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[ES] Este manual, dirigido tanto a usuarios finales de productos obtenidos a partir de datos InSAR, como a aquellos sin experiencia en la explotación de este tipo de datos, tiene como objetivo ser una introducción a las técnicas InSAR. Se presenta con un lenguaje sencillo respaldado por explicaciones visuales. El documento se estructura de la manera que se describe a continuación. El Capítulo 2 ofrece una aproximación a los fundamentos de la técnica InSAR, describiendo los sensores SAR y las particularidades de las imágenes SAR. También se explican de manera simplificada las técnicas de procesado InSAR, haciendo especial hincapié en las precauciones para interpretar correctamente los resultados. En el Capítulo 3 se revisan los servicios públicos que proporcionan datos InSAR ya procesados, con un enfoque específico en el servicio de Copernicus European Ground Motion Service (EGMS). El Capítulo 4 recopila varios ejemplos de aplicación y explotación de los datos InSAR, todos ellos extraídos del EGMS abarcando diferentes fenómenos que ocasionan movimientos del terreno. Finalmente, el Capítulo 5 presenta una serie de ejemplos que reflejan las limitaciones y particularidades de la técnica InSAR. Asimismo, este manual se complementa con tres anexos que incluyen un glosario de términos, recursos de aprendizaje y una lista del software de procesado SAR libre más utilizado en la comunidad científica.

[EN] In this study, we utilized three different indices to assess drought conditions in the Doñana National Park (DNP) located in southern Spain. These indices included the Standardized Precipitation Index (SPI), which is based on precipitation statistics, the Standardized Precipitation Evapotranspiration Index (SPEI), which incorporates both precipitation and air temperature data, and the Groundwater Recharge Drought Index (GRDI), a newly developed index specifically designed to evaluate groundwater drought. The analysis covered the time period from 1985 to 2015, and future projections were made for the years 2030–2060 under different climate scenarios (RCP 4.5 and RCP 8.5). Our findings revealed a significant decrease in total precipitation of approximately 13–14% compared to historical records (1985–2015). Moreover, severely to extremely wet periods exhibited a reduction ranging from 25% to 38%. A key contribution of this study is the application of the GRDI index, which allowed us to assess groundwater recharge rates. We observed a decline in the simulated mean recharge rates during the 21st century when compared to the historical period spanning from 1950 to 2009. This decline can be attributed to increased evapotranspiration. The results of this research provide valuable insights for the Spanish water resources administration. The observed reductions in precipitation and groundwater recharge rates emphasize the need for appropriate mitigation measures. The findings will aid the administration in formulating an integrated water resources management strategy in the Doñana National Park and its surrounding basin. By understanding the projected changes in drought conditions, the administration can make informed decisions to ensure sustainable water resource management in the region.

[EN] This 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.

[EN] Direct interpolation of groundwater levels often leads to contour maps which are hydrogeological inconsistent since numerical algorithms do not consider changes in flowline patterns caused by hydrogeological heterogeneities and aquifer boundary conditions. In the present work, this issue is assessed by conducting a geostatistical analysis based on Gaussian process method, using space-time groundwater level observations, to generate reliable spatial maps of groundwater level variability and to identify groundwater level patterns over the island of Crete, Greece. Besides, two innovative tools are employed in the process: the Manhattan distance metric to obtain spatial correlation where faults are present in the aquifer and the spatiotemporal Spartan covariance function to obtain spatiotemporal interdependence. The results show significant prediction improvement over convectional geostatistical methods. Useful information is obtained from the delivered map notifying areas under high risk of groundwater resources shortage. The developed approach could be applied to other areas with analogous hydrogeological properties. It will be especially valuable in semi-arid areas prone to droughts, where groundwater represents the main source of water.

[EN] Recent studies highlight the fragility of the Mediterranean basin against climate stresses and the difficulties of managing the sustainable development of groundwater resources. In this work, the main issues related to groundwater management have been identified from the stakeholder’s perspective in the following four representative water-stressed Mediterranean areas: the coastal aquifer of Comacchio (Italy), the Alto Guadalentín aquifer (Spain), the alluvial aquifer of the Gediz River basin (Turkey), and the Azraq aquifer (Azraq Wetland Reserve, Jordan). This has been achieved by designing a methodology to involve and engage a representative set of stakeholders, including a questionnaire to learn their point of view concerning the current management of aquifer systems and their experience with the already available tools for groundwater resource management, such as monitoring networks and numerical models. The outcome of the survey has allowed us to identify both particular and common challenges among the four study sites and among the various groups of stakeholders. This information provides valuable insights to improve the transfer of scientific knowledge from the research centers to the authorities managing the groundwater resources and it will help to plan more effective research activities on aquifer management. The proposed methodology could be applied in other aquifers facing similar problems.

[EN] Within the framework of the IGME-CSIC Department of Geological Hazards and Climate Change, the OBTIER research group was created in July 2021 and currently has 22 members, including scientific and technical staff, as well as young people with contracts linked to competitive national and international research projects. The main objective of the group is to provide society with scientific information, methods, tools and solutions to mitigate the impact of geohazards and the effects of Climate Change. OBTIER is currently leading 6 competitive projects (4 European and 2 national), as well as several projects in agreement with other national and international administrations. It is an active member of the EuroGeoSurveys Earth Observation Expert Group and the ASGMI Geological Hazards Group. OBTIER offers society a wide range of capabilities on: earthquakes, tsunamis, landslides, land subsidence, volcanic eruptions, droughts and floods. In 2021, the group published an article in Science entitled: Mapping the global threat of land subsidence with significant media coverage around the world.

Alaşehir-Sarıgöl sub-basin (ASSB) in Türkiye faces severe water stress mainly due to intensive agricultural irrigation. This has led to declining groundwater levels, aquifer compaction, and subsequent land subsidence. This study aims to evaluate the roles of tectonic activity and groundwater withdrawal in land-subsidence and investigate additional factors like faults and soft soil thickness. The P-SBAS algorithm was applied, using 98 and 123 Sentinel-1 SAR images in ascending and descending orbits, respectively, from 2016 to 2020. Independent Component Analysis separated long-term displacements from seasonal variations in the InSAR time series data. InSAR analysis showed displacement rates up to −6.40 cm/year. Results reveal a direct correlation between InSAR displacement and soft soil thickness, highlighting aquitard layer compaction due to groundwater withdrawal and piezometric head depletion as the primary causes of land subsidence. It was not possible to disentangle the multi-year displacements with different rates, i.e., to isolate the displacements caused by tectonic activity from displacements due to the soft soil compaction induced by groundwater withdrawal. Nonetheless, the analysis identified two spatiotemporal displacement trends: one linked to long-term, linear plastic compaction of the aquitard due to groundwater withdrawal and the other involving long-term displacements with seasonal rebounds caused by yearly water level fluctuations.

El objetivo de este trabajo es investigar las principales características de las sequías históricas y futuras en el acuífero del Alto Guadalentín (Lorca, Murcia) durante el periodo de 1950 a 2021 y 2030 a 2059. La mayor parte de la población de esta región depende de la agricultura como actividad socioeconómica y ha presentado históricamente periodos de sequía de marcada intensidad. Para conseguir dicho objetivo se han utilizado tres índices de sequía: Índice de Precipitación Estandarizado (SPI, por sus siglas en inglés), Índice de Precipitación y Evaporación Estandarizado (SPEI, de sus siglas en inglés) y índice del efecto de las sequías en la recarga del agua subterránea (GRDI, de sus siglas en inglés). Dado que las sequías normalmente tardan una estación o más en desarrollarse, se utiliza un periodo de 9 meses como indicador de sequía más relevante de acuerdo con el Plan Especial de Sequía de la Demarcación del Segura (PES, 2018). El estudio se ha realizado a partir de los datos meteorológicos de la estación 7209 (Lorca), con datos de precipitación y temperatura de la Agencia Estatal de Meteorología (AEMET), y la estimación de la recarga subterránea del acuífero del Alto Guadalentín. Los resultados de las series históricas observadas en escala de 9 meses muestran una buena relación entre el SPI9 y el SPEI9, mientras que el SPI9 y el SPEI9 presenta una evolución temporal muy diferente a la del GRDI9. En la zona de estudio el periodo de sequía extrema más intenso para el SPI9 se da entre enero 2014 y febrero 2015, mientras que para el SPEI9 se da entre mayo 2015 y noviembre 2016. A lo largo de la serie histórica, el GRDI9 presenta periodos húmedos intensos y periodos de sequía moderada. El umbral de intensidad máxima para el GRDI9 es el mismo en varios meses, esto se refleja en que hay muchos años en los que la recarga alcanza un valor mínimo o nulo. En las series futuras para los escenarios RCP 4.5 y RCP 8.5, el SPI9 y SPEI9 muestran una correlación moderada entre

Acreman et al. (2022) reviewed evidence for ecological damage to the Doñana wetlands (UNESCO World Heritage Site [WHS] and Ramsar site), Spain, associated with intensification of groundwater use, particularly for agriculture. Acreman et al. presented a multistep methodology for evidence-based risk assessment that involves identification of conservation issues, and a systematic review of scientific evidence for ecological damage and its causes. However, they involved few local scientists, used a questionable methodology in stakeholder selection and involvement, used a flawed conceptual framework, and an incomplete literature review. We propose improvements to their methodology. They overlooked or misinterpreted key evidence, and underestimated the impacts that abstraction for irrigation for red fruits (mainly strawberries), rice and other crops has had on Doñana and its biodiversity. They reported groundwater level depletion of up to 10 m in the deep aquifer, but wrongly concluded that there is no evidence for impacts on the natural marsh ecosystem, the dune ponds or the ecotone. Groundwater drawdowns are actually up to 20 m, and have inverted the formerly ascending vertical hydraulic gradient in discharge areas. Phreatic levels have been lowered from 0.5 to 2 m in some areas. Groundwater abstraction has caused multiple ecological impacts to temporary ponds and marshes in the WHS, as well as to terrestrial vegetation, and should be urgently reduced. Furthermore, Acreman et al. focused on groundwater quantity while overlooking the importance of severe impacts on quality of both surface and groundwater, intimately connected to the use of agrochemicals for irrigated crops.

[EN] The accurate estimation of flood risk depends on, among other factors, a correct delineation of the floodable area and its associated hydrodynamic parameters. This characterization becomes fundamental in the flood hazard analyses that are carried out in urban areas. To achieve this objective, it is necessary to have a correct characterization of the topography, both inside the riverbed (bathymetry) and outside it. Outside the riverbed, the LiDAR data led to an important improvement, but not so inside the riverbed. To overcome these deficiencies, different models with simplified bathymetry or modified inflow hydrographs were used. Here, we present a model that is based upon the calibration of the Manning’s n value inside the riverbed. The use of abnormally low Manning’s n values made it possible to reproduce both the extent of the flooded area and the flow depth value within it (outside the riverbed) in an acceptable manner. The reduction in the average error in the flow depth value from 50–75 cm (models without bathymetry and “natural” Manning’s n values) to only about 10 cm (models without bathymetry and “calibrated” Manning’s n values), was propagated towards a reduction in the estimation of direct flood damage, which fell from 25–30% to about 5%.

Recent studies highlight the fragility of the Mediterranean basin against climate stresses and the difficulties of managing the sustainable development of groundwater resources. In this work, the main issues related to groundwater management have been identified from the stakeholder’s perspective in the following four representative water-stressed Mediterranean areas: the coastal aquifer of Comacchio (Italy), the Alto Guadalentín aquifer (Spain), the alluvial aquifer of the Gediz River basin (Turkey), and the Azraq aquifer (Azraq Wetland Reserve, Jordan). This has been achieved by designing a methodology to involve and engage a representative set of stakeholders, including a questionnaire to learn their point of view concerning the current management of aquifer systems and their experience with the already available tools for groundwater resource management, such as monitoring networks and numerical models. The outcome of the survey has allowed us to identify both particular and common challenges among the four study sites and among the various groups of stakeholders. This information provides valuable insights to improve the transfer of scientific knowledge from the research centers to the authorities managing the groundwater resources and it will help to plan more effective research activities on aquifer management. The proposed methodology could be applied in other aquifers facing similar problems.

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.

Estudios recientes ponen en manifiesto la vulnerabilidad de las cuencas del mediterráneo y las limitaciones de los actuales organismos gestores para mantener un desarrollo sostenible de los recursos hídricos subterráneos. Con el fin de abordar esta problemática, en este trabajo se han investigado los principales inconvenientes relacionados con la gestión de agua subterránea, teniendo en cuenta la perspectiva de las partes implicadas mediante la realización de encuestas. Para llevar a cabo esta investigación, se han seleccionado cuatro cuencas mediterráneas representativas que se encuentran actualmente bajo estrés hídrico: el acuífero costero de Comacchio (Italia), el acuífero del Alto Guadalentín (España), el acuífero aluvial de la cuenca del río Gediz (Turquía), y el acuífero de Azraq (Reserva de humedales de Azraq, Jordania). Los resultados revelan el punto de vista de las partes implicadas, relacionado con la gestión actual de los sistemas acuíferos y su experiencia con las herramientas disponibles para la gestión de las aguas subterráneas, como lo son las redes de monitoreo y los modelos numéricos. El análisis realizado y ha permitido identificar algunas peculiaridades y retos en común en las cuatro áreas de estudio. Uno de estos grandes desafíos es la falta de referencias para evaluar la adecuación de la red de monitoreo en relación con la frecuencia de muestreo y la distribución espacial. La metodología aquí propuesta junto con los resultados será útil para valorar la percepción de las partes implicadas en otros acuíferos que presenten una situación similar.

Climate change could impair riparian vegetation dynamics through more intense and frequent climatic extreme events such as flash flooding. However, it is still poorly known how climate warming can also impair vegetation recovery through control on cellular traits after such extreme events. Here, we analyze how Mediterranean riparian tree species (namely Alnus glutinosa, Fraxinus angustifolia, and Salix atrocinerea) recover after wounds caused by intense floods using 239 X-ray computed tomography (XRCT) images taken on 30 trees. The XRCT imagery allowed to characterize wounds-related macroscopic parameters in different sections along the stems in three dimensions. Then, we quantified the annual wound closure rates by dating dendrochronologically each wound and measuring the annual overgrowth on the wounded area. Finally, we used linear mixed models to investigate how wound closure rates are affected by climate conditions. Our results show that wound closure varies between species. A. glutinosa and F. angustifolia presented higher wound recovery rates than S. atrocinerea. However, the statistical analyses suggest that F. angustifolia and S. atrocinerea tend to recover much less(more) during drier(wetter) years than A. glutinosa. Our results suggest that A. glutinosa could be more stressed under climate change in the Mediterranean region, where the cooccurrence of drier conditions with extreme flood events may increase.