Investigation of sedimentary aquifers in Denmark using the magnetic resonance sounding method (MRS)

In order to evaluate the applicability of the magnetic resonance sounding method (MRS) in the Danish context and its accuracy in estimating the hydraulic conductivity of different sedimentary aquifers, three MRS campaigns were conducted in Denmark between 2003 and 2007. In total, 12 sites were investigated. At two sites, it was impossible to measure with MRS due to the high level of ambient electromagnetic noise. For the present study, MRS results from 10 investigated sites throughout Denmark are used. A simplified classification of the grain-size within the investigated aquifers was established, based on a geological description of available borehole data. MRS-obtained parameters, water content ( θ MRS ) and decay time (T1), as well as normalised values of the MRS hydraulic conductivity estimator ( K MRS n ), from 23 MRS stations were compared with the aquifer class defined by geological description of adjacent boreholes. The comparison revealed a qualitative correlation. Moreover, K MRS n results revealed variations in the hydraulic conductivity within the investigated areas. The observed variations may suggest preferential locations for water- supply boreholes. Further MRS measurements close to boreholes with detailed grain-size analyses and pumping tests are required for a more quantitative estimation.