HR: 0800h
AN: H51C-0654    [Abstracts]
TI: Three-dimensional modelling of water flow through a heterogeneous vadose zone
AU: * Angulo-Jaramillo, R
EM: angulo@entpe.fr
AF: Laboratoire des Sciences de l'Environnement, ENTPE Rue M. Audin, Vaulx-en-Velin, 69518, France
AU: * Angulo-Jaramillo, R
EM: angulo@entpe.fr
AF: LTHE, UMR 5564 BP53, Grenoble cedex 9, 38041, France
AU: Cazalets, H
EM: cazalets@entpe.fr
AF: Laboratoire des Sciences de l'Environnement, ENTPE Rue M. Audin, Vaulx-en-Velin, 69518, France
AU: Goutaland, D
EM: goutaland@entpe.fr
AF: Laboratoire des Sciences de l'Environnement, ENTPE Rue M. Audin, Vaulx-en-Velin, 69518, France
AU: Winiarski, T
EM: winiarski@entpe.fr
AF: Laboratoire des Sciences de l'Environnement, ENTPE Rue M. Audin, Vaulx-en-Velin, 69518, France
AU: Delolme, C
EM: delolme@entpe.fr
AF: Laboratoire des Sciences de l'Environnement, ENTPE Rue M. Audin, Vaulx-en-Velin, 69518, France
AB: Stormwater infiltration basins have become a common alternative practice to traditional stormwater pipe networks in urban areas. They are often built in permeable subsurface soils, such as alluvial deposits. These sedimentary deposits are highly heterogeneous which generate preferential flow paths that may cause non- uniform transport of contaminants at great depths. Thus, the hypothesis of using homogeneous deposit cannot be considered valid at the scale of infiltration basin. Therefore, it is required a fine scale three-dimensional numerical simulations of fluid flow and solute transport to understand how subsurface heterogeneities affect fluid flow and contaminant transfer. The aim of our study is to improve the understanding of the water flow mechanisms occurring at the lithofacies scale in the heterogeneous vadose zone of infiltration basin. The studied basin, located in the eastern suburbs of Lyon (France), is built in quaternary glaciofluvial deposits. Results from previous studies show that the glaciofluvial deposit is composed of 4 main lithofacies: sands, bimodal sandy gravels, heterometric sandy gravels, and openframework gravels. These lithofacies are organized in braided river deposits architecture. Ground-Penetrating Radar was assessed to characterize the structural units of the studied deposits. Hydraulic properties of each lithofacies were characterized on analogous modern glaciofluvial lithofacies, leading to the definition of hydrofacies. Geophysical measurements (Ground-Penetrating Radar and Electrical Resistivity) performed on a limited zone of the basin was interpreted to define a lithofacies distribution. Hydrofacies properties were used to build a three- dimensional hydrostratigraphic model of the glaciofluvial deposit. This model was implemented in the finite element program Hydrus3D. The results show that openframework gravels cause capillary barrier effects leading to funneled flows, i.e. non- vertical water flows along lithofacies interfaces. These results may explain the heterogeneous repartition of heavy metals concentration measured in other areas of the basin.
DE: 1835 Hydrogeophysics
DE: 1838 Infiltration
DE: 1847 Modeling
DE: 1865 Soils (0486)
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting