TITLE:
Contribution of Electrical Resistivity Tomography and Boring Technique in the Realization of Ten (10) Large Boreholes in a Crystalline Basement Rocks in the Centre-West of Benin
AUTHORS:
Nesny Yanonvoh Akokponhoué, Nicaise Yalo, Bertrand Houngnigbo Akokponhoué, Rita Houngue, George Agbahoungba
KEYWORDS:
Boring Technique, Electrical Resistivity Tomography, Fractures, Savalou
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.9,
September
24,
2019
ABSTRACT:
In order to ensure access to
drinking water for Benin populations by 2021, the Emergency Measure program for
the reinforcement of the drinking water supply system of Savalou city was
initiated in 2018. This program focuses on densification and extension of
hydraulic infrastructures. Therefore, it is prominent to use rigorous approach
for implementation and execution of drilling activities. The present work has
the advantage of combining the use of electrical resistivity tomography and
borehole technique to locate ten high flow drilling in Savalou city. The electrical
resistivity tomography (ERT) panels were made based on the dipole-dipole arrays
with 48 electrodes with 5 m inter-electrode
spacing. The drilling was carried out over ten selected points and in two
stages: confirmation test using piezometer and borehole diameter enlargement.
Moreover, only piezometers with flow rate greater than 10 m3/h were
enlarged. The tomography processing has identified 10 fractured zones that are
defined by 250 - 1000 ohm.m resistivity
values and a width between 15 - 55 m. The confirmation test carried out over ten piezometers exhibits high flow rates ranging from 9 to 35 m3/h with depths of 30
to 68 m. Nine over the ten boreholes with a flow rate equal or greater than 10
m3/h, have improved their flow rates by 50% to 100% after the boring technique. Thus, the cumulative flow rate has
reached 252. 7 m3/h for Savalou city and his surrounding areas.