An experimental setup in Avignon (South of France) composed of an agricultural field and of a large scale undisturbed  lysimeter for the multiscale study of preferential flow in soil and of groundwater recharge processes

Chapelet, Arnaud; Debroux, Micheline; Tison, Franck; Di Pietro, Liliana; Doussan, Claude; Joelson, Maminirina; Marc, Vincent; Ruy, Stephane

An experimental setup in Avignon (South of France) composed of an agricultural field and of a large scale undisturbed lysimeter for the multiscale study of preferential flow in soil and of groundwater recharge processes

2012

Preferential flow in soil is of major importance for the dynamic of groundwater recharge, on aquantitative and qualitative point of view. This is particularly the case in Mediterranean regionswhere this phenomenon is increased due to flood irrigation, high intensity rainfall events andseasonal soil water deficit leading to soil shrinkage and cracking.A large scale experimental setup devoted to a multiscale study of preferential flow in soil and ofgroundwater recharge processes has been set up in Avignon, South of France in 2002. It is composedof a large scale undisturbed lysimeter associated to a 0.7 ha field. Agricultural practices are the sameon both plots. The field plot is equipped with piezometers, groundwater level probes working at afine time step, water balance sites and porous cups for soil water sampling. The lysimeter is equipedwith soil moisture probes and tensiometers, and with an automatic device for measuring drainageflow at the bottom of the lysimeter. Physical and hydrodynamic properties of the field plot andlysimeter have been measured using geophysical devices (electrical tomography and electromagneticprospection) and the kinematic wave theory for preferential flow. Local hydrodynamic properties ofthe aquifer are also known.We present some results concerning (i) rainfall simulation on the lysimeter and on the field usingchemical tracers and water stable isotopes, (ii) drainage hydrographs obtained at the bottom of thelysimeter under natural rains, (iii) groundwater level variations. This is an original experimentaldevice, combining tracers experiments, geophysical and physical monitoring of soil water andgroundwater dynamics, for studying in situ bypass flow in soil and rapid groundwater recharge at thefield scale.

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