1,720,984 research outputs found
Time-dependent methods to evaluate the effects of urban sprawl on groundwater quality: a synthesis
Full text linkFreshwater resources are threatened worldwide with unknown and unpredictable fate, due to non-stationarity and change of water cycle dynamics, and increasing demand resulting from population growth and economic expansion. Thus, practical actions, strategies and solutions are necessary to ensure the short-term and long-term provision of adequate, affordable, accessible and safe freshwater supply to meet the needs of the growing human population and ecosystems. Since the mid-1950s, Europe is experiencing the phenomenon of urban sprawl, characterized by an unplanned incremental urban development, no more tied with population growth (EEA 2006). Impacts of urban sprawl threaten both the natural and rural environments and the quality of life for people living in cities, with worsening of air quality, and surface- and groundwater quality and quantity. For the protection of groundwater, the European Union issued a series of Directives (Water Framework Directive, 2000/60/EC; Groundwater Directive, 2006/118/EC) that require member states to achieve a good chemical status of their groundwater bodies and the identification of areas where groundwater suffers increasing trends in contaminant concentrations. In order to cope with EU Directives, a time-dependent approach for groundwater vulnerability assessment is developed to account for both the recent status of groundwater contamination and its evolution in the Po Plain area of Lombardy Region (northern Italy). Such approach takes the advantages of a Bayesian spatial statistical method to assess groundwater vulnerability and satellite scatterometer data to delineate urban areas and monitor their evolution. The proposed approach can determine potential impacts of contamination events on groundwater quality, if policies are maintained at the status quo or if new measures are implemented for safeguarding groundwater resources
Specific yield of aquifer evaluation by means of a new experimental algorithm and its applications
Full text linkA simplified method to determine specific yield (i.e., effective porosity) from hydraulic conductivity data obtained through pumping tests is proposed. This new method derives from a reprocessing of literature data and a subsequent calibration with results from pumping tests performed in different hydrogeological contexts. The use of the algorithm allows obtaining values of specific yield (Sy), which could be useful for the resolution of problems concerning the water balance and the transport of contaminants in groundwater.
The proposed algorithm is applied to a large-scale area (Milan and its suburbs, northwestern Italy) to determine a map of the specific yield of a sandy-gravel aquifer and the effects on the estimation of water volumes stored in the subsoil from a hydrogeological point of view, considering about seventy years of measures. It is demonstrated that the great variation in water volumes reflects the socio-economic history of the territory
Combination of hydrochemical graphical methods and multivariate statistical analysis to delineate groundwater bodies
Full text linkThe identification of hydrogeological boundaries and the assessment of the quantitative and qualitative state of groundwater are necessary for the delineation of groundwater bodies, according to the European Guidelines. In this context, this study attempts to verify the current delineation of groundwater bodies (GWBs) focusing on their hydrochemical features through the application of hydrogeochemical methods and multivariate statistical analyses. The areas of interest are three adjacent GWBs located in the north-western sector of Campania Region in Southern Italy: the Volturno-Regi Lagni Plain, a coastal plain constituted of fluvial, pyroclastic and marine sediments; the Plain of Naples, an innermost plain of fluvial and pyroclastic sediments and the Phlegrean Fields, an active volcanic area with a series of monogenic volcanic edifices. Physicochemical data measured in groundwater samples collected at more than 200 sampling points were considered. Results reveal five different hydrogeochemical processes variably influencing the chemical features of the three GWBs: dissolution of carbonate rocks, influence of volcanic deposits and/or gas/hydrothermal fluid upwelling, salinisation, reducing conditions, and anthropogenic contamination. Combining hydrochemical diagrams and multivariate statistical analysis (i.e., factor analysis) allows depicting areas characterised by one or more hydrogeochemical processes, mostly reflecting known processes, but also highlighting the influence of groundwater flowpaths on water chemistry. The current delineation of the three GWBs should be revised considering that some hydrochemical features and processes are peculiar to each GWB, but others are in common between two or more GWBs. Uncertainties in the delineation of GWBs based on their hydrochemical features could be reduced by improving the distribution of the monitoring well network to ensure a more homogeneous coverage
Towards a dynamic landslide susceptibility assessment: evaluation of a novel climate-related variable
Full text linkHow do hydrogeological and socio-economic parameters influence the likelihood of NO3− pollution and Cl− salinization? An application within the campania region (Italy)
Full text linkGroundwater pollution is increasing because of long-term human activities. This study aims at assessing the probability of nitrate (NO3−) and chloride (Cl−) pollution. The approach firstly involved applying a Gaussian simulation to reconstruct the spatial distribution of the pollutants in three areas in the Campania Region (Italy). Then, probability maps were used to determine how different hydrogeological and socio-economic parameters affect groundwater quality in the three regions. To prioritize the factors affecting the target pollutions, two distinct groups of parameters were considered: hydraulic head, recharge, distance from inland water, distance from the coastline, ground elevation, hydraulic conductivity, and fine sediment content to assess Cl− salinization; while hydraulic conductivity, recharge, fine sediment content, crops fertilizer request, depth to water table, and distance from wells to assess NO3− pollution. Three different algorithms, Decision Tree (DT), Random Forest (RF), and Information Gain Ratio (IGR), were employed. The results of the prioritization of parameters affecting NO3− pollution indicate that recharge, hydraulic conductivity, water depth, and crops fertilizer request are the most influential factors, while the results for Cl− salinization show that hydraulic head, recharge, hydraulic conductivity, distance from inland water, and fine sediment content have the strongest impact. This study highlights that, as different processes govern NO3− pollution and Cl− salinization, an informed management is essential to effectively tackle protection measures to safeguard groundwater resources. The protocol here employed can be extended to other regions, assisting policymakers and managers in identifying areas exposed to potential human and naturally driven pollution processes
Acque sotterranee, cambiamenti climatici e migrazioni: seconda edizione della “Piattaforma internazionale per una corretta gestione delle risorse idriche sotterranee”
Full text linkChanges in geochemical and isotopic contents in groundwater before seismic events in Ischia Island (Italy)
No full textWe analysed the hydrogeochemical and isotopic contents in groundwater for the period 2002-2020, in the Ischia Island, a volcanic island in Southern Italy, and compared them with seismic events that occurred in the same period. The study is based on a large hydrochemical database, which includes chemical (major and minor compounds, metals and trace elements) and isotopic analyses (δ18O and δ2H). For each of the 34 seismic events occurred in the studied period, we considered coordinates, date, time, depth and magnitude. To exclude the influence of meteorological variability on the hydrochemistry, we examined rainfall time series measured in four stations located in the island. Results show hydrogeochemical anomalies for some chemical elements observed months before the seismic events. Arsenic, electrical conductivity, chromium and vanadium have been identified as potentially affected by hydrogeochemical anomalies related to the earthquakes. The variations in stable isotopes (δ2H and δ18O) in groundwater also seem associated with the earthquakes. This study aims to contribute to the individuation of components in groundwater prone to register sudden changes related to seismic events and it highlights the need of a continuous and long-term hydrogeochemical monitoring in seismic areas. Indeed, the conclusions of this study must be further confirmed by a future continuous monitoring of major compounds, trace elements and isotopes in groundwater to evaluate the effective temporal coincidence/lag with the seismic events
A versatile method for groundwater vulnerability projections in future scenarios
No full textWater scarcity and associated risks are serious societal problems. A major challenge for the future will be to ensure the short-term and long-term provision of accessible and safe freshwater to meet the needs of the rapidly growing human population and changes in land cover and land use, where conservation and protection play a key role. Through a Bayesian spatial statistical method, a time-dependent approach for groundwater vulnerability assessment is developed to account for both the recent status of groundwater contamination and its evolution, as required by the European Union (Groundwater Directive, 2006/118/EC). This approach combines natural and anthropogenic factors to identify areas with a critical combination of high levels and increasing trends of nitrate concentrations, together with a quantitative evaluation of how different future scenarios would impact the quality of groundwater resources in a given area. In particular, the proposed approach can determine potential impacts on groundwater resources if policies are maintained at the status quo or if new measures are implemented for safeguarding groundwater quality, as natural factors are changing under climatic or anthropogenic stresses
The Last Glaciation in Valchiavenna (Italian Alps): maximum ice elevation data and recessional glacial deposits and landforms
Full text linkThis work presents the first extensive, 1:10,000-scale field survey data concerning glacial deposits and glacigenic landforms in the Valchiavenna territory, which has an area of 578 km2. Valchiavenna is an inner Alpine valley in Northern Italy between the Lepontine and Western Rhaetian Alps. A comprehensive 1:25,000 map of deposits and landforms from the last glaciation to the present is provided, describing i) glacial trimline evidence and associated features, such as moraine ridges, erratic boulders, ice- moulded bedrock surfaces and kame terraces; ii) glacial, ice-contact, lacustrine/peat and gravity-reworked till deposits; iii) other supraglacial, marginoglacial and subglacial landforms; and iv) erratics in glacial deposits. Establishing an absolute chronology of glacier dynamics was not the objective of this work. However, a relative chronology was inferred from sedimentological and geomorphological evidence: this allowed the description of the general behaviour of glaciers in the area during and after the Last Glacial Maximum (LGM). The palaeogeography at the LGM and the palaeo-ice-flow pattern were reconstructed on the basis of field data; this data confirmed that the valleys were almost completely filled by glacier ice, covering about 88% of the study area, with only the most elevated ridges and a few nunataks emerging above the ice surface, and allowed the identification of different source areas for the erratics found on opposite sides of the main valley. The observation of stratigraphical and geomorphological relationships between glacial deposits and landforms made it possible to propose a relative chronology of glacial advances and to outline the general glacial dynamics of the area. Both at the LGM and during the deglaciation after the LGM, the valley glacier inserted offshoots in tributary valleys, thus generally blocking the advance of local glaciers. With the gradual melting of the valley glacier during the deglaciation after the LGM, tributary glaciers could deposit tills on areas previously covered by valley glacier ice and at lower altitudes than the older lateral moraines. The main outcome of this work is a rich and homogeneous database of glacial deposits and glacigenic landforms that will be useful for further local and regional studies. It can guide the planning of geochronological dating and represents a fundamental step in the identification of glacial stadials and ice mass modelling. It can also support biogeography studies and the evaluation of the effects of climate change, slope dynamics modelling and hazard prediction
Combining groundwater budget, hydrochemistry and environmental isotopes to identify the groundwater flow in carbonate aquifers located in Campania Region (Southern Italy)
Full text linkStudy region
Carbonate mountains of Mt. Maggiore and Mt. Tifata, Campania Region, southern-central Italy, Mediterranean basin.
Study focus
The hydrogeological relationship between the carbonate massifs of Mt. Maggiore and Mt. Tifata is investigated. Archival and newly acquired data on groundwater availability, hydrochemical and isotopic data were considered. Their combined use led to the proposal of new hypotheses regarding the connection between these aquifers. The exchange of groundwater through this connection would be induced by the strong groundwater withdrawals from the well fields at Mt. Tifata; the area of possible connection was also identified. A mineralization model of some local springs showing high CO2 and TDS values is also proposed.
New hydrological insights for the region
The carbonate rocks are widely outcropping with a mountainous morphology and host important groundwater resources in the studied region. The springs related to these carbonate aquifers have excellent chemical characteristics and, for these reasons, the major aqueducts in Campania Region rely on these groundwater resources. The well fields of the Mt. Maggiore and Mt. Tifata supply part of the metropolitan area of Naples, with 3.8 million inhabitants. The quantitative evaluation of groundwater resources and the proposed groundwater circulation scheme can support a sustainable and diversified use of the resource taking into account the presence of waters already used for drinking purposes and waters with high TDS values
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