Abstract:
Performance assessment in irrigation systems plays a vital role in identifying the gaps
and applying mitigation measures. The possible benefits of the Allawuha irrigation
scheme is scarcely understood, hence the objective of the study was evaluating the
hydraulic performance of Allawuha small scale irrigation scheme. This study was carried
out for a single irrigation season from February to June, 2016. Hydraulic performance of
the scheme was evaluated by comparing irrigation water demand with actual supply, and
using 10 internal process indicators classified under water delivery, utility of water
supply and maintenance indicators. As per the result, deficit of supply has been advanced
in April and May; hence actual irrigation water supply was 35.16 % in April and 25.53 in
May more than the demand. However, supply was exceeding the demand by 60.47%
during March. On average, irrigation water supply was observed in shortage of the
requirement at the outlet point one, three and five, whereas in excess of the requirement
at the outlet point two and four. The overall water delivery performance indicators;
adequacy, dependability, equity and efficiency were found to be 0.56, 0.47, 0.0.22 and
0.96 respectively. According to these values, performance of water delivery canals was
rated as poor in terms of adequacy and dependability; however it was good and fair in
relation to efficiency and equity respectively. Utility of water supply indicators;
deficiency, delivery performance ratio and equity ratio for head to tail were found to be
0.30, 0.63, and 2.73 respectively. These values indicate that, the performance of the main
canal was declining from the intended and distribution of water between the head and tail
was unfair. Maintenance indicators; water surface elevations ratio, effectiveness of
infrastructure and sustainability of irrigated area were found to be 78%, 26.09% and
97.8% respectively. These values indicate that, actual water level as well as command
area was reduced from initially designed, and a number of structures initially installed
were becoming nonfunctional, then maintenance of the system is necessary. 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 maintenance, and
management aspects have been strongly affected the hydraulic performance of the
schemes. Therefore, it is suggested that, frequent maintenance, optimal crop plan, and
apply a strong water delivery plan are required to mitigate these problems
