Evaluating the Adequacy Performance of Sprinkler Irrigation Systems at Finchaa Sugar Cane Plantation, Eastern Wollega Zone (Ethiopia)

The success of a sprinkler irrigation system largely depends on its actual performance in field conditions. Although the uniformity of water application is the most important aspect of the sprinkler system's performance, adequacy better explains the performance of the system. In this study, the adequacy of irrigation performance was measured in field conditions considering three operating hydrant pressures (4.0, 4.5 and 5.0 bars) and two sprinkler nozzle sizes (2.4 × 4.4 and 2.4 × 4.8 mm). The main objective of this study was to determine the level of current adequacy of irrigation performance in relation to predicted performance during the design period. Three different aspects of adequacy performance (delivery, infiltration and storage) were determined from the measurements of the two important basic sprinkler performance parameters: discharge and uniformity. The study result indicates excess irrigation water application more than the crop net irrigation requirement and soil moisture deficit, especially for the 2.4 × 4.8 mm nozzles sprinkler at all pressure ranges considered. In line with this, tremendous losses in terms of deep percolation (≅ 40%) have been observed, the consequence of which is leaching of soluble nutrients, loss of valuable water resources, reduced crop yield and rise of the groundwater table. The latter might lead to drainage problems, which require construction of expensive drainage systems and can also lead to the overall waterlogging, salinization and alkalization of the area.