@article{fdi:010066016,
  title = {{D}eclining water budget in a deep regional aquifer assessed by geostatistical simulations of stable isotopes : case study of the {S}aharan "{C}ontinental {I}ntercalaire"},
  author = {{G}oncalves, {J}. and {V}allet-{C}oulomb, {C}. and {P}etersen, {J}. and {H}amelin, {B}runo and {D}eschamps, {P}ierre},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he stable isotopes of water were used to improve the determination of the groundwater budget of the deep {S}aharan "{C}ontinental {I}ntercalaire" ({CI}), a deep confined aquifer. {M}ixing processes between the {CI} and shallower aquifers have been described in several regional studies over the last few decades, based on observed isotopic differences between local water masses. {H}ere, we improve the quantitative determination of the discharge flux of this aquifer in one of its main outlet regions, the {D}jeffara plain in {T}unisia, based on geostatistics and a simple mass balance mixing model, applied before and after the beginning of extensive pumping in the 1970s. {F}irst, the average values of delta {O}-18 and delta {H}-2 were precisely documented in the mixing zone between {C}l water and the local recharge, based on conditional simulations using spatially distributed isotopic data. {T}ogether with the available estimate of local recharge and conservative hypotheses on the isotopic end-members, we estimate the discharge flux of the {C}l in the {D}jeffara plain at 1.78 +/- 1.03 m(3) s(-1) in 1970, probably near natural steady-state, reduced to 1.02 +/- 0.58 m(3) s(-1) in 2004 under strong anthropogenic pressure, related to the drastic increase in pumping rates in the deep {C}l aquifer during this period. {C}onsidering the general groundwater budget over the entire {CI} aquifer, we estimate a recharge value of 5.13 m(3) s(-1), or 6.5 mm yr(-1) over the 25,000 km(2) of recharge area in the {S}aharan {A}tlas. {T}his value is in line with the evaluation of 2.1 mm yr(-1) obtained recently from the {GRACE} satellite gravity data for the overall outcrops considering that recharge occurs mostly in the {A}tlas region.},
  keywords = {{G}eostatistical conditional simulation ; {S}table isotopes ; {R}egional aquifers ; {G}roundwater budget ; {TUNISIE}},
  booktitle = {},
  journal = {{J}ournal of {H}ydrology},
  volume = {531},
  numero = {3},
  pages = {821--829},
  ISSN = {0022-1694},
  year = {2015},
  DOI = {10.1016/j.jhydrol.2015.10.044},
  URL = {https://www.documentation.ird.fr/hor/fdi:010066016},
}