Aquifer over-exploitation may increase coastal seawater intrusion by reducing freshwater availability. Fractured subsurface formations commonly host important freshwater reservoirs along sea coasts. These water resources are particularly vulnerable to the contamination due to seawater infiltration occurring through rapid pathways via fractures. Modeling of density driven fluid flow in fractured aquifers is complex, as their hydrodynamics are controlled by interactions between preferential flow pathways, 3D interconnected fractures and rock-matrix porosity distribution. Moreover, physical heterogeneities produce highly localized water infiltrations that make the modeling of saltwater transport in such aquifers very challenging. The new approach described in this work provides a reliable hydrogeological model suitable to reproduce local advancements of the freshwater/saltwater wedge in coastal aquifers. The proposed model use flow simulation results to estimate water salinities in groundwater at a specific depth (1 m) below water table by means of positions of the Ghyben-Herzberg saltwater/freshwater sharp interface along the coast. Measurements of salinity in 25 boreholes (i.e., salinity profiles) have been used for the model calibration. The results provide the groundwater salinity map in freshwater/saltwater transition coastal zones of the Bari (Southern Italy) fractured aquifer. Non-invasive geophysical measurements in groundwater, particularly into vertical 2D vertical cross-sections, were carried out by using the electrical resistivity tomography (ERT) in order to validate the model results. The presented integrated approach is very easy to apply and gives very realistic salinity maps in heterogeneous aquifers, without simulating density driven water flow in fractures.

In recent years, the identification and monitoring of polluted sites have become very important due tothe widespread of contamination phenomena. The environmental assessment of contaminated sites iscomplex and difficult for the variety of the pollutants and for the physical and chemical heterogeneity ofpolluted sites. Some studies promote an integrated approach, which combines geophysical investigationwith geochemical analysis carried out on subsoil samples to quantitatively estimate the extent and thelevel of the contamination. In this work, a contaminated site located close to Taranto city, in the southof Apulia Region (Italy), has been investigated by chemical and geophysical surveys in order tocharacterize and evaluate the pollution which is occurring since years. Soil chemical analyses of texture,electrical conductivity, pH, organic carbon content, nitrogen, available phosphorous and carbonatecontent have been carried out to characterize soil properties of this site. Analytical investigations ofpollutants have been performed using Gas Chromatography/Mass Spectrometry (GC/MS) andInductively Coupled Plasma Mass Spectrometry (ICP-MS) to identify organic or inorganic compounds,respectively. Geophysical survey has been carried out to assess the geological features of the test siteand support the results of the physical and chemical soil analysis. Particularly, an Electrical ResistivityTomography (ERT) profile has been performed to visualize geo-lithological layers and hydrogeologicalproperties for evaluating the vulnerability of the area. Moreover six high resolution ERT and InducedPolarization (IP) profiles have been conducted close to the soil sampling points to image electricalstructures in the upper part of the soil, severely contaminated by inorganic and organic pollutants.Preliminary results highlight that this integrated approach can efficiently support soil contaminationassessment.

In Puglia le falde idriche sotterranee rappresentano una risorsa fondamentale per l'approvvigionamento idropotabile.I principali sistemi idrogeologici pugliesi sono caratterizzati da acquiferi porosi, come quelli che si impostano in rocce calcarenitiche, e acquiferi ospitati in rocce calcaree fratturate e/o carsificate.Sempre più frequentemente tali sistemi sono soggetti a processi di depauperamento qualitativo legati a situazioni di sovrasfruttamento e/o contaminazione. Per tali ragioni la conoscenza dettagliata delle proprietà idrauliche, che governano i fenomeni di flusso e trasporto della zona insatura, è di fondamentale importanza per una gestione sostenibile delle risorse idriche; in particolar modo una precisa valutazione della velocità di flusso nella zona vadosa risulta necessaria per prevedere i tempi di migrazione dei contaminanti e quindi valutare la vulnerabilità della falda.Negli anni sono stati sviluppate differenti metodologie di investigazione allo scopo di caratterizzare il sottosuolo e monitorare il flusso e il trasporto in questi complessi sistemi idrogeologici.Questo studio presenta i risultati di un approccio metodologico multidisciplinare che combina misure infiltrometriche con indagini geofisiche, precisamente, misure di resistività elettrica, eseguite in due differenti siti della Puglia, caratterizzati da differenti formazioni geologiche e quindi caratteristiche idrauliche.Un sito, vicino Altamura, in provincia di Bari, è rappresentato da calcari carsificati e fratturati, che contengono una importante falda profonda; tale area è stata soggetta a sversamento di fanghi derivanti dal trattamento di acque di scarico industriali.Il secondo sito, vicino San Pancrazio Salentino, in provincia di Brindisi, è rappresentato da una cava di calcarenite utilizzata per lo stoccaggio di rifiuti prodotti da un' industria farmaceutica. In entrambi i casi, lo sversamento ha causato contaminazione del suolo e sottosuolo.Il flusso verticale è stato monitorato misurando l'abbassamento del livello idrico all'interno di un largo anello infiltrometrico, realizzato e installato direttamente sulla roccia affiorante, e contemporaneamente sono state condotte misure di resistività elettrica del sottosuolo al fine di monitorare l'infiltrazione dell'acqua, quindi l'approfondimento del fronte umido nella zona insatura.In aggiunta, è stata condotta un'indagine di resistività elettrica azimutale, al fine di individuare eventuali direzioni di fratturazione principali presenti nelle rocce, che rappresentano vie preferenziali di flusso e trasposto di inquinanti.I risultati ottenuti supportano l'efficacia dell'approccio metodologico combinato in questi sistemi idrogeologici complessi per stimare il flusso verticale nei due differenti acquiferi.

Electrical resistivitymethods arewidely used for environmental applications, and they are particularly useful for thecharacterization and monitoring of sites where the presence of contamination requires a thorough understandingof the location and movement of water, that can act as a carrier of solutes. One such application is landfill studies,where the strong electrical contrasts between waste, leachate and surrounding formations make electrical methodsa nearly ideal tool for investigation. In spite of the advantages, however, electrical investigation of landfills posesalso challenges, both logistical and interpretational. This paper presents the results of a study conducted on adismissed landfill, close to the city of Corigliano d'Otranto, in the Apulia region (Southern Italy). The landfill is locatedin an abandoned quarry, that was subsequently re-utilized about thirty years ago as a site for urban waste disposal.The waste was thought to be more than 20 m thick, and the landfill bottom was expected to be confinedwith an HDPE (high-density poli-ethylene) liner. During the digging operations performed to build a nearby newlandfill, leachate was found, triggering an in-depth investigation including also non-invasivemethods. The principalgoal was to verify whether the leachate is indeed confined, and to what extent, by the HDPE liner.We performedboth surface electrical resistivity tomography (ERT) and mise-à-la-masse (MALM) surveys, facing the severe challengesposed by the rugged terrain of the abandoned quarry complex. A conductive body, probably associated withleachate,was found as deep as 40 mbelowthe current landfill surface i.e. at a depth much larger than the expected20 mthickness of waste. Given the logistical difficulties that limit the geometry of acquisition,we utilized syntheticforward modeling in order to confirm/dismiss interpretational hypotheses emerging from the ERT and MALM results.This integration between measurements and modeling helped narrow the alternative interpretations andstrengthened the confidence in results, confirming the effectiveness of non-invasive methods in landfill investigationand the importance of modeling in the interpretation of geophysical results.

Due to the high wells drilling cost, monitoring sites are usually selected among existing wells; nevertheless, the resulting monitoring network must assure a good assessment of the main characteristics of the considered aquifer. Groundwater managers, need to find a good balance between two conflicting objectives: maximizing monitoring information and minimizing costs. In this paper, a couple of groundwater monitoring optimization methods are presented, related to the local shallow aquifer of the Alimini Lakes, located in Apulia (South-Eastern Italy) where a large number of existing wells have been pinpointed and the need of optimally reducing exists. The proposed methods differ each other for the required amount of prior information. The first proposed method, namely Greedy Deletion, just requires the geographical position of the available sites, while the second, the Simulated Annealing, also requires the knowledge of the spatial law of the considered phenomenon. The managerial need was to halve the number of monitoring sites minimizing the information loss.

The Alimini water system, located in south eastern part of Italy, named Salento peninsula, is constituted from two connected coastal lakes, Alimini Piccolo and Alimini Grande. Specifically, Alimini Piccolo is a small freshwater body, directly fed by rainfall and by shallow porous aquifer through of several springs. From '50s Alimini Piccolo provides the surrounding area with water for agriculture and domestic use. In June 2013, IRSA-CNR started a study concerning the quali-quantitative characterization of the hydrogeological system feeding the Alimini Piccolo, in order to investigate the potential for additional exploiting of the lake as a resource for drinking water. For the purpose, a monitoring system has been set up for an entire hydrological year. Continuous measurements of water level, electrical conductivity and temperature, such as quantitative and qualitative monitoring monthly campaigns both in groundwater and in the lake have been carried out. In order to support the above mentioned surveys, Electrical Resistivity Tomography (ERT) has been carried out to identify geological structures and hydrogeological features, to better understand the system feeding the Alimini Piccolo and to set the boundary conditions of the hydrological model useful to represent the water balance of the lake.

The knowledge of the unsaturated flow rate is essentialfor both groundwater protection and management, howeverit is not easy to determine experimentally, especiallyon the rocks and in the field.This study aims to evaluate the flow rate of potentialcontaminants in a porous aquifer using an integrated approachthat combines electrical resistivity measurementswith a large ring infiltrometer test.Specifically, the field tests were carried out on the outcropof sandstone in a quarry, located in Southern Italy,which has recently been affected by mycelium sludge derivedfrom pharmaceutical industry waste. The electricalresistivity tomography was carried out to visualise the infiltrationof water in the subsoil in order to evaluate the unsaturatedwater flow in the sandstone. Simultaneously, thevertical flow into the unsaturated subsoil was investigatedby measuring water levels in a large adjustable ring infiltrometer,sealed directly on the rock. The results of thisstudy confirm the efficacy of the combined methodologiesto monitor the vertical flow through unsaturated porous rock.

Although Italy boasts an age-old and solid experience in the exploitation of geothermal energy for power generation, very limited was the development regarding the direct uses. However, recently the interest in low enthalpy geothermal energy is growing mainly because, unlike the other kinds of green energies, the geothermal energy suitable for direct uses can be found anytime and almost everywhere. Particular attention should be paid to the open-loop geothermal systems that use groundwater as geothermal fluid. The installation of these kind of geothermal systems is particularly attractive in the coastal areas where, generally, the aquifers are shallow, and often affected by seawater intrusion. In this work an experimental approach was proposed for a detailed characterization of a costal area finalized to exploitation of low enthalpy geothermal resource. A costal karst area near Bari (Southern Italy), extended for about 20 Km2, was investigated. A specifically defined monitoring network, consisting of about 35 wells, was used to monitor groundwater parameters (temperature, water level, electrical conductivity). The influence of an open-loop geothermal systems on the sea water intrusion was also studied by means of a long-term pumping test. The investigated portion of aquifer was found to have a high hydraulic conductivity and transmissivity values, as well as a very short time of recharge, highlighting a good productivity of aquifer. The results of the long pumping test have showed that, the extraction of water does not affect the equilibrium of the aquifer both qualitatively and quantitatively. The high level of contamination observed in groundwater, due to both the presence of urban and industrial pollution and to the seawater intrusion, causes the absence of a strong competition for use of groundwater by making them available for geothermal use.Overall the experimental approach utilized for this study represents a good effort to define a standard methodology in order to characterize a coastal area. This approach reveals useful for a feasibility study to install an open-loop geothermal system, and to support the potential geothermal evaluation.

Nowadays due to the worldwide increase of environmental contaminations, the characterization of polluted sites has become very important. In light of this/As a consequence, the development of new methodologies, able to quickly and cheaply evaluate contamination is an arduous challenge but necessary. The use of geophysical techniques combined with the direct measurement techniques (such as groundwater and soil analysis) can be useful adopted as an integrated approach for a rapid pollution detection and assessment. In this work, a PCB historically contaminated area located close to Taranto city (Southern Italy) was investigated by chemical pollutant analyses and geophysical surveys in order to characterize and evaluate the pollution, which is occurring since years. Particularly, Electrical Resistivity Tomography (ERT) profiles were carried out close to the soil sampling points to image electrical structures in the upper part of the soil, severely contaminated by organic pollutants. The obtained results evidenced that geophysical surveys can efficiently support soil contamination assessment in an area of Southern Italy severally affected by high recalcitrant organic contaminants (PCB).

In recent years, geophysics is increasingly used to study the flow and transport processes in the vadose zone. Particularly, when the vadose zone is made up of rocks, it is difficult to install sensors in the subsurface to measure hydrological state variables directly. In these cases, the electrical resistivity tomography (ERT) represents a useful tool to monitor the hydrodynamics of the infiltration and to estimate hydraulic parameters and state variables, such as hydraulic conductivity and water content. We propose an integrated approach aimed at predicting water content dynamics in calcarenite, a sedimentary carbonatic porous rock. The uncoupled hydrogeophysical approach proposed consists in 4D ERT monitoring conducted during an infiltrometer test under falling head conditions. Capacitance probes were installed to measure water content at different depths to validate the estimations derived from ERT. A numerical procedure, based on a data assimilation technique, was accomplished by combining the model (i.e., Richards' equation) with the observations in order to provide reliable water content estimations. We have used a new data assimilation method that is easy to implement, based on the ensemble Kalman filter coupled with Brownian bridges. This approach is particularly suitable for strongly non-linear models, such as Richards' equation, in order to take into account both the model uncertainty and the observation errors. The proposed data assimilation approach was tested for the first time on field data. A reasonable agreement was found between observations and predictions confirming the ability of the integrated approach to predict water content dynamics in the rocky subsoil.

Sustainable groundwater management requires a thorough knowledge of the behavior of the unsaturated zone. Particularly, the evaluation of the flow rate in the unsaturated zone is important to estimate the travel time of the infiltrated water and dissolved substances in the subsurface and, hence, to quantify the recharge rate and to assess the quality of the subsurface.A quarry of calcarenite near the town of Canosa, in southern Italy, was chosen to perform an integrated hydrogeophysical field study that combines infiltrometer measurements with Electrical Resistivity Tomography (ERT). Infiltration data were collected using a 0.5-m-diameter metallic infiltrometer ring, which was installed directly on the rock, filled with about 8 L of water. A falling-head test was conducted for many hours, the water level in the ring was monitored with a pressure transducer and a metric rod fixed to the ring. Electrical resistivity measurements were carried out, using the "time-lapse" technique, to observe the dynamics of infiltration/redistribution of water in the vadose zone. Hydrogeophysical data were acquired for long periods to gain a more complete understanding of subsurface flow. The observations were used to independently estimate travel times and infiltration rates using a numerical model.

In the past decade, over-exploitation has led to a de-pletion of water resources, with impact both on quality and quantity. A sustainable groundwater management needs a detailed scientific knowledge of the behaviour of the un-saturated zone. Particularly, the evaluation of the flow-rate in the unsaturated zone is important to estimate the travel time of the infiltrated water in the subsurface and, hence, to assess the recharge rate and groundwater vul-nerability. A quarry of calcarenite near the town of Canosa, in South Italy, has been chosen to perform the field tests using an integrated hydrogeophysical approach, combin-ing infiltrometer measurements with electrical resistivity tomography (ERT). The infiltration data were collected using a metallic infiltrometer ring of 0.5 m in diameter, installed directly on the rock, filled with about 8 L of water. The test was conducted for many hours at falling head condition, and the water level within the ring was measured by means of a pressure transductor and a metric rod fixed to the ring. Simultaneously, electrical resistivity measurements were carried out using "time-lapse" technique, in order to monitor the dynamics of infiltration/redistribution of the water in the unsaturated zone. Hydrogeophysical data have been acquired for sev-eral hours to obtain a reliable hydrogeological model of the subsurface investigated. Field-saturated hydraulic conductivity has been de-termined for the calcarenite, and ERT surveys support these results.

The interest in the low enthalpy geothermal resources is growing, owing to its wide availability, and the possibility of overcoming the problems related to energy storage. Among the low enthalpy plants, the installation in coastal areas of the open-loop groundwater heat pump (GWHP) systems, that use groundwater as the geothermal fluid, is particularly attractive because of the presence of shallow aquifers. Nevertheless, these aquifers are often affected by seawater intrusion, so strict monitoring before GWHP installation is needed to check the feasibility of the plant.This work reports a detailed quali-quantitative characterization of a costal aquifer, in Southern Italy, for its exploitation as a very low enthalpy geothermal resource. The main groundwater parameters were monitored to assess the groundwater suitability to be used as geothermal fluid. A long-term pumping test, simulating the designed open-loop GWHP system, was performed to evaluate its potential impact on seawater intrusion. The results revealed that the open-loop GWHP plant do not affect the quali-quantitative equilibrium of the studied coastal aquifer. Furthermore, the study demonstrated that the used methodological approach is proper for the early assessment of the feasibility of the GWHP plant without affecting the seawater intrusion processes, and with minimum impact.

Compared to other European countries, there is limited use of geothermal resources in Italy for the heating and cooling of buildings (UGI-CNG, 2007). Low-temperature geothermal resources, which can be readily used for this purpose, can be found throughout Italy. The high cost and scarcity of fossil fuels have promoted the increased use of natural heat for a number of direct applications. Just as for fossil fuels, the exploitation of geothermal energy should consider its environmental impact and sustainability.Particular attention should be paid to so-called open loop geothermal systems, which use groundwater as geothermal fluid. From an economic point of view, the implementation of this kind of geothermal system is particularly attractive in coastal areas, which have generally shallow aquifers. The potential problem of seawater intrusion has led to laws that restrict the use of groundwater. The limited availability of freshwater could be a major impediment for the utilization of geothermal resources. We propose a methodology, based on an experimental approach, to characterize a coastal area in order to exploit low-enthalpy geothermal resources. A coastal karst-area near Bari, in Southern Italy, was selected for this purpose.A long-term pumping test was performed to create analog for an open-loop geothermal system. Electrical resistivity measurements were carried out, using "time-lapse" techniques, to monitor the dynamics of the freshwater-seawater interface. The results show that the pumping does not affect the quantitative and qualitative characteristics of the aquifer. The electric conductivity values suggest very limited sea water intrusion.

Up to now, field studies set up to measure field-saturated hydraulic conductivity to evaluate contamination risks, have employed small cylinders that may not be representative of the scale of measurements in heterogeneous media. In this study, a large adjustable ring infiltrometer was designed to be installed on-site directly on rock to measure its field-saturated hydraulic conductivity. The proposed device is inexpensive and simple to implement, yet also very versatile, due to its large adjustable diameter that can be fixed on-site. It thus allows an improved representation of the natural system's heterogeneity, while also taking into consideration irregularities in the soil/rock surface. The new apparatus was tested on an outcrop of karstic fractured limestone overlying the deep Murge aquifer in the South of Italy, which has recently been affected by untreated sludge disposal, derived from municipal and industrial wastewater treatment plants. The quasi-steady vertical flow into the unsaturated fractures was investigated by measuring water levels during infiltrometer tests. Simultaneously, subsurface electrical resistivity measurements were used to visualize the infiltration of water in the subsoil, due to unsaturated water flow in the fractures. The proposed experimental apparatus works well on rock outcrops, and allows the repetition of infiltration tests at many locations in order to reduce model uncertainties in heterogeneous media.

The huge demand of fresh water for irrigation together with water scarcity encourages the reuse of wastewater as a water resource in agricultural practices. The efficient use of wastewater, combined with irrigation strategies, could led to save water within an integrated management of water resources. ERT (Electrical Resistivity Tomography) technique could represent an useful tool to estimate the crop water requirements, the soil moisture and the impact of using poor quality water on crop and soil. In an experimental site close to Bologna (north of Italy), two different water saving irrigation techniques, Partial Root-zone Drying (PRD) and Regulated Deficit Irrigation (RDI), combined with brackish secondary treated wastewater and fresh water were tested in an irrigated corn crop. Particularly, during an irrigation cycle, lasted almost 72 hours, soil drainage through water uptake by the roots and the structural changes of the soil due to the poor quality of the used irrigation water, have been observed by means ERT survey in order to support water management models. Site specific petrophysical relationships ?-? have been obtained in laboratory to convert electrical resistivity into soil moisture content. Water content images, derived by ERT, were calibrated both by means the soil water content measured in laboratory on the undisturbed samples, and the soil moisture sensors installed in the field.