Evaluating of kibirigwi the technical performance, sprinkler irrigation system

Abstract

This study was to evaluate the technical performance of Kibirigwi sprinkler irrigation system in the Upper Tana Basin, Kenya. Development of irrigation in this area is constrained by water availability and not land availability. The available water resources therefore need to be utilized as efficiently as possible. In this study, some shortcomings in, crop water management practices in the scheme, System maintenance resulting mainly to pressures and water losses in the system and low sprinkler performance efficiencies. On average, the christiansen uniformity coefficient was 77 percent, sprinkler application efficiency was 70 percent, distribution uniformity was 64 percent, potential application efficiency of the low quarter was 65 percent and the application efficiency of the low quarter was 56 percent. The pressures and discharge imbalances in the system were caused by multiple leakages in the distribution network, mainly at the control valves, pipe junctions, hydrants and connections of the portable irrigation equipments at the farms. Irrigation water was insufficiently filtered and the remaining sediments had caused sprinkler nozzle diameters to wear by an average of 9.1 percent. An alternative irrigation schedule responsive to the prevailing weather conditions and the type of crop growing in the season was proposed. This was to replace the existing schedule of an application duration of 10 hours and an irrigation interval of 7 days for all the crops. If farmers would follow the developed irrigation schedule in this study and in addition have pipe leaks in the distribution network, at the gate valves and at pipe connections at the farms repaired, the irrigation efficiency of the scheme would greatly improve. Though the scheme experiences water shortages during some periods in the year, the shortages cannot be attributed to inadequate river discharge during these periods. River flow analysis showed that the water flowing past the water abstraction point was much higher than the required scheme irrigation discharge throughout the year.