Observation of ground surface deformation in coastal areas by SAR Interferometry
Résumé
Sea-level rise is one of the most unavoidable consequences of anthropogenic climate change. Coastal managers need to anticipate impacts and adaptation needs at local scale, which implies considering all components of sea-level changes, including vertical ground motions. Subsidence phenomena can exacerbate the local consequences of sea-level rise in terms of hazard (flooding, erosion) and coastal vulnerability.
In addition, studies attempting to reconstruct past-sea-level changes or to validate satellite altimetry also need to correct the local values obtained by tide gauges using vertical ground motions. Indeed, local surface deformation can affect the link between the global sea level evolution and its local expression measured by the tide gauges: subsidence enhance local sea level, upheaval reduces it.
In all these cases, Differential SAR Interferometry – in combination with other in-situ measurements such as tide gauge, permanent GPS and DORIS Stations – provides useful complementary information on the spatial variability of vertical ground motions. Performances of DInSAR can be consistent (depending on the used processing technique) in terms of precision, with the observation of sea-level rise. In addition, using archived data (since the 1990’s using past space-borne SAR missions) SAR interferometry allows to observe surface deformations on areas where no ground based geodetic network were available in the past.
We present results on coastal areas - mostly urbanized that are more suitable for DInSAR use – for illustrating the potential of the application of the SAR interferometric techniques to this research domain.