The effect of water storage variations on in-situ gravity measurements and their use for hydrology
Water storage variations in the soil, groundwater, snow cover and in surface water bodies cause a gravitational effect due to mass attraction. Thus, there exists a strong interrelation between hydrology and gravity. From a hydrological perspective, the estimation of water storage and its spatio-temporal changes is essential for setting up water balances and for effective water use and management. However, direct measurements of local water storage changes are still a challenging task while time-variable gravity observations are a promising tool as an integrative measure of total water storage changes. From a geodetic perspective, the hydrological gravity effect is an interfering signal, which imposes noise on gravimetric measurements and thus has to be eliminated from the gravity records.
Superconducting gravimeters (SG) enable the in situ observation of the temporal changes of the earth gravity field. These SG data contain information about polar motion, earth tides, oscillations of the earth, atmospheric pressure and hydrology. But still variations in local water masses have a significant influence on SG measurements. Hence, the question is: How does local water storage change influence the signal of SG measurements?
The objective of the HYGRA project is to separate the local hydrological signal from the integral signal of the SG records. From the geodetic perspective, this will provide a tool to remove the unwanted hydrological noise in SG recordings. At the same time, the hydrological gravity signal bears the potential to estimate hydrological state variables (ground water, soil moisture).
The water cycle with the different storage components and the high-precision gravimeter for the estimation of water storage dynamics
The HYGRA project focuses the relation of local hydrology and gravity in following study areas:
Geodätisches Observatorium Wettzell, Deutschland
South African Geodynamic Observatory (SAGOS)
Observatorio Geodésico TIGO, Concepción, Chile
The investigation of the interrelation between hydrology and geodesy is done by following worksteps:
- 4D Simulation of the influence of water storage changes on the superconducting gravimeter
- Measuring and modelling of the different water storages; namely groundwater, soil moisture and snow
- Transformation of the water storage changes to a gravimetric signal
- Comparison between the measured gravity change by the SG and the estimated hydrological gravity response
The hydrological variables and processes are measured with following hydrological monitoring systems installed at the different study areas, whereas the different instrumentation varies depending on the study area and the environmental settings:
Project period and co-operations:
The HYGRA project is funded by GFZ Potsdam and is scheduled from mid 2006 to 2009.
HYGRA is performed in co-operation with the Federal Agency for Cartography and Geodesy (BKG) and co-operates with the project TASMAGOG (Temporal And Spatial Multiscale Assessment of mass transport by combination of Gravity Observations from GRACE and terrestrial stations) in the Priority Program ‘ Mass transport and mass distribution in the system Earth ' by the German Research Foundation (DFG).
Creutzfeldt, B., Güntner, A., Vorogushyn, S., and Merz, B., 2010: The benefits of gravimeter observations for modelling water storage changes at the field scale, Hydrol. Earth Syst. Sci., 14, 1715-1730, doi:10.5194/hess-14-1715-2010
Creutzfeldt, B., Güntner, A., Wziontek, H., and Merz, B., 2010: Reducing local hydrology from high precision gravity measurements: a lysimeter-based approach, Geophysical Journal International, in press, doi:10.1111/j.1365-246X.2010.04742.x.
Creutzfeldt, B., A. Güntner, H. Thoss, B. Merz, and H. Wziontek (2010), Measuring the effect of
local water storage changes on in situ gravity observations: Case study of the Geodetic Observatory Wettzell, Germany, Water Resour. Res., 46, W08531, doi:10.1029/2009WR008359.
Creutzfeldt, B., A. Guntner, T. Klugel, and H. Wziontek, 2008, Simulating the influence of water storage changes on the superconducting gravimeter of the Geodetic Observatory Wettzell, Germany: Geophysics, 73, WA95-WA104.
Creutzfeldt, B.; Güntner, A.; Klügel, T. (2008):
Simulating the influence of water storage changes on the superconducting gravimeter of the Geodetic Observatory Wettzell, Germany,
, General Assembly European Geosciences Union (Vienna, Austria 2008).
Creutzfeldt, B., 2009. Hydrometry -- Gravimetry: Monitoring the hydrological cycle in the context of gravimetric measurements COST Action ES0701: Improved Constraints on Models of Glacial Isostatic Adjustment. Workshop on local effects in absolute gravity measurements, Brussels.
Creutzfeldt, B., Güntner, A., Klügel, T., Wziontek, H. and Wilmes, H., 2009.
Local hydrological mass effects in gravity observations at the Geodetic Observatory Wettzell, Germany
, General Assembly European Geosciences Union. European Geosciences Union, Vienna.
Creutzfeldt, B., Güntner, A., Merz, B. and Wziontek, H., 2009.
Gravimetric observations of water storage change - lysimeters and superconducting gravimeters
, 2009 AGU Fall Meeting. American Geophysical Union, San Francisco, USA.
GeoForschungsZeitung, April 2009: Der Moderne Messbecher (german).
Contact at the GFZ Section 5.4 Engineering Hydrology :