Abstract:
Assessment of irrigation performances is very essential in taking different water
management strategies. However, the performance of Tahtay Tsalit and Mychew
irrigation schemes were not assessed yet and hence, this research was undertaken to
investigate and compare the performance of the two small-scale irrigation schemes.
Moreover, identification of the cause and effect for malfunctionality of irrigation
structures was also another objective of this study. Hence, comprehensive field
observations and focus group discussions was held to investigate the cause and effect of
failed hydraulic structures. Moreover, field measurements on canal dimensions and water
flow measurements were undertaken at selected sampling points. Simple descriptive
statistics was employed for analysis of the data collected from group discussions and
observations. However, hydraulic performance indicators were used to evaluate the
performance of the two irrigation schemes. Several factors such as flooding,
sedimentation, design problem, damage of sluice gates, abstraction of irrigation water by
unwanted plants has been identified in both schemes for malfunctionality of different
structures.
There was no any problem in irrigation adequacy, equity, dependability and efficiency of
irrigation water in Tahtay Tsalit irrigation schemes. However in Mychew, the adequacy
(0.75) and equity (0.28) of irrigation water was categorized as poor, while good and fair
for dependability (0.08) and irrigation efficiency (0.79) respectively. For both irrigation
schemes, the average water surface elevation ratio, delivery performance ratio, and
delivery duration ratio of the main canal during the monitoring period was less than one,
greater than 5% , and 150% respectively. The highest sediment accumulation was
observed at head and middle reaches of the irrigation schemes than the tail reaches for
both irrigation schemes. Generally, in both irrigation schemes there were a number of
irrigation structures which were malfunctioned. Now needs sustainable solution to
improve the performance of the irrigation schemes. Hence, it was recommended that
Water should be fairly distributed spatially and temporally particularly at Mychew
irrigation scheme. Moreover, capacity building and awareness creation to concerned
bodies holds the key to bring a difference in irrigation water management in both
irrigation schemes.
