Approach of Water Balance for Evaluating the Potential Source of Water in Gidabo Dam for Irrigation Purposes

Abstract

The implementation of irrigation by constructing dam is the main approach to reducing poverty by increasing productivity. Many dams are multi-purpose dams that are designed to provide water for different purposes. This paper was to study the water balance approach for evaluating the potential source of water in Gidabo dam for Irrigation purposes that is located in the Abaya-Chamo sub-basin of the Rift Valley Lakes Basin. Rainfall and inflow data of 20 years (1997-2017) was used in this study. During the periods of high runoff, the water stored in the dam typically increased and overflow through the spillway occurred. There are rainy and dry seasons in the Gidabo sub-basin. The main rainy season is from April to October with a peak rainy season from April to May and a second peak rainy season from September to October. The mean annual precipitation of the sub-basin varied from 954.98 to 1843.70 mm while mean monthly variation is between 36.82 mm to 187.93 mm. The total inflow into the dam from streams and outflow from the dam were 6387 m³/s and 6170.1096m3/s respectively and the residual volume storage was 216.9904m³/s. The physical characteristics of Gidabo river catchment has similarity characteristics.