Land subsidence monitoring in the Lucca plain (central Italy) with ERS and Envisat

Leonardo Disperati(1) , Salvatore Virdis(1) , Kurt L. Feigl(2) , Andrea Rindinella(1) , and Riccardo Salvini(1)

(1) Università di Siena - Centro di GeoTecnologie, Via Vetri Vecchi, 34, 52027 San Giovanni Valdarno (AR), Italy
(2) CNRS UMR 5562, 14 ave E. Belin, 31400 Toulouse, France

Abstract

We present preliminary results of a category 1 project in the Lucca plain, central Italy, to study land subsidence by integrating satellite radar interferometry with ground-truth levelling surveys. The subsidence appears to be related to the withdrawal of groundwater over the last two decades. Moreover, considering the geological framework, we cannot exclude regional vertical motions. Levelling measurements provide vertical motion rates of about 5 mm/year averaged over 10 years. To monitor such slow changes using interferometry requires accounting for land cover changes, temporal decorrelation, atmospheric effects and differential ground displacements. We consider over a hundred ERS and ENVISAT images in track/frame pairs 215/873 and 165/2727. Using least-squares method for extract time series from multiple interferograms. Levelling data help constrain the inversion. Preliminary results of vertical displacements observed using ERS1&2 and ENVISAT data will be discussed and interpreted in relation to water table changes and stratigraphic data.

 

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