Study of the land subsidence in Orihuela City (SE Spain) using PSI data: Distribution, evolution and correlation with conditioning and triggering factors

This paper presents a study about the subsidence affecting the city of Orihuela, placed on the Western sector of the Vega Baja of the Segura River Basin (SE Spain). The study is based on deformation data obtained by Differential SAR Interferometry (DInSAR), and more precisely by the coherent pixels technique (CPT), an algorithm of the Persistent Scatterers Interferometry (PSI) family. Images acquired between June 1993 and April 2009 by ERS and ENVISAT satellite sensors have been processed by the CPT technique in order to retrieve the ground subsidence affecting this area. Accumulated deformation maps and displacement time series are analyzed. Moreover, these data have been contrasted with subsidence triggering and conditioning factors by means of a Geographical Information System (GIS) interface. The performed analysis shows that there exists a relationship between subsidence and piezometric level evolution in time. Moreover, the correlations among subsidence and location of pumping wells, distance to the river, geology, and soil thickness have been derived from this analysis.