Evaluating land suitability for irrigation purpose in Abaya district, Borena zone, Ethiopia

Assessment of land suitability for irrigation purpose is important to utilize limited resources efficiently and for the sustainable production of crops and food security of the ever increasing people in our country especially the study area. The existing small scale irrigation system in the Guangua Badiya river basin farming area has no adequate soil and land resource information and also the irrigated area is very small. Thus irrigation land suitability assessment plays an imperative role for sustainable utilization of scarce physical land resources. This study was initiated with the objective of assessing land suitability evaluation for agriculture under irrigation of the River Guangua Badiya in Abaya District of Borena Zone, Oromiya Region, Ethiopia. Watershed delineation, assessment of soil and slope parameters were the steps followed to evaluate land suitability for irrigated agriculture. To identify land suitability for irrigation purpose, the following factors such as soil type, slope, and distance from water supply (sources) were taken into account. Soil sampling spots were selected based on free and grid survey techniques and their locations were taken using Global Positioning System (GPS). Soil samples were collected and used for suitability assessment. Soil samples used as criteria for irrigation suitability analysis were pH, texture, soil depth, EC, ESP, top and sub soil stoniness. Slope suitability map of the study area was derived from digital elevation model of the area clipped from SRTM of NASA satellite with 30 m resolution by masking layer of sub catchment. Qualitative evaluation was carried out with the help of FAO land evaluation method. Result of suitability of land evaluation ratings based on the qualitative land suitability for irrigation indicated that, 9.32% (1303 ha) are highly suitable (S1), 32.5% (4558 ha) are moderately suitable (S2), 23.82% (3335 ha) marginally suitable (S3) and 34.30 (4802 ha) are not suitable (N) for surface irrigation systems. Hence, the majority of the study areas are in a range value of highly to marginally suitable for surface irrigation purpose. Due to high slope range value 4802 ha of lands are non-suitable for irrigation purpose.