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- OpenAccess
Anisotropic Properties of Fractures in Parts of Ibadan, Southwestern Nigeria: Using Azimuthal Resistivity Survey (ARS)
並列摘要
This study investigated the groundwater potentials and anisotropic properties of fractures for sustainable groundwater development within Ibadan metropolis. Eighteen Vertical Electrical Sounding (VES) and three Azimuthal Resistivity Surveys (ARS) were conducted in an area covering about 135km^2 in northeastern part of Ibadan. Graphical interpretation of the VES data revealed the area to be underlain by three to four geo-electric layers; top soil (14.7 to 441.4 Ωm), weathered layer (2.95 to 712 Ωm), fractured bedrock (10.0 to 255 Ωm) and fresh/basal bedrock (307.6 to 2188.8 Ωm) with depth to fracture systems ranging from 15-160m. The directions of electrical anisotropy lie dominantly at NW-SE and NE-SW, while N-S and W-E are less prominent. Coefficient of anisotropy ranges between 8.79 and 1.0 and fracturing porosity varies between 1.62 and 0.01 assuming the anisotropy is due to fracturing. Result of groundwater head contouring also showed that groundwater flow is dominantly in NW-SE and NE-SW directions which possibly could be associated to fracture-controlled flow.