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Deltas are highly valuable environmental systems, ensuring various livelihoods through their ecosystem services. However, human impact and climate change stressors are impacting deltas immensely. Consequently, many deltas, including Ghana's Volta Delta, are facing increasing risks, especially as hazards are increasing in magnitude and impacting coastal livelihoods. To provide a better understanding of coastal hazards in the Volta Delta, this study assessed the Delta's subsidence regime and its consequences for the potential impact of sea-level rise (SLR). Using the Interferometric Synthetic Aperture Radar (InSAR) technique and Global Navigation Satellite System (GNSS) surveys, vertical land motion (VLM) was documented. Interferograms of Sentinel-1 data from 2016 to 2020 indicated subsiding rates of up to −9.2 mm/yr. By combining local VLM information with recent SLR projections and elevation data, this study updates those projections and provides local assessments of potential Relative SLR (rSLR) impact. According to these locally improved scenarios, up to ∼45 % of the Delta will fall below local sea level by 2100, of which close to 10 % is explained by the integration of local VLM data alone. Depending on the climate change scenarios used, land subsidence will increase the deltaic area at risk by 4.31 % (96.27 km2) to 10.18 % (227.64 km2) and consequently exacerbate its exposure to coastal inundation. To avert the projections, the study recommends robust monitoring regimes; alternative freshwater sources to groundwater; reduced sediment trapping and river obstruction; and the need to stall ongoing oil and gas prospecting and subsequent extraction in the Voltain Basin.

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.

Coastal areas are home to a myriad of essential services. However, population growth and climate change along with their cascading impacts have had profound impacts on their topography and evolution. Consequently, many coastal regions, of which Ghana's coast is no exception, are incessantly plagued with hazards that are increasing in magnitude and frequency. Predominantly through the recurrence of floods and erosion, Ghana's coast is becoming increasingly susceptible to huge socio-economic implications considering its environment-dependent economy. Therefore, attempts have been made to assess Ghana's coastal vulnerability to comprehend the complexities underpinning the occurrence of these hazards. However, most studies attribute the recurrence of floods and erosion to global sea-level rise, but coastal land subsidence could also have significant impacts. Indeed, land subsidence is a major component of relative sea-level rise (rSLR) in many coastal cities worldwide. Drawing on extant literature, this scoping study provides an overview and evaluation of three thematic areas—SLR, subsidence and coastal vulnerability—within the Ghanaian context along with their existing relationships. Additionally, it seeks to also assess available knowledge and data and to identify crucial knowledge gaps which impede comprehensive risk assessment of Ghana's coast. The survey findings, however, indicate a significant understudy of the selected thematic areas albeit posing potential threats to Ghana's coast. It brought to light the absence of a ground-validated subsidence study; a non-identification of potential local subsidence drivers; a non-availability of a subsidence-infused coastal vulnerability assessment; non-existing studies on the combined effects of climate change and subsidence; and huge deficits in available data for numerical modelling of coastal subsidence. Guided by the identified knowledge and data gaps and the need to mitigate impacts, the study recommends a thorough as

Underground gas storage (UGS) is a worldwide well-established technology that is becoming even more important to cope with seasonal peaks of gas consumption due to the growing uncertainties of the energy market. Safety issues concerning the reactivation of pre-existing faults might arise if the target reservoir is located in a faulted basin, where human activities can trigger (micro-)seismicity events. In the Netherlands, it has been observed that fault activation can occur somehow "unexpectedly" after the primary production (PP), i.e., during cushion gas injection (CGI) and UGS cycles, when the stress regime should be in the unloading/reloading path. To understand the physical mechanisms responsible for such occurrences, a 3D mathematical model coupling frictional contact mechanics in faulted porous rocks with fluid flow is developed, implemented and tested. The final aim of this two-part work is to define a safe operational bandwidth for the pore pressure range for UGS activities in the faulted reservoirs of the Rotliegend formation. Part I of this work concerns the development of the mathematical and numerical model of frictional contact mechanics and flow in faulted porous rocks. A mixed discretization of the governing PDEs under frictional contact constraints along the faults is used. A slip-weakening constitutive law governing the fault macroscopic behavior is also presented. The model is tested in the setting of an ideal reservoir located in the Rotliegend formation. The analyses point out how fault reactivation during PP can lead to a stress redistribution, giving rise to a new equilibrium configuration. When the fault is reloaded in the opposite direction during the CGI and/or UGS stages, further activation events can occur even if the stress range does not exceed either the undisturbed initial value or the maximum strength ever experienced by the formation., Comment: 22 pages, 20 figures

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] 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.

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.

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.

Over the past decades coastal marshes around the world have declined dramatically. Their deterioration is controlled by scarcity of sediments, erosion and accelerated rise of relative sea-level. The feedbacks between these processes control marsh evolution and determine their long-term survivability. Aggradation of a marsh to keep pace with relative sea-level rise mainly depends on the interplay between sedimentation and autocompaction, but their interactions are severely understudied. Here we present an in-situ loading experiment applied in the Venice Lagoon, Italy, to assess long-term autocompaction, with subsurface displacements and pressure monitored during loading cycles, up to ∼40 kN applied on a ∼4 m2 surface. Two identical experiments carried out in inorganic and organic soil-dominated marshes provided unique insights on the spatio-temporal subsurface dynamics. The large differences in behavior and maximum compaction (6 vs 32 mm) underscore the crucial role of autocompaction and soil heterogeneity when predicting the fate of coastal marshes worldwide.

The awareness on the importance that land subsidence plays on coastal processes at the regional scale is increased over the last two decades, and it clearly appears that land subsidence can contribute primarily to the relative sea level rise affecting coastal zones. Jakarta is one of the cities mostly affected by the combination of sea-level rise and land subsidence. In this paper, the activities carried out in Jakarta under the umbrella of the IGCP Project 663 were presented, and the possible measures and best practices mitigating land subsidence for the research associates and potential stakeholders were provided, with which can serve as inspiration for authorities and communities facing land subsidence. Meanwhile, major achievements of IGCP 663 in Jakarta were summarized and introduced, including dissemination session, scientific session and field trips. Specifically, major advances on coastal subsidence studies regarding the effect of relative sea level rise, subsidence mapping, monitoring and simulation, as well as the support of policy making are highlighted and summarized.

Depletion of groundwater aquifers along with all of the associated quality and quantity problems which affect profitability of direct agricultural and urban users and linked groundwater-ecosystems have been recognized globally. During recent years, attention has been devoted to land subsidence-the loss of land elevation that occurs in areas with certain geological characteristics associated with aquifer exploitation. Despite the large socioeconomic impacts of land subsidence most of these effects are still not well analyzed and not properly recognized and quantified globally. In this paper we developed a land subsidence impact extent (LSIE) index that is based on 10 land subsidence attributes, and applied it to 113 sites located around the world with reported land subsidence effects. We used statistical means to map physical, human, and policy variables to the regions affected by land subsidence and quantified their impact on the index. Our main findings suggest that LSIE increases between 0.1 and 6.5% by changes in natural processes, regulatory policy interventions, and groundwater usage, while holding all other variables unchanged. Effectiveness of regulatory policy interventions varies depending on the lithology of the aquifer system, in particular its stiffness. Our findings suggest also that developing countries are more prone to land subsidence due to lower performance of their existing water governance and institutions.

Depletion of groundwater aquifers along with all of the associated quality and quantity problems which affect profitability of direct agricultural and urban users and linked groundwater-ecosystems have been recognized globally. During recent years, attention has been devoted to land subsidence-the loss of land elevation that occurs in areas with certain geological characteristics associated with aquifer exploitation. Despite the large socioeconomic impacts of land subsidence most of these effects are still not well analyzed and not properly recognized and quantified globally. In this paper we developed a land subsidence impact extent (LSIE) index that is based on 10 land subsidence attributes, and applied it to 113 sites located around the world with reported land subsidence effects. We used statistical means to map physical, human, and policy variables to the regions affected by land subsidence and quantified their impact on the index. Our main findings suggest that LSIE increases between 0.1 and 6.5% by changes in natural processes, regulatory policy interventions, and groundwater usage, while holding all other variables unchanged. Effectiveness of regulatory policy interventions varies depending on the lithology of the aquifer system, in particular its stiffness. Our findings suggest also that developing countries are more prone to land subsidence due to lower performance of their existing water governance and institutions.

Depletion of groundwater aquifers along with all of the associated quality and quantity problems which affect profitability of direct agricultural and urban users and linked groundwater-ecosystems have been recognized globally. During recent years, attention has been devoted to land subsidence—the loss of land elevation that occurs in areas with certain geological characteristics associated with aquifer exploitation. Despite the large socioeconomic impacts of land subsidence most of these effects are still not well analyzed and not properly recognized and quantified globally. In this paper we developed a land subsidence impact extent (LSIE) index that is based on 10 land subsidence attributes, and applied it to 113 sites located around the world with reported land subsidence effects. We used statistical means to map physical, human, and policy variables to the regions affected by land subsidence and quantified their impact on the index. Our main findings suggest that LSIE increases between 0.1 and 6.5% by changes in natural processes, regulatory policy interventions, and groundwater usage, while holding all other variables unchanged. Effectiveness of regulatory policy interventions vary depending on the lithology of the aquifer system, in particular its stiffness. Our findings suggest also that developing countries are more prone to land subsidence due to lower performance of their existing water governance and institutions.

Subsidence, the lowering of Earth's land surface, is a potentially destructive hazard that can be caused by a wide range of natural or anthropogenic triggers but mainly results from solid or fluid mobilization underground. Subsidence due to groundwater depletion (1) is a slow and gradual process that develops on large time scales (months to years), producing progressive loss of land elevation (centimeters to decimeters per year) typically over very large areas (tens to thousands of square kilometers) and variably affects urban and agricultural areas worldwide. Subsidence permanently reduces aquifer-system storage capacity, causes earth fissures, damages buildings and civil infrastructure, and increases flood susceptibility and risk. During the next decades, global population and economic growth will continue to increase groundwater demand and accompanying groundwater depletion (2) and, when exacerbated by droughts (3), will probably increase land subsidence occurrence and related damages or impacts. To raise awareness and inform decision-making, we evaluate potential global subsidence due to groundwater depletion, a key first step toward formulating effective land-subsidence policies that are lacking in most countries worldwide.

Depletion of groundwater aquifers along with all of the associated quality and quantity problems which affect profitability of direct agricultural and urban users and linked groundwater-ecosystems have been recognized globally. During recent years, attention has been devoted to land subsidence-the loss of land elevation that occurs in areas with certain geological characteristics associated with aquifer exploitation. Despite the large socioeconomic impacts of land subsidence most of these effects are still not well analyzed and not properly recognized and quantified globally. In this paper we developed a land subsidence impact extent (LSIE) index that is based on 10 land subsidence attributes, and applied it to 113 sites located around the world with reported land subsidence effects. We used statistical means to map physical, human, and policy variables to the regions affected by land subsidence and quantified their impact on the index. Our main findings suggest that LSIE increases between 0.1 and 6.5% by changes in natural processes, regulatory policy interventions, and groundwater usage, while holding all other variables unchanged. Effectiveness of regulatory policy interventions varies depending on the lithology of the aquifer system, in particular its stiffness. Our findings suggest also that developing countries are more prone to land subsidence due to lower performance of their existing water governance and institutions.

Depletion of groundwater aquifers along with all of the associated quality and quantity problems which affect profitability of direct agricultural and urban users and linked groundwater-ecosystems have been recognized globally. During recent years, attention has been devoted to land subsidence—the loss of land elevation that occurs in areas with certain geological characteristics associated with aquifer exploitation. Despite the large socioeconomic impacts of land subsidence most of these effects are still not well analyzed and not properly recognized and quantified globally. In this paper we developed a land subsidence impact extent (LSIE) index that is based on 10 land subsidence attributes, and applied it to 113 sites located around the world with reported land subsidence effects. We used statistical means to map physical, human, and policy variables to the regions affected by land subsidence and quantified their impact on the index. Our main findings suggest that LSIE increases between 0.1 and 6.5% by changes in natural processes, regulatory policy interventions, and groundwater usage, while holding all other variables unchanged. Effectiveness of regulatory policy interventions vary depending on the lithology of the aquifer system, in particular its stiffness. Our findings suggest also that developing countries are more prone to land subsidence due to lower performance of their existing water governance and institutions.

Subsidence, the lowering of Earth's land surface, is a potentially destructive hazard that can be caused by a wide range of natural or anthropogenic triggers but mainly results from solid or fluid mobilization underground. Subsidence due to groundwater depletion (1) is a slow and gradual process that develops on large time scales (months to years), producing progressive loss of land elevation (centimeters to decimeters per year) typically over very large areas (tens to thousands of square kilometers) and variably affects urban and agricultural areas worldwide. Subsidence permanently reduces aquifer-system storage capacity, causes earth fissures, damages buildings and civil infrastructure, and increases flood susceptibility and risk. During the next decades, global population and economic growth will continue to increase groundwater demand and accompanying groundwater depletion (2) and, when exacerbated by droughts (3), will probably increase land subsidence occurrence and related damages or impacts. To raise awareness and inform decision-making, we evaluate potential global subsidence due to groundwater depletion, a key first step toward formulating effective land-subsidence policies that are lacking in most countries worldwide.

Interpretation of land subsidence time-series to understand the evolution of the phenomenon and the existing relationships between triggers and measured displacements is a great challenge. Continuous wavelet transform (CWT) is a powerful signal processing method mainly suitable for the analysis of individual nonstationary time-series. CWT expands time-series into the time-frequency space allowing identification of localized nonstationary periodicities. Complementarily, Cross Wavelet Transform (XWT) and Wavelet Coherence (WTC) methods allow the comparison of two time-series that may be expected to be related in order to identify regions in the time-frequency domain that exhibit large common cross-power and wavelet coherence, respectively, and therefore are evocative of causality. In this work we use CWT, XWT and WTC to analyze piezometric and InSAR (interferometric synthetic aperture radar) time-series from the Tertiary aquifer of Madrid (Spain) to illustrate their capabilities for interpreting land subsidence and piezometric time-series information.

A novel methodological approach to calibrate and validate three-dimensional (3D) finite element (FE) groundwater flow and geomechanical models has been implemented using Advanced Differential Interferometric SAR (A-DInSAR) data. In particular, we show how A-DInSAR data can be effectively used to (1) constrain the model set-up in evaluating the areal influence of the wellfield and (2) characterise the aquifer system, specifically the storage coefficient values, which represents a fundamental step in managing groundwater resources. The procedure has been tested to reconstruct the surface vertical and horizontal movements caused by the Manzanares-Jarama wellfield located northwest of Madrid (Spain). The wellfield was used to supply freshwater during major droughts over the period between 1994 and 2010. Previous A-DInSAR outcomes obtained by ERS-1/2 and ENVISAT acquisitions clearly revealed the seasonality of the land displacements associated to the withdrawal and recovery cycles that characterized the wellfield development. A time-lag of about one month, which is in the order of the time span between two SAR acquisitions, between the hydraulic head changes and the displacements has been detected in this site by a wavelet analysis of A-DInSAR and piezometer time series. The negligible delay between the forcing factor and the system response and the complete subsidence recovery when piezometric head recovers supported the understanding of a minor role played by the pore pressure propagation within clay layers and the almost perfectly elastic behavior of the system (viscosity is negligible), respectively. The developed geomechanical model satisfactorily reproduces the pumping-induced deformations with a Root Mean Square Error (RMSE) between observed and simulated land displacements in the order of 0.1-0.3 mm. The results give insights about the approach benefits in deeply understanding the spatio-temporal aquifer-system response to the management of this strategic water r

Advanced Differential Interferometric Synthetic Aperture Radar (A-DInSAR) techniques and 3-D groundwater flow and geomechanical models are integrated to improve our knowledge about the Tertiary detritic aquifer of Madrid (TDAM). In particular, the attention is focused on the Manzanares-Jarama well field, located to the northwest of Madrid, which experienced five cycles of extensive groundwater withdrawal followed by natural recovery, to cope with the droughts occurred in summer 1995, 1999, 2002, 2006, and 2009. Piezometric records and A-DInSAR data acquired by ERS-1/2 and ENVISAT satellites during the periods 1992–2000 and 2002–2010, respectively, have been used to calibrate the groundwater flow and the geomechanical models. A time-lag of about one month between the hydraulic head changes and the displacements of the land surface has been detected by a joint wavelet analysis of A-DInSAR and piezometer head time series. Overall, the results show the effectiveness of the proposed integrated approach composed of A-DInSAR and 3-D geomechanical model to characterize the aquifer-system response during and after the groundwater withdrawal.

Advanced Differential Interferometric Synthetic Aperture Radar (A-DInSAR) techniques and 3-D groundwater flow and geomechanical models are integrated to improve our knowledge about the Tertiary detritic aquifer of Madrid (TDAM). In particular, the attention is focused on the Manzanares-Jarama well field, located to the northwest of Madrid, which experienced five cycles of extensive groundwater withdrawal followed by natural recovery, to cope with the droughts occurred in summer 1995, 1999, 2002, 2006, and 2009. Piezometric records and A-DInSAR data acquired by ERS-1/2 and ENVISAT satellites during the periods 1992–2000 and 2002–2010, respectively, have been used to calibrate the groundwater flow and the geomechanical models. A time-lag of about one month between the hydraulic head changes and the displacements of the land surface has been detected by a joint wavelet analysis of A-DInSAR and piezometer head time series. Overall, the results show the effectiveness of the proposed integrated approach composed of A-DInSAR and 3-D geomechanical model to characterize the aquifer-system response during and after the groundwater withdrawal.

Interpretation of land subsidence time-series to understand the evolution of the phenomenon and the existing relationships between triggers and measured displacements is a great challenge. Continuous wavelet transform (CWT) is a powerful signal processing method mainly suitable for the analysis of individual nonstationary time-series. CWT expands time-series into the time-frequency space allowing identification of localized nonstationary periodicities. Complementarily, Cross Wavelet Transform (XWT) and Wavelet Coherence (WTC) methods allow the comparison of two time-series that may be expected to be related in order to identify regions in the time-frequency domain that exhibit large common cross-power and wavelet coherence, respectively, and therefore are evocative of causality. In this work we use CWT, XWT and WTC to analyze piezometric and InSAR (interferometric synthetic aperture radar) time-series from the Tertiary aquifer of Madrid (Spain) to illustrate their capabilities for interpreting land subsidence and piezometric time-series information.

A novel methodological approach to calibrate and validate three-dimensional (3D) finite element (FE) groundwater flow and geomechanical models has been implemented using Advanced Differential Interferometric SAR (A-DInSAR) data. In particular, we show how A-DInSAR data can be effectively used to (1) constrain the model set-up in evaluating the areal influence of the wellfield and (2) characterise the aquifer system, specifically the storage coefficient values, which represents a fundamental step in managing groundwater resources. The procedure has been tested to reconstruct the surface vertical and horizontal movements caused by the Manzanares-Jarama wellfield located northwest of Madrid (Spain). The wellfield was used to supply freshwater during major droughts over the period between 1994 and 2010. Previous A-DInSAR outcomes obtained by ERS-1/2 and ENVISAT acquisitions clearly revealed the seasonality of the land displacements associated to the withdrawal and recovery cycles that characterized the wellfield development. A time-lag of about one month, which is in the order of the time span between two SAR acquisitions, between the hydraulic head changes and the displacements has been detected in this site by a wavelet analysis of A-DInSAR and piezometer time series. The negligible delay between the forcing factor and the system response and the complete subsidence recovery when piezometric head recovers supported the understanding of a minor role played by the pore pressure propagation within clay layers and the almost perfectly elastic behavior of the system (viscosity is negligible), respectively. The developed geomechanical model satisfactorily reproduces the pumping-induced deformations with a Root Mean Square Error (RMSE) between observed and simulated land displacements in the order of 0.1-0.3 mm. The results give insights about the approach benefits in deeply understanding the spatio-temporal aquifer-system response to the management of this strategic water r

Relative sea level rise (RSLR), that has been occurred along the entire coastal areas of the Northern Adriatic Sea, includes land subsidence, both natural and man-induced, and eustacy. Their combined effect has produced relative ground settlements ranging from centimetres to meters. RSLR represents one of the geologic hazards threatening the low-lying coast. Recent progresses made in understanding these two processes are presented. Synthetic Aperture Radar (SAR) interferometry has significantly improved the knowledge of actual land subsidence. In particular, comprehensive maps of the vertical displacements occurred over the period 1992-2009 in the region between Venice and Ravenna reveal a significant spatial variability, ranging from a slight 1 to 2 mm•yr-1 uplift, to a serious subsidence of more than 15 mm•yr-1. The availability of tide gauge data in Trieste, Venice, and Ravenna allows accurate assessment and meaningful observations on sea level change. The period 1896-2006 is characterized by an average rise of 1.2±0.1 mm•yr-1. The analyses here performed show that a time series at least 50 yr long must be used to obtain statistically significant results and reliable trend, due to the 7-8 year pseudo-cyclicity, recorded at many Mediterranean coastal stations. In Venice and Ravenna the influence of land subsidence on the RSLR amounts to 57% and 85%, respectively. This percentage has been estimated in 95% at the Po Delta.