EVALUATION OF LAND RESOURCES SUITABILITY, WATER AVAILABILITY AND IRRIGATION WATER DEMAND IN THE CASE OF OMO KURAZ-2 FACTORY, SOUTH ETHIOPIA REGION

Abstract

Land suitability is key to developing effective irrigation systems that enhance crop yields and establish long-term irrigation infrastructure. But crop yield is attributed to the variability of rainfall conjugated with inadequate soil fertility management. Irrigation water demand refers to the amount of water required to maintain healthy crop growth and achieve optimal yields in agricultural fields. It is influenced by several factors, including climatic factors, crop factors, soil characteristics, irrigation system and management practice. The alignment of irrigation water demand and water availability refers to the process of synchronizing the water needed for agricultural irrigation with the actual water resources that are accessible. This ensures that crops receive adequate water without overusing or depleting water supplies, promoting sustainability and efficiency. This study aimed on evaluating suitability of land, water resources availability and irrigation water demand at Omo Kuraz 2 factory, South Ethiopia; specifically mapping suitable area, identifying water potential, analysing low flow and determining irrigation water requirement of selected crops. The research employed the Analytical Hierarchy Process (AHP) to assess various factors such as slope, land use, soil drainage, proximity to water sources, proximity to roads, soil texture, and soil type by applying a weighted overlay to determine soil suitability for surface irrigation. The weighted overlay method then integrated these factors to pinpoint the most suitable irrigation locations. Land suitability was classified according to the Food and Agricultural Organization's standards into four categories: S1 (Highly Suitable), S2 (Moderately Suitable), S3 (Marginally Suitable), and N (Not Suitable). Water availability for surface irrigation was evaluated using the SCS-CN method. The low flow available in the area analyzed for dry seasons by using FDC 2.1 software and finally, the irrigation water requirement of crop analyzed with CROPWAT 8 model. The study found that 0.002% of the land was Highly Suitable, 96.6% was Moderately Suitable, 3.4% was Marginally Suitable in the study area. The minimum (36.6mm) and maximum (126.7mm) water available per month in April and January respectively and the average monthly water availability for irrigation was 92.9 mm, which is insufficient compared to the crop water requirements of 0 at December to 106.1mm in February. The low flow available 90% in the study area was; minimum of 36.5m3/s in January and maximum of 604m3/s in July. This result reveal that the Omo Gibe river is huge water requirement of crops. The insights of findings from this study can aid researchers and policymakers in making more informed decisions for irrigation project planning. flow in the vicinity of the study area. Generally, the water available in the study area fit the