Investigation of Subsidence in the Manfredonia Gulf (Southern Italy) Though Multitemporal DInSAR Techniques

In the last decades, the coast of the Apulia Tavoliere plain has been subject to a considerable retreat. During strong hydrodynamic and meteorological events, sea waters penetrate deeply inland. Such phenomena, together with the presence of failure damages over anthropogenic structures, indicate the presence of subsidence over an extended area. To analyze the recent evolution and rates of occurrence of the phenomenon, Persistent Scatterers Interferometry (PSI) techniques have been applied, to obtain millimetric displacement maps from series of radar interferograms. 103 ERS-1/2 and ENVISAT scenes have been analysed, with acquisition dates spanning the interval 1995-2000 (ERS) and 2003-2008 (ENVISAT), respectively. The analysis is restricted to objects characterized by strong radar return signals, generally coinciding with man-made features. The rural nature of the investigated area requires processing independently small patches on urban centres. Nevertheless, taking into account indirect observations and ground truth, a coherent picture emerges. Results indicate the presence of deformations affecting the entire temporal interval analysed, spatially distributed to form a "bowl" centered on the Ippocampo village with average rates exceeding 20 mm/y and an increasing trend in the most recent years. ...