Water Storage Dynamics of a Forest Landscape: Monitoring with a Superconducting Gravimeter
Abstract
Terrestrial gravimetry allows for integrative measurements of mass changes associated with water storage variations in all storage compartments above and the below the Earth surface. The local footprint of the gravimeter typically covers a radius of 5 to 10 km around the instrument, with most of the signal originating from within 100 meters. Superconducting gravimeters (SG) currently are the most precise instruments for continuous monitoring of gravity changes but have so far never been deployed in forests. To further develop the use of high-precision terrestrial gravimetry for hydrological field research, we installed a SG (iGrav033) in a mixed pine-beech forest in the TERENO observatory of the lowlands of north-eastern Germany. Within a small field enclosure with less than 1 m2 base area, the SG was deployed on top of a concrete pillar at about 1 meter above the terrain surface. Complementary hydro-meteorological monitoring data are available at the site, including a weather station, a groundwater monitoring well, clusters of soil moisture sensors along deep soil profiles, interception measurements and stand-scale near-surface soil moisture from Cosmic Ray Neutron Sensing. For quantification and correction of the instrumental SG drift, two measurement campaigns with a FG5 absolute gravimeter were carried out so far. We report on the experiences of the first two successful years of operating the iGrav at the site since November 2017, in terms of technical stability of the setup and noise of the gravity time series. We interpret the gravity residuals (gravity measurements reduced to the local hydrological effect) with respect to short-term storage variations by rainfall events and evapotranspiration and in terms of water storage depletion associated with the summer drought events 2018 and 2019 in Central Europe.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H43H2092G
- Keywords:
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- 1217 Time variable gravity;
- GEODESY AND GRAVITY;
- 1218 Mass balance;
- GEODESY AND GRAVITY;
- 1835 Hydrogeophysics;
- HYDROLOGY;
- 1895 Instruments and techniques: monitoring;
- HYDROLOGY