Sedimentation in small-scale irrigation schemes in Ethiopia:Its sources and management  

作　　者：Zerihun Anbesa Gurmu Henk Ritzema Charlotte de Fraiture Mekonen Ayana 

机构地区：[1]Water Resources Management Group,Wageningen University,Droevendaalsesteeg 3a,6708 PB,Wageningen,the Netherlands [2]Department of Water Science and Engineering,IHE Delft Institute for Water Education,Westvest 7,2611 AX,Delft,the Netherlands [3]Adama Science and Technology University,Adama,Ethiopia [4]Arba Minch University,Arba Minch,Ethiopia

出　　处：《International Journal of Sediment Research》2022年第5期576-588,共13页国际泥沙研究（英文版）

基　　金：the auspicious of the“Capacity Development of HEIs in Small-Scale Irrigation(and Micro Irrigation)”project(Nuffic/Niche/Eth/197)funded by the Netherlands government。

摘　　要：Numerous irrigation schemes in sub-Saharan Africa(SSA)exhibit excessive sedimentation,resulting in underperformance and high maintenance costs.In the current study,a participatory monitoring program was used to investigate sediment causes and sources,measure the annual sediment load,and monitor desilting campaigns in two small scale irrigation schemes in Ethiopia,Arata-Chufa(100 ha)and Ketar(430 ha),for three years(2016-2018).Sedimentation quantities were huge,where the annual river sediment influx ranged from 220 m^(3)for the Arata-Chufa scheme to 1,741 m^(3)for the Ketar scheme.On average 0.3 m^(3)/m of sediment were removed from the main canal for Arata-Chufa costing 794 days of labor per year.In Ketar,sediment quantities were even greater:1.1 m^(3)/m was removed requiring 3,118days of labor per year.The sediment influx from the river source amounts to up to 95%for Arata-Chufa and moderately reaches 46%for Ketar,with the remainder of the sediment entering with overland erosion flows.Farmers reported increased sedimentation over time and difficulty paying operation and maintenance fees instead preferring to contribute labor for the desilting campaigns.Sedimentation management is fragile and mainly involves frequent desilting campaigns and unharmonized efforts to reduce overland sediment inflows.Factors contributing to sediment deposition include mild longitudinal bed slopes,the location of the intake,canal layout,and lack of canal banks for protection against surface water inflow in addition to sub-optimal canal operations.Excessive sedimentation is a major challenge resulting in underperformance of numerous irrigation schemes in SSA,and the stakeholders’lack of awareness of the sources of sedimentation is an underlying factor aggravating sedimentation problems.It is concluded that investigating the sources,extent,and types of sedimentation entering a small-scale irrigation scheme is the basis for reducing maintenance costs and for effective management of sedimentation problems.

关 键 词：Sediment sources Sediment management Irrigation performance Soil loss River sediment EROSION 

分 类 号：S157.1[农业科学—土壤学]