1,720,964 research outputs found
Aquifer building and apennine tectonics in a quaternary foreland: the southermost Lodi plain of Lombardy
No full textNumerical modeling of regional groundwater flow in the AddaTicino Basin: advances and new results
No full textThe Adda Ticino basin is a densely-populated area, dependent massively on groundwater resources not only for industrial uses but also
for agricultural and domestic ones. A large scale hydrogeological assessment study over 8000 Km2 area northwest of Lombardy Region was done in reason to implement a groundwater flow model. The main objective was to give a quantitative estimate of groundwater budget into the Adda-Ticino basin and to deliver a tool to support Public Authorities in regional groundwater management required by the European Directive 2000/60/CE. The approach consists of improving the hydrogeological conceptual model and better define hydraulic properties of the aquifer units and all components in the basin influencing the groundwater flow (rivers, wells withdrawal). Then the collected GIS information were added into the numerical model Modflow. Regional steady-state flow was calibrated under current stress conditions with an inverse calibration code (Doherty, 2005) mainly by changing hydraulic conductivity and vertical recharge inflow. The water mass balance computed shows a total flow of 3279 Mm3/y. Vertical recharge provides 65% of the total groundwater inflows, whereas the 30% is coming from pre-Alps up-gradient boundary. Discharge from basin aquifers occurs through flow to rivers (60%), groundwater supply wells (30%) and underground outflow at the S-SE border (1 0%
SOLUZIONI ANALITICHE PER LA DETERMINAZIONE DELLO SPARTIACQUE PIEZOMETRICO DELLA ZONA DI CATTURA DI UNA BARRIERA DI POZZI
No full textCome noto, le barriere di pozzi spesso vengono sottodimensiona-
te, riducendone gravemente l’efficacia. E’ opportuno quindi disporre
di un metodo speditivo per delineare lo spartiacque piezometrico del-
la zona di cattura anche per geometrie non lineari dei pozzi, in modo
da favorire una efficace progettazione di questo importante strumento
operativo. Lo studio descrive un metodo analitico - grafico che può
essere usato per progettare una barriera le cui dimensioni (in parti-
colare l’ampiezza del fronte di richiamo all’altezza dei pozzi), siano
sufficienti per il contenimento dell’inquinante. La funzionalità del
metodo grafico è stata validata e supportata confrontando le curve di
cattura con un codice numerico esistente, quale Modflow
Aquifer building and apennine evolutionin a quaternary foreland: the southermost Lodi plain of Lombardy
No full textSaltwater Intrusion and Freshwater Storage in Sand Sediments along the Coastline: Hydrogeological Investigations and Groundwater Modeling of Nauru Island
Full text linkWater resources sustainable management is a vital issue for small islands where groundwater is often the only available water resource. Nauru is an isolated and uplifted limestone atoll island located in the Pacific Ocean. Politecnico di Milano performed a feasibility study for the development of sustainable use of groundwater on the island. This paper focuses on the first phase of the study that concerns the conceptual site model development, the hydrogeological characterization and the 2D model implementation. During the project, different activities were performed such as GNSS topographic survey of monitoring wells and groundwater level surveys taking into account tidal fluctuation. This data collection and the analysis of previous studies made it possible to identify the most suitable areas for groundwater sustainable extraction. The characterization findings suggested, unlike previous studies and surveys, the presence of only few drought resilient thin freshwater lenses, taking place in low conductivity sandy deposits, unexpectedly next to the seashore. Thanks to the 2D modeling results, it has been possible to clarify the mechanism that allows the storage of freshwater so close to the se
Multivariate data analysis and numerical modeling: a combined approach to assess the Groundwater contamination in Milan Functional Urban Area
No full textThe Italian law D.Lgs.152/2006 adopted the EU Water Framework Directive principles and entrusted the Regions
with the task to identify the areas affected by groundwater diffuse pollution and to assess their contamination level. The
proposed methodology (the Whole work has been supported by Regione Lombardia and ARPA Lombardia within the
PLUMES Project) combines the numerical model approach, which defines the areas interested by a plume transit, with
the statistical approach, in order to identify both point-source contamination (i.e. hot spots) and multiple point
contamination that determine a status of diffuse contamination. The methodology was applied to the Functional Urban
Area of Milan, where, at least since 40 years, chlorinated aliphatic hydrocarbons (TCE, PCE, TCM) have been the main
groundwater contaminants in the unconfined and confined Aquifers and they have been constantly monitored by public
authorities.
The study was divided into 2 different steps. In the former, the Cluster Analysis (CA, Vega et al., 1998; Otto, 1998)
allowed to identify, for each contaminant, the hot spots that have been used as sources in the numerical transport model
(MT3DMS, Zheng & Wang, 1999 and MODFLOW-2000, Harbaugh et al., 2000). The contaminant transport model,
calibrated on the concentration values of 2014, gave important information about the influence of the plumes on the
groundwater chemical status observed in the monitoring wells network. In the latter step, the monitoring wells located
inside the plume areas were removed from the ARPA Lombardia contaminant concentration value dataset with the aim
to keep just the concentrations representing the multiple-point diffuse contamination component. The new dataset was
then used for the geostatistical analysis (Inverse Distance Weighted) in order to map the diffuse contamination, not
directly influenced by hot spots. Lastly, the work defined reference values of diffuse contamination levels identified in
the maps. To sum up, the results of the work provide a better understanding of the relationship between hotspot sources,
multiple sources and diffuse pollution in the FU
Assessment of aquifers groundwater storage for the mitigation of climate change effects
No full textIn the coming decades, the effects of expected climate change will affect key aspects of our society including quantity and quality of available water resources. It is believed that water resources will play a growing important role in Europe and in particular in the countries south of the Alps, where climate change could hit harder (EEA, 2014). Without appropriate interventions, water will turn from a good hearty undervalued to a scarce and precious resource, whose distribution will be less and less equitable, resulting in growing conflicts for its use. As already recognized by the European directives (2000/60/EC and 2006/118/EC), the theme of quantitative management of water resources is therefore a strategic issue that can allow the reduction of the risks and costs associated with climate change. Integrated management of both surface and groundwater for sustainable use nowadays represents more and more a key concern in environmental policies and water management. The goal of this work is to assess the effects on groundwater storage of a new management of irrigation waters. The highly variable availability of water resources during the hydrological season could be particularly troublesome in the management of irrigation systems, since they need water in seasons (spring-summer) when usually its availability has a depletion. Storage of groundwater in aquifers in colder seasons could be used to soften irrigation systems water deficit in drier ones. Specifically, the practice of "winter irrigation", i.e. the use of the main irrigation channels to recharge aquifers during the colder seasons, could increase water resource availability for irrigation during the drier growing seasons. A pilot groundwater flow transient model (MODFLOW2000, Harbaugh et al., 2000) with a domain of about 255 km2 was implemented in the north zone of Lodi Province, including a large part of the Consorzio Muzza irrigation district. The model was then run to estimate change in groundwater resource availability in two main scenarios: in the first scenario the storage in the shallow aquifer was computed in the colder period (October–March), when irrigation is not occurring; for this case, it was used measured monthly rainfall, average temperature for the period 2004-2013 (representing actual climate conditions) and an estimations of water volume used for irrigation. In the second scenario, an integrated management approach of irrigation and groundwater was tested, adopting "winter irrigation". Both scenarios want to assess if water storage in aquifers in colder periods could represent an additional water volume useful to mitigate possible climate changes effects on crops
FLOW MODELLING OF TICINO-ADDA BASIN FOR PREDICTION OF GROUNDWATER LEVELS IN CLIMATE CHANGE SCENARIOS
No full textUndergoing climate change could affect substantially water resources in a long term period, not only for an overall drop of them, but for a different distribution of their availability during the hydrological season. Particularly irrigation systems could suffer of that problem, since they need water in specified seasons (springsummer) when usually it has a depletion. Storage of groundwater in aquifers in cold and wetter seasons, when cultivations don't need irrigation, could be used in order to soften irrigation systems water deficit in warmer and drier ones. Regional groundwater models have a key role in the management of groundwater resources, not only evaluating resource availability nowadays, but also predicting effects of management measures in different scenarios. The hydrogeological conceptual model of Ticino-Adda groundwater basin (having an extension of about 8000 km2 between Ticino and Adda river) was implemented based on a revision of the previous study on aquifers of the Lombardy region, conducted by ENI and Regione Lombardia. 87 hydrogeological cross-sections were used to build the bottom of the first 3 aquifers of the groundwater basin (Group Aquifer A, B and C) by means of a detailed
database of hydrostratigraphic logs (about 15 thousands in the whole basin) from ARPA Lombardia. The conceptual model was the starting point for the implementation of a basin scale groundwater flow model (MODFLOW), whose steady-state calibration was performed by means of groundwater survey data conducted by Lombardy Region in
May 2014 in 440 observation points in the 3 aquifers examined. Results of the calibration process point out a residual absolute mean scaled on observation range of about 4 %, suggesting a good accuracy. A pilot groundwater flow sub-model of about 255 km2 was then implemented in the north zone of Lodi Provincia, comprising a large part of the Consorzio Muzza Bassa Lodigiana irrigation district, in order to evaluate the quantity of groundwater resource in climate change and current climate scenarios. Using a down-scaled model (Quantile Mapping method) from the Regional Climate Model, predicted temperature and rainfall for the period 2071-2100 was obtained so that a transient model could be built to estimate change in groundwater resource availability. Furthermore, some analysis had made on the possible exploitation of the groundwater resource for the
softening of irrigation deficit in the global warming scenario first implemente
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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