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TitleMonitoring groundwater changes in southern Ontario using GRACE satellite gravity measurements
DownloadDownload (whole publication)
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorCrowley, J WORCID logo
SourceRegional-Scale Groundwater Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House; by Russell, H A JORCID logo; Ford, D; Holysh, S; Priebe, E H; Geological Survey of Canada, Open File 8528, 2019 p. 8, Open Access logo Open Access
Alt SeriesOntario Geological Survey, Open File Report 6349
PublisherNatural Resources Canada
PublisherGovernment of Ontario
MeetingRegional-Scale Groundwater Geoscience in Southern Ontario: Open House; Guelph; CA; February 27-28, 2019
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Regional-Scale Groundwater Geoscience in Southern Ontario: An Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario Geoscientists Open House
File formatpdf
NTS30; 31B; 31C; 31D; 31E; 31G; 40; 41A; 41G; 41H/03; 41H/04; 41H/05; 41H/06; 41H/12; 41H/13
AreaSouthern Ontario; Great Lakes; Lake Huron; Lake Erie; Lake Ontario; Canada; United States of America
Lat/Long WENS -84.0000 -74.0000 46.0000 41.5000
Subjectshydrogeology; geophysics; groundwater; aquifers; groundwater resources; satellite geodesy; gravity field; watersheds; hydrologic environment; hydrologic properties; hydrologic budget; surface waters; lakes; soil moisture; snow; ice; water levels; water wells; correlations; Gravity Recovery and Climate Experiment (GRACE); Canadian National Frameworks Dataset; monitoring
ProgramGroundwater Geoscience Aquifer Assessment & support to mapping
Released2019 02 08
AbstractThe Gravity Recovery and Climate Experiment satellite mission(s) (GRACE) have been measuring variations in the Earth's gravitational field since 2002. Changes in groundwater, melting glaciers, ocean circulation, and large deformations associated with post-glacial rebound, continental tectonics and earthquakes all produce signals that can be detected and monitored. In this talk, I will provide an introduction to the GRACE missions, briefly mention some new analysis methods being developed at the Canadian Geodetic Survey, and show some new results related to groundwater variations in Southern Ontario. The new method uses watershed regions from the Canadian National Frameworks Dataset to build mascons (regions of interest) for Canada, ensuring that the boundaries of the numerical method correspond to real hydrological boundaries and reducing leakage between adjacent watersheds. Three distinct mascons are designed using watershed geometry that include Lake Huron, Lake Erie, and Lake Ontario and estimates of total water storage (TWS) change are obtained using GRACE data from the Center for Space Research (U. of Texas at Austin) spherical harmonic Release 5 dataset. These TWS estimates are split into a contribution from surface water (SW) change and a common large-scale background signal across Southern Ontario that represents groundwater, soil moisture, snow and ice. The surface water changes are almost entirely due to lake level changes within the Great Lakes and can be compared to water level observations from gauges on the lakes provided by the Canadian Hydrographic Service. The GRACE derived and observed lake level changes agree well with correlations of 0.95, 0.92, and 0.82 for the Lake Huron, Erie, and Ontario regions, respectively. The amplitudes also agree well and, to our knowledge, this is the first study to effectively detect the changing water levels of the different Great Lakes using GRACE. The common background signal is found to have peak to peak variations of ~20 cm equivalent water thickness (EWT) and is compared to 301 wells from across Southern Ontario (data from the Provincial Groundwater Monitoring Network). The signals agree well with a correlation of 0.85. This result has important implications for the relative size and/or dynamics of the groundwater and remaining surface terms (soil moisture, snow and ice). Furthermore, variations in water storage from groundwater are found to be comparable to variations in water storage from the Great Lakes themselves - highlighting the importance that groundwater plays in any water budget of the Great Lakes system. Comparisons between individual groundwater wells and that of GRACE reveal the spatial extent of wells that show regional signals (high correlation) and those that show more local variability (poor correlation). Wells that correlate poorly reveal additional spatial patterns and the influence of local topography, geology, and water usage.
Summary(Plain Language Summary, not published)
Volume of abstracts for Ontario Geological Survey and Geological Survey of Canada groundwater geoscience Open house with Conservation Ontario.

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