In the Piedmont region (NW Italy) between the SW Alps (Paleozoic - Mesozoic) and the hills of the Langhe domain (Tertiary) there is an extensive flood plain (3.000 km2) consisting of a series of overlapped alluvial fans originated by the quaternary geological activity produced by the evolution of several rivers which drain the Alps. These alluvial deposits overlap a Tertiary sedimentary succession through a series of erosional unconformity surfaces. The quaternary deposits highlight a variable thickness ranging from 80 to 100 m in the foothills of the mountains up to a few meters in the more distal portion of the plain. In these deposits there are several unconfined aquifers which are not respectively interconnected from the hydraulic point of view due to the deep fluvial incisions that reach the underlying tertiary substrate. This plain is intensively populated and lot of villages and farms characterize the landscape. In the overall area it is present an intensive agricultural and livestock activity predominantly represented by crops of wheat and corn and farms of cattle and pigs. All these activities require a considerable amount of groundwater which is withdrawn from the quaternary aquifers by means of thousands of water wells. These aquifers are generally very productive due to the high permeability of the alluvial deposits and the large water losses from many rivers which drain the mountain sectors of the SW Alps. The depth to groundwater ranges from 60 m in the foothills of the mountains to few meters in the more distal plain sector where it is possible to observe the groundwater outcropping through several springs. The groundwater flow nets highlight the mechanisms of the aquifers recharge and their evolutive dynamics. Rivers lost most of their water directly in the aquifers during the limited discharge flow periods (summer and winter) in the area located at the foothills of the mountain sectors. On the contrary, in the more distal portion of the plain the rivers highlight significant increases in their surface flow due to the contribution of groundwater supplied by the quaternary aquifers. Effectively, several springs which supply the rivers are present in the river valleys incisions in correspondence of the separation surfaces between the quaternary alluvial aquifer and the underlying less permeable tertiary substrate. The groundwater circulating in these aquifers has a predominantly calcium-bicarbonate hydrochemical facies with a significant presence of sulphates in some areas. The groundwater quality is strongly influenced by the content of nitrates and manganese. The nitrates are certainly linked to pollution due to agricultural activities and livestock and increase along the groundwater flow lines. The manganese content is quite high in the foothills of the mountains and in some restricted areas of the plain and appears to be linked to the natural lithological composition of the aquifers. Below the alluvial deposits of the Quaternary succession there is the Plio-Pleistocene succession, it is outcropping in the Roero hills, in some sectors of the Monregalese and next to the valley edge of the main streams. Three main tectonic sequences have been recognised and they are separated by important unconformities which identify three principle allogroups. These allogroups have been named: Late Messinian allogroup (LM), Early Pliocene allogroup (EP) and Late Pliocene allogroup (LP. These allogroups are characterised by a succession of sediments that have been deposited over different periods and in different environments and to which different informal stratigraphic units have been attributed. In this work, the units that have been recognised have been correlated to their respective hydrogeological units. These units, which are characterised by different facies, have been assigned their hydraulic conductibility values. The correlation between the surface data and the underground data has made it possible to define a hydros
Groundwater nitrate contamination is a source of rising concern that has been faced through the introduction of several regulations in different countries. However the methodologies used in the definition of Nitrate Vulnerable Zones are not included in the regulations. The aim of this work was to compare different methodologies, used to asses groundwater nitrate contamination risks, based on parametric systems or simulation modelling. The work was carried out in Piedmont, Italy, in an area characterised by intensive animal husbandry, high N load, a shallow water table and a coarse type of sub-soil sediments. Only N loads from agricultural non-point sources were considered. Different methodologies with different level of information have been compared to determine the groundwater nitrate contamination risk assessment: N load, IPNOA index, the intrinsic contamination risk from nitrates, leached N and N concentration of the soil solution estimated by the simulation model. The good correlation between the IPNOA index and the intrinsic nitrate contamination risk revealed that the parameters that describe the soil in this area did not lead to a different classification of the parcels.
The intrinsic nitrate contamination risk was greatly influenced by N fertilisation, however the effect of the soils increased the variability in comparison to the IPNOA index. The leached N and N concentration in the leaching were closely correlated. The dilution effect of percolated water was almost negligible. Both methodologies were slightly correlated to the N fertilisation and the two indexes. The correlations related to the intrinsic nitrate contamination risk was higher than those related to IPNOA, and this means that the effect of taking into account soil parameters increases the correlation to the prediction of the simulation model.
Climate change is the main factor that induces alterations in the hydrological cycle and mountains represent its first indicators, because they respond rapidly and intensely to climatic and environmental modifications. Obtaining reliable scenarios on water resources availability is a prerequisite to planning management measures. The snowfall and the resulting seasonal snow cover represent an important source of water, including surface and subsurface flows. A terrestrial laser scanning (TLS) was employed to measure snow depth and snow cover in the Mascognaz basin at 1850 m (Ayas municipality, Regione Autonoma Valle d'Aosta, Italy). We choose this site because the Politecnico di Torino installed an advanced meteorological station in 2010 (equipped with sensors measuring snow depth, snow density and snow water equivalent). Furthermore downstream the area are located two springs, both equipped with probes measuring water level, temperature and electrical conductivity. The aim of this study is to recognize the accumulation areas from melting areas through the generation of high dense digital snow elevation model. In this way is possible better understand the snowmelt process that contributes widely to the groundwater recharge. We used the Riegl VZ 4000 that is very powerful for measurements of snowcovered surfaces in high alpine catchment thanks to the long-range acquisition. The TLS monitoring consists in three phases: a summer acquisition, with the purpose to obtain a DSM (Digital Surface Model); a winter acquisition, that aims to evaluate accurately the snow cover and the snow accumulation areas and a spring acquisition with the purpose to investigate the snow-pack development and evaluate the available volume of water generate by snow during the melting phenomena. Finally, we used the ArcGIS 10.2 software to improve spatial analysis evaluation, estimate the Snow Water Equivalent (SWE). and obtain important information on the amount of water resources available for human consumption
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