Space borne radar imagery can be used for numerous applications in groundwater science: delimit sedimentary units and fault systems, map land cover and spatial patterns of aquifer recharge, or to monitor ground level and its relation to aquifer hydraulic pressure, compressibility, and thickness. Until recently, these techniques based on radar imagery were challenging to apply in Australia due to either the lack of radar imagery archives or to the difficulties in obtaining the archives when available. Since 2015, Sentinel-1 satellites are automatically acquiring images over Earth’s landmass and (with constant acquisition geometry) at a 12 days frequency, unleashing an important potential of applications for Australia. In 2019, few years after the start of Sentinel-1 missions, large temporal stacks of archive radar imagery are available throughout Australia. In this presentation, I explain the principles of acquisition and processing of radar imagery and provide an overview of applications in Australia using recent Sentinel-1 data. I also illustrate the challenges that hydrogeologists might face while integrating this data into their work.
Radar Interferometry (InSAR) allows to derive ground level changes from radar image time-series. Over Perth basin and Murrumbidgee regions, trends in ground level changes (subsidence or uplift) are obtained from InSAR and show that significant groundwater storage changes have occurred during 2016-2019. In other areas, the interpretation of InSAR results is challenged by the important clay content of the surficial layers of soils, which induces large seasonal changes in ground level not attributable to groundwater storage. Using other information derived from the same radar imagery datasets, it is also possible to map and monitor Groundwater-Dependant Ecosystems (GDEs). In fact, the structural stability of vegetation (and resilience during droughts) can be inferred from radar imagery and used as a proxy for GDEs.