000004286 001__ 4286
000004286 005__ 20191003080612.0
000004286 037__ $$aCTALK-2019-0126
000004286 100__ $$aVan Camp, M.
000004286 245__ $$aHydrogeological effects on terrestrial gravity measurements
000004286 260__ $$c2019
000004286 269__ $$c2019-12-12
000004286 500__ $$aMeasuring gravity at Membach and Rochefort for more than twenty years!
000004286 520__ $$aFor the 20 last years, terrestrial and satellite gravity measurements have reached such a precision that they allow for identification of the signatures from water storage fluctuations. In particular, hydrogeological effects induce significant time-correlated signature in the gravity time series. Gravity response to rainfall is a complex function of the local geologic and climatic conditions, e.g., rock porosity, vegetation, evaporation, and runoff rates. The gravity signal combines contributions from many geophysical processes, source separation being a major challenge. At the local scale and short-term, the associated gravimetric signatures often exceed the tectonic and GIA effects, and  monitoring gravity changes is a source of information on local groundwater mass balance, and contributes to model calibrations. Main characteristics of the aquifer can then be inferred by combining continuous gravity, geophysical and hydrogeological measurements. In Membach, Belgium, a superconducting gravimeter has monitored gravity continuously for more than 24 years. This long time series, together with 300 repeated absolute gravity measurements and environmental monitoring, has provided valuable information on the instrumental, metrological, hydrogeological and geophysical points of view. This has allowed separating the signal sources and monitoring partial saturation dynamics, convective precipitation and evapotranspiration at a scale of up to 1 km², for signals smaller than 1 nm/s², equivalent to 2.5 mm of water.  Based on this experience, another superconducting gravimeter was installed in 2014 in the karst zone of Rochefort, Belgium. In a karst area, where the vadose zone is usually thicker than in other contexts; combining gravity measurements at the surface and inside accessible caves is a way to separate the contribution from the unsaturated zone lying between the two instruments, from the saturated zone underneath the cave, and the common mode effects from the atmosphere or other regional processes.  Those experiments contribute to the assessment of the terrestrial hydrological cycle, which is a major challenge of the geosciences associated with key societal issues: availability of freshwater, mitigation of flood hazards, or measurement of evapotranspiration.
000004286 594__ $$aNO
000004286 6531_ $$aHydrogeodesy
000004286 6531_ $$aGravimetry
000004286 6531_ $$aMembach
000004286 6531_ $$aRochefort
000004286 6531_ $$aRainfall
000004286 6531_ $$aHydrogeology
000004286 6531_ $$aKarst
000004286 6531_ $$aVadose zone
000004286 6531_ $$aSaturated zone
000004286 700__ $$aDassargues, A.
000004286 700__ $$aDelforge, D.
000004286 700__ $$aDelobbe, L.
000004286 700__ $$ade Viron, O.
000004286 700__ $$aFrancis, O. 
000004286 700__ $$aKaufmann, O.
000004286 700__ $$aLecocq, O. 
000004286 700__ $$aVan Clooster, M.
000004286 700__ $$aWatlet, A.
000004286 773__ $$tAGU Fall Meeting 2019, San Francisco
000004286 8560_ $$fmichel.vancamp@observatoire.be
000004286 906__ $$aInvited
000004286 980__ $$aCTALKINVI