Groundwater-surface water interaction revealed by meteorological trends and groundwater fluctuations on stream water level

The importance of considering groundwater (GW) and surface water (SW) as a single resource of two interconnected components has rapidly increased during the last decades. To investigate GW-SW interaction in an aquifer system exploited by several pumping wells, an integrated continuous monitoring of the hydrological conditions was carried out. The sub-catchment (14 km2), located in the Aspio basin near Ancona (Central Italy), is drained by a small stream named Betelico, and it is characterised by the presence of an unconfined alluvial aquifer and a semi-confined limestone aquifer. The aim of this study is to evaluate the drivers of stream drying up occurred during the last couple of years. This has been achieved by applying a trend analysis on rainfall, air temperatures, piezometric and stream level, and well pumping rates. Precipitation trends were analysed over a 30-years period through the calculation of the Standard Precipitation Index (SPI) and through heavy rainfall events frequency plots, while the correlation between piezometric stream levels and pumping rate was analysed during the last six years. The groundwater level was compared with the stream baseflow level, highlighting the interconnection between GW-SW over the years. The analysis on the water surplus (WS) trend, together with the rainfall events characterisation, supports the hypothesis of the decrease in recharge rate as the main driver of the stream drying up. This case study stresses the importance of studying GW-SW interactions in a continuously changing climatic context characterised by a decreasing precipitation trend, coupling both the advantages of a robust method like trend analysis on time series and the field continuous monitoring

The new engineering geological map (carta litotecnica) of Tuscany (Italy)

Municipal administrations in Italy must be provided with thematic maps and documentation which describe the geological, geomorphological, lithological, hydrogeological and hydraulic characters useful to manage spatial planning issues. Among these documents, a “Lithotechnical” (or “Lithological-Technical”) map is drawn up, generally at the scale of 1:10,000, by organizing the geological formations into lithotechnical units according to their lithological and physical-mechanical properties. Often, this map also integrates the results of previous field and borehole investigations. However, this map is characterized by a certain degree of subjectivity because it is supported by few specific quantitative data. We present a new method for the regional scale engineering geological classification of sub-surface rock and soil masses obtained by integrating the geological map at the scale of 1:10,000 as a reference document, with a large set of data obtained through the collection and processing of new lithological and physical-mechanical observations and measurements of the outcropping geological formations. The adopted procedure involves both the extensive in situ use of the Schmidt's hammer and the execution of laboratory tests, such as the Slake Durability Test (Franklin & Chandra, 1972) and the determination of the rock unit weight. These tools and tests allow us to acquire a large set of quantitative in situ and laboratory data with known repeatability to obtain a regional scale GIS database providing the classification of the lithological and physical-mechanical characteristics of a wide range of geological formations. As a first step, each outcrop is classified according to a new engineering geological nomenclature system described by the code XXv[y]_[Z] whose values are obtained by integrating: i) a lithological parameter XXv evaluated from both typical characters of the geological formations under analysis and outcrop observations; ii) an engineering geological parameter [y] obtained by the results of the Slake Durability Test; iii) an engineering geological parameter [Z] (Rockmass Quality Index - RQI) evaluated at the outcrop scale on the basis of a large set of sclerometric measurements. The results of outcrop classification are stored into a point topology GIS dataset and are then processed and spatialized in order to assign the XXv[y]_[Z] code to the geological formations, thus obtaining the new engineering geological map. Within the framework of research agreements among Regione Toscana administration, the Consorzio LaMMA, the CNRIGG and the Department of Earth, Environmental and Physical Sciences of the University of Siena, the latter being the leader for their implementation, more than 300 geological formations were analysed and classified, and the new engineering geological GIS map was realized in Tuscany for the provinces of Arezzo, Florence, Lucca, Massa-Carrara, Pistoia, Prato and Siena (ca. 15,000 km2)

A Holistic Approach to Study Groundwater-Surface Water Modifications Induced by Strong Earthquakes: The Case of Campiano Catchment (Central Italy)

Carbonate aquifers are characterised by strong heterogeneities and their modelling is often a challenging aspect in hydrological studies. Understanding carbonate aquifers can be more complicated in the case of strong seismic events which have been widely demonstrated to influence groundwater flow over wide areas or on a local scale. The 2016–2017 seismic sequence of Central Italy is a paradigmatic example of how earthquakes play an important role in groundwater and surface water modifications. The Campiano catchment, which experienced significant discharge modifications immediately after the mainshocks of the 2016–2017 seismic sequence (Mmax = 6.5) has been analysed in this study. The study area is within an Italian national park (Sibillini Mts.) and thus has importance from a naturalistic and socio-economic standpoint. The research strategy coupled long-period artificial tracer tests (conducted both before and after the main earthquakes), geochemical and discharge analyses and isotope hydrology with hydrogeological cross-sections. This study highlights how the seismic sequence temporarily changed the behaviour of the normal faults which act predominantly as barriers to flow in the inter-seismic period, with water flow being normally favoured along the fault strikes. On the contrary, during earthquakes, groundwater flow can be significantly diverted perpendicularly to fault-strikes due to co-seismic fracturing and a consequent permeability increase. The interaction between groundwater and surface water is not only important from the point of view of scientific research but also has significant implications at an economic and social level

A new approach for engineering geological mapping of subsurface rock masses by means of fieldwork-based rebound hardness indexes and non-parametric Bayesian networks

I sistemi di classificazione degli ammassi rocciosi noti in letteratura sono numerosi. Tuttavia, si tratta in genere di sistemi sito-specifici che valutano e integrano una serie di fattori, tra cui l'assetto strutturale e la variabilità locale della litologia, della fratturazione e delle proprietà fisico-meccaniche delle rocce, risultando quindi estremamente dispendiosi per la loro applicazione e non adeguati per analisi e classicazioni di ammassi rocciosi su vaste aree (a scala regionale). In questa tesi di dottorato, viene proposto un metodo relativamente rapido di valutazione della qualità degli ammassi rocciosi basato sulla raccolta di misure in-situ. Il metodo viene implementato su un'ampia area di studio (circa 3.000 km2) situata nell'Appennino settentrionale, al fine di dimostrare la capacità di descrivere la variabilità spaziale della qualità dell'ammasso sub-superficiale. Durante un intenso lavoro sul terreno, della durata di oltre un anno, sono stati sottoposti a misura oltre 700 afforamenti rocciosi sub-superficiali attraverso l'utilizzo del martello di Schmidt e di Equotip. Questi due strumenti, noti in letteratura, sono utili alla determinazione della resistenza dei materiali. E' stata riconosciuta una correlazione molto buona (r = 0.83) tra i due dispositivi. La qualità degli ammassi rocciosi in-situ è stata valutata attraverso un indice di qualità (Rsite(obs)). Durante le attività di campagna sono state talora riscontrate problematiche di acquisizione del valore di rimbalzo R del martello di Schmidt in condizioni di rocce alterate e fratturate. Al fine di stimare questo valore, è stato applicato un approccio probabilistico su un sottoinsieme di 20 siti utilizzando reti Bayesiane non parametriche (NPBN). Il modello Bayesiano mostra una migliore accuratezza rispetto ad un'analisi di regressione lineare multipla, utilizzata per confrontare i due diversi approcci. Rsite(obs) è stato confrontato con GSI, uno degli indici più noti e utilizzati in geomeccanica, ottenendo buone correlazioni. Successivamente è stata messa a punto una procedura basata sull'integrazione di clustering, analisi morfometrica multiscala e modelli Bayesiani al fine di interpolare il dato puntuale di campagna a scala regionale. La spazializzazione si è focalizzata sulla formazione geologica più estesa dell'area di studio: il flysch arenaceo della formazione del Macigno (Oligocene - Miocene inferiore). I risultati hanno evidenziato che i cluster individuano tre regioni diverse per caratteristiche geo-strutturali connesse alla tettonica estensionale Neogenica. Inoltre, per un cluster specifico (regione sud-orientale dell'area di studio, approssimativamente all'interno della provincia di Pistoia), la strategia di selezione dei siti di misura ha consentito di analizzare le relazioni tra condizioni morfologiche e (Rsite(obs)). I risultati evidenziano che la varianza di Rsite(obs) può essere parzialmente descritta dalla morfometria della terra solida. Le procedure e le tecniche sviluppate durante questa ricerca di dottorato hanno in definitiva consentito di ottenere un nuovo approccio per la realizzazione di cartografia litologico-tecnica, la quale può essere di utile supporto alla progettazione ingegneristica di opere e l'implementazione di modelli numerici di stima della suscettibilità da frana. Many geomechanical classification systems for rock masses have been developed in the literature for geological applications. Nevertheless, these are site-specific systems evaluating and explicitly including the effects of structural setting and local variability of lithology, jointing and physical-mechanical properties of rocks. Hence, they are extremely time consuming and not adequate in order perform analyses and rock mass classifications of geological formations over wide (regional scale) areas. In this PhD thesis, an expeditious method based on collection of quantitative fieldwork hardness measurements is proposed and implemented in order to demonstrate its capability to describe the variability of subsurface rock masses quality at the regional scale. The capability of the method was assessed and demonstrated for a study area of about 3,000 km2 located in the Northern Apennines (Italy). A set of more than 700 subsurface rock mass outcrops representative of different structural and lithologic conditions underwent measurement by means of the Schmidt hammer (SH) and Equotip (EQ) sclerometers during an intensive fieldwork of more than one year. A good correlation (r = 0.83) between the two devices has been found. Nevertheless, the Schmidt hammer is known to be unsuitable for application to weak rocks, where the impact energy is dispersed in rupture or plastic deformation, resulting in a "missing" R measurement. In contrast, the Equotip, cause its lower impact energy (1/66 of the Schmidt hammer) has been found more suitable for measuring weathered, fractured and weak rocks. In order to predict values under the lower threshold of the Schmidt hammer (R < 10), a probabilistic approach by using non-parametric Bayesian Networks (NPBNs) has been applied on a subset of 20 measurement sites. The model has better accuracy in respect to a multi regression analysis, used to make comparison between the two different approaches. By this method, a correction factor for the R values has been calculated for correcting all the SH measurements affected by inoperability of the SH. The corrected SH measurements and the non-corrected measurements (Rj(obs)) are used to compute the median value for each site (Rsite(obs)), an index representing the quality of rock masses. Rsite(obs) has been compared to other rock mass quality indicators known from the literature like the Geological Strength Index (GSI), one of the most known and frequently used indexes describing the actual geostructural conditions of the rock mass. Good correlations between Rsite(obs) and the GSI have been found and discussed for two of the most widespread geological formations within Northern Apennines: the Macigno formation and the Monte Ottone Flysch formation. With the aim to obtain a continuous (regional scale) representation of the Rsite(obs) values, a procedure based on the integration of clustering, multiscale morphometric analyses and Bayesian inference modelling has been implemented. At first, clustering analysis of point measurements was performed on the arenaceous flysch of the Oligocene-Lower Miocene Macigno formation (MAC). Results showed clusters following three large regions which are well related with the geometry of the main geo-structural features characterizing the study area. Moreover, for a specic cluster (SE region of the study area, approximately within the Pistoia province) the strategy for measurement sites location allowed to analyse data collected on both flat ridges and steep slope areas. Here, the results highlight a relationship between Rsite(obs) and morphometric parameters, suggesting that variance of Rsite(obs) may be partially described by landscape morphometry. Thus, a multiscale morphometric analysis has been performed in order to obtain the kernel sizes providing the best correlation with Rsite(obs). Scenarios of the final engineering geological map were obtained, through a Bayesian Network approach based on the Rsite(obs) measurements as well as land morphometric parameters. The effects of raster data down-sampling were also assessed

La "Ferriere-Mollieres Shear Zone" (Massiccio dell'Argentera, Alpi Occidentali): rilevamento, analisi strutturale e cinematica del flusso nella zona di Ferrere (Argentera, CN)

La Ferriere-Mollieres Shear Zone (FMSZ) è una zona di taglio localizzata nel Massiccio Cristallino dell’Argentera (Alpi Occidentali), il più Occidentale dei Massicci Cristallini Esterni. E’ orientata NW-SE e si estende per circa 30 km dall’abitato di Ferriere (CN) fino all’abitato di Mollières (Francia). Questa zona di taglio è interposta tra due complessi migmatitici di alto grado metamorfico entrambi di età varisica, rispettivamente il complesso Gesso-Stura-Vesubie ad Est ed il complesso Tinèe ad Ovest, ed è posta al di sotto delle coperture sedimentarie Permo-Triassiche ed Elvetico-Delfinesi. Lo scopo della tesi è stato quello di cartografare in dettaglio (scala 1:5000) una porzione della zona di taglio di circa 24 km2 di estensione, situata tra i Valloni di Ferrere e di Pontebernardo, e di caratterizzare la cinematica del flusso ad essa associato. Al rilevamento geologico strutturale è stata affiancata l’analisi delle microstrutture e degli indicatori cinematici associati alla zona di taglio. Su campioni opportunatamente selezionati è stato svolto uno studio della vorticità cinematica e delle deformazione finita. L’analisi mesostrutturale ha evidenziato che la FMSZ è una zona di taglio duttile ad alta deformazione, caratterizzata da una foliazione penetrativa con orientazione N110-130, immersione prevalentemente verso NE, e lineazioni mineralogiche inclinate di 20-30° verso NW. La cinematica è prevalentemente destra, con un senso di movimento top verso SW. La deformazione milonitica interessa micascisti a biotite e sillimanite, micascisti a clorite e mica bianca, leucograniti, e le migmatiti dei due complessi adiacenti. All’interno della zona di taglio è stato possibile riconoscere una variazione di deformazione con lo sviluppo di protomiloniti, miloniti, ultramiloniti e filloniti passando dalle zone più esterne alle zone a massima deformazione al nucleo della zona di taglio. Sulla foliazione milonitica è stata riconosciuta la ricristallizzazione sincinematica di sillimanite e biotite. Nei micascisti è presente cristallizzazione di clorite e mica bianca sulla foliazione milonitica. Le coperture sedimentarie Permo-Triassiche giacciono in discordanza stratigrafica al di sopra delle miloniti, ad eccezione di una lente decametrica, interessata dalla milonitizzazione, ed inglobata nei micascisti a clorite e mica bianca milonitici. Ciò ha permesso di ipotizzare età varisiche per l’attivazione della FMSZ, successivamente localmente riattivata in età alpine anche con il coinvolgimento delle quarziti Permo-triassiche. Al di sopra dei depositi Permo-Triassici, marcati dalla presenza di una breccia tettonica, poggiano i termini della Successione Sedimentaria Elvetico-Delfinese. L’analisi della vorticità cinematica è stata eseguita sia con il metodo PAR (Passchier, 1987) che con il metodo delle Shear bands tipo C’ (Kurz e Northrup, 2008). Entrambi i metodi hanno messo in evidenza la presenza di una forte componente di taglio puro variabile tra il 59-63% e il 59-79%, rispettivamente per il primo e secondo metodo. Le analisi della deformazione finita, effettuate con il metodo di Fry hanno evidenziato un ellissoide di tipo oblato. Combinando i dati di vorticità cinematica e di deformazione finita seguendo Wallis et alii. (1993) è stato stimato un raccorciamento perpendicolare ai limiti della zona di taglio del 20-28% ed un allungamento parallelo ai limiti del 26-39%. I dati raccolti sono in accordo con lo sviluppo della FMSZ in un regime transpressivo dominato da taglio puro, con cinematica destra top verso SW. La sua attivazione potrebbe essere riconducibile all’evento collisionale dell’Orogenesi Varisica, che ha provocato la migmatizzazione dei due complessi (datata a 323±12 Ma, Compagnoni et al., 2010) e la messa in posto dei leucograniti datati a 327±3 Ma (Musumeci e Colombo, 2002). Successivamente alcune porzioni sarebbero state riattivate in età alpina, come mostrato dalle quarziti Permo-Triassiche milonitizzate. In un contesto regionale più ampio la FMSZ potrebbe rappresentare una porzione della East Variscan Shear Zone, una zona di taglio regionale destra top verso SW lunga circa 1500 km, attivatasi dal Carbonifero medio al Permiano, osservata anche negli altri Massicci Cristallini Esterni, nel massiccio dei Mauri, in Corsica e in Sardegna

Tritium as a Tracer of Leachate Contamination in Groundwater: A Brief Review of Tritium Anomalies Method

Environmental isotopes are essential in hydrogeological studies, thanks to their contribution to the understanding of aquifers dynamics, vulnerability, water resources assessment, and management issues. The environmental isotopic approach plays a vital role in tracing the hydrological cycle and identifying various sources of contamination in the environment and gives independent information concerning what can be determined by a traditional hydrogeological study. Even in the framework of COP-26, isotopes have been indicated as fingerprints of climate change and therefore suitable for the evaluation of water balance and assessment of processes involved therein; in pollution studies they are used as fundamental support of traditional geochemical measures. Tritium, in particular, has been used since the 1960s to identify potential leaks in the containment walls of waste disposal sites, since its presence in the leachate (at very high levels in some cases) depends on the incorrect waste disposal of some peculiar items. Its use as a tracer of pollution by landfills is highlighted and emphasized by the very low concentrations of tritium in the natural environment. By comparing tritium content of leachate to that of water downflow from the waste disposal site, it is therefore possible to establish with a good success rate whether leachate have migrated or not out of the landfill, in the surrounding environment. An additional potential of tritium is to give a prompt indication of pollution risk in the environment indicating leaching even before the chemical indicator of pollution can be detected. This article wants to provide a contribution to the scientific community, collecting all the existing research in this field and providing data and benchmarks about this method, in particular stressing the role of tritium as an indicator of leachate transfer out of waste disposal sites

WaterbalANce, a WebApp for Thornthwaite–Mather Water Balance Computation: Comparison of Applications in Two European Watersheds

Nowadays, the balance between incoming precipitation and stream or spring discharge is a challenging aspect in many scientific disciplines related to water management. In this regard, although advances in the methodologies for water balance calculation concerning each component of the water cycle have been achieved, the Thornthwaite–Mather method remains one of the most used, especially for hydrogeological purposes. In fact, in contrast to physical-based models, which require many input parameters, the Thornthwaite–Mather method is a simple, empirical, data-driven procedure in which the error associated with its use is smaller than that associated with the measurement of input data. The disadvantage of this method is that elaboration times can be excessively long if a classical MS Excel file is used for a large amount of data. Although many authors have attempted to automatize the procedure using simple algorithms or graphical user interfaces, some bugs have been detected. For these reasons, we propose a WebApp for monthly water balance calculation, called WaterbalANce. WaterbalANce was written in Python and is driven by a serverless computing approach. Two respective European watersheds are selected and presented to demonstrate the application of this method

Defining a Non-Destructive In Situ Approach for the Determination of Historical Mortar Strength Using the Equotip Hardness Tester

The determination of mechanical parameters of historical mortars is a crucial aspect in the analysis of masonry in ancient buildings, especially for evaluating their quality and planning the appropriate restoration interventions. Due to conservation reasons, creating a comprehensive database is generally not possible because cutting out masonry specimens relates to damaging historical structures. This study starts with the need to characterize the mortar quality of different buildings in the town of Camerino (Central Italy) which has been strongly damaged by the 2016–2017 seismic sequence. A non-destructive collecting data strategy based on the use of the Equotip hardness tester (EQ) has been set up by evaluating the most appropriates impact strategy (single or repeated) and the range of measurements to calculate the basic statistics. The seismic damage suffered by the buildings allowed the rare opportunity to take samples from several walls and carry out laboratory tests to determine their Uniaxial Compressive Strength (UCS). The comparison between the results of the two types of tests made it possible to calibrate a relationship between the EQ values and the UCS. The Pearson’s coefficient of determination derived from an exponential interpolation (R2 = 0.81) confirmed a strong relationship between the EQ values derived from the tests on the specimens and the UCS. Moreover, comparing the in situ EQ measurements with the ones performed on the specimens prepared for the compressive tests, a general underestimation of the in situ EQ values has been observed, possibly due to the presence of a superficial alteration layer of the exposed mortar. From these results, we propose a correction of the in situ measurements able to obtain a more appropriate strength estimate of the historical mortars