Degradation risk owing to contamination and overdraft for Apulian groundwater resources (southern Italy

The remarkable and rapid socio-economic development over the past few decades has further stressed the Apulian hydrogeological system. The whole Apulian groundwater has undergone a twofold pollution, all originated by human action: saline pollution evolves progressively as it affects increasingly large portions of land; biological and chemico-physical pollution is gaining importance and is mainly concentrated around urbanised areas. The latter is due to the circumstance that the aquifers are increasingly bound to become a kind of ultimate "receptacle" for domestic and industrial waste waters. In order to characterise the features of human-related pollution, data was gathered by a monitoring network. It uses 157 wells, some of which hundred meters deep, and 19 coastal springs. Periodical water samples were taken from the network to be submitted to chemical, physical and bacteriological analyses. The effects of human activity on groundwater pollution and depletion are so characterised

Degradation risk owing to contamination and overdraft for Apulian groundwater resources (southern Italy)

The remarkable and rapid socio-economic development over the past few decades has further stressed the Apulian hydrogeological system. The whole Apulian groundwater has undergone a twofold pollution, all originated by human action: saline pollution evolves progressively as it affects increasingly large portions of land, biological and chemico-physical pollution is gaining importance and is mainly concentrated around urbanised areas. The latter is due to the circumstance that the aquifers are increasingly bound to become a kind of ultimate “receptacle” for domestic and industrial waste waters. In order to characterise the features of human-related pollution, data was gathered by a monitoring network-encompassing 157 wells, some of which hundred meters deep, and 19 coastal springs. Periodical water samples were taken from the network to be submitted to chemical, physical and bacteriological analyses. The effects of human activity on groundwater pollution and depletion are so characterised

I modelli numerici per la previsione degli effetti dell'utilizzo delle acque sotterranee nelle aree urbane soggette all'intrusione marina, il caso di Bari

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

The role of meteorological and climatic conditions in the occurrence of damaging hydro-geologic events in Southern Italy

Damaging Hydro-geologic Events (DHEs), de- fined as landslides and floods caused by heavy or prolonged rainfall, represent an important source of economic damages. We propose an approach to classify DHEs, considering 1) meteorological antecedent conditions, 2) the season during which the event occurs, 3) the return period of maximum daily rainfall triggering the event, 4) geographic sectors hit, 5) types of triggered damaging phenomena; and 6) induced damage. We applied this approach to a case study of time series of DHEs that occurred over 85 years in Calabria (southern Italy). We analysed 13 DHEs that, between 1921 and 2005, triggered landslides, floods and secondary floods, causing severe damage and tens of causalities all over the Calabria region. During the analysed events, 64% of Calabria’s municipalities suffered many types of damage. The most relevant rain phenomena and the largest damages were caused by the persistent effects of perturbations on Calabria, which were preceded by the appearance of low-pressure fields in two different areas located westwards. We sorted the events into three types based on geographic damage distribution and types of triggered phenomena and induced damage. The first two types are characterised by similar severity levels, while the third shows the highest severity, in terms of both damage and victims. Independent of the type of event, the S-SE and E sectors of the region are the most frequently affected by DHEs. As regards human life, floods are the most dangerous type of phenomenon, causing the highest number of fatalities. Our analysis indicates a decreasing frequency of DHEs during the study period, and an absence of the most severe type for more than 50 years. The number of victims is also decreasing over time

Condizioni di emergenza della sorgente Niella di Lagonegro

The Niella spring is located on north Mount Sirino slope. The spring aquifer is characterized by the presence of localized fissures in carbonatic rock. The spring is the highest of the aquifer end is placed at half slope. Flinty limestone outcrops along the whole slope; the spring area is characterized by debris outcrops. Spring water comes out in these conditions for described tectonic influence on aquifer permeability. Geological-structural conditions end the effects on groundwater flow are described

Hydrogeological monitoring and image analysis of a mudslide in Southern Italy

This paper describes a methodological example of a data-integration procedure to improve the knowledge of landslide hazard related to a seismic area in the southern Apennine (Italy). Attention is focused on remote sensing data. The analysis is validated using detailed topographical, geophysical, geotechnical and hydrogeological data as ground truth. The investigated phenomenon, which started at the end of 1993, is an earthflow. The presented methodology recommends the combined use of DEM, multi-temporal panchromatic visible aerial photographs and thermal infrared images. The integration between these data and multidisciplinary monitoring data proved useful. The main hydrogeological pattern, the geological and geomorphological framework and the areas of latent instability can be clearly determined. Insight can be gained through the synoptic slope view in the relative short time needed to carry out the analysis. The proposed approach can be regarded as a useful contribution to the evaluation of landslide hazard, particularly during emergency periods

Le calamità idrogeologiche dell'inverno 1995-96 nel territorio tarantino

Throughout 1995 is most of the territory of Taranto, heavy rainfalls have followed dry years of infrequent precipitation. The trend has persisted for three more months in 1996, thus leading to multiple calamitous events. Between January and February 1996, many municipalities in the province of Taranto have been hit disasters due to such unprecedented rainfalls. Hydrologic events of various duration and intensity and altered climatic conditions have resulted in simultaneous disasters, namely river overflowing, water-logging, massive flooding, extensive landslides, intense erosions and severe damage to transport and water facilities. The hydrogeologic disasters were not triggered by the extraordinary amount of surface flowing water alone. Also underground water bodies, subject to significant recharge have increased spring water flows, somewhere acquiring an artesian attitude and thus steadily worsening the existing hydrogeologic emergency. A characterization of the newly arisen set of conditions has been atternpted by studying daily rainfall rates, peak annua1 precipitation lasting 1, 3, 6, 12 and 24 hours and temperature. The examination of the hydrogeologic disaster within an extended time frame has indicated the prominerzt role played by long lasting drought on the efficiency of the watercourse network and on the fragili01 of the territory. 1t follows that the drawbacks of different natura1 phenomena have overlapped in the Jirst three months of 1996 in the province of Taranto. Moreover; the effects of these phenomena have been occasionally enhanced by the irnpact of human activity unsuitable maintenance of the hydrographic network and poor contro1 over the territory. A true natura1 calamity has thus occurred which has brought about particularly severe situations in some areas where the risk of subsequent ydrogeologic disasters remains

Failure of infrastructure embankments induced by flooding and seepage: a neglected source of hazard

The risk of failure of transportation embankments due to seepage induced by temporary and occasional impoundments taking place on the upstream side as a consequence of exceptional rainfalls is frequently underestimated. These failure events result from a combination of three main factors, i.e. the flooding event, the hydraulic weakness and the geotechnical weakness of the embankment. Based on the case study of a railway embankment in Southern Italy that collapsed in 2005 due to an upstream impoundment that occurred after few hours of a very intense rainfall, the paper describes a methodological approach aimed at assessing hazard of failure of transportation embankments induced by flooding and seepage. In particular, ccording to hydrological, hydraulic and geotechnical studies performed to define the factors affecting the process of the embankment failure, three subsequent activities are proposed: the historical analysis of flood damages at the watershed scale; and the assessment of the upstream peak impoundment based on hydrological analysis and the embankment stability analysis, these latter to be carried out at the site specific scale. The approach here proposed is planned to be further validated and improved by means of the application to other case studies, characterised by different contexts and embankment structures

Flood risk mitigation and anthropogenic modifications of a coastal plain in southern Italy: combined effects over the past 150 years

A study of the effects of human modification of a coastal plain mainly involving land reclamation and flood protection is proposed. The approach involves historical, geomorphological and hydrological data as a whole, taking into account the equilibrium of rivers, plains and coastal areas. <br><br> The test area, a telling example of profound economic and social transformation of a coastal plain, is the <i>Piana di Sibari</i> (Calabria, southern Italy), subject to major human modifications over the last 150 years. The study area, at most 300 m a.s.l., is 450 km<sup>2</sup> wide and comprises 24 hydrographic basins. <br><br> The approach is based on the creation and analysis of four databases: 1) a historical series of geo-coded flood damage (DAMAGES database), concerning damaging floods which occurred over the past few centuries in the study area; 2) a geocoded series of protection works for land reclamation, protection from floods and improvement of soil stability in steep areas (WORKS database), gathered from the archives of the agencies that carried out the works, organized in a GIS-format; 3) a historical series of maximum flood discharges and extreme rainy events (HYMAX database) aimed at defining the trends of occurrence and the intensity of flooding; 4) a coastal line position and migration over time (COASTAL database), created using mainly literature data based on discontinuous data such as historical maps and images. <br><br> The work describes the complex succession of floods, protection and reclamation works, human transformation of the plain and major land use changes over the last two centuries in the test area. The new characteristics of the plain and its modifications, including major engineering works, land-use transformation and urbanisation, are illustrated. The damaging floods of the last 200 years, the modifications of runoff and flooding due to works built over the basins, hydrological data and the records concerning coastal modifications were used to create specific databases and a GIS in which these data can be analyzed by typology, location and extension. <br><br> The proposed approach highlights the high degree of correlation between drainage basin management, mainly in terms of increasing protection from natural hazards, and anthropogenic development in a broad coastal plain

The occurrence of floods and the role of climate variations from 1880 in Calabria (Southern Italy)

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 ... <i>m</I>-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. <br><br> The approach was tested for the Calabria region (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