented that the causes of sedimentation vary according to different stakeholders' perceptions [6]; some ascribe sedimentation to design problems, most engineers identify soil erosion in the upstream river catchment and a lack of appropriate technology and materials as prime causes, and farmers see poor operation and maintenance as a major cause. Some scholars argue that cattle accessing streams, grazing, and trampling of stream banks cause an increase in soil erosion, destruction of in-stream banks, and changes to stream morphology [16][17][18].…”

Sediment Influx and Its Drivers in Farmers’ Managed Irrigation Schemes in Ethiopia

“…While many stakeholders recognize upstream erosion as a major driver of sedimentation in irrigation canals, most focus on erosion occurring upstream of the intake [16]. However, much of the overland sediment inflow emanates from the catchment upland of the main canal of the scheme itself.…”