1,720,980 research outputs found
Classical Karst hydrodynamics: a sheared aquifer within Italy and Slovenia
Full text linkClassical Karst transboundary aquifer is a limestone plateau of 750 km2 that extends from Brkini hills in Slovenia to Isonzo River in Italy.
Since ten years, the Mathematic and Geosciences Department of Trieste University is conducting a monitoring project in order to better understand the groundwater hydrodynamic and the relation between fracture and conduit. 14 water points among caves, springs and piezometers are monitored: hourly temperature, level and EC data are recorded. Two sectors are highlighted: the south-eastern one mainly influenced by the sinking of the Reka River, and a north-western one connected to the influent character of the Isonzo River. Water table fluctuation are significant with risings of more than one hundred meters and during floods the most part of the circuits are under pressure and only a comparative analysis of levels, temperature and conductivity permits a precise evaluation of the water transit times in fractured and/or karstified volumes
Saltwater intrusion in Friuli Low Plain
No full textIn coastal areas, the interaction between seawater and fresh water is in a dynamic equilibrium and occurs both in surface bodies (saltwater ingression) and in groundwater (saltwater intrusion in aquifers). Human actions and climatic changes, especially sea level rising, can alter this equilibrium leading to a contamination of the fresh water and soils by seawater.
The shift of salt wedge towards inland can be a consequence of both natural and anthropogenic processes. Natural processes have generally slow effects, except in the case of tsunami, as in Sri Lanka (Villholth and Neupane, 2011). The sea level rising due to climatic changes (Melloul and Collin, 2006) and local subsidence along coastal areas cause a slow salt wedge shifting. Instead, human actions have rapid effects on the coast system. Examples of the human actions are the overexploitation of aquifer, the incorrect and extreme watercourse regimentation, the excavation of floodway canal and dredging for navigation.
The salt wedge intrusion can lead to freshwater contamination and consequently to a decrease of water reserve, to coastal area desertification by ground salinization and to a loss of faunistic and floristic species
Multi-disciplinary surveys for the new geologicla maps of the low Friuli plain (Italy)
No full textThe study site is located in the central area of the Friuli Venezia Giulia (Italy) and is covered by geological map sheets 087 Palmanova and 108 Lignano Sabbiadoro. The area under consideration extends between the spring horizon to the north and Marano lagoon to the south. It covers a total area of 760 km2. The zone under consideration is characterised above all by the presence of alluvial deposits dating back to the Last Glacial Maximum (LGM; 30,000-17,000 b.C.) and by the presence of deposits originated by the activity of resurgent rivers including Stella, Zellina, Corno and Aussa. The western sector of the Lignano sheet also includes deposits that can be ascribed to the post-LGM activity of river Tagliamento (last 17,000 years). Along the coastline post-LGM deposits reach a thickness of 10 m. Along the lagoon fringe there are territories that were reclaimed in the Twentieth century where lagoon deposits outcrop.
The project was conducted within the framework of the GEO-CGT by the Regional Geological Survey – DG Environment and Public Works of the autonomous region of Friuli Venezia Giulia and the University of Trieste and Udine. It involved the preparation of 1:10,000 geological maps of Friuli Venezia Giulia which integrated new geological data (surveyed and processed to this very aim) into already existing information. Reference criteria for the cartographic representation and digitalisation are those set by the Italian Government for the preparation of the new national geological cartography at a scale of 1:50,000 (CARG project).
The Technical Geological Map (CGT) has been the primary source of grain-size and geotechnical information as far as the soil and the immediate subsoil of the areas taken into consideration. The bibliography collected has been integrated with the most recent studies and data on the geology and pedology of the areas involved. Also archaeological aspects have been taken into consideration to better define the history ad evolution of more recent deposits.
The map representing microrelief, together with the observation of aerial photographs taken in different years and satellite images, has proven a useful tool to analyse and define the area of the most frequent morphologies connected with river erosion and deposition phenomena.
This information has been subsequently cross-checked during surveying campaigns. More in detail, historic maps helped identify natural and/or man-made modifications of the hydrographic network ad of the use of soil in recent past. Some information on the age of the deposits were also taken from the numerous Roman archaeological sites present in the study areas.
Field surveys were aimed at identifying geomorphological landforms and sedimentologic characteristics and at defining the age of deposits. As the areas observed are plain ones and no deep natural outcrops are present, particular attention was given to the stratigraphy of the deposits that outcrop along the walls of artificial excavations. In the areas with no significant outcrops and in the most interesting ones, borehole logging was performed by means of a manual Edelmann probe. These boreholes reached a depth of 2-3 m and sometimes 6 m. The sediment samples collected were tested for grain-size distribution and carbon-14 dating.
Simultaneously, mechanical surveys were performed on the whole area reaching a depth of 10 m plus approximately a hundred static penetrometer probes reaching a 30 m depth.
The comprehensive geomorphological, sedimentological and geotechnical data collected permitted to define stratigraphic units, sedimentation environments, texture of surface deposits and the main landforms that characterise the western low Friuli plain.
The last surveying phase consisted in organising and processing the data collected thanks to the special functions of GIS. The entire project was conducted using a comprehensive set of hardware and software tools which permitted to maintain a close relation between the data collected on the field (database) and their digital geo-referenced map representation (geo-database). Data could therefore be viewed and interpreted according the standards set within the framework of the CARG project
Rock Fall Characterization in Climbing Spots: The Case Study of the “Napoleonica” Tourist Route (Trieste, NE Italy)
No full textIn NE Italy, fast-moving landslides represent a significant threat both to the population and the built environment. In the eastern portion of the Italian Alps, rock falls are common and are often responsible for casualties or severe damage to infrastructure. This type of landslide is characterized by strong relief energy and is triggered by earthquakes or copious rainfall, which often exceeds 2000 mm/yr. To assess rock fall hazard using software analysis, field surveys are crucial to accurately recognize the source areas of falling rock phenomena, to quantify the volumes of unstable blocks and identify the possible block trajectories. The current work takes in detailed geological and geomorphological mapping, through the identification of dislodged blocks, fractures and fallen blocks on a much-frequented limestone cliff in the Trieste Karst used as a climbing spot. Moreover, a popular tourist path (the Napoleonica) lies at the foot of the climbing cliffs. In-depth traditional activities, such as field surveys and aerial photo analysis were undertaken, including morphometric and geomechanical characterization of the whole rock mass, in order to perform a first identification of the more hazardous sections of the Napoleonica. The field data were collected using UAV (Unmanned Aircraft Vehicle) images and videos and this innovative technique allow the reaching and study of difficult sites with excellent resolution and precision. The final output is a GIS-developed map, that will be the starting point for future 2D and 3D simulations, that will lead to the creation of a rock fall susceptibility evaluation of the whole area
GYPSUM’S ROLE IN THE SINKHOLES OF THE TAGLIAMENTO RIVER VALLEY (NE ITALY)
No full textIn an area of several kilometers in the Tagliamento Valley, between the villages of Ampezzo and Villa Santina (Friuli, NE Italy), are present frequent points of absorption associated with large and deep sinkholes collapsed in the shallow cemented fluvial-glacial deposits, in the recent alluvial deposits overlying a karstified evaporitic bedrock.
In the Quinis village the situation is particularly complex, some houses are affected by failures and in the past, in the fields around the village sudden sinkholes were recorded and some building were demolished also in the centervillage. During the last years a tightening in the phenomena took to the necessity of a deep and multidisciplinary study in order to define the vulnerability of the different areas. For the purpose, were realized 20 piezometer (equipped with devices), 3 seismic lines, 1 electrical tomography, the establishment on the buildings of a topographical monitoring network, 2 assestimeters and a groundwater tracing test campaign.
The main vulnerable areas were identified with the presence of holes or caves in the gypsum and soft and unconsolidates alluvial horizons. The big variations in the groundwater levels recorded during the past years and linked to the regime imposed by the dam outflow, underlined an increase in the karstification processes inside the gypsum bedrock and in the above deposits
Groundwater sustainability in the Friuli Plain
No full textGroundwater resources in the Friuli Venezia Giulia (FVG)
Region (northeast Italy) are an important natural wealth in terms of
quantity, quality and ease of supply. This optimal condition, however,
has long believed that it allowed an irrational and uncontrolled
exploitation that inevitably produced tangible consequences on the
water resources availability.
The goal of the present research is the evaluation of groundwater
sustainability in the Friuli Venezia Giulia Region aimed at providing
guide-lines for its rational use
The Sr-isotope systematics as a groundwater tracer: an application to the Classical Karst
No full textThe preferential flow path of groundwaters through limestone
aquifers by matrix flow within rock pores or networks of micro
fractures and by fast conduit flows in large fissures and openings
has important consequences on solute concentration, and poses
critical problems in terms of contaminant transport. In particular,
fast conduit flows can transmit contaminants rapidly, and
pollutants may arrive earlier to pumping stations for drinkable
water supply yielding peaks in concentrations. The slow draining
of the resident mass water and diffusion into rock pores produce
a continuous source of contamination, even if generally at lower
concentration. The detection of the preferential flow paths,
residence times and flow dynamics is hence of the uppermost
importance in carbonate karst aquifers, with implications on the
possible seasonal variations in water quality. Conduit flow and
diffuse flow often result in springs with different chemical
patterns, temperature and discharge rates, and anthropogenic
tracers such as chlorofluorocarbons are effective for tracing
groundwater flow. However, the usefulness of the Sr-isotope
systematics has been in many cases demonstrated in the
reconstruction of the water-carbonate rock interaction, becoming
an important tracer of groundwater movement. In fact, the
87Sr/86Sr ratios in groundwaters reflect the water-rock interaction.
In this study, surface, cave and spring waters have been
collected during high and low-flow conditions in the Classical
Karst area (northern Italy and Slovenia), a carbonate plateau
that rises above the northern Adriatic Sea and consisting in a
thick sequence of limestones and dolostones dated Cretaceous
and Tertiary. Waters belong to the Ca-HCO3 and Ca-Mg-HCO3
hydrofacies. The 87Sr/86Sr ratio in surface, cave waters and
springs ranges between 0.70781÷0.70838, 0.70787÷0.70824
and 0.70757÷0.70786, respectively, during low flow, and
between 0.70760÷0.70843, 0.70749÷0.70810 and
0.70759÷0.70800 during high flow. The data indicate the relative
contribution of the Isonzo and Reka rivers, with relatively high Sr
isotopic composition, as inputs to the Classical Karst aquifer.
Furthermore, cave waters have 87Sr/86Sr ratio higher with respect
to the Sr isotopic composition measured in limestone rock
samples (87Sr/86Sr=0.70743÷0.70752), while springs range from
near-isotopic equilibrium with limestones towards a more
radiogenic character, suggesting different water-rock contact
times. These data are interpreted in terms of the role of the
processes in the upper, phreatic zone and on the different flow
dynamics in the area, which have a different vulnerability
towards pollution.
This study is supported by the Italy-Slovenia crossborder
cooperation Programme 2007-2013, INTERREG Project standard
02/2009, priority line 1: HYDRO KARST”
Marine notches in the Maltese islands (central Mediterranean Sea)
Full text linkWe present the first detailed survey of tidal notches in the central Mediterranean area, in particular along
the coastline of Gozo and Comino (Malta). The Maltese Islands represent one of the few sites in the Sicily
Channel which exhibits coastal carbonate rocks. Marine notches on the islands of Gozo and Comino were
surveyed by means of a seven day continuous snorkeling survey around the entire perimeter of the two
islands. We surveyed the occurrence, lack and typology of marine notches and we correlated them with
late Holocene sea level changes. Sea temperature (T) and electrical conductivity (EC) were collected along
the route in order to locate the submarine springs and to relate them to the surveyed notches.
A well-carved continuous roof notch was discovered along most of the plunging cliffs. It is well-carved
out, in particular along the northern and western coast of Gozo. It develops from about 0.2 m above the
mean sea level down and it can be up to 1.5e2 m deep. On the contrary, tidal notches are localised only in
8 sites. In 2 sites, Vermetid trottoirs develop at low tide level. In addition, at about 7mto10 m m.s.l., a
2e5 m wide marine terrace develops along extensive tracts of plunging cliffs, always in correspondence
with the roof notches. This submerged terrace seem to be the result of the late Holocene slowdown of the
sea level rise, which started to smooth the terrace and to carve out the submerged part of the roof notch,
thanks to the exposed location of the islands and the favourable lithology.
Through the collection of hydrological data, the presence of 21 submarine springs were detected. They
occur mainly in the south-western coast of Gozo and on eastern coast of Comino. Anyway, marine
notches seem not to be related to the freshwater outflow, such as those in the Adriatic Sea, because the
studied islands are very exposed. As a consequence, along the Maltese islands bioerosion seems to be the
most effective process in notch developmen
A multidisciplinary approach in sinkhole analysis: The Quinis village case study (NE-Italy)
Full text linkDuring the last recent years, in Quinis, a small village sited in the Alta Val Tagliamento valley (Friuli Venezia Giulia
Region, NE Italy), the inhabitants facedwith instability phenomena related to the presence of soluble rocks in the
subsurface. The evaporite bedrock is mainly mantled, in fact, by high thickness deposit. This paper explains the
methodological approach thatwe used to identify the instabilities in a very complex geo-structural environment
where the urbanization limits the applicability of several investigation techniques. Different methods were used
to define the bedrock morphology, to characterize the mantling deposits and to identify the processes behind.
What emerged from the study is a mandatory multidisciplinary approach to characterize the subsoil, because
each technique is not able individually to take to a unique result. The data collected allowed to draft a geo–
hydrogeological conceptual model of the Quinis village.
The lessons learned, even ifwith some site-specific dependency, demonstrate the importance of broad-spectrum
investigations,which are essential to understand the subsurface characteristics avoiding relevant socio-economic
impact and supporting an adequate future territorial planning
Interaction between karst and porous aquifers, the case of Mt. Mia transboundary aquifer.
No full textThe Mount Mia massif is located in the eastern side of the Friuli Venezia Giulia Region, across the border between Italy and Slovenia. It is an important karst hydrostructure bounded in the N, E and S by the Natisone River (Figure 1). Several springs are emerging at the toe of the massif mainly in the south-eastern side along the river. The two main springs, Poiana and Tologu, are tapped for the Cividale town water supply. The aim of the present paper is to assess the spring recharge area, its potentialities and vulnerabilities in order to quantify a possible increase withdrawal for the water supply
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