Systematic assessment of available water and potential land surface suitable for irrigation at Basin level is essential for the planning and decision-making of new irrigation development projects. Hence, the intended aim of this research is to assess the land suitable for surface irrigation and available surface water in Beles Basin using Geographical Information System (GIS). The surface water availability was evaluated by developing flow duration curve (FDC) and analyzing 90% available flow of main Beles River. The land surface suitability was determined through GIS-based multi-criteria evaluation (MCE) technique, which considers the interaction of major land suitability factors such as slope, river proximity, Distance from water supply, soil type, soil texture, soil depth, soil drainage, road proximity and land use land cover. The factors were weighted using a pair-wise comparison matrix to evaluate the importance of one factor over the other, for physical land suitability. The result indicated that about 13.77, 72.69, and 13.05 % of the basin were found to be highly, moderately, and marginally suitable, respectively. In terms of water availability, the flow duration curve (FDC) result indicated that the 90% available flow throughout the year of Beles River is 1.6 m 3 /s. Hence, in the month of December, the river has a capacity of irrigating only 0.25% of total irrigable land, while in the months of May to September, the river has a capacity of irrigating the whole irrigable land. The low flow of the river has a potential of irrigating less area. Hence, water storage structures are needed to irrigate the whole potential irrigable land during dry season. Keywords: Beles, GIS, Irrigation, Land suitability, Multi-criteria evaluation