Technical Note Multiband PSInSAR and long-period monitoring of land subsidence in a strategic detrital aquifer (Vega de Granada, SE Spain): An approach to support management decisions Rosa María Mateos a,b,⇑ , Pablo Ezquerro b , Juan Antonio Luque-Espinar a , Marta Béjar-Pizarro b , Davide Notti c , Jose Miguel Azañón c , Oriol Montserrat d , Gerardo Herrera b , Francisca Fernández-Chacón a , Tomás Peinado a , Jorge Pedro Galve c , Vicente Pérez-Peña c , Jose A. Fernández-Merodo b , Jorge Jiménez a a Geological Survey of Spain (IGME), Urb. Alcázar del Genil, 4-Edif. Bajo, 18006 Granada, Spain b Geohazards InSAR Laboratory and Modelling Group, Geohazards Unit, Geological Survey of Spain (IGME), Spain c Department of Geodynamics, University of Granada, Avd. Fuentenueva s/n, 18071 Granada, Spain d Centre Tecnològic de Telecomunicacions de Catalunya, Parc Mediterrani de la Tecnologia (PMT)-Building B4, Av. Carl Friedrich Gauss 7, 08860-Castelldefels, Spain article info Article history: Received 23 February 2017 Received in revised form 14 June 2017 Accepted 26 July 2017 Available online 28 July 2017 Keywords: PSI monitoring Land subsidence Detrital aquifer Clay content Management Sentinel-1 Spain abstract This work integrates detailed geological and hydrogeological information with PSI data to obtain a better understanding of subsidence processes detected in the detrital aquifer of the Vega de Granada (SE Spain) during the past 13 years. Ground motion was monitored by exploiting SAR images from the ENVISAT (2003–2009), Cosmo-SkyMed (2011–2014) and Sentinel-1A (2015–2016) satellites. PSInSAR results show an inelastic deformation in the aquifer and small land surface displacements (up to 55 mm). The most widespread land subsidence is detected during the ENVISAT period (2003–2009), which coincided with a long, dry period in the region. The highest displacement rates recorded during this period (up to 10 mm/ yr) were detected in the central part of the aquifer, where many villages are located. For this period, there is a good correlation between groundwater level depletion and the augmentation of the average subsi- dence velocity and slight hydraulic head changes (<2 m) have a rapid ground motion response. The Cosmo-SkyMed period (2011–2014) coincided with a rainy period, and the land subsidence is only con- centrated in some points. Rates of average subsidence up to 11.5 mm/yr are obtained for this period and are anthropogenic in origin, being related to earthmoving works. During the Sentinel-1A monitoring per- iod (2015–2016) most of the region showed no deformation, except for some points of unknown origin in the NE sector. A general conclusion is that there is a clear lithological control in the spatial distribution of ground subsidence; all the subsiding areas detected are located where a higher clay content was identi- fied. Although the SE sector of the aquifer had more intense groundwater exploitation, no land subsi- dence processes were detected, as coarse-grained sediments predominate in the substratum. This research will contribute to the drawing-up of a management plan for the sustainable use of this strategic aquifer, taking into account critical levels of groundwater depletion to avoid land subsidence in the areas identified as vulnerable. The European Space Agency satellite Sentinel-1A could be an effective decision- making tool in the near future. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction In many agricultural regions worldwide, prolonged groundwa- ter exploitation has caused land subsidence related to falling groundwater levels. During recent decades, numerous cases of land subsidence related to intensive agricultural practices have been reported in many developed aquifer systems (Motagh et al., 2008; Amelung et al., 1999; Calderhead et al., 2011; Galloway and Burbey, 2011; Papadaki, 2014; Zhu et al., 2015; Farr and Liu, 2015; Faunt et al., 2016). In Spain, the most arid country in Europe, http://dx.doi.org/10.1016/j.jhydrol.2017.07.056 0022-1694/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author at: Geological Survey of Spain, Research Centre in Granada, Urb. Alcázar del Genil, 4-Edif Bajo, 18006 Granada, Spain. E-mail addresses: rm.mateos@igme.es (R.M. Mateos), p.ezquerro@igme.es (P. Ezquerro), ja.luque@igme.es (J.A. Luque-Espinar), m.bejar@igme.es (M. Béjar- Pizarro), davidenotti@gmail.com (D. Notti), jazanon@ugr.es (J.M. Azañón), oriol. monserrat@cttc.cat (O. Montserrat), g.herrera@igme.es (G. Herrera), paquifcha- con@gmail.com (F. Fernández-Chacón), t.peinado@igme.es (T. Peinado), jpgal- ve@ugr.es (J.P. Galve), geolovic@gmail.com (V. Pérez-Peña), jose.fernandez@igme. es (J.A. Fernández-Merodo), j.jimenez@igme.es (J. Jiménez). Journal of Hydrology 553 (2017) 71–87 Contents lists available at ScienceDirect Journal of Hydrology journal homepage: www.elsevier.com/locate/jhydrol