%0 Journal Article %T Is the Dupuit assumption suitable for predicting the groundwater seepage area in hillslopes? %+ Géosciences Rennes (GR) %A Bresciani, Etienne %A Davy, Philippe %A de Dreuzy, Jean-Raynald %< avec comité de lecture %Z PL03279 %@ 0043-1397 %J Water Resources Research %I American Geophysical Union %V 50 %N 3 %P 2394-2406 %8 2014 %D 2014 %R 10.1002/2013WR014284 %Z Sciences of the Universe [physics]/Earth SciencesJournal articles %X Many physically based hydrological/hydrogeological models used for predicting groundwater seepage areas, including topography-based index models such as TOPMODEL, rely on the Dupuit assumption. To ensure the sound use of these simplified models, knowledge of the conditions under which they provide a reasonable approximation is critical. In this study, a Dupuit solution for the seepage length in hillslope cross sections is tested against a full-depth solution of saturated groundwater flow. In homogeneous hillslopes with horizontal impervious base and constant-slope topography, the comparison reveals that the validity of the Dupuit solution depends not only on the ratio of depth to hillslope length d/L (as might be expected), but also on the ratio of hydraulic conductivity to recharge K/R and on the topographic slope s. The validity of the Dupuit solution is shown to be in fact a unique function of another ratio, the ratio of depth to seepage length d/LS. For d/LS<0.2, the relative difference between the two solutions is quite small (<14% for the wide range of parameter values tested), whereas for d/LS>0.2, it increases dramatically. In practice, this criterion can be used to test the validity of Dupuit solutions. When d/LS increases beyond that cutoff, the ratio of seepage length to hillslope length LS/L given by the full-depth solution tends toward a nonzero asymptotic value. This asymptotic value is shown to be controlled by (and in many cases equal to) the parameter R/(sK). Generalization of the findings to cases featuring heterogeneity, nonhorizontal impervious base and variable-slope topography is discussed. %G English %2 https://insu.hal.science/insu-00979585/document %2 https://insu.hal.science/insu-00979585/file/bresciani.pdf %L insu-00979585 %U https://insu.hal.science/insu-00979585 %~ INSU %~ UNIV-RENNES1 %~ UR2-HB %~ CNRS %~ GR %~ OSUR %~ UR1-HAL %~ UR1-SDLM %~ UR1-SDLMJONCH %~ GR-DIMENV %~ UNIV-RENNES2 %~ TEST-UNIV-RENNES %~ TEST-UR-CSS %~ UNIV-RENNES %~ INRAE %~ UR1-ENV %~ GR-ET