Imaging land subsidence in the Guadalentín River Basin (SE Spain) using Advanced Differential SAR Interferometry

Aquifer overexploitation can lead to the irreversible loss of groundwater storage caused by the compaction or consolidation of unconsolidated fine-grained sediments resulting in land subsidence. Advanced Differential SAR Interferometry (A-DINSAR) is particularly efficient to monitor progressive ground movements, making it an appropriate method to study depleting aquifers undergoing overexploitation and land subsidence. The Guadalentín River Basin (Murcia, Spain) is a widely recognized subsiding area that exhibits the highest rates of groundwater-related land subsidence recorded in Europe (>10 cm/yr). The basin covers an extension of more than 500 km2 and is underlain by an overexploited aquifer-system formed by two contiguous hydraulically connected units (Alto Guadalentín and Bajo Guadalentín). Although during the last years the piezometric levels have partially stabilized, the ongoing aquifer-system deformation is evident and significant, as revealed by the A-DInSAR analysis presented. In this work, we submit the first vertical and horizontal (E-W) decomposition results of the LOS velocity and displacement time series of the whole Guadalentín Basin obtained from two datasets of Sentinel-1 SAR acquisitions in ascending and descending modes. The images cover the period from 2015 to 2021 and they were processed using the Parallel Small BAseline Subset (P-SBAS) implemented by CNRIREA in the Geohazards Exploitation Platform (GEP) on-demand web tool, which is funded by the European Space Agency. The output ascending and descending measurement points of P-SBAS lie on the same regular grid, which is particularly suited for the geometrical decomposition. Time series displacements are compared to a permanent GNSS station located in the Bajo Guadalentín basin.This study has received funding in framework of the RESERVOIR project (Sustainable groundwater RESources managEment by integrating eaRth observation deriVed monitoring and flOw modelIng Results), funded by the Partnership for Research and Innovation in the Mediterranean Area (PRIMA) programme supported by the European Union (Grant Agreement 1924; https://reservoir-prima.org/). The study has also been supported by the Grant FPU19/03929 (funded by MCIN/AEI/10.13039/501100011033 and by “FSE invests in your future”); the Project CGL2017-83931-C3-3-P (funded by MCIN/ AEI/10.13039/501100011033 and by “ERDF A way of making Europe”); the ESA-MOST China DRAGON-5 Project (ref. 59339) and the SARAI Project PID2020-116540RB-C22 (funded by MCIN/AEI/10.13039/501100011033). Copernicus Sentinel-1 IW SAR data were provided and processed in ESA’s Geohazards Exploitation Platform (GEP), in the framework of the GEP Early Adopters Programme

Análisis preliminar tipológico, temporal y espacial de los registros publicados sobre paleoinundaciones en España

[EN] Palaeofloods are past flood events recorded in natural archives of different typologies: geologicalgeomorphological (sediments, marks and forms), hydrological-glaciological (water, snow or ice) and biologicalbotanical (dendrochronology and lichenometry). Over the last 25 years, various projects have been undertaken to gather regional palaeoflood data, such as Paleotagus (1997-1999) or SPHERE-GIS (1999-2003). However, to date there is no a national palaeoflood database including palaeohydrologic data. In this context, this research introduces PaleoRiada, a palaeoflood database covering all of Spain and including records of all types of palaeofloods published in the scientifictechnical literature. This database is composed of alphanumeric attributes stored in 7 Access tables that are related (N:M) to two vector files. PaleoRiada contains information from over 70 journal articles, books, and technical reports, which has been used to document more than a hundred palaeoflood events. From the typological, temporal and spatial analyses using query and statistics tools, the following results have been obtained: (i) most of the palaeoflood records correspond to geological typologies of fluvial detrital deposits (67%), followed by botanical biological typologies of dendrogeomorphological evidence such as trees scars (28%); ii) the temporal distribution of paleofloods in the natural record is heterogeneous, with a predominance of events in the last three centuries, although also between 8500-5000 BC (Holocene); iii) the spatial distribution of palaeofloods shows concentrations in certain locations (Puente del Arzobispo, Rambla Mayor, Valsaín... ), due both to the ideal conditions of conservation and to the number of published studies. It is evident that there is a considerable number of palaeoflood records, but it would be appropriate to increase efforts in analyzing more typologies and searching for evidence in those sectors of Spain with scarce records.[ES] Las paleoinundaciones son eventos de inundación pretéritos cuya ocurrencia queda registrada en elementos naturales de diferentes tipologías: geológico-geomorfológicos (sedimentos, marcas y formas), hidrológico-glaciológicos (agua, nieve o hielo) y biológicos-botánicos (dendrocronología y liquenometría). En España, durante los últimos 25 años,se han dedicado considerables esfuerzos a la recopilación de registros de paleoinundaciones en diversas bases de datos regionales, entre las que destacan Paleotagus (1997-1999) o SPHERE-GIS (1999-2003). No obstante, a día de hoy, no existe ninguna base de datos que aúne a nivel nacional los registros recogidos en la literatura científico-técnica, incluyendo todas las tipologías de paleoinundaciones y sus datos paleohidrológicos. En este contexto, este trabajo presenta PaleoRiada, una base de datos georreferenciada formada por atributos alfanuméricos, almacenados en siete tablas de Access, que se relaciona (N:M) con dos ficheros vectoriales (de puntos y de polígonos). La información utilizada para elaborar la base de datos, que contiene más de un centenar de registros de paleoinundación, se recopiló a partir de aproximadamente 70 artículos de revistas, libros e informes técnicos. El análisis tipológico, temporal y espacial de los resultados, realizado utilizando herramientas estadísticas y de búsqueda, arrojó los siguientes resultados: i) la mayor parte de los registros de paleoinundaciones corresponden a tipologías geológicas de depósitos detríticos fluviales (67%), seguidas por tipologías biológico-botánicas con evidencias dendrogeomorfológicas como descortezados en árboles (28%); ii) la distribución temporal de las paleoinundaciones en el registro natural es heterogénea, con un predominio de eventos en los últimos tres siglos, aunque también entre los años 5000-8500 BC (Holoceno); iii) la distribución espacial de las paleoinundaciones muestra una concentración preferente de los eventos en determinadas ubicaciones (Puente del Arzobispo, Rambla Mayor, Valsaín…), motivado tanto por las condiciones idóneas de conservación, como por el número de estudios publicados. Es posible concluir que, aunque el número de registros es considerable, sería oportuno dedicar esfuerzos adicionales al análisis de otras tipologías y a la búsqueda de nuevas evidencias en zonas de España donde el número de registros es limitado.Peer reviewe

Analysis of SAR-derived products to support emergency management during volcanic crisis: La Palma case study

International audienceThis paper analyses the performance of SAR-based results to support emergency management operations during the volcanic crisis of La Palma island. Tajogaite eruption began on September 19th 2021 affecting a high populated area and the surrounding farmland, used for different agricultural purposes. SAR datasets obtained from Sentinel-1, COSMO-SkyMED, PAZ-TerraSAR-X and Capella satellites, were processed to calculate amplitude, coherence and differential interferograms. These results have permitted to map the morphology of the volcanic cone, the evolution of lava flows and the regional displacements. The comparison of the results obtained with the different satellites has been useful to understand their performance during an emergency scenario triggered by a volcanic eruption. COSMO-SkyMED has provided the most useful information for the analysis of the cone morphology and the lava flows. Sentinel-1 showed the best performance for regional displacements monitoring, whereas PAZ results was the second best option for all the retrieved products