A large single-ring infiltrometer test was performed in order to characterize the saturated hydraulic conductivity
below an infiltration basin in the well field of Lyon (France). Two kinds of data are recorded during the experiment:
the volume of water infiltrated over time and the extension of the moisture stain around the ring. Then numerical
analysis was performed to determine the saturated hydraulic conductivity of the soil by calibration.
Considering an isotropic hydraulic conductivity, the saturated hydraulic conductivity of the alluvial deposits is estimated
at 3.8 10–6 m s–1. However, with this assumption, we are not able to represent accurately the extension of the moisture
stain around the ring. When anisotropy of hydraulic conductivity is introduced, experimental data and simulation results
are in good agreement, both for the volume of water infiltrated over time and the extension of the moisture stain.
The vertical saturated hydraulic conductivity in the anisotropic configuration is 4.75 times smaller than in the isotropic
configuration (8.0 10–7 m s–1), and the horizontal saturated hydraulic conductivity is 125 times higher than the vertical
saturated hydraulic conductivity (1.0 10–4 m s–1).
Artificial basins are used to recharge groundwater and protect water pumping fields. In these basins, infiltration
rates are monitored to detect any decrease in water infiltration in relation with clogging. However, miss-estimations
of infiltration rate may result from neglecting the effects of water temperature change and air-entrapment. This study
aims to investigate the effect of temperature and air entrapment on water infiltration at the basin scale by conducting successive
infiltration cycles in an experimental basin of 11869 m2 in a pumping field at Crepieux-Charmy (Lyon, France).
A first experiment, conducted in summer 2011, showed a strong increase in infiltration rate; which was linked to a potential
increase in ground water temperature or a potential dissolution of air entrapped at the beginning of the infiltration. A
second experiment was conducted in summer, to inject cold water instead of warm water, and also revealed an increase
in infiltration rate. This increase was linked to air dissolution in the soil. A final experiment was conducted in spring with
no temperature contrast and no entrapped air (soil initially water-saturated), revealing a constant infiltration rate. Modeling
and analysis of experiments revealed that air entrapment and cold water temperature in the soil could substantially
reduce infiltration rate over the first infiltration cycles, with respective effects of similar magnitude. Clearly, both water
temperature change and air entrapment must be considered for an accurate assessment of the infiltration rate in basins.