Mario Floris, Alessandro Fontana, Gabriele Fontanel, Matteo Mantovani, Alessandro Pasuto, Livio Ronchi, Giulia Bossi, Paolo Riccardi, Giulia Tessari,, 2018, Monitoring of subsidence in the lowland area between the Piave and Livenza rivers using A-DInSAR techniques, 6° Congresso Nazionale AIGA 2018, pp. 29–29, Courmayeur, 27-29/06/2018,
URL: http://www.cnr.it/prodotto/i/389051

Space-borne SAR data acquired by ERS 1/2, ENVISAT, COSMO-SkyMed and Sentinel-1 missions from 1992 to 2017 were processed through both PS-InSAR and SBAS techniques to evaluate the rate of subsidence affecting the lowland area between the Piave and Livenza rivers (about 250 square kilometers). The plain was formed by the interplay between the fluvial system of the rivers and lagoon and marine environments. Velocity maps and time series of displacements were compared to ancillary data such as geological and geomorphological maps, orthophotos and satellite images collected between 1988 and 2015. Five subareas were analyzed in detail, investigating the relationships between the change in land cover and/or the spatial variation of geological and geomorphological features and the different rates of displacement. The main aims of this study are to test DInSAR techniques as a tool for geological and geomorphological mapping and to verify if geomorphological surveys may support the detection of areas prone to subsidence. Results show that subsidence is mainly related to the geological characteristics of the subsoil. Downlift can be generally detected where recent structures and infrastructures are present; we observed a rapid growth of displacement rate (up to 9 mm/yr) in the first 8 years after the construction of new buildings, a decrease (about 3 mm/y) in the following 10 years and a final stabilization in the last 7 years of the observation period (1992-2017). This sequence can be related to the different steps of the consolidation process. We also observed different rates of displacement affecting a well-defined sector of the town of S. Stino di Livenza, where the faster rates can be related to the presence of a minor paleo-channel filled by recent unconsolidated deposits. Our findings show that DInSAR can be a tool for geomorphological and geological mapping through the identification of subsidence pattern caused by different geotechnical properties of the deposits, especially in urbanized zone, where direct observations are limited. The clear relationship between the difference in the rate of ground displacement and the spatial variation of geomorphological features, suggests that geomorphology can be used as an effective tool for the predicting land subsidence.

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