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The study of land subsidence has recently been expanded due to its increased occurrence and magnitude worldwide. This paper develops and applies an optimal control model of groundwater extractions under conditions of land subsidence. We include, in a traditional groundwater management model, two types of negative externalities associated with land subsidence: damage to infrastructure and to economic activities, and the loss of aquifer storage capacity. Using a two-stage optimal control method, characterized by two sub-problems corresponding to the phase before and after the occurrence of subsidence, we find the economically sustainable paths of groundwater extractions and water table levels under the existence of land subsidence impacts. The theoretical results indicate that the presence of land subsidence dictates the optimal paths of groundwater withdrawals and water table levels. The model has been applied to the Alto Guadalentín over-exploited aquifer system in the Segura River Basin of Spain. The empirical outcomes indicate that by following the optimal paths, groundwater extractions should be curtailing to avoid reaching the critical water level at which subsidence takes place. Results suggest that regional net present value of welfare over the planning period, under the two land subsidence scenarios, is reduced by nearly 1–5%, compared to the no land subsidence scenario. Furthermore, under subsidence, even with relatively small impacts of both types of externalities, groundwater optimal extractions are kept at levels that avoid these externalities. These outcomes clearly call for government intervention in order to reduce groundwater withdrawals in aquifers with propensity to face undesirable subsidence effects.

[EN] Groundwater is a vitally important resource for humans. One of the main problems derived from the overexploitation of aquifers is land subsidence, which in turn carries other associated natural risks. Advanced Differential satellite radar interferometry (A-DInSAR) techniques provide valuable information on the surface displacements of the ground, which serve to characterize both the deformational behaviour of the aquifer and its properties. RESERVOIR is a research project belonging to the European PRIMA programme, whose main objective is to design sustainable groundwater management models through the study of four areas of the Mediterranean subjected to water stress. One of the main tasks of the project is the integration of the terrain deformation data obtained with satellite remote sensing techniques in the hydrogeological and geomechanical models of the aquifers. In the present work, a first evaluation of the deformation of the ground in each study area is carried out using the tools contained in the Geohazards Exploitation Platform (GEP). This is a service financed by the European Space Agency (ESA) that allows processing directly on its server, without need to store data or applications locally., [ES] Las aguas subterráneas son un recurso de vital importancia para el ser humano. Una de las principales problemáticas derivadas de la sobreexplotación de acuíferos es la subsidencia del terreno, que a su vez lleva asociados otros riesgos naturales. Las técnicas avanzadas de interferometría radar diferencial de satélite (A-DInSAR) aportan información muy valiosa sobre los desplazamientos superficiales del terreno, que sirven para caracterizar tanto el comportamiento geomecánico del acuífero como sus propiedades. RESERVOIR es un proyecto de investigación perteneciente al programa europeo PRIMA, cuyo principal objetivo es diseñar modelos sostenibles de gestión de aguas subterráneas mediante el estudio de cuatro zonas del Mediterráneo sometidas a estrés hídrico. Una de las principales tareas del proyecto es la integración de los datos de deformación del terreno obtenidos con técnicas de teledetección por satélite en los modelos hidrogeológicos y geomecánicos de los acuíferos. En el presente trabajo se realiza una primera evaluación de la deformación del terreno en cada zona de estudio utilizando las herramientas contenidas en la Geohazards Exploitation Platform (GEP). Este servicio financiado por la Agencia Espacial Europea (ESA) permite realizar procesados directamente en su servidor, sin necesidad de almacenar datos ni aplicaciones en local.

[EN] Groundwater is one of the most important hydric resources of the Spain territory. Nevertheless, heavy groundwater withdrawal generates severe consequences, being land subsidence one of them. The Interferometric Synthetic Aperture Radar (InSAR) technique have been recently exploited to detect and monitor aquifer related deformations. In the present work, relationship between piezometric levels drawdowns and land subsidence has been studied for the higher withdrawals areas within Almonte-Marismas aquifer system (which holds the Doñana Natural Space). Four datasets of radar satellite images, obtained from Sentine-1 satellite, have been processed using the InSAR technique in the period 2014 - 2020. Results show that in some of these areas, like those surrounding El Rocío and Matalascañas villages, the correlation between these two variables is high., [ES] El agua subterránea es uno de los recursos hídricos más importantes en el territorio español. La gran cantidad de agua que se retira de ellos puede tener graves consecuencias, entre las que destaca, en algunos acuíferos, la subsidencia del terreno. La técnica de interferometría radar (InSAR), ha sido desarrollada en las últimas décadas para detectar y monitorear las deformaciones relacionadas con los acuíferos. En este trabajo se estudia la posible relación existente entre la variación de los niveles piezométricos y el movimiento del terreno en zonas con grandes extracciones del acuífero Almonte-Marismas (sobre el que se ubica el Espacio Natural de Doñana). Para ello, se han analizado los datos de deformación del terreno obtenidos del satélite Sentinel-1 en el periodo 2014-2020 Los resultados muestran que, en alguna de estas zonas, como las cercanas a las poblaciones de El Rocío y Matalascañas, la correlación entre ambas variables es alta.

In the last two decades, advanced differential interferometric synthetic aperture radar (A-DInSAR) techniques have experienced significant developments, which are mainly related to (i) the progress of satellite SAR data acquired by new missions, such as COSMO-SkyMed and ESA’s Sentinel-1 constellations; and (ii) the development of novel processing algorithms. The improvements in A-DInSAR ground deformation time series need appropriate methodologies to analyse extremely large datasets which consist of huge amounts of measuring points and associated deformation histories with high temporal resolution. This work demonstrates A-DInSAR time series exploitation as valuable tool to support different problems in engineering geology such as detection, characterization and modelling of land subsidence mechanisms. The capabilities and suitability of A-DInSAR time series from an end-user point of view are presented and discussed through the analysis carried out for three test sites in Europe: the Oltrepo Pavese (Po Plain in Italy), the Alto Guadalentín (Spain) and the London Basin (United Kingdom). Principal component analysis has been performed for the datasets available for the three case histories, in order to extract the great potential contained in the A-DInSAR time series

Big cities improvement usually requires the construction of large underground infrastructures, in order to ensure proper communication and optimize urban use. Monitoring ground subsidences is therefore one of the main challenges in changing urban environments. The "Madrid Río" project (2003-2008) is an effort to reclaim the riverfront land and improve the busy M-30 beltway that involved the construction of 7.93 km of tunnels underneath the southern center of Madrid City. This paper presents a remote-sensing approach to monitor ground subsidences induced by tunneling excavation. The Persistent Scatterers Interferometry technique (PSI) was used to estimate subsidence and displacement time series from Synthetic Aperture Radar images, acquired between August 2003 and April 2008 from ENVISAT. Remote sensed results were compared to traditional extensometric measures, fitting adequately for selected sectors. Spatial analysis of displacements allowed evaluating impacts of tunneling on surrounding buildings and facilities, highlighting critical areas. The availability of a spatial distribution of displacements in a time series allowed analyzing longitudinal, cross-sectional and temporal dynamics. The main limitations during this work were the heterogeneous spatial distribution of Persistent Scatterers, the absence of measurement points in work areas, the threshold for velocity detection and low temporal resolution of ENVISAT images. Nevertheless, these limitations of DInSAR for monitoring infrastructures are overcome by actual satellites, being a complementary technique with an exceptional added value and temporal analysis capability., Mejorar las grandes ciudades requiere la construcción de importantes infraestructuras subterráneas para asegurar la movilidad y la optimización del uso urbano del suelo. La monitorización es uno de los grandes retos del mega-proyecto “Madrid Río” (2003-2008). El soterramiento de la autovía de circunvalación M-30, que discurre junto al río Manzanares, requirió la ejecución de dos túneles de 7,93 km en la zona sureste de la ciudad. Este artículo presenta los resultados del estudio de las subsidencias que dichas obras indujeron en el terreno, mediante el uso de la técnica DInSAR (Interferometría diferencial con radar de apertura sintética). Esta técnica fue aplicada a las imágenes radar ENVISAT tomadas entre agosto de 2003 y abril de 2008, utilizando la técnica PSI (Persistent Scatterers Interferometry). Los resultados obtenidos se compararon con las medidas de los extensómetros tradicionales instalados en la zona, llegando a la conclusión de que esta técnica produce unos buenos resultados y es complementaria de cualquier otra tradicional. El análisis espacial de los desplazamientos permitió evaluar el impacto de la ejecución de los túneles en los edificios e infraestructuras, destacando las áreas críticas. La disponibilidad de la distribución de los desplazamientos en el tiempo permitió realizar un análisis longitudinal, transversal y dinámico-temporal. Las principales limitaciones que se encontraron durante el desarrollo de este trabajo fueron la distribución heterogénea de los PSI, la ausencia de puntos de control en la zona de trabajo, el umbral para detectar la velocidad de variación y la baja resolución temporal de las imágenes ENVISAT. A pesar de estas limitaciones esta técnica complementaria ha demostrado ser útil para monitorizar movimientos de estructuras con un excepcional valor añadido y capacidad de análisis temporal.