Remote sensing monitoring of infrastructure in complex and coastal areas

Coastal areas are very complex and dynamic environments where protection of valuable and vulnerable habitat is a priority, consequently principles of sustainable engineering must be adopted. Coastal erosion, aggressive pollution of sensible ecosystems, unstable slopes and cliffs, adverse chemical conditions related to the high concentration of chlorides, presence of cultural heritage or fragile natural sites, hard impacts of human activities and anthropization are only some examples of the severe issues that typically have to be considered and tackled. Satellite monitoring has become a very versatile tool, allowing for assessment of these situations, for example the infrastructure stability through MT-InSAR techniques, as well as the evolution of coastal erosion progress through the monitoring of the coastline. In addition, the definition of indices derived by multispectral data, such as the Normalized Difference Water Index (NDWI), Normalized Difference Moisture Index (NDMI), and Shortwave Infrared Composite (SWIR), can provide valuable information on water body mapping, vegetation water content and changes in land-cover. This study presents some preliminary results of integrating multi-level information for the creation of a checklist of useful indicators, suitable to define an early-warning index for the infrastructure and the areas concerned, to guide detailed on-site analysis with more conventional inspection techniques such as total stations or drone inspections. MT-InSAR was used to identify displacements over transport infrastructure. The NDWI and NDMI were used to monitor variations of the coastal area over time, while the SWIR indicator allows the detection of changes in land cover enabling infrastructure and coastal dynamics monitoring. An integrated analysis of these factors including the analysis of historical time-series of such indicators derived from multispectral data from the Sentinel-2 constellation was performed, along with the evaluation of additional information, including the temperature. This study paves the way for a novel method aimed at identifying potential risks for transport infrastructure located in coastal areas, to instruct decision-making towards a more effective provision of coastal defense works.