An integrated exploration technique for groundwater on a part of the basement complex of southwestern Nigeria

Abstract

Akure is underlain by the basement complex rocks of southwestern Nigeria. It is faced with difficulty in the search for groundwater due to lateral discontinuity of basement lithologies. This study therefore delineates possible groundwater potential zones through the integration of remote sensing and electrical resistivity data. Landsat TM data was digitally processed and used to produce lineament, lineament density and intersection maps while hydrogeological parameters were obtained from electrical resistivity method and used in the production of overburden/fractured map. Weighted overlay method was utilized in ArcGIS® in order to integrate the two maps so as to produce groundwater potential map of the study area. The groundwater potential map showed four major areas of groundwater potentials viz; very low, low, high and very high groundwater potential areas. An average of 0.9445litres of groundwater is discharge per second in the area i.e., approximately 3, 400litres per hour of groundwater is disharge in th area. However, a critical analysis of borehole yields show that boreholes with the poorest yields pump at a rate of between 0.2 to 0.5 l/s which is higly inadequate while very good boreholes pump at the rate of 1.14 to 2.16 l/s . Infact, most areas with good yields are cited in the southwestern portions of the study area.

KEYWORDS: Electrical resistivity, Groundwater, Remote sensing, Landsat TM, Lineament, Yields.