Abstract :
[en] In developing countries, superficial aquifers are potential water resources for irrigation in agriculture. Cost effective
methodologies are required to characterize those deposits in order to identify better locations for groundwater
abstraction. This study has investigated the potential use of combined electrical resistivity tomography (ERT) and
horizontal-to-vertical spectral ratio (HVSR) to characterize the heterogeneity and thickness of superficial deposits
deployed along of a river. The ERT and HVSRmethods are non-invasive geophysical techniques, simple, efficient, robust
and easy-to-use in alluvial environment contexts. Using these geophysicalmethods in the Kou basin in Burkina
Faso (West Africa), a good correspondence is obtained between ERT images and resonance frequencies determined
on theHVSR profiles perpendicular to the Kou River. The superficial deposits and the bedrock depth have been characterized
and mapped. The role of faulting andmagmatic intrusions in the accumulation of fractured, deconsolidated
andweathered bedrockmaterials and the filling of superficial deposits have been observed and highlighted. Froma
hydrogeological point of view, the thickness of (clay-free) superficial deposits presents a relatively important
groundwater reservoir and potentially high productivity. The ERT and HVSR were proven to be efficient and
complementary methods in superficial deposit environment characterization, and a viable option for exploration
of superficial deposits in terms of groundwater reservoir in environments where the bedrock exhibits strong lateral
variation due to faulting or volcanic activities.
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