Browsing by Author "Macchione, Francesco"

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Accuracy aspects in flood propagation studies due to earthfill dam failures
(2015-10-30) Razdar, Babak; Costabile, Pierfranco; Costanzo, Carmelina; Macchione, Francesco
Flooding due to dam failing is one of the catastrophic disasters which might cause significant damages in the inundated area downstream of the dam. In particular, there is a need of trustworthy numerical techniques for achieving accurate computations, extended to wide areas, obtained flood mapping and, consequently, at the implementation of defensive measures. In general several key aspects are required for accurate simulations of flood phenomena which are ranging from the choice of the mathematical model and numerical schemes to be used in the flow propagation to the characterization of the topography, the roughness and all the structures which might interact with the flow patterns Regarding general framework discussed before this thesis is devoted to discuss two aspects related to accuracy issues in dam breach studies. In the first part a suitable analytical relation for the description of reservoir have been discussed and the second part the influence exerted by the methods used for computing the dam breach hydrograph on the simulated maximum water levels throughout the valley downstream of a dam, has been investigated. As regards the first aspect, the influence of reservoir morphology on the peak discharge and on the shape of outflow hydrograph have been investigated in the literature. The calculation of the discharge released through the breach requires the knowledge of the water level in the reservoir. It is considerable that the reservoir morphology in computational analyses cannot be expressed exactly by an analytical formula because of natural topography of the reservoir. For this reason, the information about reservoir morphology is usually published as a detail tables or plots which each value of elevation from bottom to top has a corresponding value for lake surface and reservoir volume. However, in the cases for which there is a scarcity of data, analytical expression can be obtained by interpolation of the values of the table. Usually one of the most suitable technique for interpolation data is using polynomial function but unfortunately utilizing this function for solving the problem demand several parameters. Using power function in numerical computations of breach phenomena would be advantageous, because this function is monomial type and only one parameter needs to be estimated. In this thesis, we want to present that this approach is very accurate and suitable to represent the morphology of the reservoirs, at least for dam breach studies. To reach this aim, 97 case studies have been selected from three different geographical regions in the world. The results of this research have been shown that the power function is suitable to obtain an accurate fitting of the reservoir rating curve using a very limited number of surveyed elevations and volumes or areas. Furthermore in this part of the research it has been shown that two points are enough for a good fitting of the curve, or even only one if volume and surface are both available for an elevation close to normal or maximum pool. Results obtained for dam breach calculations using this equation, have the same quality of those achieved using the elevation-volume table. Moreover, this research have been shown that the exponent of power equation can be expressed by a formula which has a precise morphological meaning, as it represents the ratio between the volume which the reservoir would have if it were a cylinder with its base area and height equal to the respective maximum values of the actual reservoir, and the real volume of the reservoir. Regarding the second aspect, over the complexity of the mathematical models which have been used to predict the generation of dam breach hydrograph, it is considerable that the historical observed data of discharge peak values and typical breach features (top width, side slope and so on) have been usually utilize for model validation. Actually, the important problem which should be considered here is traditionally focused on what has been observed in the dam body, because the effects of the flood wave realized in the downstream water levels usually have been neglected. This issue seems considerable because required information for the civil protection and flood risk activities are represented by the consequences induced by the flood propagation on the areas downstream such as maximum water levels and maximum extent of flood-prone areas, flow velocity, front arrival times etc. The water surface data is almost never linked to the reservoir filling/emptying process which can be important information for the estimation of discharge coming from the breach, are available. Moreover, it is quite unusual to have records on the flood marks signs or other effects induced on the river bed, or on the man-made structures, downstream. For this reason finding well documented case study is one of the important part of any simulation study, especially for model validation. One of the few cases in this context is represented by the Big Bay dam, located in Lamar County, Mississippi (USA), which experienced a failure on 12 March 2004. In general analyzing the simplified models for dam breach simulation is the main purpose of this second important activity of the thesis. The simplified model have been utilized in this study, in order to identify a method that, on the basis of the results obtained in terms of simulated maximum water levels downstream, might effectively represent a preferential approach for its implementation not only in the most common propagation software but also for its integration in flood information systems and decision support systems. For the reasons explained above, attention here focuses on the parametric models, widely used for technical studies, and on the Macchione (2008) model, whose predictive ability and ease of use have been already mentioned. To reach this purpose both a 1-D and 2-D flood propagation modelling have been utilizing in this study. The results show that the Macchione (2008) model, without any operations of ad hoc calibration, has provided the best results in predicting computation of that event. Therefore it may be proposed as a valid alternative for parametric models, which need the estimation of some parameters that can add further uncertainties in studies like these.
Analisi dell'erosione di fondo in materiale coesivo
(2014-06-09) Massaro, Giorgia; Calomino, Francesco; Macchione, Francesco
Applicazione della shallow water equations per la simulazione numerica a scala di bacino degli eventi alluvionali
(Università della Calabria, 2020-04-16) Gangi, Fabiola; Critelli, Salvatore; Macchione, Francesco; Costanzo, Carmelina
La valutazione del rischio idraulico connesso alle piene dei corsi d’acqua è particolarmente delicata quando gli eventi alluvionali hanno carattere impulsivo, come accade nei bacini di modeste dimensioni. L’approccio correntemente utilizzato per l’analisi idraulica è quello di individuare dei singoli tratti di interesse dei corsi d’acqua. L’analisi è condotta sulla base di idrogrammi di progetto ricavati mediante modelli idrologici del tipo afflussi-deflussi. In questa memoria sarà invece applicato un approccio basato sull’analisi degli effetti idraulici provocati da un evento meteorico considerando come dominio per il calcolo idraulico l’intero bacino idrografico. Tale approccio è in grado di individuare situazioni di pericolo in zone che magari non sarebbero state esaminate. L’uso di modelli idrodinamici basati sulle shallow water equations, è diventato oggetto di crescente interesse per simulare eventi a scala di bacino. Un fattore che può essere limitante ai fini dell’ottenimento di risultati conseguibili con il dettaglio fisico garantito dalle SWEs è la dimensione delle celle di calcolo. Questa deve essere sufficientemente piccola da garantire un’accurata simulazione degli effetti idraulici e contestualmente non troppo piccola per non rendere proibitiva la mole dei calcoli su domini estesi. In questa ottica, il presente lavoro propone di occuparsi dell’individuazione dei criteri per la delimitazione delle aree a pericolosità idraulica definendo la più grande dimensione che può essere assegnata alla cella di calcolo per ottenere risultati sufficientemente affidabili. A tal fine, un modello numerico basato sulle SWE, sviluppato dagli autori e parallelizzato utilizzando le direttive OPENMP e MPI, è stato applicato al bacino del fiume Beltrame, collocato sulla costa Est della Calabria. Il torrente Beltrame, come altri torrenti della fascia ionica calabrese, è stato interessato, in passato, da eventi alluvionali di notevoli dimensioni. Si prenderà qui in esame l’evento accaduto il 10 settembre 2000. La risoluzione dei dati topografici a disposizione è variabile. Il 39% ha una copertura di dati DTM a risoluzione 5 metri, il 59% ha copertura di dati LiDAR a risoluzione 1 metro e l’2% ha copertura di dati LiDAR a risoluzione 2 metri. A partire dai dati topografici, sono stati generati quattro domini computazionali con griglie di tipo non strutturato, uniforme, con elementi triangolari (con area variabile da 36 a 900 m2). Le differenze tra i risultati ottenuti sono stati confrontati in termini di estensione di aree allagate e distribuzione dei valori della pericolosità all’interno delle aree perimetrate, quest’ultima quantificata secondo il prodotto hV, dove h è la profondità della corrente in un assegnato punto e in un assegnato istante e V è la contestuale velocità. La valutazione della sovrapponibilità delle aree per ciascuna classe di pericolosità è stata eseguita utilizzando diversi indici quali: Hit Rate, False Alarm Ratio, Critical Success Index. L’analisi condotta nella presente memoria ha messo in luce che, a scala di bacino, gli errori sui massimi tiranti crescano significativamente al crescere delle dimensioni delle celle di calcolo, sebbene essi si mantengano più contenuti, anche usando le griglie più grossolane, per la parte valliva, caratterizzata da estensioni più ampie dell’area allagata. In ogni caso sembra che questo abbia una scarsa ricaduta sulla valutazione della pericolosità. I calcoli e i confronti hanno mostrato che le aree a diversa pericolosità si distribuiscono all’interno dell’area del bacino in maniera simile. Inoltre, anche se non si arriva ad una perfetta sovrapposizione areale, esse sono collocate spazialmente in modo che o si sovrappongono parzialmente o, se sono delle strisce sottili, hanno dislocazioni molto prossime le une alle altre. si ritiene che anche con la griglia più grossolana si possa impiantare una buona analisi della pericolosità a scala di bacino, certamente con precisione maggiore andando dai rami montani del reticolo – più stretti - a quelli più ampli che provocano esondazioni in zone vallive.
Characterization of real aquifers using hydrogeophysical measurements. An application to the chambo aquifer (Ecuador)
(2014-10-29) Mendoza Trujillo, Benito Guillermo; Macchione, Francesco; Straface, Salvatore
Coherent structures of turbulence in wall-bounded turbulent flows
(2011-10-24) Ciliberti, Stefania Angela; Macchione, Francesco; Alfonsi, Giancarlo
Direct Numerical Simulation (DNS) of a fully developed turbulent channel flow represents a powerful tool in turbulence research: it has been carried out to investigate the main characteristics of wall-bounded turbulence. It consists of solving numerically the Navier-Stokes equations with physically-consistent accuracy in space and time. The major difficulty in performing turbulence calculations at values of the Reynolds number of practical interest lies in the remarkable amount of computational resources required. Recent advances in high performance computing, especially related to hybrid architectures based on CPU/GPU, have completely changed this scenario, opening the field of High Performance Direct Numerical Simulation of turbulence (HPDNS), to which new and encouraging perspectives have been associated with the development of an advanced numerical methodology for studying in detail turbulence phenomena. The research activities related to the Ph. D. Program concerns the high performance direct numerical simulation of a wall-bounded turbulent flow in a plane channel with respect to the Reynolds number dependence in order to investigate coherent structures of turbulence in the wall region. The objectives of the research have been achieved by means the construction and the validation of DNS turbulent flow databases, that give a complete description of the turbulent flow. The Navier- Stokes equations that governs the flow of a three-dimensional, fully developed, incompressible and viscous fluid in a plane channel have been integrated and a computational code based on a mixed spectral-finite difference scheme has been implemented. In particular, a novel parallel implementation of the Navier-Stokes solver on GPU architectures have been proposed in order to perform simulations at high Reynolds numbers. In order to deal with large amount of data produced by the numerical simulation, statistical tools have been developed in order to verify the accuracy of the computational domain and describe the energetic budgets that govern the energy transfer mechanisms close to the wall. Flow visualization has been provided in order to identify and evaluate the temporal and morphological evolution coherent structures of turbulence in the wall region. The objectives of the research have been achieved by means the construction and the validation of DNS turbulent flow databases, that give a complete description of the turbulent flow. The Navier- Stokes equations that governs the flow of a three-dimensional, fully developed, incompressible and viscous fluid in a plane channel have been integrated and a computational code based on a mixed spectral-finite difference scheme has been implemented. In particular, a novel parallel implementation of the Navier-Stokes solver on GPU architectures have been proposed in order to perform simulations at high Reynolds numbers. In order to deal with large amount of data produced by the numerical simulation, statistical tools have been developed in order to verify the accuracy of the computational domain and describe the energetic budgets that govern the energy transfer mechanisms close to the wall. Flow visualization has been provided in order to identify and evaluate the temporal and morphological evolution threedimensional, fully developed, incompressible and viscous flow. The second part is devoted to the study of the numerical method for the integration of the Navier-Stokes equations. A mixed spectral-finite difference technique for the numerical integration of the governing equations is devised: Fourier decomposition in both streamwise and spanwise directions and finite difference method along the wall-normal direction are used, while a third-order Runge-Kutta algorithm coupled with the fractional-step method are used for time advancement and for satisfying the incompressibility constraint. A parallel computational codes has been developed for multicore architectures; furthermore, in order to simulate the turbulence phenomenon at high Reynolds numbers, a novel parallel computational model has been developed and implemented for hybrid CPU/GPU computing systems. The third part of the Ph. D. thesis concerns the analysis of numerical results, in order to evaluate the relationship between turbulence statistics, energy budgets and flow structures, allowing to increase the knowledge about wall-bounded turbulence for developing new predictive models and for the control of turbulence
Contributo alla riossigenazione naturale della zona eufotica dei corpi idrici dovuto all'attività fotosintetica
(2010-10-27) Nigro, Gennaro; Macchione, Francesco; Frega, Giuseppe; Infusino, Ernesto
Erosione di dune costiere soggette ad attacco del moto ondoso. Studio con modello fisico, analitico e numerico
(2012-11-28) Ricca, Andrea; Macchione, Francesco; Frega, G.; Frega, F:; Tomasicchio, R.
Escavazione localizzata a valle di strutture trasversali in fondo incoerente o coesivo: osservazioni sperimentali e modellazione numerica
(2013-10-29) Dodaro, Giuseppe; Gaudio, Roberto; Tafarojnoruz, Ali; Macchione, Francesco; Calomino, Francesco
Experimental study and qualitative and quantitative modelling of sustainable urban drainage systems (SUDS)
(2013-11-27) Mancuso, Antonello; Macchione, Francesco; Piro, Patrizia; Carbone, :Marco; Laucelli, Daniele B
Climate changes have become always more frequent, increasing the interest of researchers in finding the causes and, above all, the structural or non-structural solutions to solve the problem. Economic development together with rapid population growth constantly increase the demand of goods and services. As the same as drought, also precipitation became more intense and frequent, even with more ever short duration. These events for their heavy impact are called ‘extreme rainfall events’. The actual management of urban waters is unsustainable thus, foregoing reasons lead to an imperative need to develop new urban ecosystems, requiring a rethink of traditional development techniques. Traditional urban drainage systems are designed to rapidly collect and convey overland flows to the treatment plants, without taking into account of their qualitative characteristics. In order to reach the aim of the qualitative and quantitative control of stormwater in urban areas, a possible way is the widespread implementation in urban areas of ‘blue-green infrastructure’ that provide an holistic and integrated approach to the problem. They are one step beyond other ‘classic’ sustainable urban drainage measures such as LID (Low Impact Development), SUDS (Sustainable Urban Drainage Systems) or BMPs (Best Management Practices), allowing to emphasize their beneficial effects. Use of BGC as a part of sustainable drainage system concept is a winning approach, that allow managing and treatment of stormwater runoff within urban areas, using practices made of green and blue components. Generally green components are represented by any kind of existing vegetation (floral plants, grass, hedges) while the blue one by lakes, ponds, rivers and canals (natural or artificial). Together, these infrastructures allow to create a network between them at regional scale. The real behaviour of these structures is not yet properly modelled. Most of the software currently used in urban hydrology (SWMM by EPA, Music by eWater CRC, etc…) model in a reasonable way the hydraulic behaviour of infiltration practices (such as bioretention cells, infiltration trenches, vegetated filter strips, porous pavement) using a simple mass balance approach. Generation, inflow and transport of pollutants are, instead, determined by the land use assigned to each subcatchments, namely through buildup and washoff laws describing accumulation and washout by either a mass per unit of subcatchment area or per unit of curb length. This approach completely lack of quality algorithms within LID models that take into account of their quality performances as, for instance, reduction of efficiency due to the clogging effect. The clogging phenomenon, described as the decrease in infiltration rate of the soil due to the reduction in soil porosity and hydraulic conductivity, occurs for the majority within infiltration practices such as bioretention cells, infiltration trenches, vegetated swales and permeable pavers. Precisely these latter practices are one of the easiest to implement into urban environment, being aimed to reduce impervious areas and work as ‘link’ within BGCs networks. From these premises the research in the following thesis is developed, whose main objective is to study the implementation of 'blue and green' elements in urban areas and their effect on pollutant loads reduction. Initially, a study of common errors retrieved within a DTM (Digital Terrain Model) has been faced because, if not corrected, they will affect the overland flow network generation and the subsequent hydraulic modelling. DEMs (Digital Elevation Models) can include both terrain elevation data, which commands flow direction of floodwater, and land cover information, which dictates resistance to floodwater distribution. Very often DTMs originate from a variety of ground observations supplemented by various remote sensing techniques (aerial and satellite measurements, total stations, dGPS, aerial LiDAR, terrestrial laser scanning) thus, containing systematic or random errors to individuate and eliminate. A study were carried out to evaluate how DTM resolutions and presence of building affect overland flow network delineation in the Liguori Channel basin, situated in Cosenza (Italy). To achieve this aim, three different DEMs of the study area, generated from different sources, were used: two contour-based DTMs with contour interval respectively of 30 m (DTM 30) and 20 m (DTM 20), and one LiDAR-based DEM, with horizontal resolution of 1 m (LIDAR DTM). Moreover, for a more in depth analysis, LIDAR DTMb (with buildings) cell size has been down sampled from 1 to 5 meters coarse resolution, in order to evaluate also, how cell size affect ponds delineation. Individuation of likely flood areas (ponds) has been carried out using Arc Hydro Tools developed at Centre for Research in Water Resources at University of Texas at Austin. Research highlighted how the correction of DEM generated from LiDAR data and other sources overlapping the buildings (i.e. retrieved from cadas maps) help to diminish the total accumulated water volume into surface ponds, real or spurious, and also that their number does not depend by the raster cell size, but from the accuracy of the source data. Afterwards, a first attempt of best management practices implementation has been carried out within the Liguori Channel situated in Cosenza, Italy. The overland flow network of a highly urbanized sub area has been enhanced through the addition of a certain percentage of green roof and porous pavements. A series of simulations were carried out, using in input the historical annual rainfall series (between 2008 and 2011) and considering a first scenario without LIDs (reference case) and a second scenario with the new practices implemented. Moreover, the same simulation were repeated in continuous, namely considering a single time series composed by 4 years of precipitations (2008-2011) and taking into account, in addition to the two previous cases, of a third scenario where LIDs may deal with clogging phenomenon. In order to perform the EPA SWMM modelling, a ‘residential’ land use has been defined, characterised by build-up and wash off laws for the considered pollutant (Total Suspended Solids – TSS). As regards the green roof and porous pavement simulation parameters, currently these values has been gathered from literature. Within SWMM, the clogging phenomenon is taken into account through a parameter called ‘clogging factor’ that considers the possible decay of LID performance due to the fine material carried by infiltration waters. The empirical formulation is affected by some parameters such as the number of years it takes to fully clog the system (Yclog), the annual rainfall amount over the site (Pa), the pavement's capture ratio CR (area that contributes runoff to the pavement divided by area of the pavement itself), the system's void ratio (VR), the Impervious Surface Fraction (ISF) and the pavement layer thickness (T). The yearly simulation performed show how the percentage reduction of volumes into the network is around 35% on average each year, the mass of Total Suspended Solids is around 30% on average while the relative concentration undergoes an increment around 15%. The latter result can be explained looking at the SWMM runoff quality algorithm. In fact, currently SWMM takes into account of the reduction of pollutants only in terms of reduction of overland flow, due to the lacking of quality algorithms for LIDs simulation. Consequently, the presence of BMPs increases the amount of stormwater that infiltrates, decreasing runoff, therefore the mass of pollutants reaching the sewer outlet. The lower is the volumes of water reaching the sewer, keeping constant the total mass of pollutant over the catchment, the higher is the average outlet concentrations. The results of the continuous simulation are, also, very interesting. While during the annual simulations the trend of volumes for the scenario ‘LIDs with clogging’ ranges always between the other two cases, without and with LIDs, when the continuous simulation is considered, the volumes of the clogged LID are even higher than the volumes occurring without any BMP implemented. The efficiency tends to decrease during time, from 50% when simulation starts to almost 0% at the end of the second year, continuing then to swing around zero per cent for the remaining part of the simulation. In this case, in fact, during the first two simulated years the trend is similar to what it has been found during the annual simulation, while starting from the third year (January 2010), volumes generated for the case ‘LIDs with clogging’ are equal or even higher than those ones generated when no LIDs are used. Although EPA SWMM results are interesting and indicative of LID operation, they are not very accurate, especially concerning the qualitative simulation of the stormwater management practices. For this reason, later, the research has been focused on improving the qualitative simulation algorithms, with particular attention to porous pavements. Data collected into an experimental laboratory rig of three different and widely used permeable pavement types has been analysed. The investigated systems were: monolithic porous asphalt (PA), modular Hydrapave (HP), and monolithic Permapave (PP). The rig, made of three vertical compartments in which the three porous pavers stratigraphies has been rebuilt, has been subjected to a semi-synthetic hyetograph, made of five different rain intensities (wetting regime) plus several drying periods. From the frequency curve typical of Brisbane (AU), in correspondence of different percentile ranges four flow rates has been chosen (A, B, C, D). In addition, a 1 in 5 year storm of 5 min duration was selected; this represents the typical design storm where the porous pavers are likely to be developed. The accelerated laboratory test allowed to simulate 26 years of operation under Melbourne climate. About the water quality monitoring, an intense sampling regime has been conducted in which samples were collected from inflow and outflow and analysed for Total Suspended Solids (TSS), Total Phosphorus (TP) and Total Nitrogen (TN). Afterwards, a correlation analysis has been performed in order to individuate the key variables affecting the porous pavement functioning. According to these results, the key variables identified to affect the pollutant concentration values were: the cumulative flow every 6, 12 and 24 hours before the sampling time, the cumulative inflow volume in each time step and the cumulative trapped mass. Initially, it has been tried to analyse the phenomenon through the ‘k-C* model’, that is a conceptual model used to simulate the pollutant behaviour through the system, based on a first-order kinetic decay equation. Notwithstanding the wide popularity and tested applicability on various other treatment practices such as sand filters, wetlands, ponds, infiltration systems and vegetated swales, the model did not show satisfying results when applied to porous pavements, especially about heavy metal and total nitrogen modelling. The predictive power of the model has been assessed through the calculation of the Nash–Sutcliffe model efficiency coefficient, widely adopted in the Anglo-Saxon world to evaluate behaviour and performance of the hydrologic models. Nash-Sutcliffe coefficient is an indicator of the model’s ability to predict about the 1:1 line between observed and simulated data. NSE ranges between −∞ and 1.0 (1 inclusive), with NSE = 1 being the optimal value. Values between 0.0 and 1.0 are generally viewed as acceptable levels of performance, whereas values < 0.0 indicates that the mean observed value is a better predictor than the simulated value, which indicates unacceptable performance. Considering this, the concentration data collected has been processed, also taking into account of the correlation analysis previously carried out, which allowed to estimate the concentrations of the main pollutants such as TSS (Total Suspended Solids), TP (Total Phosphorous) and TN (Total Nitrogen) to the output section of the porous pavements. The reliability of the new proposed formulas has been demonstrated both by high values of the Nash- Sutcliffe coefficients, always positive, and also by very low errors (between 10% and 25%) among modelled and measured concentrations
Hydrodynamic and morhodynamíc study of a drained beach
(2011) Saponieri, Alessandra; Damiani, L.; Veltri, Paolo; Macchione, Francesco
An integrated modeling approach for the assessment of land use change effects on wastewater infrastructures
(2014-04-14) Primativo, Francesca; Macchione, Francesco; Giustolisi, Orazio
The simulation of sewage systems and wastewater treatment plants is a strategic aspect for assessing the effect of new dwellings on the existing water facilities. This constitutes a quite common problem, since usually new edification areas are planned without looking at the effect that new scenarios will cause on the existent infrastructures. In this Thesis integration of water pollution and land use change models is presented and applied to a case study. The water pollution is meant as the complex relationship between proposed housing development and wastewater pollution incident control. The aim of these models is about the impact of new edification areas on the existent watercourse. This Thesis introduces an integrated framework made by a land use change model, a sewage system simulator and a wastewater treatment plant simulator. This is a complex system since each element is characterized by different dynamics. The land use change model simulates the expansion of an urban area according to planners’ guidelines; the sewage system simulator investigates the response of the drainage system to the expansion as well as its flexibility. The wastewater treatment plant is simulated in order to assess the impact of the new inflowing discharges on the existing plant. This Thesis describes the motivation, the rational and implementation details of a modeling framework namely Stochastic System Dynamics Integrative Model (SSDIM), which is an effort to bridge the gap of integrated models for decision making in urban planning. By combining automatic decision support tools with an integrated framework that brings together land use change and wastewater network infrastructure, it enables the analysis of the effect of alternative long-term urbanisation plans on the quality of the surrounding environment, measured through water indicator. The functionality of the SSDIM was demonstrated through a semi-hypothetical case study, in which three planning scenarios were evaluated for a new housing area against the quality of the wastewater drained by a sewer system and eventually treated by a wastewater treatment plant. On the one hand, the study highlighted the flexibility in representing planning scenarios and settingup the sewer networks in the framework and demonstrated that the framework, as a conceptual and quantitative tool, can easily accommodate for the complexity involved in a real-world case study. On the other hand, the results emphasised that the framework was able to capture the evolving ABSTRACT 10 impact of urban planning over a long term period, which play an important role in understanding the existing system and environmental capacities, and thus SSDIM provides a valuable decision support aid in the urban planning process. In the first part of this Thesis, the setting and motivation for the framework proposed and an extensive review of the studies available from literature are discussed as well as the legal background related to the problem at stake The second part of the Thesis presents the elements of the models implemented: in particular, both the conceptual representation and the implementation details are discussed in depth. Finally in the last part of the Thesis, an application of the developed framework to a real world environmental problem and the results of the application of the framework to a case study is described. The case study represents a sewage network of a town located in south west of Scotland and its wastewater treatment plant, where some urban development scenarios are assumed
La calibrazione delle reti idriche con il modello UNINET: modellazione di reti teoriche e reali
(2012-10-30) Gigliotti, Maria Cristina; Macchione, Francesco; Veltri, Paolo; Fiorini Morosini, Attilio
La calibrazione delle reti idriche: tecniche, applicazioni e nuovi approcci. Il caso delle perdite in rete.
(2013-10-29) Costanzo, Francesco; Macchione, Francesco; Veltri, Paolo
La caratterizzazione del grado di giunzione delle reti fluviali: approcci teorici e sperimentali
(2014-09-12) Frandina, Giuseppe; Macchione, Francesco; De Bartolo, Samuele; Orlandini, Stefano
<> rappresentazione virtuale delle simulazioni 2-D delle piene in aree urbane per il miglioramento della comunicazione del rischio idraulico
(2019-05-10) De Santis, Rosa; Critelli, Salvatore; Macchione, Francesco; Costabile, Pierfranco; Pantano, Pietro Salvatore
I fenomeni di allagamento di aree urbane rappresentano un problema molto attuale, poiché il numero di persone potenzialmente coinvolte ed il valore degli elementi a rischio, in termini economici, artistici e culturali, può essere notevole in larghe parti del territorio e delle aree urbanizzate. Nel contesto europeo, la Direttiva 2007/60/CE del Parlamento Europeo del 23 ottobre 2007, relativa alla valutazione e alla gestione del rischio alluvionale, prescrive di valutare il rischio attraverso studi di natura idraulica. In tale ambito, vi è l'esigenza di utilizzare strumenti predittivi e metodologie di analisi adeguati per la determinazione delle reali condizioni di rischio associate al realizzarsi di un determinato evento alluvionale. Uno studio di inondazione in area urbana, per essere di reale supporto per l'implementazione di adeguate misure di previsione e prevenzione, necessariamente deve coinvolgere una serie di aspetti che spaziano dall'acquisizione di dati topografici alla descrizione dei processi fenomenologici tipici del moto di una corrente in piena e della sua interazione con edifici e infrastrutture, agli algoritmi da utilizzare per la risoluzione delle equazioni del modello, alla restituzione dei risultati. Questa notevole mole di lavoro deve necessariamente trovare il suo sbocco naturale nella rappresentazione finale dei risultati tramite prodotti grafici che la Direttiva vigente individua nelle mappe di pericolosità e di rischio. Tuttavia la medesima Direttiva, richiama anche l’importanza della comunicazione del rischio, finalizzata al coinvolgimento dei diversi stakeholders e all’implementazione di una corretta gestione dell’emergenza. Vi è, dunque, una crescente necessità di presentare i risultati delle simulazioni idrauliche delle alluvioni in un formato che consenta una comprensione più immediata per i decisori finali e per la popolazione esposta. A tale scopo, potrebbe essere di notevole ausilio l’uso di rappresentazioni tridimensionali di alluvioni attraverso scenari virtuali ad integrazione delle classiche mappe di pericolosità da inondazione. Esse consentirebbero un incremento enorme della comprensibilità dei risultati dei complessi calcoli idraulici che sono alla base della redazione delle mappe di pericolosità. Per questo motivo, sarebbe auspicabile una competenza di base nelle tecniche di visualizzazione 3-D per la comunicazione del rischio idraulico per gli ingegneri idraulici che operano nel campo dell’analisi del rischio di alluvione. Questa tesi di Dottorato si inserisce proprio in tale contesto, e si articola in una proposta di criteri di rappresentazione di simulazioni idrauliche bidimensionali all'interno di un ambiente di realtà virtuale 3-D, con contenuti informativi diversi, destinati a differenti target di utenti, finalizzati ad una migliore comunicazione della pericolosità idraulica Si tratta dunque di restituire i risultati dei calcoli in immagini (e, in prospettiva, in video) che possano rappresentare, sotto forma di scenari virtuali, in maniera immediata le condizioni in cui si verrebbe a trovare un luogo nel corso di un’alluvione. Dovendo le immagini rappresentare visivamente le superfici idriche calcolate, necessariamente la procedura deve basarsi su modelli di calcolo che descrivano in maniera corretta i fenomeni idraulici che occorrono nelle correnti di piena. Escludendo l’uso delle equazioni di Navier-Stokes, poiché attualmente ancora troppo onerose per l’applicazione su aree vaste, occorre riferirsi alle equazioni complete delle acque basse, formulate in modo che possano correttamente rappresentare i fenomeni cui si è fatto cenno. Per tale motivo, la tesi ha inizio con l’analisi della modellistica 2-D completa, basata sulle equazioni delle acque basse (Shallow Water Equations, SWE) formulate originariamente da De Saint Vénant. Si focalizzerà l’attenzione sulla formulazione e sui metodi di integrazione numerica idonei per ottenere delle soluzioni in grado di inglobare correttamente anche i fenomeni locali presenti nella propagazione della corrente, anche con riferimento all’interazione con la topografia e i manufatti. Inoltre, saranno descritti tutti gli elementi necessari per la simulazione di un evento alluvionale, in particolare i criteri per la corretta rappresentazione della topografia e dei manufatti, la definizione delle condizioni iniziali e delle condizioni al contorno, la stima della scabrezza. Il secondo capitolo analizzerà i concetti teorici e metodologici relativi alla mappatura della pericolosità e del rischio di alluvione, in relazione allo stato dell’arte, ai metodi e alle sperimentazioni presenti nella letteratura scientifica internazionale e, più dettagliatamente, in ambito europeo. Verranno, dunque illustrati i criteri idonei per ottemperare alla Direttiva 2007/60/EC, relativi alla redazione delle mappe di pericolosità e di rischio idraulico. Il capitolo è finalizzato a mettere in luce peculiarità e criticità delle prassi correnti, da utilizzare come riferimento per la realizzazione di strumenti intuitivi ed efficaci per la comunicazione del rischio. È stata inoltre condotta un’analisi sugli aspetti cartografici della mappatura del rischio di inondazione, mettendo in luce alcune peculiarità relative all’elaborazione e alla redazione delle mappe. Dopo l’inquadramento generale operato dai capitoli precedenti, nel capitolo 3 si focalizzerà la proposta centrale di questa tesi di dottorato, con riferimento alla situazione Calabrese. La Regione Calabria, con le risorse POR Calabria 2000-2006 si è già dotata, per l’esecuzione degli studi sulle alluvioni, di “Metodologie di individuazione delle aree soggette a rischio idraulico di esondazione”. Tali metodologie e le relative Linee Guida sono state elaborate dal Laboratorio di Modellistica numerica per la Protezione Idraulica del Territorio (da ora in avanti LaMPIT) dell’Università della Calabria in collaborazione con il CUDAM (Università di Trento), con l’Università di Pavia e con l’Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS (Trieste). Questa tesi, svolta all’interno del LaMPIT, vuole essere un ideale sviluppo di quelle Metodologie. Esse sono basate sulle SWE trattate secondo i metodi e gli accorgimenti che appartengono alle categorie descritte nel capitolo 2 e, pertanto, le soluzioni da esse ottenute sono compatibili per l’uso finalizzato a una corretta trasposizione in immagini. La presente tesi ha perciò preso in esame i risultati di un caso di studio sviluppato per la Regione Calabria. Tali risultati furono rappresentati nelle Linee Guida secondo i classici canoni delle mappe di pericolosità. Tuttavia, come già osservato, le potenzialità di simulazione dei dettagli fisici conseguibili con i modelli numerici utilizzati potrebbero consentire la restituzione di tali risultati in immagini virtuali. Tra tutti i casi trattati nelle Linee Guida, si è voluto qui prendere in esame quello della mappa di pericolosità di inondazione del centro storico di Cosenza. Cosenza è attraversata dai fiumi Crati e Busento, che confluiscono proprio all’interno del centro urbano. Nonostante la città sia stata preservata da alluvioni negli ultimi 60 anni, Cosenza ha storicamente subito molte volte le conseguenze delle esondazioni dei suoi fiumi. Per documentare questo, una parte del lavoro di questa tesi si è voluto dedicarla alla descrizione degli eventi storici ricavata da documenti consultabili presso l’Archivio di Stato, la Biblioteca Nazionale, la Biblioteca Civica di Cosenza e concentrando l’attenzione non solo sugli aspetti idrologici, ma anche sugli effetti idraulici e sull’uso del suolo. L’ultima alluvione si verificò il 24 novembre 1959 e benché esista una discreta documentazione fotografica della situazione post-evento, non si ha nessuna immagine della città con l’alluvione in corso di svolgimento. Pertanto solo alcuni anziani abitanti dei luoghi alluvionati ricordano gli scenari vissuti. Le nuove generazioni non sono consapevoli di quali sarebbero questi scenari se oggi si verificasse l’esondazione dei fiumi. In verità le classiche mappe non sono lo strumento più intuitivo per trasferire tale consapevolezza alla popolazione. È questo il motivo per il quale si è scelto di implementare la procedura di visualizzazione oggetto di questa tesi proprio per la città di Cosenza. Pertanto, il terzo capitolo dopo un excursus storico, ha analizzato la simulazione idraulica di un’ipotetica alluvione di progetto riferita a un tempo di ritorno di 500 anni. Il quarto capitolo è incentrato sullo sviluppo di un workflow per rappresentare simulazioni idrauliche bidimensionali all'interno di un ambiente 3-D realizzato utilizzando la tecnica della texture mapping. Vengono discussi i risultati conseguiti, nonché le potenzialità di questo tipo di rappresentazione ai fini di un miglioramento della consapevolezza e della percezione del rischio da parte della popolazione, ai fini della preparazione e pianificazione dell’emergenza e supporto nella stima del danno alluvionale. La procedura proposta è stata applicata per la visualizzazione di immagini virtuali relative al caso studio descritto nel capitolo precedente. Il quinto capitolo propone un secondo prodotto di realtà virtuale realizzato utilizzando dati provenienti dal laser scanner terrestre. Sono descritte le campagne di acquisizione nonché le diverse fasi di gestione dei dati e di visualizzazione. Inoltre, si proporrà un ambiente interattivo, basato sulla tecnologia Web-GL, per la visualizzazione di scenari di inondazione utilizzando nuvole di punti di grandi dimensioni. Segue una discussione sulle potenzialità di questo prodotto ai fini del disaster management. Il capitolo finale è dedicato alle conclusioni generali e alle prospettive future.
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