Assessment of the Geophysical Location of Water Boreholes in a Geological Transition Zone, Burkina Faso

Abstract

Mouhoun Loop region is one of the 5 regions having the lowest rates of access to drinking water. Further, the failure rate of Borehole is greater than 30%. This area is underlined by both bedrock and sedimentary rocks. In the area, borehole siting is performed using 1D geophysical investigation techniques such as electrical profiling and electrical sounding. In this study, we decided to analyse this approach in order to see if it is adapted to the geological context. To achieve this, the methodology consisted in analysing the geophysical data of the settlements. Then the results were analysed using statistical tools. The results indicate that failure rates are higher on sedimentary rocks than bedrock rocks. In fact, 91% of the boreholes were implanted in sedimentary zone on the consolidated sandstone. These behave like basement rocks that are very heterogeneous. Also, in these geological formations, the boreholes are not deep enough to reach the deep aquifers. So in order to reduce this failure rate, we suggest the use of electrical resistivity tomography. This is a 2D technique that allows you to observe vertical and lateral variations.