The deep percolation below temporary ponds in the Sahel (semi-arid West Africa) is a major source of aquifer recharge. The aim of this study is to assess the ability of the magnetic resonance sounding (MRS) method to help quantify temporal changes in groundwater storage near ponds in a sedimentary porous aquifer. In the well-documented Wankama site, a magnetic resonance tomography (MRT) with 8 coincident loops was carried out during the dry season and the MRS signal was monitored as close as possible from the pond (6 measurements from 2008 to 2010). The MRT shows 1) ranges of water content in agreement with previous observations (absolute gravimetry and pumping tests) and 2) smooth lateral heterogeneities in the water content distribution. These heterogeneities were taken into account for modelling the response of MRS to water table fluctuations observed in a series of piezometers. It was shown that the detection by MRS of changes in piezometric levels is limited by the accuracy of measurements. A significant increase in MRS amplitude was observed for extremely wet conditions, partially due to the presence of the pond at the edge of the MRS loop.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error