Surface Deformation Associated with Water Storage Change in Southern Ontario Observed By InSAR and GPS

This study examine if surface deformation in the southern Ontario, which was measured by inteferometric synthetic aperture radar (InSAR) technology and GPS, is related to water storage change. We used InSAR from a set of 40 Radarsat-2 (RS-2) images over five years (Jan. 2013 - Sept. 2017) and the RTK GPS weekly solution data for the measurement of surface deformations. An annual subsidence rate of 1mm to 10 mm with seasonal variations of up to 2 cm in south Ontario is observed from Radarsat-2 InSAR measurements. The greatest subsidence (> 7mm per year) is found along the shore of the Lake Ontario. The InSAR results are confirmed by the RTK GPS measurments. We compared the surface deformations to the terrestrial water storage (TWS) data derived from GRACE satellites, in-situ water level data of the Great Lakes and monthly precipitation data in the study area. The comparisons showed that both multi-year trend and seasonal variations in surface deformation are consistent with water storage changes. The results implied that the surface deformation in southern Ontario could be caused by the water loading.