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Alpine ski resorts attract large temporary populations at relatively high altitudes, causing both urban and ski infrastructure development in ecologically vulnerable regions frequently subject to geo-hydrological risk. This study deals with the impacts of urbanization comprising housing, roads, parking and heliports, impacts of ski runs such as slope grooming and drainage and impacts of artificial snow production for example snow grooming, water storage reservoirs and water pipelines in the French and Italian Alps. Ski resort infrastructure is both at risk from natural hazards including landslides, rockfalls, avalanches and floods and from artificially induced hazards related to artificial snow infrastructure and ski slope manipulation for instance landslides, debris flows and erosion. Managing such risks is often only partially successful after 4-5 decades, however many impacts are irreversible. Climate change and intensification of ski resort development is likely to increase geo-hydrological risks in future.

Catastrophic floods or mass movements occur all too often owing to small streams overflowing their banks or to slope instabilities whose evolution has a more or less tragic impact on people and property; these events are the consequence of a poor understanding of the dynamics of geomorphological processes and of the laws governing them. This paper is focused on the case study of Castellammare del Golfo, a town in the province of Trapani. The study analysed the geological risk due to the geomorphology of the area and to the urban sprawl that it has experienced in the past decades. Geomorphological processes have a strategic role to play in spatial planning and management instruments and in their adaptation. Geomorphological dynamics may evolve over timescales comparable with those of human life, interfering with it and affecting the socio-economic development of the communities involved. Geomorphological and hydrological research studies are useful tools of analysis, not only to suggest appropriate rehabilitation works, but also to prevent the recurrence of events whose consequences are not always predictable, but increasingly calamitous.

La valutazione dello stato di conservazione di biodiversità, funzioni e servizi degli ecosistemi di acque interne e la stima della loro vulnerabilità ai cambiamenti climatici sono affrontate considerando tipologie omogenee di ecosistemi acquatici, alla scala integrata del bacino idrografico e della zona di transizione adiacente. Gli ecosistemi acquatici sono ripartiti, secondo uno schema tradizionale, in: bacini fluviali, laghi, zone umide e acque lentiche85 di piccole dimensioni, ecosistemi dipendenti dalle acque sotterranee (Groundwater Dependent Ecosystems - GDE) e ambienti di transizione a mare. I bacini fluviali e i laghi sono inoltre analizzati nel contesto della regione geografica cui appartengono, assumendo che vi siano associate diverse pressioni e minacce derivanti dai cambiamenti climatici. I cambiamenti climatici hanno effetti diretti sulla fenologia e sulla distribuzione delle specie che si manifestano in seguito a modificazioni della durata delle fasi di crescita, anticipazione o ritardo nelle migrazioni, sfasamento dei cicli vitali di predatore e preda, e migrazione verso nord e verso monte delle specie sensibili all’aumento di temperatura. Negli ecosistemi acquatici queste perturbazioni sono causate non solo dall’aumento della temperatura, ma anche dalle variazioni del regime idrologico e delle proprietà fisiche delle masse d’acqua. Tra gli ecosistemi a maggiore vulnerabilità si annoverano le acque lentiche di piccole dimensioni, i GDE e i laghi d’alta quota, e i corsi d’acqua appenninici e delle isole maggiori, sui quali già insistono pressioni importanti per l’elevato tasso di sfruttamento del territorio e delle risorse idriche. La vulnerabilità dei grandi corsi d’acqua dipende dall’interazione tra le pressioni locali (uso del suolo, urbanizzazione, alterazioni idro-morfologiche), le variazioni del regime idrologico e la gestione delle risorse idriche. Attualmente si segnalano problemi legati al dissesto idromorfologico dei corsi d’acqua, al deflusso residuo a valle delle derivazioni idriche, alle variazioni improvvise e intense delle portate dovute all’esercizio delle centrali idroelettriche (hydropeaking), all’inquinamento delle acque, alla perdita di specie indigene e alla crescente diffusione di specie aliene. Queste situazioni potrebbero essere amplificate dalle variazioni del regime idrologico indotte dai cambiamenti climatici. I grandi laghi subalpini profondi sono regolati e costituiscono la più importante riserva di acqua dolce in Italia. Negli ultimi decenni si sono osservate condizioni critiche per il bilancio termico e la conseguente stratificazione della colonna d’acqua: l’aumento della temperatura atmosferica ha già causato una notevole riduzione della frequenza del rimescolamento delle intere masse d’acqua (oligomissi) e potrebbe portare a un rimescolamento limitato ai soli strati superficiali (meromissi). Le condizioni di meromissi sono in genere accompagnate dall’esaurimento dell’ossigeno disciolto nelle acque di fondo e da notevoli alterazioni della composizione delle comunità lacustri. Nel lungo termine, la diminuzione degli apporti nivali e glaciali e l’aumento dei prelievi potrebbero determinare oscillazioni del livello idrico con gravi impatti anche sulle zone litoranee di basso fondale. Condizioni di particolare vulnerabilità sono previste per i laghi dell’Italia centrale, in particolare per quelli poco profondi come il Lago Trasimeno, nei quali si stanno verificando l’interramento delle zone litoranee, l’aumento delle concentrazioni dei soluti e il riscaldamento delle acque. Nei laghi artificiali dell’Italia meridionale e delle isole, la diminuzione delle precipitazioni e l’aumento della temperatura, combinate con un maggiore consumo idrico, potrebbero accentuare le variazioni di livello, favorendo così il peggioramento della qualità delle acque e l’affermazione di specie invasive e di cianobatteri tossici. Le acque di transizione (foci fluviali e lagune costiere) sono esposte alle variazioni del regime idrologico dei bacini di monte, all’innalzamento del livello marino e all’aumento della temperatura. Trattandosi di sistemi a bassa profondità, sono attesi effetti particolarmente marcati nelle comunità bentoniche, con comparsa di fioriture di macroalghe, microalghe tossiche e cianobatteri e scomparsa delle specie animali maggiormente sensibili. Le opere di difesa idraulica a protezione dei centri abitati e delle zone agricole subsidenti potrebbero fare aumentare il confinamento delle aree lagunari interne, con rischi crescenti di stagnazione e anossia delle acque, condizioni che comportano la perdita di specie sensibili al tenore di ossigeno e alla temperatura. Complessivamente, si ritiene che le tendenze evolutive degli ecosistemi lagunari possano essere sfavorevoli per le specie native a vantaggio di quelle esotiche, con possibili impatti anche sulle attività di pesca e acquacoltura. Nelle foci fluviali, nei periodi di secca si potrà verificare la risalita del cuneo salino, un fenomeno che si è già manifestato in modo significativo in anni particolarmente siccitosi, ad esempio dal 2003 al 2007. Nella maggior parte degli ambienti acquatici considerati, al crescere della temperatura e della durata della stagnazione delle masse idriche potranno aumentare il metabolismo microbico e l’eterotrofia, con possibili retroazioni sulle emissioni di gas clima-alteranti (CO2, N2O e CH4).

East Herzegovina (in Bosnia and Herzegovina) is characterized by considerable water resources, whose main feature is abundant precipitation from October to May. As a result, the karst poljes of East Herzegovina experience significant and protracted floods during this period, while the water budget in the summer months exhibits a recharge deficit and streams often dry out. This renders the karst poljes, which are the largest arable lands in the area, virtually useless during most of the year. To address this issue, the idea was born to build multi-purpose systems-the Trebisnjica Hydropower Scheme in the so-called Lower Horizons and Upper Horizons, the ultimate and primary goal being the management of water resources in the area. The scheme, which encompasses hydraulic structures, surface reservoirs, hydroelectric power plants, irrigation systems and drinking water supply facilities, was largely completed in the 1970s. The remaining project in Upper Horizons, which includes the transfer of water from the Neretva River Basin to the Trebisnjica River Basin, is still under evaluation. The hydraulic model and preliminary environmental impact assessment indicate that there will be no significant adverse impacts.

This contribution, as an introduction to the main topic of the session “Engineering problems in karst”, aims at providing some guidelines about how to deal with engineering problems in karst environments: these include, but are not limited to, pollution, different types of geological hazards (sinkholes and subsidence, flash floods, etc.), and the related geotechnical constraints. Eventually, the assessment of human impacts on karst landscapes, with specific regard to the disturbance induced by man’s activities, is discussed, pointing out to the problems in managing water resources in karst, and providing some guidelines for possible developments in this fragile environment.

Rock-fall poses a continuous hazard in mountain areas worldwide. Despite the fact that rock fall is a simple landslide type to model, only a few attempts have been made to establish rock-fall hazard and the associated risk at regional scales. We developed a three-dimensional simulation program that generates simple maps useful to assess rock-fall hazard, using GIS technology to manipulate existing thematic information available in digital format. The program requires as input a digital terrain model, the location of rock-fall detachment areas, the dynamic friction coefficient used to simulate the loss of velocity during rolling, and the coefficients for normal and tangential energy restitution at the impact points. The program allows for the natural variability of the input data by using a random component approach. Raster outputs include the count of rock-fall trajectories, the maximum velocity and the maximum height computed at each grid cell. Vector outputs consist of the planar (two dimensional) and the three-dimensional trajectories of the rock falls. The program outputs proved to be consistent with the results of other rock-fall simulation programs, to be reliable for modelling rock-fall in three-dimensional geomorphological settings, and to help in the quantitative assessment of rock-fall hazard over large areas.

It is widely recognised that soil slips and debris flows frequently occur in coincidence with intense rainfall. As a consequence, analysis of rainfall is the most frequently adopted approach for forecasting the occurrence of shallow landslides. The basis for a complete approach, which examines landslide triggering by rainfall, lies in the different response to rainfall that soils or rock masses show because of their physical, mechanical and hydraulic characteristics. Furthermore, morphologic and anthropogenic features control surface, sub-surface and deep groundwater flow and they can strongly influence both slope stability and triggering conditions. Different rainfall thresholds and hydrologic models have been proposed in the literature. Among these threshold relationships and hydrologic models, it is possible to find some important differences that are sometimes neglected in their application. Most of the proposed thresholds and models are related to shallow landslides along open hillslopes or hollows but they are sometimes incorrectly adopted to forecast channelled instabilities. Again, most of these relationships determined for catastrophic events with occurrence of tens or hundreds of instabilities are adopted to forecast single or recurrent slope failures. This paper uses rainfall and landslide data, available in the literature, to explain the observed differences and to illustrate possible applications. Examples of global (regional) and local rainfall thresholds are presented and discussed together with the principles to be followed for a correct collection of data.

We present two applications of GIS technology to groundwater studies aimed at the assessment of pollution risk. The first study were carried out over the entire Po Plain, an highly developed area that depends entirely on groundwater for water supply; the second regarded a small portion of it. The research aimed at producing maps of the factors controlling groundwater-pollution risk to support decision-making for an effective land planning and management. The proposed risk-assessment procedure considers factors related to natural vulnerability, hazard due to human activities, and costs resulting from pollution. To evaluate existing hazard, a census was carried out over a test area. Industrial, agricultural and quarrying sites were mapped, and industrial activities were divided into four groups according to national waste type regulations. A land information system was used to store and manage the vast amount of spatial data and to prepare thematic output maps.

Population growth, urbanization and technological developments may benefit from increased development of the subsurface. The possible uses of the subsurface however also result in fierce debates on societal needs, economic benefits and environmental impacts. Think for instance of siting land-based carbon capture and storage (CCS) facilities like in Barendrecht, the Netherlands. The public opinion was strongly against it and as a result the project was canceled. This paper proposes a subsurface lease model to gain community support and better take costs and benefits into account from different stakeholders’ perspectives. Sustainable development of the subsurface requires cooperation in a well-defined framework that on the one hand enables stakeholders to make their own choices, but also includes mechanisms to fully account for the costs and benefits to society, providing them feedback in order to reach a social optimum. Looking at the three pillars of sustainability (planet, people, profit) the societal dimension may well be the most challenging one in projects relating for example, to large scale subsurface construction, siting projects for the extraction of shale gas or injection such as carbon capture and storage. The viability of a subsurface leasing model is discussed as a policy option to gain public support over and above the required stakeholder consultations and risk communication to create a situation in which citizens feel that they have a stake in the chosen solution with a fair distribution of the costs and benefits to society. Multiple use of space can strongly benefit from such an alignment of stakeholders with seemingly opposing interests. The distribution of ownership is an important factor here, which can hinder the decision-making process involved in the use of the urban environment. Full ownership is not always feasible, especially in case of the multiple use of space. Therefore in day to day practice communication, stakeholder acceptance and (perceived) risks also have shown to be important factors in governance and the ability to reach decisions regarding subsurface development effectively.