Polemio, Maurizio

The literature contains many examples, which demonstrates the importance of climatic conditions, particularly of rainfall but also temperature, on landslide activation. Normally landslides occur during specific hydrologic conditions; the relative importance of each factor will however vary with the landslide type. Heavy rains are one of the main natural factors producing landslides as they may cause pore pressure to increase on slopes or can create adverse seepage conditions, modify the slope's geometry as a result of erosion and originate swelling and softening processes in clay soils. According to their different behaviour, it is necessary to distinguish shallow or deep-seated landslides, first-time or reactivated landslides, the nature of landslide body (terrain or rock) as well as the hydrogeological nature of soils. Shallow landslides in soils and weathered rocks are often generated on steep slopes during the most intense part of a storm (lasting from minutes to several hours). The higher permeability of the outermost portion of the slope, compared to the bedrock below, allows for the creation of a temporary perched water-table, inducing the progressive increase of pore-water pressure. On the other hand, deep-seated landslides can be mobilised as a consequence of moderate intensity rainfalls lasting several days, owing to the longer recharging time required for ground-water level to rise and cause a significant build up in pore-water pressure. Pioneer studies, concerning landslides triggered by rainfalls, go back to '30s. Were selected 138 papers and key information was collected in a database. Nearly 82 % of all records are local investigations carried out in 23 countries. Italy provides the largest sample as for author’s nationality and widespread proneness to landslides; followed by United States (15 %), Hong Kong (8 %), Japan and United Kingdom. Two main approaches have been used to investigate rainfall-induced landslides: -empirical or semi-empirical relationships, using statistical correlation and forecasting techniques; -deterministic modelling of groundwater recharge and pore-water pressure changes. Studies concerning the first type of approach have reached interesting results about combination of antecedent rainfall and rainstorms intensity able to trigger widespread soilslip activation in specific geological, morphological and climatic settings. Relationships between rainfall intensities and duration associated with shallow landslides and debris flows activation has also been found and they are often used for warning purposes. For the activation of widespread mass movements, some authors underline the role of an effective rainfall period ended by a pronounced increased of rainfall intensity; in this situations hazard precursors may be considered as a combination of cumulate rainfall and rainfall intensity. The second approach requires the development of a clear picture of the modes of water flow on and below the ground surface: where groundwater flow is concerned, attention is focused on both the saturated and the unsaturated zones and complete hydrological models of slopes must be defined. The present paper is a critical overview of recent international research activity on this subject. Methods and experiences are compared and classified. Some author's direct experiences are utilised for these purposes.

La nota ricostruisce la serie dei principali fenomeni di dissesto idrogeologico registrati in epoca storica nel territorio comunale di Gerace (Calabria sud-orientale) e analizza i rischi di degrado del patrimonio storico-artistico connessi all’innesco di tali fenomeni. L’analisi degli eventi pregressi e delle attuali condizioni del centro abitato, effettuata considerando anche gli interventi realizzati a protezione dell’edificato, consente di trarre alcune indicazioni sulle più probabili tipologie di dissesti attesi, nei diversi settori dell’abitato, in occasione di eventi pluviali estremi.

The coastal karstic aquifer of Mt. Oyramanges (1864 m asl) is located in the Vlora Bay, along the Adriatic coast. The quality of the spring water there is so high that it is used to supply the drinking supply of the second largest Albanian town, Vlora. Starting from a geological and tectonic conceptualization of the area, a GIS approach based on long-term rainfall, temperature and river yield time series has been used to define hydrologic balance. The assessment of recharge and the measurement of sub-aerial spring discharge permit the rough assessment of submarine groundwater discharge. The definition of the flow domain and of groundwater chemical features is pursued with an on-going survey which includes chemical and isotopic analyses of rainfall, groundwater and sea water.

This work is based on data acquisition and analysis of chronology sequences of piezometric, rainfall and thermometric data of Apulian aquifers. Methods of time series analysis are used. This approach has allowed characterising the piezometric regime and trend related to the natural recharge variation.

The coastal carbonate Apulian aquifers, located in southern Italy, feed numerous coastal cold springs and constitute the main local source of high quality water. The group of Santa Cesarea springs constitutes the unique occurrence of thermal groundwater outflow, observed in partially submerged coastal caves. The spring water is rich of hydrogen sulfide; temperature ranges from 25 to 33 C°. For their properties, spring waters are used for spa activities from several decades. Hydrogeological spring conceptualisations proposed up now were not able to justify water geochemical peculiarities or were not completely confirmed up now. To reduce these uncertainties, a complex hydrogeological survey has been defined. Geological and structural surveys, chemical and isotopic groundwater analyses, spring and well discharge measurements, well loggings, multi-parameters spring automatized measurements, and cave explorations are ongoing. All available data have been used to improve the knowledge of groundwater flow system, including the valuable deep aquifer, the origin of the thermal waters, and to investigate the possibility of using low-enthalpy geothermal fluids to fulfil the thermal needs of the town of Santa Cesarea Terme.

l territorio murgiano-salentino, data la sua natura prevalentemente carsica, è praticamente privo di risorse idriche superficiali; d’altra parte lo stesso è dotato di risorse idriche sotterranee anche notevoli, che hanno a tutt’oggi consentito, per vaste aree, lo sviluppo delle attività produttive. La natura di tali risorse idriche sotterranee, le particolari fenomenologie che regolano i processi di alimentazione, di deflusso e di svuotamento nonché l’influenza esercitata dal mare, rendono quanto mai delicato il problema di una oculata gestione e di un corretto impiego delle acque sotterranee. Sono dunque di attualità i problemi relativi alla degradazione delle acque sotterranee, sia per fenomeni di contaminazione salina che per fenomeni di inquinamento antropico, derivanti dalla pratica di utilizzare il sottosuolo come ricettacolo di reflui anche non trattati. La corretta gestione e tutela del patrimonio idrico sotterraneo rappresenta quindi un obiettivo prioritario da perseguire a breve termine; a tal fine si fa ricorso a due tipi di approccio, attuati a diversa scala: a scala regionale si opera un controllo continuo dei fenomeni evolutivi che interessano la disponibilità e la qualità delle risorse idriche sotterranee; a scala locale, con il massimo dettaglio, si studiano le iniziative di tutela delle acque sotterranee di maggior pregio destinate al consumo umano attraverso la delimitazione delle aree di salvaguardia.

The aim of this work is to highlight the influence exerted by meteoric events on landslide triggering. Taking into account the main geomorphological and hydrogeological features at the mass movements, simple hydrological/statistical methods are suggested. Cumulative daily rainfalls over 1 to 180 days are studied to determine probability distribution functions. Hence the critica1 rainfall period is determined for a specific landslide and the return period of the hydrological event associated with the landslide is quantified.

The main aim of study is the evaluation of water resuorces, the vulnerability and the definition of groundwater flow outline of carbonate aquifer of Volturino arid Calvelluzzo Mounts (Basilicata, Southern Italy). The aquifer vulnerability map is presented and discussed. Many parameters, as defined for SINTACS method, were used (lithology, fracture density, effective rainfall, slope, …).

Carbonate aquifers, located in foreland tectonic settings, could represent important thermal water resources outside the volcanic areas, supplying spas or geothermal installations. Thermal springs constitute the discharge areas of deep marine and continental groundwaters flowing within these carbonate aquifers whose hydraulic conductivity and the relevant geothermal fluid migration are strictly controlled by both the discontinuity network and the karst processes involving the foreland environment. An example of these springs occurs along the south-easternmost portion of the Apulia region (Southern Italy) where some sulphurous and warm waters (22-33 °C) flow out in partially submerged caves located along the coast, thus supplying the spas of Santa Cesarea Terme. These springs are known from ancient times (Aristotele in III century BC) and the physical-chemical features of their thermal waters resulted to be partly influenced by the sea level variations. Some hypotheses about the origin of these warm waters were proposed up to now by previous researches but some uncertainties still exist. For this reason, the area has been selected in order to define the conceptual model of the geothermal resources related to the thermal springs and, as a consequence, the origin of the thermal springs. It is one of the pilot site of the Vigor Project (Evaluation of the geothermal potential of Regions of Convergence), promoted by the Italian Ministry of Economic Development and National Research Council. Santa Cesarea Terme zone is located within the Apulia carbonate platform, the foreland of the southern Apennines, which consists of Jurassic-Cretaceous limestones, thick more than 5 km in the study area and affected by intense karst processes, resting above the Late Triassic evaporite (Burano Fm) and, unconformably, overlaid by Cenozoic calcareous successions. Belonging to a coastal area, the studied groundwater, whose top is located almost to the sea level, is involved in saltwater intrusion and therefore the salt-fresh water interface occurs at some meters below the sea level moving inland. Geological and hydrogeological surveys, including geo-electrical prospecting, and chemical and isotopic analyses of both groundwater and seawater have been carried out. Stable isotopes (δ18O, δD) were used to define the origin of the thermal waters and the recharge mechanism of the geothermal systems while the unstable isotope (3H) was determined for estimating the age of the thermal waters and to define the conceptual model of this low temperature geothermal resource. All the data have been analysed to improve the knowledge of the groundwater flow system, thus assessing the possibility of using low-temperature geothermal fluids to fulfil the thermal needs of the town of Santa Cesarea Terme. In this narrow area, the source of geogenic salinization of spring groundwater was referred to ascending very deep groundwater, more saline than current sea water.The geochemical composition and the physical features of the sampled waters suggest that thermal waters should be moving from ancient seawaters subjected to intense evaporation processes, infiltrated at great depth within the seabed substratum. Afterwards, these thermal fluids should flow up through the almost vertical structures, related to the transtensional structures, identified within a narrow sector of the studied territory.

A methodology is proposed for groundwater quality classification, using a restricted number of analytical parameters (chemical-physical and not desirable substances). For Apulian aquifers, the authors experiment and modify previous scientific experiences in relation to the hydrogeological specific setting.