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Acque Bresciane is a public company that manages the integrated water cycle for more than 580,000 inhabitants in the Province of Brescia, in the north of Italy, providing drinking water, waste water treatment, and sewer systems. Drinking water systems are supplied with different types of groundwater, springs, and surface water sources (from lakes and rivers) whose availability and quality can be affected by climate change events. A multidisciplinary team, in collaboration with the University of Milano Bicocca, developed a specific Water Safety Plan (WSP) risk matrix focusing on the evaluation of climate-related hazardous events and calculation of their likelihood of occurrence, also using thematic maps. Moreover, to reduce the residual risks, in the risk matrix, possible control measures are suggested, such as the activation of an emergency plan, the use of other water sources, storage tanks, and interconnection with other water distribution networks. This work shows a simple and effective tool that can be applied by drinking water utilities to evaluate climate-related catchment risks, using a WSP risk matrix, thematic maps, and possible control measures to reduce risks in terms of water quality and availability and to respond with resilience to changes.

Basin-scale studies addressing the transfer of pollutants among groundwater and surface water bodies are essential to support local authorities in the sustainable management of freshwater resources. This work revealed that, in the hydro-system of the Oglio River basin (Northern Italy), nitrate pollution in groundwater, originated by overfertilization, is trans- ferred downstream to surface water bodies via outflow through lowland springs and base- flow to gaining rivers. Downstream groundwater is unaffected due to reducing conditions that facilitate denitrification. It follows that efficient measures to reduce nitrate pollution in surface water bodies should not be applied solely to rivers/streams but, instead, they should include the upstream groundwater body. The work aimed at understanding nitrate pollution dynamics in an intensively irrigated hydro-system, focusing on the role played by the com- plex interaction among irrigation water, surface water and groundwater. The study relied on nitrate concentration, Cl/Br ratio, stable isotopic composition of water, nitrate and boron in groundwater, river, lake, spring, and rainwater samples. Results highlighted a well-defined spatial distribution of nitrate concentrations in groundwater, mainly driven by irrigation practices: (1) where groundwater-fed irrigation is done, return flow promotes high nitrate concentrations (>50 mg/L) due to groundwater recirculation; (2) where intensive surface-wa- ter-irrigation is practised, fed by low-nitrate river water, return flow generates lower nitrate concentrations (<50 mg/L) due to dilution. This work highlighted the importance of a holistic approach jointly investigating surface water, groundwater, and irrigation water when nitrate pollution is examined at a basin scale.

In a climate change context, a sustainable water resource management is crucial and long time series of monitoring data become necessary. Recently, monitoring networks were improved, but the consequent extension of available data requires specific and reproducible procedures to effectively manage future big data. In groundwater studies, water suppliers could be valuable providers of long time series data. Indeed, they often store millions of groundwater level and abstraction rate data with a high temporal resolution, which often lie unexploited due to a missing dedicated operating procedure. In this work, a reproducible procedure to exploit long time series of groundwater levels and abstraction rates from data logger in operating wells is presented. This procedure allows the extraction of hydrogeological information from the data, improving monitoring networks’ efficiency and data management. This work relies on over 9 million of hourly data of groundwater level and withdrawal rate of 107 public wells over 10 years (2013-2022). These wells, managed by the water supplier Acque Bresciane S.r.l., serve 50 municipalities in the province of Brescia (N Italy). This method includes a first pre-processing phase consisting of: (1) homogenization of data acquired from different sources, (2) errors and outliers treatment, and (3) data association with the geographical localization and the well’s structure. The successive analysis phase allows to (1) separate static from dynamic groundwater levels, (2) classify groundwater levels according to abstraction rate ranges, (3) quantify the available static data and select the groundwater levels associated with the minimum withdrawal class (< 5 L/s), (4) extract and compare pluriannual, annual and seasonal trends of groundwater level, and (5) investigate the groundwater drawdown related to abstraction rates. Nowadays, in-depth analyses and elaborations of high-resolution hydrogeological data from automatic sensors are vital. Such e

Urbanization, worldwide, led to progressive increase in the use of the subsurface. Therefore, interactions between groundwater and underground infrastructures (UIs) (i.e. subway lines, public and private car parks) come to attention. As a results, episodes of infiltrations and corrosion can occur for these subsurface elements. In this sense, numerical models are widely applied to manage these issues. Infiltration episodes were documented over the years also for the city of Milan. In the framework of a further subsurface development to be achieved by 2030, the Plan of Government of the Territory has already defined the construction of new UIs. Hence, proper tools must be adopted to support stakeholders in urban planning, also considering these hydrogeologic aspects. Thus, a steady-state numerical model, calibrated against a groundwater maximum condition, was developed for the western portion of Milan metropolitan city to simulate the UIs (i.e. subway lines and public car parks) and quantify their infiltrations. MODFLOW-USG was used, combining the Wall (HFB) and DRN packages to model the UIs. Model cells range from 100 up to 6.25 meters close to the UIs. A total of 18 layers modelled 100 – 120 meters of depth, with the UIs falling inside the first 8 layers (25 meters of depth). Different scenarios were simulated to cope with the wall conductance uncertainty of non-waterproofed subway lines, testing respectively: intact walls, a progressive saturation over time (i.e. a prolonged interaction with groundwater), and leaky walls. Results pointed out those UIs suffering major groundwater infiltrations that were historically identified as critical in previous studies (i.e. submerged by the water table). Particularly, this occurred for the western branch of subway line M1 (i.e. Bisceglie station), and for the surroundings of Sant’Agostino (subway line M2), showing a maximum infiltration of 5.29 L/d. The use of MODFLOW-USG was pivotal, as the HFB package was used to simulate n

Over the past few decades, groundwater quality monitoring networks have grown, and considerable time series of quality data are currently available. Hence, a research effort is required to investigate novel methods for exploiting groundwater quality time series. In this work, time series of groundwater pollution data are exploited with the aim of developing data-driven monitoring strategies, and early warning systems to support groundwater resource management for drinking water purposes. The research area is Brescia municipality (N Italy): an urban area with a complex hydrogeological context and numerous superimposing historical pollution sources. The dataset, provided by A2A Ciclo Idrico Spa, consisted in concentrations of Tetrachloroethylene (PCE), Trichloroethylene (TCE) and Cr(VI) on raw water before any potabilization treatment, from 2009 to 2020 for 68 wells and 16 springs. Time series exploratory analysis and time series cluster analysis were performed on groundwater pollution data, to identify groups of wells with homogeneous responses to anthropogenic inputs and highlight critical situations. The exploratory analysis was performed through Mann-Kendall test and Sen's slope estimator for the trend identification and quantification. A multivariate time-series clustering was performed on PCE and TCE, with the Dynamic Time Warping method. The clustering revealed 3 clusters linked to diffuse background contamination and 7 clusters linked to discrete hotspots, distinguished by distinct time profiles. Similarly, Cr(VI) data were subjected to a univariate time series cluster analysis, which revealed 3 background clusters and 7 hotspots, including 4 singletons. Based on the clustering outputs, data-driven monitoring strategies and early warning systems were designed for each group of wells. For the clusters associated with diffuse background contaminations and those with constant trends, the 95th percentile was used to calculate trigger levels, which represent future

Over the past 30 years, groundwater (GW) age derivation has attracted attention in researchers and professionals to overcome quality-related challenges in the management of aquifer systems. GW ages can be determined following either hydraulic-based techniques or isotope-based approaches. By the term age modelling, instead, reference is made to developed methods that qualitatively couple hydrodynamics with isotope-based ages in order to reduce the uncertainties involved. Here we present an age modelling application to the shallow alluvial aquifer in the Po River Basin. We used the 3H/3Hetri method to assess the aquifer renewability in a portion of the plain where the extremely variable recharge contributions and the intrinsic variability in aquifer geometry, make sometimes water management arduous. Results from 44 wells showed 3H activities ranging from 0.52 to 5.02 T.U.. To use 3He for age computations, the fraction produced by 3H decay (3Hetri) must be separated by other sources: dissolved He in solubility equilibrium with the atmosphere (Heeq), excess air trapped at the vadose zone (Heea) or 3He produced from 6Li (3Herad). The 3He/4He ratios normalized to that of the atmosphere range from 0.30 to 3.25 revealing the dominant presence of 3Hetri with a minor contribution of Herad. The slight Herad contribution to the Hetot identifies older GWs, reaching values of 60±20yr, detected near the piedmont and in the higher plain. The downstream middle plain, instead, revealed younger ages of about 24±2yr. Chronometers also unraveled mixing processes, detailing older GWs in the higher plain as the result of a young component containing 3H and another older than 70 years mostly 3H-free. In the middle plain, oppositely, mixing counts at least two components where the youngest portraits shorter flowpaths able to lower background aquifer age values, particularly where return flow due to intensive irrigation occurs, thus acting as a young recharge component to the aquifer. The ag

Freshwater pollution by nitrate is a major threat to human and ecosystem health. Basin-scale studies on nitrate pollution generally focus separately on surface water or on groundwater bodies, thus the role played by their interaction on nitrate concentrations, possibly including also agricultural irrigation, is often overlooked and so is addressed here in the intensively irrigated hydro-system of the Oglio River basin (Northern Italy). Tracers of groundwater recharge (stable water isotopes and Cl/Br ratio) together with nitrate and boron stable isotopes indicate that the main source of the diffuse nitrate pollution affecting groundwater resources in the area is related to agricultural activities and, locally, to untreated civil/industrial effluents. Moreover, these data reveal the strong control of irrigation return flow on groundwater nitrate concentrations, with contrasting effects: groundwater-fed irrigation promotes higher concentrations due to the recirculation of high-NO3 groundwater, whereas intensive surface-water-irrigation, fed by low-NO3 river water, generates lower concentrations due to dilution. The control of irrigation return flow on groundwater nitrate links nitrate pollution and climate change: if surface-water-irrigation will be abandoned, as a consequence of intensified summer droughts, in favor of groundwater-fed irrigation, an increase in groundwater nitrates is expected due to a basin-scale groundwater recirculation and the cessation of the dilution effect. In addition to the reduction of the N input to soils from fertilizers, i.e., the sole pollution mitigation strategy able to solve the problem, an adaptation strategy to climate change might be the implementation, during non-irrigation rainy periods, of managed aquifer recharge operations, such as the so-called “forested infiltration areas”, to take advantage of water abundancy from rivers under high-flow conditions, thus combining a supplement on groundwater recharge with the beneficial dilu

As groundwater quality monitoring networks have been expanded over the last decades, significant time series are now available. Therefore, a scientific effort is needed to explore innovative techniques for groundwater quality time series exploitation. In this work, time series exploratory analysis and time series cluster analysis are applied to groundwater contamination data with the aim of developing data-driven monitoring strategies. The study area is an urban area characterized by several superimposing historical contamination sources and a complex hydrogeological setting. A multivariate time series cluster analysis was performed on PCE and TCE concentrations data over a 10 years time span. The time series clustering was performed based on the Dynamic Time Warping method. The results of the clustering identified 3 clusters associated with diffuse background contamination and 7 clusters associated with local hotspots, characterized by specific time profiles. Similarly, a univariate time series cluster analysis was applied to Cr(VI) data, identifying 3 background clusters and 7 hotspots, including 4 singletons. The clustering outputs provided the basis for the implementation of data-driven monitoring strategies and early warning systems. For the clusters associated with diffuse background contaminations and those with constant trends, trigger levels were calculated with the 95° percentile, constituting future threshold values for early warnings. For the clusters with pluriannual trends, either oscillatory or monotonous, specific monitoring strategies were proposed based on trends’ directions. Results show that the spatio-temporal overview of the data variability obtained from the time series cluster analysis helped to extract relevant information from the data while neglecting measurements noise and uncertainty, supporting the implementation of a more efficient groundwater quality monitoring.

Freshwaters constitute a fundamental and extremely limited resource for atoll islands' population. The interplay of climatic and human-driven processes, which affect both the quantity and the quality of freshwater resources, may exacerbate the problem of water security and availability. This work evaluated the effects of good spectrum of anthropic impacts on groundwater quality in a typical and representative native inhabited island (c.a. 850 people) of Maldives, analyzing and interpreting hydrological and hydrochemical data, collected during a specific field survey on 51 sampling points after a rainy season. The island groundwater is constituted by a thin asymmetric lens, periodically recharged by rain. The lifestyle of people and water exploitation seem to be sustainable, even if groundwater resources are already experiencing moderate contamination and, limited to some areas, heavy pollution. The sources of impacts have been identified in diffuse organic matter contamination due to a poor domestic wastewater treatment, farming (poultry) and gardening activities. To face these impacts, it is essential to build a sewer system paired with a possibility to recycle wastewater reducing water over-exploitation. The collaborative and educational initiatives organization, at different levels, can increase the capacity for planning a sustainable development. Our results provide useful information for sustainable management plans to preserve freshwater resources of the island, which conservation is especially important considering the context of the future lifestyle changes and climatic scenarios for the Maldives. These findings can be extended by analogy to others atoll islands.

At the end of 2019, 10.5 GW of wind capacity was installed in Italy, all onshore. The National Integrated Climate and Energy Plan sets a target of 18.4 GW of onshore wind capacity and 0.9 GW of offshore wind capacity by 2030. Significant exploitation of offshore wind resources in Italy is expected after 2030, using floating wind turbines, suitable for water depths greater than 50 m. This technology is at the demonstration phase at present. Results of a preliminary techno-economic assessment of floating wind plants in Italian marine areas in a medium (2030) and long-term (2060) scenario are presented. In 2030, a reference park with 10 MW wind turbines will be defined, and parametric costs, depending on distance from shore, were assessed. In 2060, possible wind resource variations due to climate change, and cost reductions due to large diffusion of the technology were considered in three case studies. The economic model used was the simple Levelized Cost of Energy (sLCoE). Different values of Weighted Average Cost of Capital (WACC) were considered too. The results show LCoEs comparable to the ones expected for the sector in 2030. In 2060, even in the more pessimistic scenario, wind resource decreases will be abundantly compensated by expected cost reductions.

Po Plain is the result of complex endogenous processes which induced the growth of a large and deep subsiding foredeep basin for the south-vergent thrusting from the Alpine Chain first, and then for the Apennine structure, verging in the opposite direction. The Po Plain foredeep was nourished by large amount of debris coming from exogenous processes of erosion of both mountain chains. During Pleistocene, the foredeep has assumed a W-E direction along the Appenine margin, corresponding to the Po River course, deeper eastward. At the same time, at the northern margin of the plain, isostatic processes have been responsible of relevant raising. Sediments in the area have been deposited firstly in a marine basin, then in a wide delta-lagoon region, and more recently, a continental sedimentation prevailed. The area was dominated by large alluvial fans coming from the main Alpine valleys while in the southern part of the plain, where finer sediments are widespread, intense subsidence phenomena due to compaction of the sedimentary deposits occurred. During Quaternary, fluvial transport and sedimentation was strongly influenced by climate changes and, in the cold stages, large amount of debris were produced on the mountain chains and remarkable sea-level changes caused marine ingression in the middle of the Po Plain alternating to as much relevant regressions. Through the use of GOCAD software, using SGRID frame, voxels 500 × 500 m were obtained interpolating between Topo and A surfaces subdivided in 90 intervals, between A and B surfaces in 84 intervals and between B and C surfaces in 74 intervals respectively. The surfaces A, B and C, (Regione Lombardia & ENI-Divisione AGIP, 2002) were dated back respectively to 450, 870 and 1240 Ky In each voxel, gravel, sand and clay texture distribution have been interpolated using percentage of texture for each metre assumed from stratigraphie data of the wells (11, 993) stored in TANGRAM database. Interpolation has been carried ou

Recent studies have highlighted an increase of chloride in many lakes worldwide, with negative effects on chemical and physical properties of inland waters and freshwater biota. In this study, we assessed the long-term trend (1993–2017) of chloride in Lake Iseo, located in the midlatitudes, and analyzed its relationship with discharge data of the inflows and hydrological and hydroclimatic changes. Additionally, we performed a specific annual survey, collecting water samples at a biweekly frequency in tributaries, calculating chloride load, and comparing the result with the chloride increase observed in lacustrine water. The combined use of Geographic Information System (GIS) and multivariate analyses allowed identification of possible sources of chloride and their seasonal dynamic within the mixed-land-use watershed: impervious surface and deicing salt, population and sewage effluents, livestock, and rainwater. Their potential contribution to total mass balance was assessed, cross-checking the results between chloride source evaluation and load estimation. Chloride load from wastewater treatment plants played an important role, albeit we highlighted that the main source was the road deicing salt, with a primarily winter contribution. The increased anthropization in the watershed was likely the main cause of the chloride enhancement. This study demonstrates that the problem of salinization can also affect lakes located in the midlatitude areas and provides a reproducible method for the identification and quantification of the different sources. Our results will help to better understand the potential sources of salinity in rivers that may reveal processes controlling the salinization of freshwater systems, with implications for future management practices.

The town of Mantua is a good example of an urban area with an intricate surface water system leading to complex groundwater/surface-water interactions. In this context, the Site of National Interest (SIN) “Laghi di Mantova e Polo Chimico”, is characterized by intense pumping activity by means of industrial wells and hydraulic barriers. In order to establish the interactions between groundwater and the surface water system, evaluating their relation with the pumping activities, a transient groundwater numerical model was developed (January 2016 - December 2018) using MODFLOW-2005 and the Streamflow-Routing (SFR2) package, following a participatory approach. Results show how, depending on the minimum/ maximum groundwater conditions and the discharge values of the surface channels, the relation between groundwater/surface-waters can vary during the year, also affecting the operation of the hydraulic barriers. The stakeholders could use the calibrated model in the future to ensure optimal management of the pumping activities within the SIN.

The significant increase in urbanization has resulted in greater use of the subsurface in urban planning and, therefore, increased interaction between groundwater and underground infrastructure. Numerical models are the primary tool adopted to manage the resulting problems; however, their construction is time- and cost-consuming. Groundwater-level time-series analysis can be a complementary method, as this data-driven approach does not require an extensive understanding of the geological and boundary conditions, even if providing insights into the hydrogeologic behaviour. Thus, a data-driven approach was adopted to analyse groundwater time-series of the shallow aquifer, occupied by several underground structures, beneath Milan city (Northern Italy). Statistical (Mann-Kendall and Sen’s slope estimator, autocorrelation and cross-correlation, hierarchical cluster analysis) and geospatial techniques were used to detect the potential variables influencing the groundwater levels of 95 monitoring wells, covering the period 2005–2019. A general rising trend of the water table was identified, with local hydrogeologic differences in the western and southernmost areas. Based on time-series analysis results, four management areas have been identified. These areas could act as future geographic units with specific groundwater management strategies. In particular, subsurface public car parks can be classified with respect to groundwater flooding as (1) not submerged, (2) possibly critical, or (3) submerged at different groundwater conditions. According to these outcomes, targeted guidelines for constructing new car parks have been elaborated for each management area. The methodology proved to be efficient in improving the urban conceptual model and helping stakeholders design the planned underground development, considering groundwater aspects.

Groundwater constitutes a key resource and the most relevant reservoir of drinking water at global scale. Despite the recognized resilience of groundwater bodies to climate variations, the fifth IPPC report identifies climate change as the main stressor impacting groundwater resource. For this reason, it is necessary to focus the attention on groundwater availability, considering the main input and output of different aquifers. This exploratory analysis intends to present a first approach for the definition of the groundwater level temporal pattern in the province of Brescia (Lombardy, Italy). To do so, a statistical analysis of groundwater level time series from 17 ARPA wells and meteorological data from 11 ARPA stations was conducted. Further in-depth analyses will allow to identify possible mitigation actions for a sustainable use of this resource.

Urbanization is a worldwide process that recently has culminated in wider use of the subsurface, determining a significant interaction between groundwater and underground infrastructures. This can result in infiltrations, corrosion, and stability issues for the subsurface elements. Numerical models are the most applied tools to manage these situations. Using MODFLOW-USG and combining the use of Wall (HFB) and DRN packages, this study aimed at simulating underground infrastructures (i.e., subway lines and public car parks) and quantifying their infiltrations. This issue has been deeply investigated to evaluate water inrush during tunnel construction, but problems also occur with regard to the operation of tunnels. The methodology has involved developing a steady-state groundwater flow model, calibrated against a maximum groundwater condition, for the western portion of Milan city (Northern Italy, Lombardy Region). Overall findings pointed out that the most impacted areas are sections of subway tunnels already identified as submerged. This spatial coherence with historical information could act both as validation of the model and a step forward, as infiltrations resulting from an interaction with the water table were quantified. The methodology allowed for the improvement of the urban conceptual model and could support the stakeholders in adopting proper measures to manage the interactions between groundwater and the underground infrastructures.

Water abstraction is a key aspect when performing drinking water risk assessment within the scope of Water Safety Plan (WPS). In this context, evaluating aquifer vulnerability could be not exhaustive. Care must be taken to consider the well structure and dynamic behavior that can determine different water quality and vulnerability than those of the tapped aquifer. Here, a methodological approach to assess well vulnerability to natural and anthropogenic pollution is proposed. A data-driven hydrogeochemical conceptual modeling was performed through cluster analysis, supporting the identification of the main features determining well vulnerability. Well vulnerability was then assessed through a semi-quantitative method based on a well-specific analysis of the tapped aquifer type, water table depth, vadose zone permeability, natural redox conditions, and qualitative classification of the tapped groundwater age, considering evidence of mixing processes induced by the well dynamic behavior. Each feature was categorized into several classes, and a score was associated with each class according to the vulnerability induced by that specific condition. The method was applied to a dataset of ∼200 wells, in northern Italy. Each well was classified, and its vulnerability was assessed. The method was validated by analyzing the distribution of wells affected by natural or anthropogenic pollution in each of the vulnerability classes. Results of the chi-square test showed that the distribution of the polluted wells was associated with vulnerability classes, which is evidence of the robustness and reliability of the proposed method. This method was developed exploiting only hydrogeological information and raw water quality data, largely available to water managers from routine monitoring, which makes this approach widely applicable and cost-effective.

Time-dependent geolocalized analysis of pollution data allows to better understand their dynamics over time and could suggest strategies to restore a good ecological status of contaminated area. This research analyzes concentrations of pollutants in surface waters and groundwater monitored by the Regional Environment Protection Agency of Lombardy from 2017 to 2020. Lombardy is one of the richest and populous region of Europe, providing an interesting example of the impact of environmental pollutants due to anthropogenic and industrial activities, not only for Italy but also for all Europe. Results show that groundwater displays more sites with heavy metals above the legal limit with respect to surface waters, including As, Ni, Cr and Zn. Furthermore, the spatio-temporal analysis of the data clearly shows that the introduction of more restrictive laws is a proper policy to improve the ecological status of the water.

The town of Mantua is a good example of an urban area with an intricate surface water system leading to complex groundwater/surface-water interactions. In this context, the Site of National Interest (SIN) “Laghi di Mantova e Polo Chimico”, is characterized by intense pumping activity by means of industrial wells and hydraulic barriers. In order to establish the interactions between groundwater and the surface water system, evaluating their relation with the pumping activities, a transient groundwater numerical model was developed (January 2016-December 2018) using MODFLOW-2005 and the Streamflow-Routing (SFR2) package, following a participatory approach. Results show how, depending on the minimum/ maximum groundwater conditions and the discharge values of the surface channels, the relation between groundwater/surface-waters can vary during the year, also affecting the operation of the hydraulic barriers. The stakeholders could use the calibrated model in the future to ensure optimal management of the pumping activities within the SIN.

Il Rapporto Ambiente - SNPA nasce nell’ambito del SNPA per un’ampia ed efficace divulgazione dei dati e dell’informazione ambientale prodotta da ISPRA e dalle ARPA/APPA. La base dati è l’Annuario dei dati ambientali ISPRA. Il Rapporto è realizzato in un unico volume strutturato in tre parti. La prima descrive le realtà regionali attraverso l’analisi di 16 indicatori; la seconda è composta da brevi articoli che riguardano attività SNPA particolarmente rilevanti e di interesse per la collettività; la terza consiste in brevi articoli riguardanti specificità regionali.

Groundwater level forecasting is a useful tool for a more efficient and sustainable groundwater resource management. Developing models that can accurately reproduce groundwater level response to meteorological conditions can lead to a better understanding of the groundwater resource availability. Here an autoregressive neural network (NNARx) approach is proposed and compared with autoregressive linear models with exogenous input (ARx) in order to forecast groundwater level in an aquifer system where a linear groundwater level response to recharge by rainfall is observed. A well known problem regarding neural networks consists in the high risk of overfitting. Here, three NNARx model were trained using different methods to avoid overfitting: Early stopping, Bayesian regularization and a combination of both. The results show that on the short term forecasting (up to 15 days) the performance of NNARx and ARx are comparable but the ARx model generalizes better, while the NNARx trained with Bayesian regularization outperforms the linear models and the other NNARx models on longer scenarios on the test set. As linear models are less time demanding and do not require high computational power, they can be considered as suitable tools for short term groundwater level forecasting in linear systems while when longer scenarios are needed neural networks can be considered more reliable, and training them with Bayesian regularization allows to minimize the risk of overfitting.

Arsenic is found in groundwater above regulatory limits in many countries and its origin is often from natural sources, making the definition of Natural Background Levels (NBLs) crucial. NBL is commonly assessed based on either dedicated small-scale monitoring campaigns or large-scale national/regional groundwater monitoring networks that may not grab local-scale heterogeneities. An alternative method is represented by site-specific monitoring networks in contaminated/polluted sites under remediation. As a main drawback, groundwater quality at these sites is affected by human activities. This paper explores the potential for groundwater data from an assemblage of site-specific datasets of contaminated/polluted sites to define NBLs of arsenic (As) at the meso-scale (order of 1000 km2). Common procedures for the assessment of human influence cannot be applied to this type of dataset due to limited data homogeneity. Thus, an “unorthodox” method is applied involving the definition of a consistent working dataset followed by a statistical identification and critical analysis of the outliers. The study was conducted in a highly anthropized area (Ferrara, N Italy), where As concentrations often exceed national threshold limits in a shallow aquifer. The results show that site-specific datasets, if properly pre-treated, are an effective alternative for the derivation of NBLs when regional monitoring networks fail to catch local-scale variability.

In recent years, a strong interaction between groundwater and underground infrastructures has emerged, determined by a significant employment of subsurface in urban planning. Numerical models are essential to manage this problem, but their construction is time and cost consuming. Groundwater time-series analysis can represent a valid complementary approach, as an extensive approximation of the geological and boundary conditions is not required, even if providing insights into the hydrogeologic system. Thus, for Milan city, in order to identify the potential variables affecting the water table levels of 95 monitoring wells (MWs) of the shallow aquifer, occupied by numerous underground infrastructures, data-driven techniques were adopted to analyse groundwater time-series. The study covered the period 2005-2019. Four management areas (MAs), possibly representing future territorial units with specific groundwater management policies, have been identified. As for underground infrastructures, public car parks have been classified in a) not submerged, b) at risk or, c) submerged at different groundwater conditions, allowing to propose for each MA targeted guidelines for constructing new car parks. This approach enabled to improve the urban conceptual model and could help the stakeholders in designing a futureurban underground development, also considering groundwater aspects.

The reductive dissolution of Fe-oxide driven by organic matter oxidation is the primary mechanism accepted for As mobilization in several alluvial aquifers. These processes are often mediated by microorganisms that require a minimum Gibbs energy available to conduct the reaction in order to sustain their life functions. Implementing this threshold energy in reactive transport modeling is rarely used in the existing literature. This work presents a 1D reactive transport modeling of As mobilization by the reductive dissolution of Fe-oxide and subsequent immobilization by co-precipitation in iron sulfides considering a threshold energy for the following terminal electron accepting processes: (a) Fe-oxide reduction, (b) sulfate reduction, and (c) methanogenesis. The model is then extended by implementing a threshold energy on both reaction directions for the redox reaction pairs Fe(III) reduction/Fe(II) oxidation and methanogenesis/methane oxidation. The optimal threshold energy fitted in 4.50, 3.76, and 1.60 kJ/mol e- for sulfate reduction, Fe(III) reduction/Fe(II) oxidation, and methanogenesis/methane oxidation, respectively. The use of models implementing bidirectional threshold energy is needed when a redox reaction pair can be transported between domains with different redox potentials. This may often occur in 2D or 3D simulations.

The recent rapid increase in urbanization has led to the inclusion of underground spaces in urban planning policies. Among the main subsurface resources, a strong interaction between underground infrastructures and groundwater has emerged in many urban areas in the last few decades. Thus, listing the underground infrastructures is necessary to structure an urban conceptual model for groundwater management needs. Starting from a municipal cartography (Open Data), thus making the procedure replicable, a GIS methodology was proposed to gather all the underground infrastructures into an updatable 3D geodatabase (GDB) for the metropolitan city of Milan (Northern Italy). The underground volumes occupied by three categories of infrastructures were included in the GDB: (a) private car parks, (b) public car parks and (c) subway lines and stations. The application of the GDB allowed estimating the volumes lying below groundwater table in four periods, detected as groundwater minimums or maximums from the piezometric trend reconstructions. Due to groundwater rising or local hydrogeological conditions, the shallowest, non-waterproofed underground infrastructures were flooded in some periods considered. This was evaluated in a specific pilot area and qualitatively confirmed by local press and photographic documentation reviews. The methodology emerged as efficient for urban planning, particularly for urban conceptual models and groundwater management plans definition.

Positive Matrix Factorization (PMF) is a multivariate analysis aimed at source identification and apportionment, specifically designed to cope with environmental data and manage their uncertainty and distributions. The aim of this work is to test the effectiveness of PMF as a tool to perform data mining and define hydrochemical features of groundwater and surface water and to understand their relationship. Here PMF is applied to a dataset concerning groundwater, springs, rivers and a lake. Factor contributions to the samples are spatially analysed trough GIS approach and their interpretation is supported by considering the land use and hydrogeological features. The study area is a part of the Oglio River basin (N Italy) and consists in a ~2000 km2 area around the Oglio River part that outflows from Lake Iseo until the confluence with Mella River. The available dataset is the result of four field surveys conducted in February 2016, June 2016, September 2016 and March 2017, for a total amount of 270 samples collected on 68 monitoring points. The first factor represents water with a high content of oxygen, with SO4 and a small content of major ions. In this factor neither nitrate nor trace elements are represented. The profile of this factor overlaps with the characteristics of lake Iseo and surface water bodies directly connected with it. Its spatial variability highlights a contribution of this factor, also in several wells even if they are not close to the river itself. This was related to the channels net collecting water from the Oglio River and spreading it to the nearby fields. The second factor explains the whole chemical variability of As, Fe, P-tot and NH4. Furthermore, it has a significant contribution of Mn and it can be associated to the advanced stages of reducing conditions due to degradation of natural organic matter. The third factor is characterized mainly by Mn and SO4, with a contribution of the major ions. Based on the profile and on the spatial di

Riassunto: La direttiva quadro sulle acque dell’Unione Europea, recepita dall’ordinamento nazionale, richiede agli Stati Membri di valutare lo stato quantitativo e qualitativo dei corpi idrici sotterranei e superficiali e di raggiungerne il “buono” stato per tutti i corpi idrici entro il 2027. Il presente studio è stato sviluppato per determinare ai sensi della vigente normativa, tramiteapplicazione di apposite linee guida ISPRA, lo stato quantitativo delle acque sotterranee della piana d’Aosta al fine di supportare gli Enti Locali preposti alla periodica valutazione dello stato dei corpi idrici. Nell’area di studio, durante il periodo 2000-2017, i livelli piezometrici sono stati misurati su un totale di 213 pozzi/piezometri. Applicando i quattro test previsti dalle suddette linee guida, lo stato quantitativo è stato valutato in funzione delle variazioni pluriennali del livello piezometrico e del bilancio idrico, delle acque superficiali connesse e degli ecosistemi terrestri dipendenti. Si è giunti ad una valutazione di “buono” stato quantitativo, ma non senza difficoltà operative. L’applicazione delle procedure proposte dalle linee guida ha infatti permesso di evidenziare le criticità relative alla rete di monitoraggio dell’area di studio che ostacolano lo svolgimento delle valutazioni, in particolare per quanto riguarda la numerosità, la distribuzione spaziale e i periodi di riferimento delle serie di dati. Sono quindi state elaborate indicazioni a supporto del monitoraggio per migliorare la qualità dei dati e favorire le future determinazioni dello stato quantitativo., The EU Water Framework Directive requires Member States to assess the quantitative and qualitative status of groundwater bodies and to achieve a good status by 2027. The present study was developed in order to assess the groundwater quantitative status in the Aosta Plain (NW Italy), following the methodology proposed through a guideline defined by the Italian Institute for Environmental Protection and Research (ISPRA), with the aim of supporting local authorities in their periodic assessment of water bodies status. In the study area, during the period 2000-2017, groundwater levels were measured in 213 wells and piezometers. Performing the four tests required by the abovementioned guideline, the quantitative status was assessed on the basis of multi-year groundwater level variations, water balance and the interconnections of groundwater with surface water bodies and groundwaterdependent ecosystems. A good status was assessed for the study area, although some critical aspects emerged from the application of the guideline methodology: the data collected by the monitoring network are not sufficiently robust in terms of sample size, spatial distribution, temporal interval and frequency to fulfill the requirements of the guideline methodology. Therefore, some recommendations to improve the data quality and better address the future assessment of groundwater quantitative status were given.

This work aims at assessing the impact on groundwater resources of a leachate overflow occurred in the landfill of Vizzolo-Predabissi (Milan, Italy) after its closure. Hydrogeological sections, piezometric maps, spatio-temporal and multivariate analysis of hydrochemical data enabled to define a conceptual model and to build a groundwater flow model, solved and calibrated by means of MODFLOW-NWT and PEST. The results of the study pointed out that the leachate overflow produced an impulsive contamination, currently in attenuation, which behaved differently in areas with different redox characteristics.