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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. [ABSTRACT FROM AUTHOR]

Managed aquifer recharge (MAR) is becoming a common practice worldwide. MAR is carried out in different environments from coastlands to highlands, in megalopolis, farmlands and pristine areas, and in arid and humid regions. Pre‐Alpine aquifers represent an optimal target when MAR is aimed at storing large amounts of high‐quality waters. In fact, pre‐Alpine aquifers are generally characterized by high permeability and a thick unsaturated zone, with the catchments crossed by watercourses rich ofhigh‐quality water. Here, we focus the attention to a representative pre‐Alpine aquifer system located in the Friuli region, northeastern Italy. A 1‐year long MAR test was carried out through a ~700 m²infiltration basin recharged by water diverted from a nearby channel. The site was characterized from the hydrogeological viewpoint, and the MAR test was monitored through time‐lapse hydrogeophysics, water level and piezometric records, and physicochemical water characterization. The data set was used to calibrate a local ground water flow model, showing that MAR recharged the 50 m deep phreatic aquifer with 1,000 m3/day. Hydrogeologic data made available by previous studies were processed to develop a ground water model of the regional aquifer that allowed for estimating the natural groundwater recharge of the phreatic system and, subsequently, evaluating the MAR effects in the context of the natural balance. If a single MAR site, like the tested one, plays a certain effect at a local scale only, the MAR implementation on several gravel pits and large‐diameter wells scattered in the region could store several million cubic meters of water per year, significantly raising the water table and improving the groundwater quality. [ABSTRACT FROM AUTHOR]

• Unraveling the elastic and inelastic components of deformation and hydraulic head. • Quantifying the elastic and inelastic parameters at different depths. • The storage parameters are obviously correlated with the depth and lithology. • The percentage of permanent storage volume loss is estimated. Land subsidence is a geological process mainly caused by groundwater overdraft. Numerical modeling of land subsidence is the main method used for its simulation and prediction. The elastic skeletal storage coefficient (S ke), inelastic skeletal storage coefficient (S kv), and the related specific values (S ske and S skv) are fundamental parameters to quantify land subsidence. In this paper, a novel approach integrating fast independent component analysis (Fast-ICA) with variable preconsolidation head decomposition method is proposed to disentangle S ske and S skv at various depth and over time from piezometric and extensometer records. The proposed method is applied to areas affected by severe land subsidence in the North China Plain (Tianzhu, Pinggezhuang and Cangzhou stations). The elastic and inelastic parameters of the aquifer systems are quantified at different depths. It is found that S ske and S skv decrease with depth. The finer the sediment grain size is, the smaller of the ratio S ske / S skv . Moreover, S ke remains almost unchanged over time, while S kv decreases as compaction and land subsidence increase. [ABSTRACT FROM AUTHOR]

• A new methodology by coupling 3D hydro-mechanical models and A-DInSAR data. • Model catches pumping-induced aquifer drawdown and deformations. • Time-lag between pressure change and deformation is detected by wavelet analysis. • The procedure is tested in the strategic water resource of Madrid (Spain) • Madrid aquifer response to aquifer extraction/recovery is fast. 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 resource for Madrid. [ABSTRACT FROM AUTHOR]