HR: 08:15h
AN: H21A-02    [PDF]
TI: Modelling Streaming Potential (SP) Signals Induced by Water Movement in the Vadose Zone
AU: * Darnet, M
EM: mathieu.darnet@eost.u-strasbg.fr
AF: EOST - IPGS, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: Marquis, G
EM: guy.marquis@eost.u-strasbg.fr
AF: EOST - IPGS, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AB: Field estimation of soil water flux has a direct application for water resource management. Standard methods are often difficult to apply because of the heterogeneity of the subsurface. In the present study, we show that Streaming Potential (SP) monitoring can provide a cost-effective tool to help estimate the nature of the hydraulic transfers (infiltration or evaporation) in the vadose zone. We have modelled the SP response induced by the electrokinetic effect of rainfall infiltration and evaporation in an unsaturated porous medium. Our model based on Richards' equation shows that SP signals of several millivolts are generated, i.e. easily recordable with standard SP equipment and that they allow to characterize the upward or downward water flux. We have then compared our model results to two SP and hydraulic data sets acquired during both rainfall infiltration and evaporation phases and they confirmed that SP measurements allow effectively to estimate the direction of the water flux at the scale of the electrode separation (usually several decimetres), i.e. at a much larger scale than tensiometric measurements. Moreover, as streaming potential coupling coefficients are related to the nature and concentration of solutes, SP could be used in the future to characterise contaminant fluxes in soils.
DE: 0925 Magnetic and electrical methods
DE: 1875 Unsaturated zone
DE: 3914 Electrical properties
DE: 5109 Magnetic and electrical properties
SC: Hydrology [H]
MN: 2003 Fall Meeting