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Coastal and inland karst morphologies driven by sea level stands: a GIS based method for their evaluation
No full textSea level is the base level for groundwater circulation in coastal aquifers. The evolution of karst surface landforms and subsurface drainage systems in these aquifers has been conditioned in geological time by tectonics and glacio-eustatic sea-level changes. Present morpho-structural settings and the type/distribution of karst surface and subsurface forms have developed in different carbonate formations according to differences in lithology, climate and exposure time, all driving the intensity of morphologic and karst processes. The repeated and significant changes of groundwater level linked to “sea-level changes” have had the most important role in driving the continuous evolution of karstic drainage systems, and has resulted in most cases in a multiphase karst. This study aims at defining a general method for identifying, in karst coastal settings, the elevations of flat or low topographic gradient surfaces (using morphometric analysis of Digital Elevation Models (DEM) and GIS), and their comparison with elevations of distinctive karstic levels (passages, lateral solution cavities) observed in vertical shafts and horizontal caves. Of the elevations of flat or low topographic gradient surfaces only those agreeing, within ±10 m or ±20 m, with elevation ranges marked by the high frequency of distinctive karst levels were considered as representative of the more probable past sea-level stands. The method is applied to a regional coastal carbonate formation in Southern Italy, by using a 10 m DEM and information on 140 complex caves and 85 shafts. Of the 15 elevations indicated by DEM analysis (620, 600, 470, 450, 425, 385, 355, 315, 270, 250, 205, 180, 150, 110, and 70 m a.s.l.), 13 match clearly those highlighted by significant frequencies of distinctive karstic levels. These elevations are validated by comparison to the elevation of terraces and karst plains indicated in the literature
Seawater intrusion modeling in the Metaponto coastal aquifer (Basilicata, southern Italy).
No full textThe present study aims to model the seawater intrusion (SWI) in the Metaponto coastal plain (Basilicata region, southern Italy) by analysing the geological, hydrogeological, and hydrochemical features of the aquifer system and external factors such as excessive withdrawals and climate change. In the study area, groundwater supplies are crucial for agricultural and economic growth.
The Metaponto coastal plain is a relevant area for the region development due to the touristic and intensive agriculture sectors. Different anthropogenic impacts play a significant role in facilitating the SWI process in addition to the effects of climate change. In the last century, the Irrigation and Land Development Authority’s hydraulic arrangement and land reclamation works of the marshy areas have aided the development of the plain. Groundwater exploitation to support agriculture, tourism, and industrial activity, as well as the effects of climate change causing modifications in the recharge process, have strongly impacted the hydrogeological conditions of the aquifers in the whole plain, intensifying the potential SWI that must be considered relevant in this coastal system.
Nowadays, groundwater resources are exposed to quantitative degradation due to the historically unfavourable climatic conditions worsened by climate change and the growing water demand, and to qualitative degradation also caused by the SWI. The effective infiltration rate of the area is moderate due to the Mediterranean climate conditions, characterized by high temperatures and scarce precipitation concentrated mainly in winter.
Based on the outcomes of different studies conducted in the study area, such as hydrogeological and hydrochemical investigations, and the intrinsic vulnerability to SWI assessment, numerical simulations were carried out in this work for the portion of the coastal plain more susceptible to SWI. The geological, hydrogeological, hydrological, climatic, and hydrochemical data collected and processed were employed to define the aquifer conceptual model, which was the first step for the following numerical simulations of groundwater flow and the modeling of the SWI phenomenon. To evaluate and model the SWI process in the most prone area of the Metaponto coastal plain, groundwater flow and variable-density transport, under steady-state and transient conditions, were simulated with MODFLOW and SEAWAT codes integrated into Visual MODFLOW Flex 7.0 software (© 2021 by Waterloo Hydrogeologic). A three-dimensional groundwater flow numerical model was developed, and water table and groundwater salinity variations were simulated starting from the hydrogeological conceptual model of the coastal aquifer.
The pumping rates effects and the climate change impact on the aquifer recharge were considered in different scenario simulations. Considering the climate change scenario on direct recharge assessment, no significant changes to the SWI phenomenon result. On the contrary, higher groundwater pumping discharges appear to influence the inland progression of brackish water. The results highlighted that the SWI is potentially not negligible in the future under wells exploitation and may impact the groundwater SWI level risk. The numerical modeling outcomes presented in this work can support groundwater quality and quantity protection and provide indications for implementing management criteria and strategies addressing climate change and variations in water demand
Natural and induced endoreic hydrological conditions in the Alta Murgia karstic region (Apulia, Southern Italy).
No full textLa Piccola Età Glaciale nell’area di Taranto (Puglia, Italia)
No full textNell’area di Taranto depositi marini terrazzati coprono i sedimenti fini di colmamento della Fossa Bradanica confinando l’acquifero carsico della Piattaforma carbonatica Apula. In tale contesto, le variazioni del livello del mare ed i suoi stazionamenti interagendo con i meccanismi idrogeologici, hanno contribuito a determinare dinamiche geomorfologiche ed idrogeologiche. Più in particolare, mentre gli studi geologici consentono una buona ricostruzione di tali processi nel lungo periodo, indagini storiche permettono un significativo riconoscimento di eventi determinati dalla Piccola Età Glaciale dello scorso millennio nell’area di interesse.The present study focuses on the key role that the interactions between sea level changes and standing and hydrogeological mechanisms played on the evolution of the interconnected dynamics of the actual geomorphological and hydrogeological system of the Taranto area, from the Quaternary to nowadays. Moreover the retrieval of historical maps and files allowed us to recognize clear tracks of the Little Ice Age in the area of interest
I vulcanelli di fango sul bordo orientale della Fossa Bradanica (Confine Basilicata - Puglia)
No full textI vulcani di fango, nelle loro varie tipologie e dimensioni, sono l’espressione di complesse fenomenologie ampiamente diffuse nel mondo, che determinano la fuoriuscita sulla superficie della terra o sul fondo del mare di fluidi e fango, in differenti contesti sedimentari e tettonici. Molti sono i vulcanelli di fango individuati e studiati anche in Italia nelle ultime decadi. La presenza, l’origine e le dinamiche evolutive di tali singolari morfologie e delle loro emissioni sono state riferite ad attività tettonica e sismica, alla presenza di gas nel sottosuolo, alla formazione di sovrappressioni nei fluidi sotterranei. I vulcanelli di fango presenti al confine tra i territori pugliese e lucano costituiscono argomento finora inesplorato. Essi risultano posizionati in prossimità del bordo orientale della Fossa Bradanica, punto di convergenza complesso di tre domini: il substrato carbonatico, con ampie distensioni in direzione W, i domini appenninici in sovrascorrimento verso NE, il riempimento clastico della fossa, caratterizzato da una successione plio-pleistocenica di argille azzurre e depositi costieri, coinvolto parzialmente nei processi deformativi dei due termini precedenti. Nel settore E della Fossa Bradanica lungo la fascia perimurgiana, compresa tra Matera, in Basilicata, e Gravina, in Puglia, sono stati individuati due vulcanelli di fango, uno nel territorio del Comune di Gravina in Puglia, l’altro nel Comune di Matera (Basilicata). La fenomenologia è sicuramente più ampia nei territori di tale bordo, ma priva di segnalazioni che permettano una loro precisa localizzazione e identificazione. Le prime osservazioni compiute sui vulcanelli presenti nelle argille azzurre hanno permesso di evidenziare una caratteristica lenta e continua attività del fenomeno eruttivo, connessa alla presenza di fanghi pressurizzati, riconducibili all’ingresso e al movimento di fluidi attraverso sistemi di fratture profonde nell’ammasso argilloso. Il presente lavoro fornisce una prima segnalazione ed interpretazione dei fenomeni di vulcanesimo sedimentario identificati in questi territori, con l’obiettivo di evidenziare la specificità dei sistemi nei quali essi si sviluppano, la coerenza di queste fenomenologie con altre rilevate nei territori in esame. Infine si ritiene molto importante promuovere tali fenomenologie come singolarità geologiche, da ascrivere al patrimonio naturale delle regioni che le ospitano
Seawater intrusion modeling under climate and anthropogenic changes in the Metaponto coastal aquifer (Basilicata, Southern Italy)
Full text linkThe Metaponto coastal plain, located in the Basilicata region (southern Italy), is a relevant area for economic development due to the touristic and intensive agricultural sectors. In the 20th century, the land reclamation works, irrigation systems, and wells exploitation to support agriculture and industry strongly impacted the hydrogeological system, intensifying the potential seawater intrusion (SWI) that must be considered relevant in this coastal aquifer. The effective infiltration rate of the area is moderate due to the Mediterranean climate conditions, characterized by high temperatures and scarce precipitation concentrated mainly in winter. The present study aims to evaluate and model the SWI process in the most prone area of the Metaponto coastal plain. Groundwater flow and variable-density transport, under steady-state and transient conditions, were simulated with MODFLOW and SEAWAT codes integrated into Visual MODFLOW Flex 7.0 software. The pumping rate effects and the impact of climate change on the aquifer recharge were considered in different scenario simulations. The results highlighted that the SWI is potentially not negligible in the future under exploitation and may impact the groundwater SWI level risk. The numerical modeling outcomes presented in this work can be used for the effective management of the Metaponto coastal plain groundwater resources
Hydrological and hydrogeological hazard coming from man made agricultural transformations of the soils of the Murgia (Puglia, Southern Italy).
No full textReply to the discussion on ‘Coastal and inland karst morphologies driven by sea level stands: a GIS based method for their evaluation’ by Filomena Canora, Dolores Fidelibus and Giuseppe Spilotro (2012)
No full textThe authors welcome the discussion concerning their paper ‘Coastal and inland karst morphologies driven by sea level stands: a GIS based method for their evaluation’ by F. Canora, D. Fidelibus, G. Spilotro, made by J. De Waele and M. Parise. It provides an opportunity to open a debate about the significance
of geomorphological studies at different scales, both generally, and for the specific area of study (Murgia, Southern Italy)
Anisotropy of hydraulic conductivity through shallow geophysical surveys
No full textA geophysical investigation, including surface seismic refraction and electrical resistivity
methods with radial scanning, was carried out at two test sites of the Apulia region (Italy), in carbonate and
evaporite environments characterized by karstic processes. The main aim of the studies was to test the
effectiveness of the above mentioned methods to highlight the anisotropy of hydraulic conductivity of the
rock masses on the base of accurate surface and subsurface analysis of the karstic features and flow
conditions. The electrical resistivity method provided useful indications about the nature of the void filler
(water or residual soils) along the fracture and joint families; the seismic refraction method gave, in a
fractured and karstified system, information on the loss of material on the base of fractures knowledge of p-
waves velocity, density and Poisson ratio of the intact material and of the joint enlargements filler. The
radial scanning configurations revealed very useful in giving a well based forecast of karst development
directions; the combination of different geophysical techniques allowed reducing uncertainty linked to
interpretation of discrete values of physical properties in jointed rock masses and evidencing the anisotropy
features
Boron isotopes as a tool for the assessment of groundwater quality in the Mt. Vulture volcanic area (southern Italy).
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