Journal of Geography and Geology; Vol. 4, No. 2; 2012 ISSN 1916-9779 E-ISSN 1916-9787 Published by Canadian Center of Science and Education 147 Watershed Characteristics and Their Implication for Hydrologic Response in the Upper Sokoto Basin, Nigeria Ifabiyi Ifatokun Paul 1 & Eniolorunda Nathaniel Bayode 2 1 Department of Geography and Environmental Management, Faculty of Business and Social Sciences, University of Ilorin, Ilorin, Kwara State, Nigeria 2 Department of Geography, Usmanu Dan Fodiyio University, Sokoto, Nigeria Correspondence: Ifabiyi Ifatokun Paul, Department of Geography and Environmental Management, Faculty of Business and Social Sciences, University of Ilorin, P.M.B. 1515 Ilorin, Kwara State, Nigeria. E-mail: tokunifabiyi@yahoo.com Received: May 19, 2011 Accepted: June 23, 2011 Online Published: May 28, 2012 doi:10.5539/jgg.v4n2p147 URL: http://dx.doi.org/10.5539/jgg.v4n2p147 Abstract Most African river basins lack flow data, a condition which has affected river basin operations. Flood is a common occurrence on the Sokoto basin but poor data base has affected various research efforts and flood mitigation attempts in the basin. This present study will study basin variables using a GIS approach with a few to gaining insights to the flood potentials of Sokoto basin. Shuttle Radar Topographic Mission (SRTM) image covering 5 o -7 o E and 12 o to 14 o N was used in this study. The analysis was carried out using the Integrated Land and Water Information System (ILWIS) and ArcGIS environments. Sinks were removed from the STRM, and the flow direction map was generated as an input for drainage extraction, river ordering and basin catchment extraction. Drainage network overlay was carried out on the generated hill-shade map and on a portion of SPOT image covering the Upper Sokoto catchment for visual analysis. Altogether, 44 basin variables were generated with a view to appraising flood and water resource management in the basin. The results showed that the Upper Sokoto basin is an alluvial catchment; located in a relatively low lying area where high level of deposition is experienced. It is sinuous in nature, circular in shape and compact. These characteristics coupled with the relatively high volume of precipitated water of 14,511,439,620 m³/year are indications that the basin has high flood potential. The paper recommends construction of levees to protect farmlands, efficient reservoir operation and sustainable watershed management for the purpose of environmental management in the Sokoto basin. Keywords: SRTM, ILWIS, drainage density, sinuosity ratio, compaction ratio, fitness ratio, hydrology 1. Introduction One of the major problems of watershed management in Nigeria is the problem of availability of flow data. Many of the basins are ungagged. Reasons for this include inadequate funding, inadequate manpower, lack of necessary equipment, inaccessibility of some of the gauge stations, lack of political will, among others. This situation is further complicated by the fact that many of these basins are faced with annual hydrologic mishaps such as flood, low flow, erosion, siltation, sedimentation, etc. some of which claim lots of lives and destroyed properties annually. Lack of necessary data has continuously made various government planning efforts to fail, and has sometimes made planning almost impossible. Further, lack of flow data or the use of disjointed data has affected the quality and execution of hydraulic projects in Nigeria. For example, many culverts and bridges have failed; some dams are being overtopped due to inadequate spillway, while others have out- rightly collapsed. All these point to the nature of water resource management problems in Nigeria. Under the above scenario, water resources research and development efforts in Nigeria will be left with no alternative than to depend to a large extent on analyzing basin variables and the use of simple coefficients in order to provide hydrologic explanations. Analysis of drainage basin characteristics could offer alternative opportunity which some level of planning and project execution could be based. Drainage basin characteristics are of different types and they are used to measure different hydrological attributes. Prominent amongst them is the drainage density; which has been described as a variable representing