Assessment of irrigation water potential and water requirements of selected crops in the Wabe-Shebelle River Basin, Ethiopia

Abstract

Knowing water resources for irrigation available and water requirements of selected crop are important for planning irrigation. From a number of uncertainties, the watershed constrained that stream flows in the watershed have not been identified and matched with the water requirements of some crops commonly grown in the watershed. So, the study was initiated with the objective of evaluating irrigation water potential and water requirements of selected crops under the Wabe Shebelle River Basin conditions, Ethiopia. Estimation of irrigation water requirement and surface water resources of river catchments were the steps followed to assess the irrigation potential of the study area. In these identified irrigable areas, three crops such as maize, sorghum and potato were selected and their gross irrigation demands were calculated using nearby meteorology stations. The discharges at un-gauged sites were estimated from gauged sites by applying runoff coefficient method and results were obtained on a monthly basis. The irrigation requirements of the identified command area vary according to nearby meteorology stations and type of crops selected. By comparing gross irrigation demand of irrigable land with available flow in rivers, a gross irrigation demand of potentially irrigable land of 58,995.15 ha are not fulfill with the present flow. It was concluded that, the total annual irrigation water potential/annual available flow above abstraction site is 335.7 m³ s^-1 or 2.9 hm³.