DInSAR/PSI hybrid methodologies for ground-motion monitoring

Differential Synthetic Aperture Radar Interferometry (DInSAR) has been established as a significant and powerful remote sensing tool for mapping and monitoring ground motion. Due to the limitations of DInSAR, a multi-temporal approach namely Persistent Scatterer Interferometry (PSI) was developed. However, both methodologies, and especially PSI, have still constraints, one being the relatively low spatial coverage of the deformation field in natural terrains. To address the aforementioned problem, the main scope of the present research is the development of a hybrid methodology based on the two already existing and well-established methodologies, DInSAR and PSI. Firstly, the proposed hybrid methodology is tested over a natural terrain in Jordan (Middle East). Compared with the PSI method, the hybrid methodology shows a strong, significant improvement. Results show an improved spatial sampling of persistent scatterers. In the major part of the study area, the point density improved by 25-1000 pixels/ km² and in some parts >1000 pixels/km². Time series comparison between pixel locations from both PSI and hybrid results revealed that both approaches show relatively high consistency. To investigate its potential the hybrid method was additionally performed on a challenging natural terrain in Venice lagoon (NE Italy), where salt marshes exist. Specifically, the awareness of lack of information about the deformation of salt marshes, has driven this research on this area and exploring how fast the deformation rate over such vulnerable terrains is. Results show good potential as methodology for this case as the hybrid method was successfully applied and permitted to retrieve information about the deformation rates over such a complex terrain, whose subsidence cannot be detected easily with other techniques. This achievement is significant as any awareness about vulnerable terrains can help experts and policy makers to prevent their potential loss.