Integration of remote sensing data, GIS and geophysical survey for delineation of groundwater potential zones

Abstract

Assessing the potential zone of groundwater recharge is very important for the management of groundwater resources. The people of Ona-Ara have in recent times drilled many boreholes and wells without getting enough water and the water does not last long. Considering the high cost of drilling as well as time spent in it, there is a need for precision and accuracy before embarking on drilling. The present study attempts to select and delineate various groundwater potential zones for the assessment of groundwater availability in Ona-Ara Local Government Area of Oyo State, Nigeria using remote sensing, Geographic Information System Techniques (GIS) and Geophysical Survey techniques. In this study, quick bird high resolution imagery, Landsat 8 imagery on Path ∕ Row: 151 ∕ 055 for 2015 , Shuttle Radar Topographic Mission (SRTM), Digital Elevation Model (DEM) were used to prepare various thematic maps viz: Land Use/Land Cover (LULC), geomorphological, geological, slope,
drainage density and lineament density. These maps were used to identify potential groundwater zones in the study area. The results obtained were validated with Very Low Frequency Electromagnetic (VLF-EM) and Vertical Electrical Sounding (VES). VES data were processed by partial curve matching and subsequently interpreted with Winglink software. True resistivities values and thickness of geoelectric layer were deduced from the interpretation. VLF-EM data obtained were filtered with the Karous-Hjelt (KH) filtering method and presented a 2D contoured and colour coded sections making use of the KHFFILT software. Four major land use types were identified from LULC map and they include Built-up area (49.31 km2 ), Ibadan Airport (3.49 km2 ), mixed vegetation (233.74 km2) and riparian vegetation (1.34 km2). The drainage basin was delineated into four sections which are river
Ogundepo, Omi, Eripa and Eti-Olopa. Comparing the result of randomized VES with VES done at GIS delineated lineament, it was discovered that fractured zones are readily observed from the VES curve at GIS delineated areas. The study concluded that that an integrated approach involving remote sensing and GIS technique can be successfully used in identifying potential groundwater zones in the study area as it demonstrates Remote Sensing and GIS as a potential tool in locating groundwater reservoir areas. This can help in solving the complex geohydrological problems associated with groundwater occurrence and its development.