Abstract:
Performance assessment of irrigation system plays a vital role for improvement of the future
functioning of the system. This study was conducted to assess water delivery performances
and to determine water conveyance loss in the gravity irrigation system that serves the
irrigation area. Primary data were collected from fields by measuring the flows and
questionnaire survey was conducted in order to get valuable information from the users. The
velocity of the canals was measured by current meter and float methods. Secondary data
were collected from Chagni Metrological Station and other data from respective government
offices and NGOs. CROPWAT software was used to calculate crop water requirement. The
water delivery performance of the irrigation system was evaluated using adequacy,
efficiency, dependability, and equity. The computed values of adequacy, efficiency,
dependability, and equity were 0.78, 0.81, 0.27 and 0.28 respectively. This shows that
adequacy, dependability, and equity of the system were poor but the efficiency of the
irrigation system was fair. Annual relative water and irrigation supply were also used for
indicating the adequacy of the supply. The results show that the annual water and irrigation
supply in Buchiksi irrigation system was adequate with values of 3.6 and 2.4 respectively. In
this study the conveyance losses at the off-takes were determined. The water conveyance loss
at the main canal level was between 11.76% (0.267l/s/m) to 25% (0.44l/s/m). At the
secondary canal level, the conveyance losses were between 8% (0.20 l/s/m) to 55.56%
(0.1l/s/m). This result shows that the average conveyance loss increases from head to tail
reaches in both main and secondary canals. The values of water surface elevation ratio,
sustainability of irrigated area and effectiveness of infrastructure were found to be 87, 80.5
and 73.5 percent respectively. This reveals that, maintenance and operation work on the
irrigation system were not sufficient. To increase the performance of the irrigation scheme
continued evaluation and maintenance of irrigation systems are an urgent to keep the
performance on a good level.
