GIS Technique Applied To Surface Water Survey In South Western Nigeria: A Case Study Of Eleyele Dam Ibadan

A GIS is used to study the surface water in Ibadan. Data which relates to the physical parameters of the study area, were used in this study. These included a SPOT-multispectral imagery, topographic and geological maps of Ibadan, which were analyzed and interpreted. The enhancement of the digital image (SPOT- multispectral imagery) was by linear contrast stretching in standard colour composite showing vegetation as red, settlement as blue, and water bodies as black, thus making it possible to vectorize the raster dam of Eleyele, by manual digitizing for GIS processing. Spatially overlaying objects of hydrographic network features on the digital elevation model (DEM) and the geologic map, revealed that the Eleyele valley from the topographical point of view has all the topographic and physical structures conducive for the location of an effective dam. The geological conditions are adequate for proper water impoundment while the non-porous nature of the rocks and absence of faults in the enclosing rocks ensure that the impounded water is retained. KEY WORDS: Band, Colour composite , Pixel Raster, Vector Global Journal of Geological Sciences Vol.3(1) 2005: 35-38