Preprints
https://doi.org/10.5194/hess-2022-175
https://doi.org/10.5194/hess-2022-175
 
16 May 2022
16 May 2022
Status: this preprint is currently under review for the journal HESS.

Calibration of groundwater seepage on the spatial distribution of the stream network to assess catchment-scale hydraulic conductivity

Ronan Abhervé1, Alexandre Gauvain1,4, Clément Roques1,2, Laurent Longuevergne1, Stéphane Louaisil3, Luc Aquilina1, and Jean-Raynald de Dreuzy1 Ronan Abhervé et al.
  • 1Univ Rennes, CNRS, Geosciences Rennes - UMR 6118, F-35000 Rennes, France
  • 2Centre for Hydrology and Geothermics (CHYN), Université de Neuchâtel, Neuchâtel, Switzerland
  • 3Eau du Bassin Rennais, Rennes, France
  • 4Geosophy, Paris, France

Abstract. To supplement the use of hydraulic tests and assess catchment-scale hydraulic conductivity (K), we propose a methodology for shallow aquifers only based on the Digital Elevation Model (DEM) and on the observation of the stream network. The methodology requires the groundwater system to be a main determinant of the stream density and extension. It assumes that the perennial stream network is set by the intersection of the groundwater table with the topography. The topographical structures and the subsurface hydraulic conductivity divided by the recharge rate K / R determine the groundwater table depth and the development of the stream network. Using a parsimonious 3D groundwater flow model, we calibrate K / R by minimizing newly defined distances between the simulated groundwater seepage zones and the observed stream network. Deployed on 24 selected headwater catchments from 12 to 141 km2 located in north-western France, the method successfully matches the stream network in 80 % of the cases and provides catchment-scale hydraulic conductivities between 9 x 10-6 and 9 x 10-5 m s-1 for shallow aquifers sedimentary and crystalline rocks. Results show a high sensitivity of K to the density and extension of the low-order streams and limited impacts of the DEM resolution as long the DEM remains consistent with the stream network observations. With the emergence of global remote-sensing databases combining information of high-resolution DEM and stream network, this approach will contribute to assess hydraulic properties of in shallow headwater aquifers.

Ronan Abhervé et al.

Status: open (extended)

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Ronan Abhervé et al.

Ronan Abhervé et al.

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Short summary
We propose a method to leverage the widely available information on topography and rivers for determining the hydraulic properties of aquifers in regions where perennial streams are directly fed by groundwater. The estimated hydraulic conductivity appears to be especially sensitive to the extent and density of the rivers are especially sensitive. The method is especially interesting for ungauged catchments in the absence of any other data.