Land uplift linked to managed aquifer recharge in the Perth Basin, Australia

While the link between groundwater extraction and land subsidence is well documented, observations of landuplift associated with groundwater replenishment are less so. In the Perth Basin, Western Australia, a programmeof managed aquifer recharge (MAR) commenced in August 2017 and is designed to sustain levels of hydraulichead in aquifers valuable for extraction. Space-based TerraSAR-X satellite radar measurements were used tocapture the first 3.5 years of MAR, providing an insight into the evolution of ground uplift in the Perth Basin thatis spatially and temporally related to the MAR injection volumes and the injection-induced changes in hydraulichead. Significantly, the X-band InSAR has spatial coverage around the single injection point, and the time seriesbegins prior to the start of the injection, rather than a generalised study of ground surface and aquifer changefrom multiple groundwater recharge contributions. This enables the observed ground uplift to be correlated withthe time of initial injection, pause, then resumption with increased volumes. The X-band InSAR identifiedmaximum displacements of up to 20±3 mm in the vicinity of the injection bores, but which subside when injectionis paused. The spread of displacements from the injection site extends over 14 km southwards with thedispersion pattern identifying linear boundaries that sharply delineate displacements in the north-west andnorth-east. The extent of the region impacted by ground uplift is likely linked to the distribution of extractionbores and heterogeneities in the subsurface geology, including a persistent linear feature that has not yet beenconsidered in hydrogeological models of the region. This article focusses on the immediate surface response tothe MAR injection, and identifying the constraining physical features for the injected recharge, thus providing anadditional insight into the challenging and complex Perth Basin. It also demonstrates the millimetric accuracypossible from X-band radar satellites that permits MAR volumes to be ...