The book is the result of studies on the groundwater potential of Orsu area in south-eastern Nigeria. This study integrates surface direct current electrical resistivity method with pumping test results to provide an efficient estimation of aquifer parameters. Twenty-eight Vertical Electrical Soundings (VES) data sets using the Schlumberger array were obtained from various parts of the study area. The high resistivity values associated with the aquifers in the area is possibly due to the presence of loose sand and sandy formation which corresponds to the local geology of most parts of the study area (Coastal Plain Sand) and the clayey sandstone and sandy clay-stone of the Ameki Formation. The transmissivity values obtained are suitable for sustainable groundwater development. The results from the iso-resistivity depth probe show that there is no general continuous resistivity increase with depth. This indicates the variable stratigraphic units in the study area.