Evaluating performance of traditional surface irrigation techniques in Cheleleka watershed in Central Rift Valley, Ethiopia

Abstract

Unpredictability by local farmers, insufficiency and seasonality of rainfall have severely affected productivity of rain-fed agriculture in Cheleleka watershed. Thus, irrigated agriculture has a paramount role in lifesaving and insuring food security. Mismanagement of irrigation water influences agricultural productivity and efficiency of water uses. This study aimed to assess performance and potential of traditional surface irrigation schemes and to survey conflicts resulting from irrigation water use and management. Three major rivers in Cheleleka watershed (Wesha, Worka and Wodesa) where traditional irrigation has been widely practiced were selected purposively. The irrigable areas of each river were identified and categorized into upper, middle and lower parts based on its related location in the watershed. The soil samples, infiltration rate, long time meteorology, conveyance efficiency, irrigable areas and discharge at diversion points were analyzed. In addition, 49 households in irrigable areas of the three rivers were interviewed and three focus group discussions were held. About 0.16 and 0.14 m3/s of discharge were recorded in irrigation areas of the middle Wodesa and upper Worka rivers, respectively. The conveyance efficiency of the traditional surface irrigation canals at middle Wodesa and upper Wesha and Worka was less than 50%. The general potentials of surface irrigation water across the three perennial rivers were greater than 23 million cubic meters per year. The moisture stored in root zone or readily available water in existing farmers’ practices was found far beyond the carrying capacity of the soils, especially in middle Wodesa and upper Wesha and Worka areas. Performances of the traditional surface irrigation schemes are very low and had aggravated irrigation water losses and contributed to crop water scarcity and conflicts. The results also showed that farmers in the upper parts of the area and close to the diversion points excessively irrigate the cropland, whereas those far away and in lower watersheds of each river receive irrigation water insufficiently and irregularly. Even though there was irrigation management system/committee, the set principle was not respected.