Abstract:
Robit small-scale irrigation scheme is located in the Amhara National Regional State and
was constructed in 2012. However, the performance of the irrigation scheme has not been
evaluated yet. In the present study, the performance of the scheme was evaluated by
estimating water delivery performance indicators, water conveyance efficiency, water
conveyance losses, and satisfaction of irrigation users. The water delivery performance
adequacy, efficiency, equity and dependability were evaluated by monitoring discharge at
nine selected offtakes; three each at the head, middle and tail end of the scheme command
area during the crop season from April to June 2017. The water conveyance efficiency of
the main and secondary canals and thus the water losses in water conveyance were
estimated by measuring irrigation water flow at different locations along the canals. The
satisfaction of the irrigation water users from the irrigation service received was
evaluated using the binary Logit Model at the head, middle and tail end of the irrigation
scheme, and for the entire irrigation scheme. Irrigation water flow in the main and
secondary canals, as well as at nine tertiary offtakes was measured using Current meter
and 3-inch Parshall flume. The data were analyzed using STATA, CROPWAT, ARC GIS
software, and Microsoft Excel. The water delivery performance indicators adequacy,
efficiency, equity and dependability varied widely from head to tail reach and, during the
crop season from April to June with overall average value equal to 0.88, 0.92, 0.09 and
0.11 respectively. Thus, the irrigation scheme when compared with Molden and Gates
(1990) standards was found under fair condition in adequacy and dependability and
under good condition in efficiency and equity. The estimated overall water conveyance
efficiencies of the main canal and first and second secondary canals were 90.3%, 82.88%
and 82.83% respectively. Similarly, the water conveyance losses per 100 m were 2.62,
1.56 and 1.18 ls
-1
for the main canal and first and second secondary canals respectively.
The level of irrigation users' satisfaction from the irrigation service received was 57.33%,
48%, 42.67% and 49.33% at the head, middle, tail reach and the entire system
respectively. Satisfaction of irrigation users was found highly associated with the
variation in the availability of adequate water, water availability in time and farm
location from the canal head.
