Gis-Based Approach For Assessiment Of Surface Irrigation Potential In Awash Arba Watershed, Afar, Ethiopia.

Abstract

Irrigation development is one of the key strategies to increase agricultural production to generate income. One of the main factor rain fed dependent agriculture is rainfall variability and unreliability occurrences. Due to this effect, crops are failed and consequence, food insecurity often turns into famine. The main problem on this study area, potential of irrigable area, available water and irrigation water demand for dominant crops were not yet identified. In order to come with solutions for this problem, evaluation of land and surface water resource potential for surface irrigation was big issue. To meet the main objective, land suitability, available water and irrigation water demand was assessed in this study. Materials used to assessing surface irrigation potential were GIS, CROPWAT8.0, kutools, ERDAS IMAGINE2014 and PCP. Land suitability was assessed by using GIS model. The most determinant factors of surface irrigation were land use/cover, slope and soil suitability was assessed for this study. Soil suitability was examined in terms of soil depth; texture and drainage for surface irrigation using GIS model. All soil parameters were reclassified based on their suitability for surface irrigation. Land suitability potential was evaluated by overlying soil, slope and land use/cover. Based on this analysis suitability area of surface irrigation is 57,595.23ha (S1), 21057.87ha (S2), 39710.62ha (S3) and 45905.28 ha (S4) from the total study area for surface irrigation. On average, to irrigate this irrigable area 1514.7mm/growing period of water is needed for wheat, maize, onion and tomato. Throughout the season irrigation water demand was greater than available stream flow. The total irrigable area due to the available stream flow for wheat was about 274.3 ha. From total identified irrigable area for maize, onion and potato the irrigation water demand was greater than the available flow the same as wheat. Therefore, to irrigate the whole potential land the decision maker should take the mitigation measure by increasing upland infiltration, exploring water from ground and construct soil water conservation. Furthermore, other irrigation suitability factors such as soil chemical properties, socio-economic aspects, environmental hazards and ground water investigation should be studied additionally in detail for further irrigation development as well as enhancing sustainability over Awash Arba watershed.