Journal of
Geology and Mining Research

  • Abbreviation: J. Geol. Min. Res.
  • Language: English
  • ISSN: 2006-9766
  • DOI: 10.5897/JGMR
  • Start Year: 2009
  • Published Articles: 172

Full Length Research Paper

Seismic refraction study of Gurara dam phase II, northwestern Nigeria

Oladapo Michael Ilesanmi1*, Adeoye Oladapo, Oluwakemi Olanike2, Adebobuyi Foluwaso Steve3, Badejo Oluseun4 and Ifarajimi William5
1Department of Applied Geophysics, Federal University of Technology, Akure, Nigeria. 2Department of Physics, Adeyemi College of Education, Ondo, Nigeria. 3Groundwater and Geophysical Services Limited, Lagos, Nigeria. 4Gurara Water Management Authority, Abuja, Nigeria. 5Department of Geosciences, University of Lagos, Nigeria.
Email: [email protected]

  •  Accepted: 25 October 2013
  •  Published: 02 December 2013

Abstract

Seismic refraction study has been carried out on Gurara Dam Phase II proposed axis with the aim of determining its feasibility for the founding of a dam. The field techniques involved off-end/reverse and split spread shootings on five profiles. The study site is situated on the Precambrian Crystalline Basement Complex rocks of North Central Nigeria. Velocity values obtained from the shots vary between 183 ms-1 in unconsolidated soil materials and 6522 ms-1 in the fresh bedrock. The overburden is presumably characterized by low to moderately high velocity varying between 183 and 1235 ms-1. Fractured/partially weathered basement rocks within the study area are presumably defined by velocity ranging from 543 to 1667 ms-1. The fresh bedrock is presumably characterized by velocity in excess of 2000 ms-1. The results of the seismic refraction study conducted on the proposed dam axis showed that some portions of the western flank of the axis present noticeable seepage characteristics within the bedrock especially on profiles 1 and 2. Profile 4 on the eastern bank of Gurara River present a downward displacement of the bedrock. Profile 5 also on the eastern bank is characterized by significant fracturing of the bedrock with possibilities for seepage. The general characteristics of the materials within the investigated sections of Gurara Phase II dam study area indicate that they are competent and suitable. However, the existence of the delineated features susceptible to seepage requires some form of remediation to prevent seepage from the area proposed for reservoir through fractures and buried stream channels.

Key words: Seismic refraction, dam axis, velocity, overburden, seepage, fresh bedrock.