1,721,182 research outputs found
Primi risultati di un metodo d'integrazione mista in un modello di filtrazione agli elementi finiti
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Indagine sperimentale sulla localizzazione del risalto a mezzo di quinte
No full textThe paper deals with the hydraulic jump localization realized by an abrupt contraction of the section width. This contraction may be right made by two walls – the wings – located at the end of the stilling basin and structurally connected with the lateral walls. This structure ensures a major reliability to respect the stilling basin with a positive step that the sediment drift tends to reduce. A large set of laboratory experiments was made in a Froude number range spanning between 4 and 13 for several different geometrical configurations of the wings. Besides a clear highlight on the hysteresis phenomenon that characterizes the hydraulic jump localization, from the results it is manifest the relevance of the ratio between the length of the contracted width and the depth of the toe of jump in the design of the contraction ratio. Moreover, the measured basin length for the Froude range between 4 and 7 is greater that the length recommended and usually adopted
ANALISI SPERIMENTALE MULTISCALA NEGLI ACQUIFERI NATURALI. IL SITO DI SETTOLO – VALDOBBIADENE (TV)
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Analisi di rischio nelle opere idrauliche
No full textLa lezione tratta il problema della definizione del rischio nelle opere idrauliche, concetto che risulta sempre implicitamente presente nella loro progettazione. Questo per la necessità di definire in termini probabilistici un carico – in genere una portata o un tirante idrico – non altrimenti noto. Ciononostante, le incertezze legate alla definizione delle grandezze caratteristiche delle opere, alla loro realizzazione ed alla valutazione in termini economici del danno che da un loro mancato funzionamento o dalla loro perdita possa derivare, hanno messo in evidenza la necessità di una più completa analisi delle metodologie di valutazione del rischio. Dopo alcune considerazioni di carattere generale, la nota affronta le definizioni legislative – in particolare quelle relative alla valutazione del rischio idrogeologico – ed il problema della loro interpretazione alla luce di una corretta applicazione delle tecniche di calcolo probabilistico applicate alla progettazione delle opere idrauliche di difesa
Caratterizzazione idraulica degli acquiferi naturali
No full textNella lezione sono brevemente descritte alcune fra le tecniche di caratterizzazione degli acquiferi naturali. Vengono ricordate le indagini geologiche di carattere generale che devono essere preliminarmente svolte per assicurare il successo delle successive prove e come queste possano essere vantaggiosamente integrate dalle più recenti analisi di telerilevamento e di carattere geofisico. Solo alcune considerazioni di massima sono riportate nel presente testo relativamente alle prove di pompaggio e alle prove con traccianti su pozzo, come pure alla loro interpretazione. Sono comunque riportate alcune recenti voci bibliografiche
Impact of urban areas' drainage system on the quality of water bodies and mitigation strategies
No full textDiffuse urban pollution is a significant factor in compromising receiving water and groundwater standards required by the EU Water Framework Directive. Many studies (e.g., Ashley et al., 2005; McGrane, 2016) show that changes in the built environment and climatic forces contribute to the increase of combined sewer system overflows and of stormwater directly conveyed to nearby water bodies. These discharges are responsible for receiving water contamination, as a result of high concentrations of pathogens, BOD, suspended solids (SS), hydrocarbons, heavy metals and nutrients, thus being a significant source of water bodies’ pollution.
To mitigate/eliminate pathogens and BOD contamination sources, the combined drainage system is usually split into separated sanitary sewer and stormwater systems, although difficulties related to economic and technical feasibility may be relevant. Nevertheless, this solution does not solve completely pollution due to SS, hydrocarbons, heavy metals from urban areas runoff and nutrients from rural drainage.
Sustainable Drainage Systems (SuDS) deal with stormwater at source, helping infiltration and storage of water, increasing groundwater recharge, and reducing peak flood and volume in the drainage system. Moreover, filtration processes through porous media may reduce pollutants driven by first flush, usually controlled by stormwater tanks and sewer system spillways. However, clogging phenomenon limits drainage efficiency in the long-term, making sometimes porous media itself a source of contamination.
In the following, a PhD project focusing on the urban area of Treviso is illustrated. Treviso is crossed by the river Sile, one of the longest (95 km) European wellspring rivers, part of a protected area. The Sile river is polluted by discharges from both the existing combined sewer system and rural drainages.
While responsible agricultural practices will be promoted to mitigate the pollution originating from rural areas, a project aims to separate the combined system, developing a new pipe network for sanitary wastewater. When properly applied in the present drainage system devoted to the stormwater control only, SuDS solutions are able to mitigate pollution coming from wash-off and reduce flood peaks.
Discharge measurement stations will be realised on the Sile river upstream and downstream the Treviso town, to quantify drainage system outflows of the urban area during rainfall events and in dry conditions. Sampling for qualitative analysis will give a measure of the pollutants’ concentration.
SuDS solutions, e.g. porous pavements, infiltration trenches and vegetated swales, will be tested with laboratory equipment (6×2 m2) capable of considering the runoff and underground drainage in a fully controlled environment subjected to a prescribed rainfall intensity. By this way it will be possible to analyse the main physical processes and assess the SuDS solutions’ efficiency both in the short and long-term, using advanced mathematical models for the interpretation of results.
If the laboratory model will provide satisfactory results, a full-scale test will be developed on an experimental site in Treviso town. The installed qualitative and quantitative monitoring system will allow to determine the effectiveness of the solutions adopted
Monitoring and modeling of rivers crossing urban areas: The case of the Sile River in Treviso (Italy)
No full textA significant factor in compromising receiving water standards required by the EU Water Framework Directive is the use of plant protection products and fertilizers in agriculture and the diffuse urban pollution. Changes in the built environment and climatic forces contribute to the increase of combined sewer system (CSS) overflows and of stormwater directly conveyed to water bodies that, together with rural discharges, are responsible of their contamination.
Here the case of the river Sile, one of the longest European wellspring rivers and part of a protected area located in the Nord-Est of Italy is addressed.
To assess the impact of rural and urban pollution discharges on the quality of the main river and some of its tributaries crossing the city of Treviso (Figure), a monitoring system consisting of 6 discharge measurement stations and 4 sampling systems, together with 3 multiparametric probes, will soon be realized. To identify the most common pollutants and quantify rural and urban area’s drainage system outflows during both rainfall events and dry conditions continuous probe monitoring and lab analysis of automatic water samples will be developed. Monitored discharges and collected quality data will be analysed and used together with the results of a currently under development 1D-2D hydrodynamic model of natural and artificial channel network.
The hydrodynamic model, using as input the data acquired over time, will allow us to determine the nowadays conditions, identify and quantify the main sources of pollution and suggest possible mitigation strategies to improve the current status of the Sile River.
These activities will enable the promotion of responsible agricultural practices and the assessment of the effects of an ongoing project aimed at separating the CSS. Moreover, to solve pollution generating from urban areas runoff, Sustainable Drainage Systems solutions will be tested with a laboratory equipment in a fully controlled environment, to analyse the main physical processes and assess the solutions’ efficiency both in the short and long-term.
If the laboratory model gives satisfactory results, a full-scale test will be developed on an experimental area of the municipality of Treviso, to verify the effectiveness of the solutions adopted through the installed monitoring system
Definizione delle aree di salvaguardia negli acquiferi naturalmente eterogenei
No full textLa cattura di un soluto da parte di un pozzo emungente da un acquifero naturale ed i tempi di percorrenza dal punto di iniezione al pozzo, sono grandemente influenzati dalla eterogeneità spaziale delle formazioni, potendosi manifestare differenze significative rispetto le previsioni sviluppate immaginando l’acquifero omogeneo. La conoscenza delle modalità di movimento dei soluti e la corretta definizione dei tempi di arrivo risulta di fondamentale importanza nella valutazione delle aree di salvaguardia attorno alle opere di presa che estraggono acqua destinata al consumo umano. La comprensione dei processi dominati dall’eterogeneità risultano indispensabili per una opportuna predisposizione,
a valle di una sorgente inquinante, di un sistema di controllo in grado di segnalare
l’alterazione della qualità delle acque di falda con prefissato anticipo. Nella lezione
viene analizzato la stato dell’arte della letteratura tecnico-scientifica relativa all’argomento, cercando di mettere in evenienza quelle che sono le principali problematiche che s’incontrano nei casi reali e come queste possano essere affrontate. In particolare vengono presi in esame metodi e schematizzazioni, coerenti con la realtà fisica descritta, che permettano la valutazione dei tempi di percorrenza per definire in termini probabilistici le aree di cattura e i valori delle isocrone isoprobabili nell’intorno dei pozzi
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