1,721,014 research outputs found
Groundwater Flow Modeling for the Sustainable Exploitation of the Monte Castello Aquifer
No full textRavedis reservoir is located in the Carnic Prealps, within the municipality of Montereale Valcellina (Friuli Venezia Giulia, North Eastern Italy). It is fed by Cellina stream, and is situated just before the outlet of Cellina Valley in the Venetian-Friulian Plain. The reservoir was designed to mitigate flood events and to store water for hydroelectric power generation and for irrigation purposes. For this reason, the lake level is raised in summer to higher levels than in the winter or wet months.
This study focuses on Monte Castello, a thin hilly system that separates the reservoir from the plain. It hosts an aquifer characterized by the presence of variously fractured dolomitic limestone.
The reservoir’s creation resulted in a change in groundwater supply regime downstream of it. The presence of the lake guarantees, especially in the dry summer months, a constant source of recharge for the Monte Castello aquifer. This fact prompts evaluation of the Monte Castello aquifer's potential for use as an alternative to plain groundwater resources, which are more susceptible to overexploitation and climate change.
An extensive work of bibliographic research and analysis of piezometric data by means also of geostatistical techniques was carried out in order to characterize the study area from a hydrogeological point of view.
This study is aimed at developing a groundwater flow model of the study area with Modflow. The three main goals of the research are:
- To obtain, through inverse modeling, a reliable estimate of the distribution of the hydraulic conductivity parameter;
- To estimate the amount of water that leaks underground from Ravedis reservoir or, in other words, its losses;
- To simulate the effects of drilling a pumping well to supply water to Montereale Valcellina and surrounding villages.
The sustainable management of water bodies like Monte Castello’s one, small in size but with a high potential, could represent one of the ways forward to a more resilient response to the growing demand for high-quality water resources
Application of different methods for the estimation of natural groundwater recharge: the Muravera case study
No full textEvaluation of natural recharge is essential for a sustainable management of groundwater resources, especially in coastal areas where saltwater intrusion phenomena can arise. Direct recharge from precipitation represents the main source to phreatic aquifer; however, in complex hydrogeological systems, further sources as lateral recharge or surface water discharge into the groundwater systems needs to be evaluated for an accurate quantification of available resources.
In this study, several methods are used to estimate natural recharge of the Muravera alluvial aquifer, in south-eastern Sardinia (Italy), where ongoing seawater intrusion problems have led to a critical deterioration of the groundwater resource with severe environmental and socio-economic impacts.
Direct recharge from precipitation is evaluated through the application of two different methods, namely the I) Inverse Water Balance (IWB), and the II) Soil Water Balance (SWB). The IWB approach is based on spatial distribution of simple climatic dataset (precipitation and air temperature) and subsequent evaluation of the infiltration term through the definition of Potential Infiltration Indexes (CIP). The SWB approach, based on a modified Thornthwaite-Mather method, is implemented within a computer code developed by the USGS (Westenbroek et alii 2010); the code calculates spatial and temporal variations of groundwater direct recharge by integrating tabular daily climatological data with gridded datasets containing information about 1) hydrologic soil group, (2) land-use/land-cover, (3) available soil-water capacity, and (4) surface-water flow direction.
To evaluate the occurrence of supplementary alimentation sources, the Water Table Fluctuation (WTF) method is also applied. The methodology, implemented within the ESPERE Macro Excel developed by the BRGM, requires continuous groundwater level measurement, and it assumes that piezometric level rises in unconfined aquifers are directly related to aquifer recharge. Advantages of this approach include its simplicity and an insensitivity to the mechanism by which water moves through the unsaturated zone (disadvantage of the SWB). Results of the IWB and SWB methods illustrate that the average direct recharge from precipitation, referred to the same decade 2009-2018, are in good agreements and vary between 2.86 and 4.43 Mm3/year, respectively. Results of the WTF, applied to the available 2019-2020 monitoring data, indicates that a supplementary 3 Mm3/year recharge occurs, mostly from the aquifer interactions with the Flumendosa river
Testing indirect methods to infer hydraulic conductivity in streambed sediments: preliminary results
Full text linkHydraulic conductivity, grain-size parameters, empirical approach, Kozeny-Carman model
Groundwater numerical model of the Biskra inféro-flux aquifer (NE Algeria)
Full text linkQuaternary alluvium, Northeastern Algeria, 3D Hydrogeological modelling, steady state, PEST
3D hydrogeological modelling supporting studies on the sources of manganese, sulphate and trichloromethane in groundwater at Portoscuso (Sardinia, Italy)
Full text linkPortoscuso, South-Western Sardinia, volcanic aquifer, geometry of the aquifers, 3D hydrogeological modeling
An interdisciplinary methodology to design integrated and innovative MAR systems in arid and semi-arid regions. Two case studies in Algeria and in Tunisia
Full text linkDrought, desertification, Managed Aquifer Recharge (MAR), Tunisia, Algeri
Geological and hydrogeological features controlling mechanisms of fluoride enrichment in groundwater in the East African Rift System
Full text linkEast African Rift Valley, fluoride , rift architecture, groundwate
Estimation of Transit Time Along the Unsaturated Zone in the Protection of Groundwater Resources
No full textThe growing world population coupled with the expansion of agriculture and animal husbandry has led to excessive use of organic and chemical fertilizers in soils, resulting in widespread nitrate contamination of groundwater. Despite the restrictive regulations imposed by the Nitrate Directive, no improvements in groundwater quality have been observed in many Nitrate Vulnerable Zones. In studies of vulnerability to aquifer contamination, the focus is more on the groundwater body and the unsaturated zone is often neglected. The unsaturated zone is the main factor controlling water movement and pollutant leaching, depending on the soil properties and infiltration rates. Natural attenuation processes in unsaturated zones can reduce the leaching of contaminants into groundwater. The infiltration rate determines the transit time in the vadose zone and thus the water-rock interaction time that controls the transformation, the entrapment/adsorption of the transported solutes.
This research compares two regions of Sardinia with different geological, hydrogeological and pedological features: the Arborea plain (designated as a NVZ since 2005), and the southern Campidano plain, in which nitrate concentration in groundwater frequently exceeds the limit of 50 mg/L.
The main purpose of this study is to estimate the rate of groundwater recharge using stable water isotope profiles in the vadose zone at the two sites by comparing physical properties of the soils and land use.
At each of the two study sites, soil samples were collected every 10 cm along a vertical profile and were analyzed to determine their stable water isotope ratios (δ2H and δ18O) together with the water content, grain size distribution and physical-chemical parameters of the soils.
The peak-shift method was applied based on the assumption that seasonal effects on the isotopic composition of precipitation are traced through the soil vertical isotopic profile that were used along with the piston dis\placement method to estimate recharge rate.
The study of the transit time of water percolation along the unsaturated zone is therefore an influential factor in the assessment of the vulnerability of the aquifer and has implications in the optimization of agricultural practices and actions to protect the groundwater resource
Pisolithic ferricretes around the Cretaceous-Palaeocene boundary in southern Sardinia (Italy) as palaeoenvironmental proxies
Full text linkSome of the weathering deposits that formed during the emersive phase, which in Sardinia
lasted from Late Cretaceous to Palaeocene–Early Eocene, consist today of ferruginous
palaeosols (ferricretes), sometimes overlain by palustrine limestones. In this article, the two
outcrops at Nuxis and Guardia Pisano, containing a ferricrete composed of subspherical
goethitic-hematitic concretions, are studied in detail. The main components are Fe, Al, Si,
along with Ba, which is very abundant in the Nuxis outcrop. With the exception of the barite,
the pisolithic ferricretes of Sardinia can be compared, for their chemical and mineralogical
composition, with the pisoplinthites that form in modern tropical soils. They are also
comparable with the pisolithic ferricretes cropping out in southern France, that formed
around the K/T boundary. The pisolithic ferricretes of southern France and Sardinia can be
interpreted as theweathering product of identical warmandhumid climatic conditions and,
reasonably, of thesame climatic event.Therefore, they provide further evidence that Sardinia
and southern France formed part of the same palaeogeographic province. A tropical
environment is, on the other hand, consistent with the barite leaching from the Palaeozoic
substratum and with its reprecipitation into the iron pisoliths. Micro- and nanostructures,
observed using SEM analysis within and between the concentric layers of the pisoliths, are
consistent with biological processes involving bacteria during their deposition
“La Maddalena” exploratory adit - base tunnel of the Turin-Lyon high speed rail project: hydrogeological monitoring data analysis
Full text link"La Maddalena" exploratory tunnel, located in the Italy Western Alps (Susa Valley), is one of
the four exploratory adits, three in France, completed in 2010, and one in Italy, whose
realization is related to Turin-Lyon high-speed rail project.
Concerning tectonical setting ‘‘Pennidic Domain’’is involved in the excavation, and more in
details the contact between Piemontese Zone (mainly Calceshits and green stones Unit) and
Brianzonese Zone (Ambin Massif Unit and related coverage). However from pk 0+200 m the
exploratory adit crosses the Ambin Massif represented by gneiss and micascists. Several
monitoring data have been recorded during the excavation, in order to asses geological
parameters important for the future Base Tunnel realization. This exploratory adit is now still
under completion.
The main aim of this work is to compare the experimental hydrogeological monitoring data
with the project hypothesises (Italferr Spa, 2009) in order to check the correctness of inflow
forecast in term of discharge, temperature and chemical facies of groundwater. The analysed
monitoring data cover the period since the beginning of the excavation of "La Maddalena"
exploratory adit to the pk 5+548 m (July 2016). During the excavation phase, the
hydrogeological monitoring has then concerned:
• daily measure of the total inflow rate;
• bimonthly measure of conductivity, temperature and pH of each punctual water inflow;
• sampling and chemical analysis of some of the main inflows.
The comparison between expected and measured hydrogeological elements have given
important information: water inflow began only after the Ambin Massif Unit was reached by
excavation and therefore intercepted water flows were less than expected in design. At ch.
5+548 (27-07-2016) a total inflow of 55.4 l/s is reported. This value is below the minimum
stable expected inflow rate. The temperature of inflows varies between 13.7 °C at ch. 0+246
and 39.5 °C at ch. 5+289 (20-22-07-2016). The trend of the total inflow rate analysed
considering rainfall patterns registered in four rainfall stations, seems to show a generalised
lack of direct correlation with precipitation.
Temperature and chemical composition of punctual water inflow have also given the possibility
to find out some characteristics concerning the hydrogeological water supply circuits: i.e. the
values of temperature registered along the excavation and the temperature water trend
increasing with the excavation, indicate a quite slow hydrogeological circuit interesting the
excavation area, even if the water temperature is generally lower than the temperature of the rock measured over time along the excavation.
La Maddalena exploratory adit experience confirms the importance to realize exploratory
tunnels previously the excavation of a main tunnel. Having regard to the rate and temperature
of water inflows registered during the excavation, a possible geothermal use of this intercepted
water resource could be evaluated more in details.
References
Italferr Spa, 2009. Fase Progettuale della Nuova Linea Torino Lione, Progetto Preliminare 2
(PP2)-Progetto Variante Tecnica – Cunicolo Esplorativo la Maddalena. Relazione geologica e
idrogeologica
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