Determination of upward/downward groundwater fluxes using transient variations of soil profile temperature:: test of the method with Voyons (Aube, France) experimental data

The temperature variations recorded at several points of a vertical shallow-depth profile are governed both by conductive and convective heat transfers and can be used to calculate the vertical component of the Darcy velocity and thermal diffusivity in the soil. This paper describes such calculations when transient variations over tens of days are considered and tests them using data collected at Voyons (Aube, France). The temperature was recorded during a year and a half period with a 1 h sampling time step at three different depths: 0.2, 0.4 and 0.75 m. By processing the annual variation of temperature, we obtained a value of the Darcy velocity in good agreement with the value of actual/potential evapotranspiration ratio. By processing transient variations, despite the limitation of the calculations due to the lack of sensitivity of the sensors, results obtained at Voyons were in good correlation with tensiometric data. Copyright (c) 2005 John Wiley & Sons, Ltd.