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Effective infiltration variability in the Umbria-Marche carbonate aquifers of central Italy
No full textThe spatial variability of the effective infiltration parameter within the recharge areas of the main aquifer complexes of the hydrogeological group of the Umbria-Marche ridge of Central Italy was assessed. This parameter usually varies with respect to lithology and the extent of precipitation in the investigated area. The average effective infiltration, expressed in millimeters/year, was directly computed by dividing the volume of water discharged on average from a hydrogeological basin by the extent of its recharge area. This method does not directly depend on the extent of precipitation, and therefore it is not biased by uncertainty in that value. Effective infiltration was assessed for 15 hydrogeological units and ranges from 200 mm/year to 475 mm/year. The effective infiltration values for the "Scaglia" complex are always lower than those of the other aquifer complexes. The effective infiltration of the "Scaglia" complex increases southwards. This latitudinal spatial variation of effective infiltration is nearly independent of the precipitation distribution. Because this trend is much more pronounced in the "Scaglia" complex, it has been inferred that the spatial variability of the "Scaglia" fracturing is more significant than fracturing in any of the other calcareous lithotypes. The recharge area of the "Scaglia" complex is higher in the northern hydrostructures than in the southern structures because the two areas have different deformation styles. When added to the spatial fracture variability in the "Scaglia", the effects of this differentiation in deformation are responsible for the different water resource amount of the hydrostructures. The occurrence of wide outcrops of the "Scaglia" complex with reduced infiltration capability justifies the existence of less productive aquifers in the northern hydrostructures
La rete di monitoraggio idrogeologico della tenuta presidenziale di Castelporziano (Roma)
No full textHydrogeological conceptual model of the Upper Chienti River basin aquifers (Umbria-Marche Apennines)
No full textAn updated conceptual model of groundwater flow of carbonate
fractured aquifers of Apennine basin of the Chienti River (Marche
Region) has been developed. This model derives from the application of classical hydrogeological approach, which is based on a detailed field survey, by upscaling methodology, aimed to localize the main spring locations (15 springs) and to evaluate their mean discharge (total discharge of about 3280 L/s). Acquired data have been combined with the hydrogeological evaluation of the geologicalstructural setting, for defining the hydrogeological role of the lithological complexes and of the structural setting (faults and thrusts), conditioning groundwater flow direction and amount. The geologicalstructural setting is typical of Central Apennine in the Umbria- Marchean succession. The bottom carbonate unit corresponds to the carbonate platform, overlapped by calcareous complexes having marly beds and marly-clayed complexes of pelagic facies, by a total thickness of about 2500-3000 m. Compressive tectonic processes, in a E-verging thrust-and-fold belt, combined with intense translational movements gave rise to significant overthrusts at regional scale. The cores of anticlines host large basal aquifers, hydraulically separated by low-permeability boundary due to marly and clay complexes, respect with the surrounding Scaglia aquifers. Groundwater flow moves mainly along N-S direction, parallel to the main thrusts, which act as no-flow limit. The proposed hydrogeological model includes seven local aquifers. There are two independent basal aquifers, feeding a deep groundwater flow in the basal carbonate complexes, including areas out of the hydrographic basin of Chienti River. Spring fed by these basal aquifers have a mean discharge of 1460 L/s. Additional five aquifers characterized by less deep and more local groundwater flow correspond to the Scaglia complexes, with a mean discharge of about 1820 L/s. The extension and the limits of all these aquifers have been verified by the evaluation of effective infiltration values, to define the recharge area of each spring group.
The resulting conceptual model has been independently validated by chemical and isotopic analyses of groundwater, which confirmed or require modification of the preliminary model obtained by the hydrostructural approach
Scomposizione della portata dei corsi d'acqua dell'Appennino marchigiano con il metodo delle portate mensili caratteristiche.
No full textContribution of the Roccamonfina Caldera to the basal volcanic aquifer recharge: first considerations
No full textA preliminary hydrogeological investigation of the Roccamonfina Caldera was conducted in order to increase the local knowledge of the multilayer aquifer hosted within the ignimbrite deposits. Three aquifer levels were distinguished according to stratigraphic data and according to the bottom well depth. The aquifer levels recharge punctual and linear springs with a total natural discharge of about 200 L/s. A preliminary groundwater recharge of about 300 L/s was calculated using the effective infiltration value (368 mm/y) suggested by Boni et al. (1986). A more detailed groundwater budget will be calculated afterwards, using the distributed method. Groundwater effective recharge will be calculated taking into account data about rainfall, land use, runoff and withdrawals value
Fractured carbonate aquifers of Sibillini Mts. (Central Italy)
Full text linkThe aim of the present map is to illustrate a detailed pre-earthquake hydrogeological conceptual model of the Sibillini Mts. This area was struck by a prolonged seismic sequence of up to Mw 6.5 in 2016. Geological, tectonic, and hydrogeological data were collected from the literature before 2016, subsequently standardized and re-interpretated with the aim of presenting a hydrogeological map (1:50,000 scale) of the Sibillini Mts. carbonate system (Central Italy). The map is supported by 11 hydrogeological both cross and longitudinal sections, which show the underground spatial relationship between aquifers, aquicludes, and tectonic elements. This Map provides a model of comparison for the new hydrogeological conditions emerging from the post-seismic research
Evidences of different salinization sources in the roman coastal aquifer (Central Italy)
No full textThe coastal aquifer of Rome is hosted in the Tiber River Delta depositional sequence, in a densely populated area, which was reclaimed at the end of the 19th century. Moderate salinization processes characterize this aquifer. Hydrogeological and hydrochemical surveys were carried out in October 2012 and February 2013 in the southern sector of the Delta. Hydrogeological surveys updated knowledge of groundwater morphology and a detailed conceptual hydrogeological model of the coastal aquifer was realized. Hydrochemical analyses helped to identify the salinization spatial distribution and to specify the main groundwater types. The most salinized water was not detected close to the coastline, where seawater intrusion processes would be expected, but in the inner areas. Moreover, the salinization processes resulted to be slightly marked. Results so far suggest that the source of salinization may be related more to a combination of land use and historical development of the Tiber River Delta, rather than to seawater
Groundwater response to precipitation extremes: the case of the “Vaia” storm (Eastern Italian Alps)
No full textExtreme precipitation events are expected to increase in intensity in Alpine regions due to climate change. While many studies have analyzed the impact of these phenomena on flooding risk, very Jew deal with their effect on groundwater. This work analyzes the hydrograph response of three springs to an extreme storm, which occurred in Northern Italy in October 2018. We observed that the newly infiltrated storm water contributed to feeding the winter baseflow, increasing its volume up to 85 % compared to normal conditions. It was also found that the response of groundwater to heavy precipitation seems to be influenced by the type of media. A high-altitude spring belonging to the fractured carbonate aquifer shows a quick response to the storm input, while springs outflowing at the base of the mountain slopes (mixed fractured carbonate and porous deposits) exhibit a delayed response. Results are important when analyzing future water availability and to better understand the impact of extreme events on groundwater flow.
Preliminary conceptual model of an Alpine carbonate aquifer (Pale di San Martino, Dolomites, Italy)
No full textA hydrogeological and hydrochemical monitoring was conducted in the Pale di San Martino mountain ridge (Trento and Belluno Provinces, Italy) to build a preliminary conceptual model of the groundwater system. The model derives from a combination of new fieldwork and preexisting data provided by various public authorities. New data include geological and hydrogeological surveys, such as in situ measurements of the physical and chemical parameters, geochemical sampling and streamflow measurements. The lithologies outcropping in the area were grouped into seven hydrogeological complexes, each playing a different role in groundwater circulation. The dolomitic body of the ridges forms the main aquifer complex and is located above a terrigenous and evaporitic aquiclude. Due to this geometrical relationship, the site can be considered an isolated hydrostructure with well-defined no-flow boundaries. The main springs outcome near the aquifer-aquiclude boundary and in particular where the elevation of the contact is low and the tectonic pattern favors the drainage. Most of them have a calciumbicarbonate water composition, low temperature and low electrical conductivity, supporting the hypothesis of a fast flowing circulation in carbonate rocks and a high-altitude recharge. Seasonal streamflow measurements allowed the identification of linear springs and provided the first cumulative discharge data at the scale of the entire mountain group. The resulting model highlights a great spatial and temporal variability of the groundwater resources. Considering the geometry of the aquifer and the great seasonal variability of the discharge, it is possible to infer the absence of significant groundwater reserves at a regional scale. Thus, the hydrostructure shows a great capacity to supply water resources (mean discharge of 6 m3/s), but a low selfregulation capacity. It is necessary to consider this aspect when planning a long-term exploitation of the water resources that are used in the area for drinking purposes and hydropower generation
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