@article{fdi:010062340,
  title = {{T}he use of magnetic resonance sounding for quantifying specific yield and transmissivity in hard rock aquifers : the example of {B}enin},
  author = {{V}ouillamoz, {J}ean-{M}ichel and {L}awson, {F}. {M}. {A}. and {Y}alo, {N}. and {D}escloitres, {M}arc},
  editor = {},
  language = {{ENG}},
  abstract = {{H}undreds of thousands of boreholes have been drilled in hard rocks of {A}frica and {A}sia for supplying human communities with drinking water. {D}espite the common use of geophysics for improving the siting of boreholes, a significant number of drilled holes does not deliver enough water to be equipped (e.g.40% on average in {B}enin). {A}s compared to other non-invasive geophysical methods, magnetic resonance sounding ({MRS}) is selective to groundwater. {H}owever, this distinctive feature has not been fully used in previous published studies for quantifying the drainable groundwater in hard rocks (i.e. the specific yield) and the short-term productivity of aquifer (i.e. the transmissivity). {W}e present in this paper a comparison of {MRS} results (i.e. the water content and pore-size parameter) with both specific yield and transmissivity calculated from long duration pumping tests. {W}e conducted our experiments in six sites located in different hard rock groups in {B}enin, thus providing a unique data set to assess the usefulness of {MRS} in hard rock aquifers. {W}e found that the {MRS} water content is about twice the specific yield. {W}e also found that the {MRS} pore-size parameter is well correlated with the specific yield. {T}hus we proposed two linear equations for calculating the specific yield from the {MRS} water content (with an uncertainty of about 10%) and from the pore-size parameter (with an uncertainty of about 20%). {T}he later has the advantage of defining a so-named {MRS} cutoff time value for indentifying non-drainable {MRS} water content and thus low groundwater reserve. {W}e eventually propose a nonlinear equation for calculating the specific yield using jointly the {MRS} water content and the pore-size parameters, but this approach has to be confirmed with further investigations. {T}his study also confirmed that aquifer transmissivity can be estimated from {MRS} results with an uncertainty of about 70%. {W}e conclude that {MRS} can be usefully applied for estimating aquifer specific yield and transmissivity in weathered hard rock aquifers. {O}ur result will contribute to the improvement of well siting and groundwater management in hard rocks.},
  keywords = {{H}ydrogeophysics ; {M}agnetic resonance sounding ; {S}pecific yield ; {T}ransmissivity ; {H}ard rock aquifers ; {SNMR} ; {BENIN}},
  booktitle = {},
  journal = {{J}ournal of {A}pplied {G}eophysics},
  volume = {107},
  numero = {},
  pages = {16--24},
  ISSN = {0926-9851},
  year = {2014},
  DOI = {10.1016/j.jappgeo.2014.05.012},
  URL = {https://www.documentation.ird.fr/hor/fdi:010062340},
}