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TitleMeasuring water accumulation rates using GRACE data in areas experiencing glacial isostatic adjustment: the Nelson River basin
AuthorLambert, AORCID logo; Huang, JORCID logo; van der Kamp, G; Henton, JORCID logo; Mazzotti, SORCID logo; James, T SORCID logo; Courtier, N; Barr, A G
SourceGeophysical Research Letters vol. 40, issue 23, 2013 p. 6118-6122, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20130292
Mediapaper; digital; on-line
File formatpdf
ProvinceAlberta; Manitoba; Ontario; Saskatchewan; British Columbia
NTS52; 53; 54; 62; 63; 64; 72; 73; 74; 82; 83; 84
AreaNelson River watershed; Canada; United States of America
Lat/Long WENS-118.0000 -88.0000 60.0000 45.0000
Subjectshydrogeology; geophysics; watersheds; analytical methods; gravity interpretations; remote sensing; isostatic rebound; isostatic compensation
Illustrationslocation maps; geophysical images
ProgramGroundwater Geoscience, National Aquifer Evaluation & Accounting Project
Released2013 12 06
AbstractGravity Recovery and Climate Experiment (GRACE) satellite-derived total water storage can be obscured by glacial isostatic adjustment. In order to solve this problem for the Nelson River drainage basin in Canada, a gravity rate map from 110 months (June 2002 to October 2011) of GRACE gravity data was corrected for glacial isostatic adjustment using an independent gravity rate map derived from updated GPS vertical velocities. The GPS-based map was converted to equivalent gravity rate using a transfer function developed from GPS and absolute-g data at colocated sites. The corrected GRACE gravity rate map revealed a major positive anomaly within the drainage basin, which was independently shown by hydrological data to be due to changes in water storage. The anomaly represents a cumulative increase at its center of about 340mm of water, reflecting a progression from extreme drought to extremely wet conditions.
Summary(Plain Language Summary, not published)
The amount of water stored in the ground, in the soil and in lakes and rivers of the Canadian prairies can vary significantly from extreme drought to extreme saturation. A satellite known as GRACE can measure changes in water storage by detecting very small changes in gravity. However, it is also sensitive to the on-going redistribution of mass beneath the Earth's crust known as glacial isostatic adjustment (GIA). The challenge is to distinguish the water storage signal from the GIA signal. We have used a combination of ground-based GPS and high-precision gravity data, collected since the 1990's, to independently determine the GIA effect on the GRACE satellite in order to reveal the water storage signal. Our results are confirmed by hydrological data from five sites in Saskatchewan. The increase in water storage from 2002 to 2011, at its maximum in south-eastern Saskatchewan, is equivalent to a water table increase of 3.4 m, assuming a nominal porosity of 10%.

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