Water Delivery Performance Evaluation of Koga Irrigation Scheme
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Date
2018-11
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Addis Ababa University
Abstract
Water delivery performance is the degree to which whether the system delivers water at the
required rate at the right place and time so, water delivery performance evaluation of
irrigation system plays a dynamic role in identifying the gaps and applying mitigation
measures. Koga irrigation scheme was designed to irrigate around 7000ha but, it does not meet
the proposed objective, hence the objective of the study was evaluating the water delivery
performance of Koga irrigation scheme. This study was carried out for three month on a single
irrigation season from February to April; 2018. Water delivery performance of the scheme was
evaluated by comparing irrigation water demand with actual irrigation water supply by using 7
indicators classified under water delivery and water use or water supply indicators. As per the
result, deficit of supply has been progressive in March and April; because actual irrigation
water supply in March and April was less than the crop demand. However, supply was exceeding
the demand during February. The average, irrigation water supply was observed in
shortage of the requirement at the head middle and tail reach of the main canal. The overall
relative water supply, relative irrigation supply and deficiency of the scheme were 0.65, 0.75 and
0.28 respectively. As shown from the result water delivery performance indicators; adequacy,
dependability, equity and efficiency were found to be 0.68, 0.29, 0.08 and 0.95
respectively. According to these values, performance of water delivery of the main canal was
rated as poor in terms of adequacy and dependability; however it was good in relation to
efficiency and equity. These values indicate that, actual water level as well as command
area was reduced from initially designed. The results from this study are very clear to that of,
non-proportionality of irrigation water demand with supply, poor temporal water delivery
system, absence of frequent management aspect have been strongly affected the water
delivery performance of the schemes. Therefore, it is suggested that, effective water
management, supplying irrigation water based on crop demand , optimal crop plan, and apply
a strong water delivery plan are required to mitigate these problems.
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Keywords
water delivery performance, irrigation water demand and supply, water delivery and supply or use indicators, Koga irrigation scheme