000003514 001__ 3514
000003514 005__ 20180301171842.0
000003514 0247_ $$2DOI$$a10.5194/hess-22-1563-2018
000003514 037__ $$aSCART-2018-0040
000003514 100__ $$aWatlet, Arnaud
000003514 245__ $$aImaging groundwater infiltration dynamics in the karst vadose zone with long-term ERT monitoring 
000003514 260__ $$c2018
000003514 520__ $$aWater infiltration and recharge processes in karst systems are complex and difficult to measure with conventional hydrological methods. In particular, temporarily saturated groundwater reservoirs hosted in the vadose zone can play a buffering role in water infiltration. This results from the pronounced porosity and permeability contrasts created by local karstification processes of carbonate rocks. Analyses of time-lapse 2-D geoelectrical imaging over a period of 3 years at the Rochefort Cave Laboratory (RCL) site in south Belgium highlight variable hydrodynamics in a karst vadose zone. This represents the first long-term and permanently installed electrical resistivity tomography (ERT) monitoring in a karst landscape. The collected data were compared to conventional hydrological measurements (drip discharge monitoring, soil moisture and water conductivity data sets) and a detailed structural analysis of the local geological structures providing a thorough understanding of the groundwater infiltration. Seasonal changes affect all the imaged areas leading to increases in resistivity in spring and summer attributed to enhanced evapotranspiration, whereas winter is characterised by a general decrease in resistivity associated with a groundwater recharge of the vadose zone. Three types of hydrological dynamics, corresponding to areas with distinct lithological and structural features, could be identified via changes in resistivity: (D1) upper conductive layers, associated with clay-rich soil and epikarst, showing the highest variability related to weather conditions; (D2) deeper and more resistive limestone areas, characterised by variable degrees of porosity and clay contents, hence showing more diffuse seasonal variations; and (D3) a conductive fractured zone associated with damped seasonal dynamics, while showing a great variability similar to that of the upper layers in response to rainfall events. This study provides detailed images of the sources of drip discharge spots traditionally monitored in caves and aims to support modelling approaches of karst hydrological processes.
000003514 594__ $$aNO
000003514 6531_ $$aElectrical Resistivity Tomography
000003514 6531_ $$aKarst
000003514 6531_ $$aHydrology
000003514 6531_ $$aHydrogeophysics
000003514 6531_ $$aMonitoring
000003514 700__ $$aKaufmann, Olivier
000003514 700__ $$aTriantafyllou, Antoine
000003514 700__ $$aPoulain, Amaël
000003514 700__ $$aChambers, Jonathan E.
000003514 700__ $$aMeldrum, Philip I.
000003514 700__ $$aWilkinson, Paul B.
000003514 700__ $$aHallet, Vincent
000003514 700__ $$aQuinif, Yves
000003514 700__ $$aVan Ruymbeke, Michel
000003514 700__ $$aVan Camp, Michel
000003514 773__ $$c1563-1592$$pHydrology and Earth System Sciences$$v22$$y2018
000003514 8560_ $$farnaud.watlet@observatoire.be
000003514 85642 $$ahttps://www.hydrol-earth-syst-sci.net/22/1563/2018/
000003514 905__ $$apublished in
000003514 980__ $$aREFERD