Abstract:
Extensive effort and huge investment towards irrigation development is being made in Ethiopia. However, little or no attention is given to the monitoring and evaluation of the performance of already established irrigation systems. Consequently, many of the existing irrigation systems are deteriorating in their physical structures, operation and management. Thus, this study attempted to introduce the concept of internal comparative performance indicators as a tool to evaluate the performance of Tendaho irrigation canal system in the lower Awash River Valley. Inflow-outflow technique was used to measure seepage loss and current meter was used to measure velocity of flow. Water delivered to canals was measured using flow measuring structure and duration of water delivery. Actual canal water depth was measured using staff gage. Actual irrigation interval was monitored for selected fields and total numbers of installed and functional structures were accounted on selected canals. Secondary data were collected from Dupti Meteorological station and Tendaho Sugar Estate. It was found that the average seepage losses were 0.66% /100 m (0.017 lit/s/m2), 3.65% per 100 m (0.0391 lit/s/m2) and 4.27% per 100 m (0.0248 lit/s/m2) for primary, secondary and tertiary canals, respectively. These results indicate that high seepage loss which may be attributed to damage of geo-membrane lining and poor maintenance of canals. The anverage values of DPR were 0.36, 0.53, 0.54 and 0.38 for main, primary, secondary and tertiary canals, respectively. These results indicate that reliability of water delivery is very poor. The average value of WLR was 0.91, which is less one, and this shows poor canals maintenance. The average value of Dint was 1.6 revealing that the fields waited for long time to get irrigation water. The average value of functionality of the irrigation infrastructure was of 50% showing that the structures are severely damaged. In conclusion, the performance of TSE irrigation canal system was very poor by all measures of indicators and it indicated that the need of rehabilitation and maintenance.
