Matia Menichini

Surface-subsurface structural architecture and groundwater flow of the Equi Terme hydrothermal area, northern Tuscany Italy

A multidisciplinary integrated approach was used to study the structural architecture influencing the circulation pattern of geother -mal fluids in the Equi Terme area (NW Alpi Apuane, Tuscany). Geological-structural surveys were carried out to define the structural setting of the area and to characterize geometries and kinematics of fault systems. Chemical (major components) and isotopic analyses (δ18O‰, δ2H‰, 3H, δ13C‰[DIC], δ34S‰[SO4]) were performed on thermal water and cold springs. A geophysical survey was also conducted by means of both Magnetotelluric and Electrical Resistivity Tomography methodologies, in order to gain insight into the resistivity distribution at depth and to indirectly image the subsurface structure. This multidisciplinary approach proved to be a powerful tool, since it unravels the complexity of this natural geothermal system and provides useful suggestion for reconstructing the fluid circulation outflowing at the Equi Terme thermal spring. Results pointed out how the E-W oriented fault system (the Equi Terme Fault) play a key role in controlling the thermal groundwater outflow, and the chemical-physical features of this resource. This structural lineament separates high permeability carbonate complexes (footwall), in which both shallow and deep flow paths develop, from a medium-low permeability succession (hangingwall) that contains evaporitic formations from which thermal water acquires a high salinity and a composition of the Na-Cl (Ca-SO4) type. During the uprising along the fault system, the thermal water is also affected by a mixing with shallow fresh-cold waters that lead to a strong seasonal variation in the chemical-physical properties of the thermal springs.

Protection of Groundwater Resources: Worldwide Regulations and Scientific Approaches

The increasing role of groundwater in municipal water networks in many countries of the world makes the protection of groundwater resources an essential practice for safeguarding drinking water supplies. Several scientific-technical approaches are adopted worldwide to face this issue. In addition, some countries mainly depend on groundwater also for non-domestic use, making this topic even more critical. This chapter provides an overview of the main directives and their related technical aspects, concerning the protection zones of groundwater sources for human consumption. The main results of a multidisciplinary study are also presented, highlighting how the knowledge of physical and chemical aspects of groundwater bodies is a fundamental tool for protecting this vital resource and assuring its availability for the future generations.

Hydrodynamic and Geochemical Features of Metamorphic Carbonate Aquifers and Implications for Water Management: The Apuan Alps (NW Tuscany, Italy) Case Study

Carbonate rocks may be considered among the most important and strategic aquifers, given their widespread and the general high quality of groundwater flowing through them. Nevertheless, the karst systems developed within such aquifers promote conditions of high vulnerability to contamination and a high variability of groundwater flow rate, thus making the management of these water resources difficult. These critical features can be accentuated in metamorphosed carbonates, because of the massive structure of the rock that favours a low density of the karst network, and a preferential flow pattern throughout well-developed karst conduits. Furthermore, these rocks are often subject to quarrying and associated risk of pollution, mainly due to the fine slurry produced during marble cutting. This chapter presents the case of the Apuan Alps (NW Tuscany, Italy), where the main hydrogeological units are represented by metamorphosed dolostones and limestones (“Grezzoni” and marble, respectively), the latter being widely quarried to produce ornamental stones, as the famous Carrara marble. High-pressure ductile deformations and the consequent metamorphism have reduced the hydraulic conductivity of bedding surface, whereas the tectonic exhumation due to low-angle extensional faults has limited the development of diffuse fracture joints. For these reasons, an important subterranean storage of water is represented by epikarst porosity (unloading fissures and solution pockets) and vadose seepage, whereas in the epiphreatic and phreatic zones, the karst conduits have a high hydraulic conductivity but a low storage capability. Large flow rates and physical-chemical and isotopic variations, both in space and time, are observed at the springs as a consequence of differentiation of groundwater flow paths and hydrodynamic conditions. The main results derived from several years of study in the region are discussed in order to underline the high complexity of aquifer systems hosted in metamorphic carbonate rocks and to emphasize that multidisciplinary studies can provide knowledge useful for managing water resources in these very complex contexts.

Dal modello concettuale al modello numerico: il caso di studio del sistema acquifero di Follonica (GR, Toscana meridionale)

The groundwater body hosted in the Follonica coastal plain (Grosseto, Italy) is the Italian aquifer system that was chosen for the experimentation of the FREEWAT Platform, a collection of free andopen source software tools for water resource management and quantitative and qualitative modeling developed within the EU project Horizon 2020. In consideration of the studies carried out by the Institute of Geosciences and Earth Resources of the Italian National Research Council from 2006 to 2015 for the geological, hydrogeological and geochemical characterization of the 66 regional groundwater bodies (CIS), the Tuscany Region, partner of the project, has entrusted CNRIGG for the implementation of the numerical model.A conceptual model of the aquifer system was developed by processing and combining all the geological, hydrogeological and geochemical-isotopic data. The supposed hydrostructure was tested and validated through its 3D solid construction, defining the geometry and the physical limits of the multi-layered aquifer system and ensuring its coherence and consistency with respect to the other geographical databases. Hydrogeological and geochemical data processing ledto identify the aquifer system feeding components, the relationships between surface hydrography and groundwater and the main physical and chemical processes taking place (ion exchange, seawater ingress, etc). On this basis, the development and implementation of the flow model has started, based on the Modflow code.A focus group was organized as part of the project and stakeholders were involved with their active participation to the elaboration of the conceptual model by sharing data and other useful information.This paper describes the methodology used and the results obtained so far.

Un approccio integrato per la definizione della Zona di Protezione per captazioni idropotabili:applicazione su captazioni della Toscana, Italia@@@An integrated methodology to define Protection Zones for groundwaterbased drinking water sources: an example from the Tuscany Region, Italy

Water is an essential economic and social resource. It is also finite and vulnerable. For Europe, this generally accepted understanding has been translated into the European and National Directive (2000/60/EC, D.Lgs. 152/2006). This law has led to an increased awareness of the role of the resource and its importance in the socioeconomic, cultural, and political realms. To protect this resource, safeguard zones for drinking water sources must be delineated. In Italy, a drinking water source such as a well or spring is to be protected by means of a three-level safeguard zone: an absolute safety zone close to the source, a respect zone depending on groundwater travel time, and a Protection Zone. The aim of this paper is to describe an integrated methodology used to define the Protection Zone. The work, developed within the framework of a project of the Institute of Geosciences and Earth Resources (IGG-CNR) and funded by the Tuscany Region Administration through “Consorzio Lamma”, focused on the delineation of the Protection Zones for several abstraction points located throughout the regional territory. The proposed methodology for protecting drinking water sources described in this paper integrates geological, hydrogeological, and hydrogeochemical methodologies. The approach includes a definition of the hydrostratigraphy of the aquifer systems, estimates of the water volume, and the quantification of inflows and outflows, as well their interrelationships. By means of this integrated methodology, fifteen Protection Zones were defined; each of these zones was divided in two areas according to their relative importance to supplying a drinking water source. The Protection Zones were further validated by means of hydrogeological and isotopic budget calculations.

Modellazione numerica nell’acquifero costiero compreso tra il Canale Burlamacca ed il Fosso della Bufalina, Versilia Meridionale (Toscana, Italia)@@@Numerical modelling in the coastal aquifer between Burlamacca Canal and Bufalina Ditch,southern Versilia (Tuscany, Italy)

Groundwater numerical models are necessary instruments for management of water resources and for their protection, both in terms of quantity and quality. In this paper we present a study on an area located along the southern coastline of Versilia (Viareggio,LU) affected by marine intrusion. The main purpose of this work was to create a mathematical flow model based on a conceptual hydrogeological model defined by a multidisciplinary approach. For the realization of the numerical model the ModFlow code and the graphic interface Visual ModFlow was used. The procedure for defining the mathematical model involves a series of steps such as horizontal and vertical discretization of the space, the definition of the initial and boundary conditions, the assignment of the hydraulic properties of the cells and, finally, the definitions of external perturbations to the system (recharge, evapotranspiration, drainage and pumping wells). Implementation, development and calibration of the numerical flow model was performed both in steady and transient state. Both models were calibrated using the manual “trial and error adjustment” method using heads measurements. Moreover the model results gathered in transient state simulation were compared with the data continuously recorded by a piezometer of the monitoring network of the Regional Hydrological Service. There is a good correlation between the measured data and those calculated by the model which then turns out to be sufficiently representative and provides a solid basis for the development of a transport model that could be useful to control and manage the phenomenon of the salt water intrusion.