CNR-IRPI

In the present work, for a study area located in the southernmost province of continental Italy, data concerning the historical series of floods which have occurred since XVII century have been collected. Damages caused by flood events were discussed together with rainfall regime and trend (for the period in which data are available) and with main modifications due to variations in population number. The aim was to assess if the frequency of damaging floods is changing and if there is a role of rainfall and/or of anthropic modifications of land use on these changes. 150 damaging floods were analysed; 4% of the total were floods which caused damages to people, and which mainly occurred in the past centuries. Notwithstanding, the trend of damaging floods is increasing due to the effects of floods observed in the last decades. At the same time, the rainfall trend is generally decreasing, as observed at regional scale, and not significant to justify the flood recurrence increase. The population trend is characterised by a huge increase observed in the last decades. On this basis, the progressive urban enlargement, realised careless of both drainage network characteristics and extreme floods, can be considered as the main source of increasing risks due to damaging floods.

A methodological approach based on analysing landslides that occurred over a long period and climatic data characterizing that period is presented. The method investigates whether there are any effects of climate on landslide triggering. The approach has been tested in Calabria (Italy). Both landslide and climatic data have been obtained from available databases that have been expanded. Landslide data came from historical archives and newspapers, whereas the climatic analysis is based on daily and monthly series of rainfall and temperature. The method simplifies the comparative analysis of several time series by defining some indices (the monthly, bi-monthly ... m-monthly indices of precipitation, temperature, wet days and precipitation, and the monthly landslide number) that can be used to study phenomena, such as landslides, that are characterized by spatial and temporal variability. For Calabria, the number of landslides is correlated to monthly precipitation, wet days and precipitation intensity. Thus, landslide occurrence could be roughly forecast using these climatic data. Despite the favourable climatic trend, landslides are not decreasing because the recent utilization of landslide-prone areas increases the vulnerability.

Water and chemical fluxes across the sea bottom provide an important linkage between terrestrial and marine environments. From the marine perspective, these water fluxes, commonly referred to as submarine groundwater discharge (SGD), may contain elevated nutrient concentrations or high levels of other potentially harmful contaminants. Terrestrially derived SGD can also be an important source of freshwater for estuarine ecosystems that require relatively low salinities. For these reasons, the past decade has shown a rapid increase in the level of interest from estuary and marine scientists toward a better understanding of SGD. From the terrestrial perspective, SGD has also been a topic of interest to those studying saltwater intrusion and management of coastal aquifers. Saltwater intrusion studies commonly employ some form of a water balance method, whether through numerical modelling or volumetric calculations, to explain intrusion patterns and develop predictions and management plans. In developing a water balance for a coastal aquifer, estimates for all of the key components, including SGD, are synthesized. Although the motivation may be different depending on whether one works from the marine or terrestrial perspective, both groups have a common goal of obtaining accurate SGD estimates

Il contributo si basa sull’analisi di diversi tipi di dati, elaborati fino a costituire serie storiche mensili inerenti il clima (pioggia, temperatura, giorni piovosi e intensità di pioggia) dal 1877 al 2008. Nonostante la tendenza al calo della piovosità e dell’intensità di pioggia e all’incremento della temperatura e dei giorni piovosi, si osserva la crescente ricorrenza di piene e frane, a conferma della crescente antropizzazione di aree a pericolosità idrogeologica. La discussione delle relazioni clima-frane ha evidenziato delle limitazioni ragionevolmente dovute al concentrarsi delle frane in parte del territorio e alla minore qualità del dato storico.

La recente siccità che ha interessato le regioni meridionali fino all’estate 2002, causando forti ripercussioni sulla disponibilità di risorse idriche e danni alle attività agricole, ha portato all’attenzione generale l’evoluzione del clima ed in particolare della variabilità della piovosità nel tempo. Questo studio prende in considerazione la piovosità, su base mensile ed annuale, in Italia meridionale (Campania, Puglia, Calabria e Basilicata) nel periodo 1821-2001, per cui sono disponibili dati storici affidabili e con continuità temporale, integrando ed ampliando quanto descritto da Cotecchia et al. [2003]. È stata anche completata la raccolta dei corrispondenti dati termometrici, la cui analisi è in fase preliminare. Lungi dal formulare previsioni sugli andamenti futuri o dall’ipotizzare le cause su scala globale dei fenomeni osservati, si è avviata una ricerca, tuttora in corso, che ha come finalità ultima la caratterizzazione delle tendenze evolutiva dei principali fattori climatici, piovosità e temperatura, e dei relativi regimi, fattori significativi per la formazione della piovosità efficace o utile, l’aliquota della piovosità effettiva in grado di rendere disponibili risorse idriche. Particolare attenzione è rivolta alle recenti siccità e alle più importanti tra le precedenti. Le evidenze emerse dallo studio delle serie storiche sono trattate con criteri geostatistici mediante supporto GIS.

Negli ultimi anni sempre maggiore attenzione si è posta ai problemi di contaminazione delle acque sotterranee. Nel caso degli acquiferi carbonatici pugliesi, che ospitano l'unica risorsa idrica disponibile nel territorio, la più— evidente forma di contaminazione è costituita dai fenomeni di salinizzazione delle acque sotterranee dovute all'eccessivo sfruttamento. Infatti le acque dolci sotterranee in buona parte del territorio pugliese hanno come superficie di fondo le acque di mare di invasione continentale. La separazione tra i due corpi idrici è costituita da un'interfaccia a spessore variabile, detta zona di transizione. L'espansione verso l'alto di tale interfaccia, osservata nei pozzi-spia della rete di monitoraggio dell'intrusione marina, è legata al sovrasfruttamento, con conseguente salinizzazione delle acque dolci. Pertanto, estrema attenzione deve essere posta, nell'ambito della gestione delle acque sotterranee, alla presenza di forti emungimenti concentrati. Un efficace approccio al problema si basa sui modelli matematici atti a simulare il fenomeno di espansione della zona di transizione. Per simulare realisticamente tali evoluzioni è necessario adottare un modello di flusso dell'acqua sotterranea a densità… variabile, con trasporto di soluto. Un codice agli elementi finiti in grado di risolvere le equazioni alla base del suddetto problema è il SUTRA di C. I. Voss (1984). Viene esposta un'applicazione riguardante l'effetto di un gruppo di pozzi di presa e di resa realizzati in una porzione dell'acquifero carsico pugliese. In particolare è stata ipotizzata la realizzazione di due batterie di 4 pozzi ciascuna, disposte a 50 m l'una dall'altra, lungo la direzione normale al flusso della falda. Il problema considerato riguarda un impianto di condizionamento che prelevi dalla batteria di monte una data portata dalla falda idrica e la reimmetta, nelle medesime condizioni di salinità… ma con una assegnata variazione termica, a valle. La verosimiglianza del funzionamento dell'impianto è stata perseguita programmando un funzionamento nell'anno stagionale;, in cui si alternano re-immissioni con variazione termica pari a -5 °C, durante la stagione fredda, pari a 5 °C, durante la stagione calda, e pause di funzionamento. Utilizzando lo stesso codice di calcolo è stato anche simulato l'inquinamento termico della falda idrica, determinato nelle suddette ipotesi.

Population growth, urbanization and global climate change have increased urban and agricultural water demands, stressing aquifer systems where groundwater is a source of water supply. The availability and utility of groundwater may further be threatened by factors stressing the quality of groundwater, such as industrial and domestic wastes and agricultural intensification. Consequences include, for example, over-allocation of groundwater, groundwater overdraft, declining well yields and land subsidence; degraded groundwater quality due to mobilization of natural pollutants (arsenic), salt contamination caused by seawater intrusion; increased demand for conjunctively used surface water, and resulting conflicts with junior users; and streamflow capture and resulting damage to ecosystems. These consequences may occur incrementally and inequitably across an aquifer. Natural environmental problems can further complicate use of groundwater and increase strain on the aquifer system; for example, underground structures, geothermal heating (such as heat islands), and geochemical evolution (such as karst formation, excessive salinity, acidity, fluoride, radioactivity, hardness, or turbidity). To address this issue, a joint symposium on the Trends and Sustainability of Groundwater in Highly Stressed Aquifers was held during the 8th Scientific Assembly of the International Association of Hydrological Sciences, IAHS, and the 37th Congress of the International Association of Hydrogeology, IAH, in Hyderabad, India, September 2009. The symposium was organized by the IAHS International Commission on Groundwater (ICGW), supported IAH and by the IAHS International Commission on Water Quality (ICWQ). This symposium brought together scientists, including modellers, geochemists and hydro-geologists, with water supply managers and policy makers to discuss scientific and management ideas and approaches for improving the sustainability of highly stressed aquifers. The importance of this topic was reflected in the large number of contributions to the symposium. Selected papers from this symposium have been compiled in this volume. The editors gratefully acknowledge the assistance of the reviewers who made valuable contributions to this volume. We thank Penny Perrins and Cate Gardner from IAHS Press for their professional approach and help with the processing of the manuscripts.

In this paper, we present a methodological approach based on a comparative analysis of floods that occurred in a wide region over a long period and the climatic data characterising the same period, focusing on the climate trend. The method simplifies the comparative analysis of several time series by defining some indexes (e.g., the monthly, bi-monthly, and … m-monthly indexes of precipitation, temperature, wet days and precipitation intensity and the monthly flood number) that can be used to study phenomena such as floods that are characterised by spatial and temporal variability. The analysis was used to investigate the potential effect of climate variation on the damaging floods trend. The approach was tested for the region of Calabria (Italy) using historical flood and climatic data from 1880 to 2007. The results showed that the number of floods was correlated with the monthly indexes of precipitation, wet days, and daily precipitation intensity. The following trends were recognised: decreasing precipitation and wet days, almost constant precipitation intensity, increasing temperature, and linearly increasing floods. A second-order polynomial trend analysis showed a slight decrease in floods since the seventies, which might be explained by the favourable climatic conditions during the period and/or the effect of increasing awareness of flood vulnerability.

Computer techniques such as Geographic Information Systems are applied to the evaluation of the vulnerability of a deep carbonate aquifer. The study area, of about 150 km2, is located in the low Murgia Plateau (Apulia) and characterized by Mesozoic limestone and dolomite rocks of several thousand meters thickness. A wide and thick aquifer resides in these carbonate rocks. Its groundwater flows toward the sea mainly under pressure and with maximum piezometric level of about 200 m a.s.l.. Due to their high quality, the water resources of this aquifer are particularly valuable for the local communities and therefore must be protected from pollution and inappropriate use. The vulnerability map of the aquifer is an indispensable tool for the effective management of groundwater resources and to support environmental planning. Several approaches have been proposed by different authors to evaluate intrinsic vulnerability. Most of the methods for detailed vulnerability mapping are based on the integrated analysis of several variables using different algorithms. Geographic Information Systems are advanced computer tools for the analysis of georeferenced data in 2D and 3D and can be effectively applied to the implementation of evaluation models. In this study the SINTACS evaluation method was implemented in a GIS and a digital vulnerability map produced. The different data taken into consideration in this analysis, such as depth to water, actual infiltration, pollution attenuation capacity of unsaturated zone, land cover, hydrogeological features of saturated aquifer, hydraulic conductivity, terrain slope, geology and geological structures, were georeferenced and converted into digital form. Each variable corresponds to a separate data layer made of graphic and attribute data. The computerized multilayer analysis performed by the GIS is time effective and leads to more comprehensive and accurate results with better spatial resolution.

This work is based on data acquisition and analysis of chronology sequences of piezometric, rainfall, thermometric and runoff data of Apulian Tableland aquifer. Methods of time series analysis are used. This approach has allowed characterising the piezometric regime and trend related to the natural recharge variation. The historical character of measurement period, last sixty years, is very important to evaluate the human effect.