Surface deformation observed by InSAR shows connections with water storage change in Southern Ontario

•Surface deformation by InSAR and GPS showed high correlation.•InSAR observed large seasonal variations in surface deformation in S. Ontario.•Surface deformation showed multi-year subsidence in 2013–2017.•Surface subsidence corresponded to increased water loading. A 10,000 km2 area of southwestern Ontario within the Lake Erie and Lake Ontario basins of the Laurentian Great Lakes basin, Ontario, Canada, a humid northern hydrogeological setting with abundant precipitation and recharge, and a stable Paleozoic sedimentary bedrock overlain by galacial sediment forming a relatively uncompressible sedimentary succession. Examing land surface deformation in southern Ontario and its connection with water storage change. The surface deformation, observed from a set of 48 Radarsat-2 InSAR images over five years from Jan. 2013 to Sept. 2017 presents a subsidence trend of 1−10 mm/year and a seasonal variation of up to 20 mm over the region. The InSAR results are confirmed by the GPS measurements at six locations over the region. The surface deformations were compared to the water storage data derived from GRACE satellites, in-situ water levels of the Great Lakes, and precipitation data in the study area. The results indicate that the multi-year trend and seasonal variations in surface deformation are correlated to water storage changes, suggesting that the surface deformation in southern Ontario could be caused by water loading.