Sea level is the base level for groundwater circulation in coastal aquifers. The evolution of karst surface landforms and subsurface drainage systems in these aquifers has been conditioned in geological time by tectonics and glacio-eustatic sea-level changes. Present morpho-structural settings and the type/distribution of karst surface and subsurface forms have developed in different carbonate formations according to differences in lithology, climate and exposure time, all driving the intensity of morphologic and karst processes. The repeated and significant changes of groundwater level linked to “sea-level changes” have had the most important role in driving the continuous evolution of karstic drainage systems, and has resulted in most cases in a multiphase karst. This study aims at defining a general method for identifying, in karst coastal settings, the elevations of flat or low topographic gradient surfaces (using morphometric analysis of Digital Elevation Models (DEM) and GIS), and their comparison with elevations of distinctive karstic levels (passages, lateral solution cavities) observed in vertical shafts and horizontal caves. Of the elevations of flat or low topographic gradient surfaces only those agreeing, within ±10 m or ±20 m, with elevation ranges marked by the high frequency of distinctive karst levels were considered as representative of the more probable past sea-level stands. The method is applied to a regional coastal carbonate formation in Southern Italy, by using a 10 m DEM and information on 140 complex caves and 85 shafts. Of the 15 elevations indicated by DEM analysis (620, 600, 470, 450, 425, 385, 355, 315, 270, 250, 205, 180, 150, 110, and 70 m a.s.l.), 13 match clearly those highlighted by significant frequencies of distinctive karstic levels. These elevations are validated by comparison to the elevation of terraces and karst plains indicated in the literature.

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 strat- ification, 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 chem- istry. 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–salt- water 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.

The flow system in fractured aquifers is complex to define. A reliable outline of flow system in such a type of aquifers can be obtained by using natural tracers: among them, temperature demonstrates very effective. Convective thermal fields, resulting from convective disturb on conductive thermal field, can be rea-sonably interpreted like analogues of flow systems. A geostatistical approach by Ordinary Kriging has been applied to groundwater temperature data obtained from temperature logs performed in two fractured karstic and coastal aquifers (Murge and Salento) of Southern Italy. The variographic analysis shows the potential of the geostatistical approach in outlining regional and local scale anisotropies. Moreover, vertical and horizontal Ordinary Kriging temperature estimations at different depths allow recognizing main recharge areas and preferential flow-pathways.

The study is based on chemical data related to groundwater samples collected, via multilevel sampling technique, in four piezometers located along a flow line in the alluvial plain of the Po River (Italy). Multilevel pressure head measures highlight the presence of upward vertical gradients induced by the drainage system, used to reclaim the lowlands for agricultural purposes. The drainage causes the upward transport of salts due to the presence of hypersaline groundwater in the lowest portion of the aquifer. Chemical data show high TDS values almost in the entire coastal aquifer, with only small shallow freshwater lenses close to irrigation canals and palaeodunes. The aquifer structure and the paleogeography of the region, together with Br/Cl ratio, suggest that the hyperhalinity comes from solution of evaporite salts formed in inter-basins during the Holocene transgression, rather than from modern seawater intrusion or mixing processes with brines as confirmed by the relationships between the major ions of the groundwater samples, the seawater and the freshwater end-members. The chemical composition of groundwater in this lowland coastal aquifer appears to be controlled by several water-sediment interactions.

In 1930, a canal was excavated to connect the Lesina Lagoon with the Adriatic Sea, modifying the track of the previous existing Acquarotta canal. The 1100 m long stretch of the canal situated next to the coast exposed unknown highly cavernous gypsum bedrock underlying a loose sandy cover. During the last two decades, a large number of cover collapse and cover suffosion sinkholes have formed along two bands situated next to the canal, impinging the adjacent Lesina Marina residential area. The area affected by subsidence has increased exponentially from 1999 to 2009. The tight spatial correlation between the sinkholes and the canal reveals that the subsidence phenomenon has been induced by the local hydrogeological changes caused by the canal in the coastal evaporite aquifer: (1) Local lowering of the average water table. (2) Deflection of the groundwater flow lines towards the canal and increase in flow velocity. (3) Amplification of the groundwater level oscillations, largely controlled by the tidal regime. (4) Local reversals in the groundwater flow, changing the canal temporarily from effluent to influent. These changes in the hydrogeological functioning of the system have favoured both internal erosion and karstification rocesses. Hydrochemical evidence reveals that gypsum dissolution is a currently active process favoured by fresh water and sea water mixing and cationexchange processes. Most likely, the partial replacement of a concrete lining in the canal by pervious gabions in 1993 provided more adequate conditions for the evacuation of the sediments filling the karst conduits, accelerating internal erosion and sinkhole development.

I vulcani di fango, nelle loro varie tipologie e dimensioni, sono l’espressione di complesse fenomenologie ampiamente diffuse nel mondo, che determinano la fuoriuscita sulla superficie della terra o sul fondo del mare di fluidi e fango, in differenti contesti sedimentari e tettonici. Molti sono i vulcanelli di fango individuati e studiati anche in Italia nelle ultime decadi. La presenza, l’origine e le dinamiche evolutive di tali singolari morfologie e delle loro emissioni sono state riferite ad attività tettonica e sismica, alla presenza di gas nel sottosuolo, alla formazione di sovrappressioni nei fluidi sotterranei. I vulcanelli di fango presenti al confine tra i territori pugliese e lucano costituiscono argomento finora inesplorato. Essi risultano posizionati in prossimità del bordo orientale della Fossa Bradanica, punto di convergenza complesso di tre domini: il substrato carbonatico, con ampie distensioni in direzione W, i domini appenninici in sovrascorrimento verso NE, il riempimento clastico della fossa, caratterizzato da una successione plio-pleistocenica di argille azzurre e depositi costieri, coinvolto parzialmente nei processi deformativi dei due termini precedenti. Nel settore E della Fossa Bradanica lungo la fascia perimurgiana, compresa tra Matera, in Basilicata, e Gravina, in Puglia, sono stati individuati due vulcanelli di fango, uno nel territorio del Comune di Gravina in Puglia, l’altro nel Comune di Matera (Basilicata). La fenomenologia è sicuramente più ampia nei territori di tale bordo, ma priva di segnalazioni che permettano una loro precisa localizzazione e identificazione. Le prime osservazioni compiute sui vulcanelli presenti nelle argille azzurre hanno permesso di evidenziare una caratteristica lenta e continua attività del fenomeno eruttivo, connessa alla presenza di fanghi pressurizzati, riconducibili all’ingresso e al movimento di fluidi attraverso sistemi di fratture profonde nell’ammasso argilloso. Il presente lavoro fornisce una prima segnalazione ed interpretazione dei fenomeni di vulcanesimo sedimentario identificati in questi territori, con l’obiettivo di evidenziare la specificità dei sistemi nei quali essi si sviluppano, la coerenza di queste fenomenologie con altre rilevate nei territori in esame. Infine si ritiene molto importante promuovere tali fenomenologie come singolarità geologiche, da ascrivere al patrimonio naturale delle regioni che le ospitano.

Il dissesto idrogeologico è in Italia, insieme alle alluvioni ed ai terremoti, una patologia apparentemente senza tempo, a dispetto del titolo del presente convegno, che lo interroga tra il passato ed il futuro. Se fosse vera la relazione di dipendenza inversa nel tempo dell’intensità secondo la nota legge di potenza (Malamud et al. 2004), questa distribuzione di tipo statistico assolverebbe le responsabilità antropiche, per lo meno per gli eventi di grande intensità o magnitudo. Detto in termini più semplici, essendo il tempo di ritorno degli eventi maggiormente catastrofici molto lungo, questa circostanza sembrerebbe attenuare le responsabilità del mal governo del territorio (pratica che non può essere più lunga di circa 2000 anni sul verificarsi di tali eventi. In realtà grandi eventi catastrofici, vedi Vajont, i grandi wildfires dell’ultimo decennio, le spaventose erosioni costiere ed altri numerosi esempi, non confermano la deduzione derivata dal teorema precedente. La ragione risiede nella verifica dell’appartenenza dell’ ambiente alla categoria dei sistemi complessi: il che significa vedere le parti del sistema ambientale, non più separate in virtù di un gentlemen agreement a tutela di spazi accademici o corporativi da involucri impenetrabili, ma come elementi interagenti ed essi stessi a loro volta costituiti da sistemi complessi, non lineari e dinamici. Per completare la declaratoria, sistemi così fatti tipicamente devono essere guardati in scale spaziali e temporali diverse: la spiaggia può essere distrutta anche a dieci o più anni dalla costruzione di una diga a 100 km di distanza. Per quanto detto, dunque, le analisi devono essere spostate dalla dimensione (o scenario) dell’oggetto a quella del sistema e integrata con l’esplorazione delle complessità, ovvero delle specificità del sistema, che mettono in crisi i modelli noti e che, quindi, richiedono una revisione dei modelli o di loro parti (Canora et al. 2012c). L’amministrazione di un territorio su cui è posizionata una comunità passa dunque obbligatoriamente attraverso la fase di individuazione dei rischi afferenti a quel territorio, mirata in una fase successiva alla loro mitigazione, attraverso una fase di costi – benefici. Le maggiori difficoltà si incontrano generalmente nella prima parte, onde è necessario sezionare il percorso metodologico verso la misura del rischio, per individuare ed affrontare al meglio le complessità che si rivelano.

The relevance of the Carlantino large landslide, located in the Daunian sub-Apennine (Apulia, southern Italy) and extended for nearly 2 km from the hilltop down to the valley, is the presence of the town built-up area in the upper part and of a reservoir on the Fortore River, at the toe. The morphology of the area is affected by different landslides typologies as a consequence of a strong disten- sive tectonics, affecting Plio-Pleistocene sedimentary sequences and flysch formations. The most important points of interest related to the behaviour of the landslide, are the large extent of the land- slide body and the consequently coexistence in the upper, lower and lateral parts of asynchronous strain and stress fields. Temperature and conductivity logs carried out in several boreholes drilled along the slide, al- lowed tracing the preferential groundwater pathways and recognizing the groundwater feeding zones. The last investigation is related to the response, at the toe, of the seasonal changes of the reservoir level, in terms of kinematics and chemical interactions of freshwater with interstitial clay water.

Nell’area di Taranto depositi marini terrazzati coprono i sedi- menti fini di colmamento della Fossa Bradanica confinando l’acqui- fero carsico della Piattaforma carbonatica Apula. In tale contesto, le variazioni del livello del mare ed i suoi stazionamenti interagendo con i meccanismi idrogeologici, hanno contribuito a determinare dinami- che geomorfologiche ed idrogeologiche. Più in particolare, mentre gli studi geologici consentono una buona ricostruzione di tali processi nel lungo periodo, indagini storiche permettono un significativo ri- conoscimento di eventi determinati dalla Piccola Età Glaciale dello scorso millennio nell’area di interesse.

Based on the results of monitoring surveys carried out in the period 1995-1997 at the wells of the Regional Monitoring Net of Murgia aquifer (Puglia Region, Southern Italy), which includes two main recharge areas, a study was achieved with the aim of recognizing the mechanisms of recharge of the karst system. The knowledge of the recharge mechanisms is crucial in assessing the impact of pollutants on the quality of groundwater: given the complex karst system structure, the mechanisms can differ from place to place, resulting in a wide range of values of intrinsic vulnerability. Under the pressure of extreme rainfall events (intense and/or long term), the removal of water volumes and pollutants, stored in the different karst subsystems during a given period before an event, takes place at different times. In the recharge areas, monitoring shows different chemical characteristics of ground waters in the different periods. The cross-interpretation of precipitation pattern, hydraulic heads and chemical parameters (nitrates, total organic carbon and major constituents) allows formulating preliminary hypotheses about both the role played by the different sub-systems in the transfer of pollutants, and the duration of such transfer.

The objective of this work is to highlight the potentials of the Electrical Conductivity (EC) and Temperature (T) logs in seawater intrusion studies. EC logs (though discontinuous) have been carried out during a 40 year period along wells (OWS) specifically drilled for the control of seawater intrusion in the karst coastal aquifer of Salento (Southern Italy). The OWSs belong to the Regional Monitoring Network (RMN), which was established in the nineties for the control of groundwater quantitative/qualitative status. The net is presently intended for the objectives of the FWD 2000/60/EC. All the wells of the network are accessible to multi-parametric probes and samplers. The geo-statistical elaboration of T logs gives the distribution of aquifer temperature.

The application of a combined reactive transport - density dependent flow model to a real gypsum coastal aquifer (Lesina Marina, Southern Italy) is presented, with the aim of evaluating the potential of gypsum dissolution on sinkholes development. The area has been in fact highly susceptible to hazardous and rapid sinkhole formation since 1927, when a canal was excavated in an evaporite formation, strongly modifying groundwater flow patterns. To achieve this aim, firstly a conceptual model is defined, then a density- dependent, tide-influenced, flow model is set up and solved by means of the numerical code SEAWAT. Finally, the resulting transient flow field is used by the reactive multicomponent transport model PHT3D to estimate gypsum dissolution rate. The multi-disciplinary approach indicates that sinkhole formation in the Lesina Marina area, during the last 90 years, is scarcely connected to recent gypsum dissolution; rather, it is related to the erosion of paleo-cavities filling material (suffosion), caused by the new hydrodynamic conditions induced by the excavation of the canal within the evaporite formation.

The chemlcal and isotopic features of salt groundwaters in the Salento coastal karstic aquifer (Apulia, Southern Italy) reveal that they are very different from modem seawater. Chemical data allow identifying the role of water-rock interaction (Ca-Mg due to dolomitization, Na-Ca or Mg base exchange,SO4 reduction, solution of evaporite salts) in the modification of the chemical caracteristics of original seawater. 87Sr/86Sr isotope ratios and Sr indicate that salt water are very ancient and, given the structural features of this aquifer and the paleogeography of the region, they probably date back to the Flandrian transgression. Now findings in a thermal area overlooking the Adriatic Sea suggest new scenarios for the role of Ca-Cl2 brines,until now unknown.

We apply DInSAR PSI techniques to ascending and de scending data from ERS and ENVISAT satellites to extract relevant information about mean velocities of stable points located on the Lesina Marina area, a coastal tourist village in Southern Italy, where the excavation of a canal exposed grey micro and meso-crystalline gypsum which is now showing a high density of cavities and sinkholes due to gravitational collapse processes. We observe PS objects undergoing uplift displacements in all the processed data stacks. Derived vertical displacement rates exceed 3-4 mm/y on locations adjacent to the canal,gently decreasing towards the western end of the built up area. High-precision leveling measurements, performed in 1999 and 2010, are compared to the ENVISAT PSI data. Taking into account a constant offset reference ve- locity value of the PSI data, the differences in velocity measurements exhibit a statistical dispersion around 1-2 mm/y. These observations, supported by ancillary data and in situ investigations performed in the past, seem compatible with processes such as diapirism or the hydration of the residual anhydrite in the core of the gypsum mass.