SURFACE IRRIGATION POTENTIAL ASSESSMENT OF BONKOKA RIVER CATCHMENT FOR IRRIGATION SCHEME DEVELOPMENT IN DARA WOREDA, SIDAMA ZONE SOUTHERN REGION

Abstract

Surface irrigation potential assessment is very important for maximizing agricultural production by using surface irrigation method. The objective of this study was to assess surface irrigation potential of Bonkoka river catchment for surface irrigation schemes development in Dara Woreda, Sidama Zone Southern Nation Nationalities Peoples’ Regional State. Surface water irrigation potential assessment was undertaken by using ARCGIS10.3 software application, by using soil data, land slope data and land cover or land use data of study area were used in order to identify suitability of river catchment with respect to soil, land slope, land use or land cover and overlay analysis of soil suitability, slope suitability and land use or land cover suitability were undertaken. And also un-gauge Bonkoka River surface water potential discharge were estimated by using runoff coefficient of gauged Kolla river catchment which had similar soil type, land slope and land use or land cover. Water requirement of crops in the study area was estimated by using Cropwat8.0 software application and the Cropwat8.0 software estimates Reference Evapo-transpiration on monthly basis, Crop Evapo-transpiration, Potential Evapo-transpiration, Crop water requirement. Surface irrigation land suitability analysis result with respect to soil show that 100% of soil (covering an area 2,186 ha) are suitable and suitability analysis result with respect to slope 9% of slope in the study area (covering area 198.52 ha) are in the range of highly suitable to marginal suitable for surface irrigation application. Considering suitability analysis result with respect land cover or land use, land covered by agroforestry covering 28% or 606 ha area and 59% cultivated land (covering area 1,300ha) and remaining 13% grass land (covering area 280 ha) are suitable for surface irrigation application. From overlay analysis of suitability of surface irrigation with respect to soil, slope and land cover or land use result show that 31% of Bonkoka catchment (covering area 676ha) is suitable for surface irrigation.