1,720,986 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
Unconventional Pumping Tests in Carbonate Aquifers, Without Interruption of Drinking Water Exploitation
No full textThe Gran Sasso carbonate aquifer is the largest and most productive in the Apennines. Its
hydrogeological structure has been deeply studied since the middle of the last century for springs’ characterization for drinking purposes and for drilling of a motorway tunnel. Meanwhile, its hydrodynamic parametrization is less developed and is mainly limited to monitoring the discharge and chemical and isotopic parameters of springs. Starting from the ‘80s of the last century, the aquifer has also been exploited through wells especially
in its southern portion where it was possible to reconstruct the geological structure and perform pumping tests because of the lowest groundwater table depth. The aquifer is characterized by secondary porosity, i.e. by fracturing and karst features, and an underlying impermeable marly complex, which represents the basal aquiclude. In such aquifers, it might appear inappropriate to characterize the hydraulic properties via pumping tests, as their reliability is proven in homogeneous and isotropic media. However, the high extent of the aquifer (about 700 km2), the location of the wells, as well as the scarcity of information available and the lack of alternatives forced to estimate some hydrodynamic parameters as in porous aquifers and to test the aquifer experimentally, especially in conditions of maximum pumping even for the evaluation of the influence radius. Furthermore, since the aquifer testing was performed during the normal activities of abstraction and distribution, it was not possible to perform canonical tests, i.e. with only one pumping well and observing the adjacent wells. However, the high transmissivity of the aquifer, the use of a single pumping well would have not sufficed to induce a drawdown that allowed data processing. Therefore, the step-drawdown test was obtained by turning on an increasing number of wells over time and keeping fixed the observation points. This kind of test, in addition to avoid interrupting the water supply, allowed: - estimating hydraulic conductivity and transmissivity; - estimating drawdown in pumping wells and in observation piezometers in operating conditions; - evaluating the extension of the perturbation induced to the aquifer both at the test and stress discharges; - evaluating flow directions in operating conditions
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
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Human alteration of groundwater-surface water interactions (Sagittario River, Central Italy): implication for flow regime, contaminant fate and invertebrate response
No full textMany rivers worldwide are undergoing severe man-induced alterations which are reflected also in changes of the degree of connectivity between surface waters and groundwater. Pollution, irrigation withdrawal, alteration of freshwater flows, road construction, surface water diversion, soil erosion in agriculture, deforestation and dam building have led to some irreversible species losses and severe changes in community composition of freshwater ecosystems. Taking into account the impact of damming and flow diversion on natural river discharge, the present study is aimed at (i) evaluating the effects of anthropogenic changes on groundwater/surface water interactions; (ii) analyzing the fate of nitrogenous pollutants at the floodplain scale; and (iii) describing the overall response of invertebrate assemblages to such changes. Hydrogeological, geochemical and isotopic data revealed short- and long-term changes in hydrology, allowing the assessment of the hydrogeological setting and the evaluation of potential contamination by nitrogen compounds. Water isotopes allowed distinguishing a shallow aquifer locally fed by zenithal recharge and river losses, and a deeper aquifer/aquitard system fed by surrounding carbonate aquifers. This system was found to retain ammonium and, through the shallow aquifer, release it in surface running waters via the hyporheic zone of the riverbed. All these factors influence river ecosystem health. As many environmental drivers entered in action offering a multiple-component artificial environment, a clear relationship between river flow alteration and benthic and hyporheic invertebrate diversity was not found, being species response driven by the combination of three main stressors: ammonium pollution, man-induced changes in river morphology and altered discharge regime
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