@article{fdi:010063882,
  title = {{G}roundwater in hard rocks of {B}enin : regional storage and buffer capacity in the face of change},
  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 = {{G}roundwater plays a major role in supplying domestic water to millions of people in {A}frica. {I}n the future, the ability to increase reliable water supplies for domestic and possibly irrigation purposes will depend on groundwater development. {G}roundwater storage is a key property because it controls the buffering behavior of the aquifer as it is subjected to time-varying conditions such as increased pumping or land-use change. {H}owever, quantitative knowledge of groundwater storage in {A}frica is very limited. {T}his lack of knowledge is a major concern in hard rocks, which cover about 40% of the surface area of {A}frica. {T}his paper presents a unique quantitative assessment of groundwater storage in different types of hard rocks and a first estimate of the capacity of hard rock aquifers to buffer changes in climatic and anthropogenic conditions. {O}ur study area in {B}enin ({W}est {A}frica) is composed of various grades of metamorphic rocks. {W}e used the latest developments in the application of the magnetic resonance geophysical method to confront the methodological difficulty of quantifying groundwater storage. {W}e successfully conducted 38 magnetic-resonance measurements in eight (8) different geological units; each measurement was quantitatively interpreted in terms of groundwater storage. {W}e determined the groundwater storage of our study area to be 440 mm 70 mm (equivalent water thickness). {T}o assess the buffer capacity of aquifers, we compared groundwater storage to groundwater discharge. {G}roundwater discharge is the sum of natural discharge plus human abstraction. {W}e estimated natural discharge (i.e. deep drainage plus evapotranspiration) from water table fluctuations monitored in six (6) piezometers. {H}uman abstraction was calculated based on the number of operating boreholes and their average daily abstraction. {W}e found that human abstraction (0.34 mm/year +/- 0.07 mm) is far less than natural discharge (108 mm/ year 58 mm). {W}e conclude that increased abstraction due to population growth will probably have a smaller impact on storage than observed land-use change, which may lead to a change in the evapotranspiration rate. {W}e calculated buffer capacity as the ratio of current storage to total discharge, and obtained a result of 6 years +/- 47 months. {T}his buffer capacity confirms groundwater's ability to buffer changes. {F}inally, our study is intended to promote a more quantitative approach to assessing groundwater resources in {A}frica and to support our ability to adapt to current and future changes.},
  keywords = {{G}roundwater storage ; {B}uffer capacity ; {C}limate change ; {M}agnetic resonance sounding ; {S}pecific yield ; {H}ard rock aquifers ; {BENIN}},
  booktitle = {},
  journal = {{J}ournal of {H}ydrology},
  volume = {520},
  numero = {},
  pages = {379--386},
  ISSN = {0022-1694},
  year = {2015},
  DOI = {10.1016/j.jhydrol.2014.11.024},
  URL = {https://www.documentation.ird.fr/hor/fdi:010063882},
}