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Journal Articles Hydrology and Earth System Sciences Year : 2022

Recession discharge from compartmentalized bedrock hillslopes

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Jean-Raynald de Dreuzy
Laurent Longuevergne
Elizabeth R Jachens
Gordon Grant
Luc Aquilina
  • Function : Author
John S Selker

Abstract

We used numerical modelling to explore the role of the vertical compartmentalization of hillslopes on groundwater flow and recession discharge. We found that, when hydraulic properties are vertically compartmentalized, streamflow recession behaviour may strongly deviate from what is predicted by groundwater theory that considers the drainage of shallow reservoirs with homogeneous properties. We further identified the hillslope configurations for which the homogeneous theory derived from the Boussinesq solution approximately holds and, conversely, for those for which it does not. By comparing the modelled recession discharge Q and the groundwater table dynamics, we identified the critical hydrogeological conditions controlling the emergence of strong deviations. The three main controls are (i) the contribution of a deep aquifer connected to the stream, (ii) the heterogeneity in hydraulic properties, and (iii) the slope of the interface between a shallow permeable compartment and deep bedrock one with lower hydraulic properties. Our results confirm that a correct physical interpretation of the recession discharge exponent b from the classical equation -dQ/dt=aQb, and its temporal progression, requires knowledge of the structural configuration and heterogeneity of the aquifer.
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Dates and versions

insu-03762931 , version 1 (29-08-2022)

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Clément Roques, David E Rupp, Jean-Raynald de Dreuzy, Laurent Longuevergne, Elizabeth R Jachens, et al.. Recession discharge from compartmentalized bedrock hillslopes. Hydrology and Earth System Sciences, 2022, 26 (16), pp.4391-4405. ⟨10.5194/hess-26-4391-2022⟩. ⟨insu-03762931⟩
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