Characterization of Submarine Groundwater Discharge along the southeastern coast of Sicily (Italy) (original) (raw)
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Effective infiltration variability in the Umbria-Marche carbonate aquifers of central Italy
The 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.
Groundwater interaction in the coastal environment: hydrochemical, electrical and seismic approaches
Bulletin of Engineering Geology and the Environment, 2008
The heterogeneous Plio-Quaternary coastal aquifer of the Mamora Basin is the most significant reservoir of Morocco. It is composed of sandstones, conglomerates, limestones and more or less argillaceous sands. The increase in the requirements for water in this area requires further information on the relations between the geometry of the aquifer and the salinity of the water. A hydrochemical analysis was undertaken and highlighted three zones of high mineralization. A geophysical approach allowed the determination of the principal aquifer levels, the localization of the various types of water (fresh, brackish and salt) and the geometry of the aquifer base.
La comprensione dei fenomeni di intrusione marina negli acquiferi costieri è importante per un appropriato uso delle risorse idriche, soprattutto per gli acquiferi fratturati e carsici. Questo studio analizza l'intrusione di acqua salata nell'acquifero carbonatico di Monte Faito in prossimità dell'area delle sorgenti di Castellammare di Stabia. In quest'area, emergono acque sotterranee in prossimità della costa per una portata totale di circa 0.5 m 3 /s da più sorgenti che differiscono per portata e chimismo delle loro acque.
Characterisation of the ionian-lucanian coastal plain aquifer (Italy)
Boletín Geológico y …, 2003
The considered study area is, subjected to a semiarid climate, lying in Southern Italy. Data coming from 1130 boreholes have been considered to define the geological and hydrogeological set-up of the study area and for estimating the groundwater use and the salt-related groundwater quality degradation. The aquifers are constituted by marine terraces deposits, river valley alluvial deposits and alluvial and coastal deposits. Groundwater flow is mainly unconfined in the marine terraces and in the river valleys while it becomes mostly confined in the coastal plain aquifer. Being the direct natural recharge extremely low, the recharge of this coastal aquifer is mainly guaranteed by the discharge from upward aquifers and from the river leakage. Two dominant types of groundwater have been distinguished: the HCO3-Ca type (in the marine terraces and in the alluvial deposits) and SO4-Cl-Na type (in the coastal plain deposits). The variability of major ions contents is related to many factors such as the different lithologies of the aquifers, the seawater intrusion, the mixing with river water and the impact of intensive farming. As regards the presence of the seawater intrusion in the study area, the analysis of the concentration maps of TDS, groundwater electrical conductivity and of the ions present in seawater, generally indicate that seawater contamination is relevant along a strip of land stretching for 2.5-3 km from the coastline inwards. The new acquired knowledge permits to delineate scenarios useful for an optimization of the groundwater resources tapping and for pursuing the safeguard of them.
Hydrogeological behaviour of faulted, non-karstic carbonate aquifers in southern Italy.
2009
"Carbonate aquifers in southern Apennines (Italy) are essentially fractured and subordinately karstified. They may behave as “basin-in-series” systems, due to low permeability fault zones that compartmentalize the systems. The fault-controlled groundwater flow system is characterized by good interdependence of hydraulic heads upgradient and downgradient of low-permeability faults. The high hydraulic gradient (up to 66%) within these faults allows the activation of seasonal and temporary springs. Hydrogeological and geophysical investigations demonstrated the existence of epikarstic horizons, up to 10 m thick. Epikarst formation, evolution and thickening are enhanced by thickness, texture and permeability of pyroclastic soil that often overlies carbonate rocks in southern Italy, as well as by land use. Nevertheless, the hydrogeological behaviour of the epikarst is different from that schematized by several authors in classic karst aquifers. The small size (<1 m3) of rock blocks and the high number of sub-vertical discontinuity sets imply a high and diffuse infiltration through the fractured rock mass at the epikarst bottom. Thus, the contrast in permeability at the bottom of the studied epikarstic zones does not cause retention of percolation and storage of water in perched temporary aquifers within the uppermost portion of the carbonate medium. The “funnelling” effect into larger shafts does not play an important role on the hydrogeologic behaviour of the aquifer, and the epikarst does not significantly influence the recharge function of the carbonate aquifer at basin scale, as well as the transport of contaminants from the ground towards the groundwater."
This study delineates the actual hydrogeochemistry and the geological evolution of an unconfined coastal aquifer located in a lowland setting in order to understand the drivers of the groundwater salinization. Physical aquifer parameterization highlights a vertical hydraulic gradient due to the presence of a heavy drainage system, which controls the hydrodynamics of this coastal area, forcing groundwater to flow from the bottom toward the top of the aquifer. As a consequence, relict seawater in stable density stratification, preserved within low permeability sediments in the deepest portion of the aquifer, has been drawn upward. The hydrogeochemical investigations allow identifying the role of seepage and water–sediment interactions in the aquifer salinization process and in the modification of groundwater chemistry. Mixing between freshwater and saltwater occurs; however, it is neither the only nor the dominant process driving groundwater hydrochemistry. In the aquifer several concurring and competing water–sediment interactions – as NaCl solution, ion-exchange, calcite and dolomite dissolution/precipitation, oxidation of organic matter, and sulfate bacterial reduction – are triggered by or overlap freshwater–saltwater mixing The hyper-salinity found in the deepest portion of the aquifer cannot be associated with present seawater intrusion, but suggests the presence of salt water of marine origin, which was trapped in the inter-basin during the Holocene transgression. The results of this study contribute to a better understanding of groundwater dynamics and salinization processes in this lowland coastal aquifer.