Valois R., Rau G. C., Vouillamoz Jean-Michel, Derode B. (2022). Estimating hydraulic properties of the shallow subsurface using the groundwater response to earth and atmospheric tides : a comparison with pumping tests. Water Resources Research, 58 (5), p. e2021WR031666 [21 p.]. ISSN 0043-1397.
Titre du document
Estimating hydraulic properties of the shallow subsurface using the groundwater response to earth and atmospheric tides : a comparison with pumping tests
Valois R., Rau G. C., Vouillamoz Jean-Michel, Derode B.
Source
Water Resources Research, 2022,
58 (5), p. e2021WR031666 [21 p.] ISSN 0043-1397
Estimating subsurface hydraulic properties using the groundwater (GW) response to Earth tides (ET) and atmospheric pressure is an alternative approach to pumping or slug tests (passive vs. active methods). Yet testing the applicability of models under different subsurface conditions and comparing results with traditional hydraulic methods are lacking. We first review the assumptions of analytical models used to evaluate the GW response to ET and their applicability in unconfined to confined conditions. Second, we develop a robust approach to select the right model based on amplitude and phase pattern of the diurnal and semi-diurnal tides. Third, based on earlier works we develop an approach to derive the hydraulic conductivity of the screened interval using the GW response to atmospheric tides, here named "atmospheric slug test" (AST). We estimate transmissivity and storativity at three shallow aquifers in Cambodia and compare the results with subsurface properties derived from pumping tests (PT). Transmissivity values from AST and PT are in good agreement. However, we show that storativity values derived from ET show large discrepancies if borehole skin effects are ignored. Further, the GW response to ET exhibits a strong decay in amplitude with frequency while maintaining close to zero and positive phase shifts. When supplemented with the calculated transmissivity values, none of the analytical models was able to reproduce this frequency dependent behavior. Our work emphasizes the need for evaluating passive methods robustness under different subsurface conditions. Further work is required to understand the frequency dependent GW response to natural or artificial forces.
Plan de classement
Sciences fondamentales / Techniques d'analyse et de recherche [020]
;
Sciences du milieu [021]
;
Hydrologie [062]
;
Géologie et formations superficielles [064]
