Articles | Volume 21, issue 6
Hydrol. Earth Syst. Sci., 21, 3167–3182, 2017
Hydrol. Earth Syst. Sci., 21, 3167–3182, 2017

Research article 29 Jun 2017

Research article | 29 Jun 2017

Landscape-scale water balance monitoring with an iGrav superconducting gravimeter in a field enclosure

Andreas Güntner1,4, Marvin Reich1, Michal Mikolaj1, Benjamin Creutzfeldt2, Stephan Schroeder1, and Hartmut Wziontek3 Andreas Güntner et al.
  • 1Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Section 5.4 Hydrology, 14473 Potsdam, Germany
  • 2Senate Department for Urban Development and the Environment, 10707 Berlin, Germany
  • 3Federal Agency for Cartography and Geodesy (BKG), 04105 Leipzig, Germany
  • 4University of Potsdam, Institute of Earth and Environmental Science, 14476 Potsdam, Germany

Abstract. In spite of the fundamental role of the landscape water balance for the Earth's water and energy cycles, monitoring the water balance and its components beyond the point scale is notoriously difficult due to the multitude of flow and storage processes and their spatial heterogeneity. Here, we present the first field deployment of an iGrav superconducting gravimeter (SG) in a minimized enclosure for long-term integrative monitoring of water storage changes. Results of the field SG on a grassland site under wet–temperate climate conditions were compared to data provided by a nearby SG located in the controlled environment of an observatory building. The field system proves to provide gravity time series that are similarly precise as those of the observatory SG. At the same time, the field SG is more sensitive to hydrological variations than the observatory SG. We demonstrate that the gravity variations observed by the field setup are almost independent of the depth below the terrain surface where water storage changes occur (contrary to SGs in buildings), and thus the field SG system directly observes the total water storage change, i.e., the water balance, in its surroundings in an integrative way. We provide a framework to single out the water balance components actual evapotranspiration and lateral subsurface discharge from the gravity time series on annual to daily timescales. With about 99 and 85 % of the gravity signal due to local water storage changes originating within a radius of 4000 and 200 m around the instrument, respectively, this setup paves the road towards gravimetry as a continuous hydrological field-monitoring technique at the landscape scale.

Short summary
Monitoring water storage changes beyond the point scale is a challenge. Here, we show that an integrative and non-invasive way is by observing variations of gravity that are induced by water mass changes. A high-precision superconducting gravimeter is successfully operated in the field and allows for direct and continuous monitoring of the water balance and of its components, such as actual evapotranspiration.