Performance Evaluation of Irrigation System (Welenchity Surface Irrigation Scheme)
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Date
2018-06
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Publisher
AAU
Abstract
Water scarcity is a potential constraint to produce more foods to meet the demands of
increasing world population. One possible approach to conserve this scarce resource
might be through improving the performance of existing irrigation schemes. However, in
Ethiopia performance evaluation of irrigation schemes is rarely conducted in the past.
Welenchity Surface Irrigation Scheme is among the schemes in Ethiopia which do not
have a sound performance studies before in order to check and sustain efficient water
delivery system in the scheme. This study is therefore a useful start for improving
overall irrigation water management, distribution and delivery in the scheme.
Accordingly evaluating hydraulic (water delivery) performance and proposing necessary
improvements for enhancing operation in order to save irrigation water are the key
objectives to be achieved in this study. The Discharge were observed and recorded at
seven selected monitoring sites for determining water delivery performance parameters
like adequacy, efficiency, equity and dependability which are used to evaluate the
performance of Welenchity Irrigation System. Discharge was measured and monitored
using a ‗Discharge App‘ which is one of the quickest and easiest ways of acquiring
water flow measurements in streams and channels within few minutes using a
Smartphone‘s Camera. The primary canal hydraulic flow characteristics were modeled
using HEC-RAS to detect the effect that will result to the secondary and tertiary offtakes
due to change in flow at the source/primary canal. The crop water requirement was
verified by CROPWAT by the use of designers‘ scenarios. The performance evaluation
of Welenchity Surface Irrigation Scheme reveals that the overall Efficiency and Equity of
water distribution of the system are ‗poor‘ and the adequacy of water distribution and
dependability of the water supplied in the system is rated as ‗Good‘ and ‗Fair‘
respectively. The parameter of average WSER at head, middle and tail reaches of the
main canal during the monitoring period is generally less than one, thus it shows that
the main canal has a sedimentation problem. Thus, for their long term sustainability,
water distribution equity, reliability and water saving; continuous monitoring and
maintenance is required. Nevertheless, the results of the study can be considered in
proposed water saving plans for improving the performances of the scheme. It provides
to the system managers, farm staffs and policy makers a better understanding of how a
system can be operated.
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Keywords
Water-delivery Performance, Operational Performance, Performance Indicators, Canal Flow Simulation/Hydraulic Models, HEC-RAS, Discharge App