INFLUENZA DELL‟URBANIZZAZIONE SULLO STATO DI QUALITÀ DEI CORPI IDRICI RICETTORI ATTRAVERSO UN APPROCCIO DI TIPO INTEGRATO

Il cambiamento climatico è una delle principali cause che possono indurre a una modifica delle caratteristiche idrologiche e ambientali dei bacini naturali. Per quanto attiene la qualità delle acque naturali superficiali, tale fattore va combinato con quello antropogenico (urbanizzazione, variazione di popolazione e domanda idrica, etc.), che può ridurre o incrementare l‟effetto delle variazioni climatiche. Un aspetto che merita un‟attenta valutazione è l‟analisi degli effetti che i cambiamenti sia climatici che antropogenici hanno sulla qualità di un corpo idrico ricettore. Al fine di valutare tali effetti, nel presente studio è stato impiegato un modello di tipo integrato messo a punto in…

Integrated modelling of the influence of urbanization and climate change on river water quality

Climate change is one of the most important drivers modifying the hydrologic and environmental characteristics of natural catchments. When dealing with the quality of natural waters, these factors should be weighed up against anthropogenic factors that may increase or decrease the effect of climatic modifications. However, a detailed and more generalised analysis of such environmental impacts at a relatively small scale is currently lack. This paper aims to fill this gap. The use of a holistic approach is also required by the EU Water Framework Directive, which prescribes integrated analysis for river basin management in order to meet environmental and ecological objectives. In order to qua…

Riduzione delle perdite apparenti. Analisi sperimentale e modellistica dell'UFR

Analysis of intermittent supply systems in water scarcity conditions and evaluation of the resource distribution equity indices

Generally, urban water distribution shortage situations are solved by introducing discontinuous service and rationing the available water resources. This approach is widely adopted, not only in developing countries but also in developed ones, for solving short term scarcity conditions which can be caused by unpredicted drought periods. Intermittent distribution has the advantage of requiring small financial efforts but it leads to network operating conditions that are very far from the usual design ones. With the aim to analyse and describe the water supply network behaviour in intermittent conditions, a network hydraulic model has been set up in which both user and manager dependent regula…

Studio dell’incertezza connessa con l’analisi prestazionale di un sistema di drenaggio urbano

Distrettualizzazione di una rete idrica per mitigare l’iniqua distribuzione delle risorse idriche in condizioni di scarsità

Multicriteria performance analysis of an integrated urban wastewater system for energy management

AbstractThe optimization and management of an integrated urban wastewater system is a complex problem involving many processes and variables. The possible control options are defined by several management strategies that may differently impact the economic, operational or environmental performance of the system. The present paper aims to contribute to the environmental and energy sustainability of urban wastewater systems by means of a multicriteria performance analysis. The paper begins with a complete analysis of the system performance in several fields of interest (energy, environment, quality of service, operation, economy and financial resources), and it highlights the management stren…

Uncertainty Analysis in the Evaluation of the DDF Curves Parameters in Climate Change Scenarios

Abstract On the global scale, there is a robust observational evidence that, over the last decades, the frequency and intensity of extreme events significantly changed, even if regional and local studies have highlighted complex and non-uniform spatial patterns. Climate change can cause increased rainfall intensities which leads to an additional impact on drainage systems, due to the alteration of magnitude and frequency of peak flows over their service life. For this reason, the design criteria of urban drainage infrastructures need to be revised and updated, in order to take into account the possible variations of extreme rainfall. In particular, the Depth-Duration-Frequency (DDF) curves,…

Valutazione dell’incertezza connessa con i modelli di qualità dei deflussi meteorici in ambiente urbano

Derivation of short-durations DDF using scaling properties of rainfall data at partially-gauged site

The role of the tidal and wind forces on the hydrodynamic flow pattern in the Augusta Harbour (Italy)

A model of the filling process of an intermittent distribution network

In many countries, private tanks are acquired by users to reduce their vulnerability to intermittent supply. The presence of these local reservoirs modifies the user demand pattern and usually increases user water demand at the beginning of the service period depending on the tank filling process. This practice is thus responsible for the inequality that occurs among users: those located in advantaged positions of the network are able to obtain water resources soon after the service period begins, while disadvantaged users have to wait much longer, after the network is full. This dynamic process requires the development of ad hoc models in order to obtain reliable results. This paper discus…

A Systematic Review of the Hydrological, Environmental and Durability Performance of Permeable Pavement Systems

Due to urbanization, large portions of vegetated territory have been replaced by waterproof surfaces. The consequences are greater outflows, lower infiltration, and lower evapotranspiration. Pavement systems made with permeable surfaces allow the infiltration of water, ensuring reduction of runoff volume. In this paper, the methods of analysis of the hydrological and environmental performance of the pavement systems are reviewed in the context of urban drainage and regarding their durability. The purpose is to present an overview of the studies published during the last decade in the field. The Pubmed and Web Science Core Collection electronic databases were used to conduct the scientific l…

Stochastic Approach for Optimal Positioning of Pumps As Turbines (PATs)

A generic water system consists of a series of works that allow the collection, conveyance, storage and finally the distribution of water in quantities and qualities such as to satisfy the needs of end users. In places characterized by high altitude differences between the intake works and inhabited centres, the potential energy of the water is very high. This energy is attributable to high pressures, which could compromise the functionality of the pipelines

L'EFFETTO COMBINATO DELLA PRESSIONE IN RETE E DELL'INVECCHIAMENTO DEI CONTATORI SULLA STIMA DELLE PERDITE APPARENTI

A BMA Analysis to Assess the Urbanization and Climate Change Impact on Urban Watershed Runoff

Abstract A reliable planning of urban drainage systems aimed at the mitigation of flooding, should take into account the possible change over time of impervious cover in the urban watershed and of the climate features. The present study proposes a methodology to analyze the changing in runoff response for a urban watershed accounting several plausible future states of new urbanization and climate. To this aim, several models simulating the evolution scenario of impervious watershed area and of climate change were adopted. However, it is known that an evolution scenario represents only one of all possible occurrence and it is not necessary the true future state, therefore it is needed to fin…

ANALISI DEL PROCESSO DI CONSUMO ISTANTENEO DI SINGOLE UTENZE RESIDENZIALI CON IL MODELLO DI POISSON AD IMPULSI RETTANGOLARI

A mathematical model to evaluate apparent losses due to meter under-registration in intermittent water distribution networks

Apparent losses consist of water volume drawn from the network, consumed by users but not paid for. Those due to water meter under-registration were evaluated by means of a mathematical model able to analyse the complexity of intermittent supply systems with private tanks. This supply scheme is very common in the Mediterranean area where unexpected water shortage often happens and intermittent water supply is a common practice. In order to analyse such complex systems, a demand model, reproducing the effect of private tanks, and an apparent losses module were developed and coupled with an hydraulic network model based on the Global Gradient Algorithm (GGA). In distribution networks pressure…

Statistical analysis of the uncertainty linked to flood risk evaluation

Uncertainty analysis in sewer system performance evaluation

Modelli di previsione del consumo idrico istantaneo sulla base di reti neurali

Modelling the integrated urban drainage systems.

Development of an Integrated Urban Drainage System Model for the River Pollution Control

Integrated urban water modelling with uncertainty analysis

In the last twenty years, the scientific world has paid particular care towards the problems that involve the environment. Accordingly, several researches were developed to describe phenomena that take place during both wet and dry periods and to increase the knowledge in this field. In particular, attention was addressed towards the problems linked with receiving water body pollution because of the impact of rain water in the urban environment. In order to obtain a good description of the problem, it is important to analyse both quantity and quality aspects connected with all the transformation phases that characterise the urban water cycle. Today, according to this point, integrated model…

ANALISI DEGLI EFFETTI DELLA DISTRIBUZIONE TURNATA MEDIANTE LA MODELLAZIONE DEL RIEMPIMENTO DELLA RETE

The Effect of Damage Functions on Urban Flood Damage Appraisal

Flooding damage appraisal can been obtained by interpolating real damage data caused by historical flooding events or accounting the effects of a flood in terms of the depreciation of assets. Most often, the expected damage is evaluated by means of damage functions describing the relationship occurring between the damage and hydraulic characteristics of flood. The present paper aims to evaluate the uncertainty linked to the choice of the depth-damage function adopted in the flood damage analysis. Several possible depth-damage function formulations were selected in literature and applied to historical flooding events monitored in the "Centro Storico" catchment in Palermo (Italy). (C) 2013 Th…

Assessment of the integrated urban water quality model complexity through identifiability analysis

Urban sources of water pollution have often been cited as the primary cause of poor water quality in receiving water bodies (RWB), and recently many studies have been conducted to investigate both continuous sources, such as wastewater-treatment plant (WWTP) effluents, and intermittent sources, such as combined sewer overflows (CSOs). An urban drainage system must be considered jointly, i.e., by means of an integrated approach. However, although the benefits of an integrated approach have been widely demonstrated, several aspects have prevented its wide application, such as the scarcity of field data for not only the input and output variables but also parameters that govern intermediate st…

Carenza idrica: conseguenze in ambiente urbano

Liner Poliolefinici nella produzione di canalizzazioni e manufatti in calcestruzzo

Uncertainty connected with design rainfall for urban flood risk evaluation

Assessment of Modelling Structure and Data Availability Influence on Urban Flood Damage Modelling Uncertainty

Abstract In modelling application, different model structures may be equally reliable in terms of calibration ability but they may produce different uncertainty levels; moreover, available data during model calibration may influence the uncertainty linked to the predictions of the same modelling structure. In the present paper, Bayesian model-averaging was applied to several flood damage estimation models in order to identify the best model combination for urban flooding distribution analysis in Palermo city center (Italy). During the analysis, was taken into account the effect of the available data growth on the model uncertainty with respect to the different combination of models outputs.

Reliability of sewer system performance analysis

Water quality analysis in network and private storage tanks in intermittent distribution systems

In countries suffering from chronic water shortages, water distribution systems are often operated on an intermittent basis. As a consequence, the network is involved by cyclical filling and emptying periods causing water quality degradation. During the emptying period, the distribution system is unpressurised and it may occur that pollutants move into the network. Moreover, the stagnation period can promote microbial growth. For this reason water is usually heavily chlorinated in order to maintain it potable. Due to intermittent water service users acquire private tanks, which are used for collecting water during serviced periods and distributing it when public service is not available. Th…

Integrated urban drainage uncertainty assessment : the influence of the likelihood efficiency measures

Integrated urban drainage uncertainty assessment : the influence of the likelihood efficiency measures

CARE-S: un sistema di supporto alle decisioni per la riabilitazione delle reti drenanti urbane

Evaluation of the Water Scarcity Energy Cost for Users

Abstract: In systems experiencing water scarcity and consequent intermittent supply, users often adopt private tanks that collect water during service periods and supply users when the service is not available. The tank may be fed by gravity or by private pumping stations depending on the network pressure level. Once water resources are collected, the tank can supply users by gravity if it is located on the rooftop or by additional pumping if underground. Private tanks thus increase the energy cost of the water supply service for users by introducing several small pumping structures inside the network. The present paper aims to evaluate this users’ energy cost for different private tank con…

Urban Storm-Water Quality Management: Centralized versus Source Control

The continuous growth of urban areas and the increasing public awareness of the environmental impacts of storm water have raised interest on the quality of the receiving water bodies. In the past two decades, many efforts have been directed at improving urban drainage systems by introducing mitigation measures to limit the negative environmental impacts of storm water. These mitigation measures are generally called best management practices (BMPs), sustainable urban drainage systems, or low impact developments, and they include practices such as infiltration and storage tanks that reduce the peak flow and retain some of the polluting materials. Choosing the best mitigation measure is still …

Energy Recovery in Water Distribution Networks. Implementation of Pumps as Turbine in a Dynamic Numerical Model

In complex networks characterized by the presence of private tanks, water managers usually apply intermittent distribution, thus reducing the water volumes supplied to the users, or use Pressure Reduction Valves (PRV) for controlling pressure in the network. The application of Pump As Turbines (PATs) appears as an alternative and sustainable solution to either control network pressure as well as to produce energy. In the present paper, the hydrodynamic model, already presented by De Marchis et al. (2011) was further developed introducing the dynamic analysis of PATs. The model was applied to a district of Palermo network (Italy) characterized by intermittent distribution and by inequities a…

Un modello per il riempimento delle reti di distribuzione idrica in presenza di turnazione del servizio

Multivariate Statistical Analysis for Water Demand Modeling

The actual level of water demand is the driving force behind the hydraulic dynamics in water distribution systems. Consequently, it is crucial to estimate it as accurately as possible in order to result in reliable simulation models. In this paper, a copula-based multivariate analysis has been proposed and used for demand prediction for given return period. The analysis is applied to water consumption data collected in the water distribution network of Palermo (Italy). The approach showed to produce consisted demand patterns and to be a powerful tool to be coupled with water distribution network models for design or analysis problems. (C) 2014 Published by Elsevier Ltd.

Esperienze operative su sistemi di fognatura

A performance based approach for the analysis of urban water distribution systems under drought conditions

The present study proposes some performance indicators for analysing urban water distribution system characterised by intermittent supply service. Specific indicators have been proposed for investigating the reduction of quality of water service under resources scarcity conditions. A modelling procedure has been implemented in order to allow for analysing complex network schemes in which users self adapt to scarcity conditions. The procedure has been applied to analyse the performance of an existing supply system in Palermo (Italy). The network and users’ behaviour in intermittent distribution conditions have been monitored in order to calibrate the model and verify the reliability of the p…

CARE-S: Rehabilitation cost report

A numerical unsteady friction model for the transient flow arising during the filling process of intermittent water distribution systems.

Description and Validation of Hydraulic Performance and Environmental Impacts of Sewer Systems

Uncertainty related to climate change in the assessment of the DDF curve parameters

In the context of climate change, the evaluation of the parameters of Depth-Duration-Frequency (DDF) curves has become a critical issue. Neglecting future rainfall variations could result in an overestimation/underestimation of DDF parameters and, consequently, of the design storm. In this study, uncertainty analysis was integrated into trend analysis to provide an estimate of trends that cannot actually be rigorously verified. A Bayesian procedure was suggested for the updating of DDF curve parameters and to evaluate the uncertainty related to their assessment. The proposed procedure also allowed identification of the years of a series that contributed most to the overall uncertainty relat…

Analisi del processo di consumo istantaneo di singole utenze residenziali con il modello di Poisson ad impulsi rettangolari

Point and no point pollution assessment for a receiving water body quality management

Storm kinematics in urban area based on high resolution raingauge data analysis

Definition of Water Meter Substitution Plans based on a Composite Indicator

This paper presents a water meter substitution plan based on a composite "Replacement indicator" which was defined and compared with common substitution strategies based on meter age and on run-to-fail approaches. The methodology was applied to one of the 17 sub-networks in which the Palermo city water distribution network (Italy) is divided. The analysis was carried out considering a substitution budget limitation and the results showed that the use of "Replacement indicator" outperform the classical substitution strategies based on meter age because it takes into account some other variables that may affect meter precision and wearing. (C) 2013 The Authors. Published by Elsevier Ltd.

Identifiability analysis for receiving water body quality modelling considering a holistic approach

Analisi e previsione dei consumi urbani attraverso l’applicazione di modelli a rete neurale

Rainwater Reuse in Urban Areas: A Mathematical Model and a Long-Term Modelling Approach

Natural water resources are becoming increasingly limited due to global-scale climate change and water availability issues have become so severe that they must be addressed. Given these issues, reuse of wastewater and rainwater provides a promising way to cope with water shortages. This paper describes an investigation into the efficiency of rainwater usage systems. A conceptual model was built to assess the behaviour of rainwater tanks and their effectiveness in coping with water shortages. The study is based on a long-term simulation (12 years) of different rainwater reuse tank schemes. The associated reductions in residential freshwater demand (water reuse efficiency) and wet-weather run…

The benefit effects of rainwater utilization: a long term modelling approach

Calcul des contributions des incertitudes dans un modèle complexe de qualité de l'eau

The quantification of uncertainty in integrated urban drainage water quality models is of paramount interest. Indeed, the assessment of the reliability of the model results for complex water quality models is useful for understanding the significance of the results. However, the state of knowledge regarding uncertainties in urban drainage models is poor. In the case of integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating sewer system, wastewater treatment plant and receiving water body), the uncertainty produced in one sub-model propagates to the following ones depending on the model structure, the estim…

Identifiability analysis for receiving water body quality modelling

In urban drainage, new computational possibilities have supported the development of new integrated approaches aimed at joint water quantity and quality analysis of the whole urban drainage system. Although the benefit of an integrated approach has been widely demonstrated, to date, several aspects prevent its applicability such as scarce availability of field data if compared with model complexity. These aspects sometimes prevent the correct estimation of parameters thus leading to large uncertainty in modelling response. This is a typical parameter identifiability problem that is discussed in the present paper evaluating the effect of identifiability procedures in increasing operator conf…

Urban runoff quality modelling uncertainty assessment

Assessment of water shortage in urban areas

Recent history has demonstrated that extreme hydrological events such as floods and droughts can create additional stress on water supplies essential for human and ecosystem health. As stated several times by European Environmental Agency, the prudent and efficient use of water is thus an important issue in Europe and a number of policies and mechanisms have been used or have been formulated to ensure sustainable use of water in the long term. Urban uses are responsible of almost the 17% of the total European fresh water consumption and they are rapidly growing depending on the extension of urban areas and concentration of population in cities. The present chapter will discuss the phases in…

Urban water quality modelling: a parsimonious holistic approach for a complex real case study

In the past three decades, scientific research has focused on the preservation of water resources, and in particular, on the polluting impact of urban areas on natural water bodies. One approach to this research has involved the development of tools to describe the phenomena that take place on the urban catchment during both wet and dry periods. Research has demonstrated the importance of the integrated analysis of all the transformation phases that characterise the delivery and treatment of urban water pollutants from source to outfall. With this aim, numerous integrated urban drainage models have been developed to analyse the fate of pollution from urban catchments to the final receiving …

Assessment of urban drainage environmental impact on receiving water bodies: Comparison between a detailed and a simplified integrated model.

Point and non-point pollution assessment for a receiving water body quality management

Indicatori di performance per l’analisi delle reti di distribuzione in condizioni di scarsità idrica

The influence of the prior distribution on the uncertainty analysis assessment of an urban drainage stormwater quality model

Wastewater Network Challenges and Solutions

The effect of acceptability threshold over an integrated urban drainage model uncertainty.

Diffuse and concentrated pollution control at watershed-scale: an Italian case study

Le perdite apparenti nelle reti di distribuzione: implementazione di un modello numerico

Multi Sources Water Supply System Optimal Control: A Case Study

The optimal operation of a multi quality network was analysed applying Linear Programming methods. The peculiar service condition of the industrial city of Gela (Italy) was investigated. The network is supplied both from waters derived from a desalination plant and other natural sources. The method aimed to minimise energy cost and find the optimal operation control, while satisfying demand and quality constraints, specifically with regard to water temperature. The method proved to be effective in the selection of the optimal management strategy after the definition of a specific water quality target. (C) 2014 Published by Elsevier Ltd.

Strategies for Improving Optimal Positioning of Quality Sensors in Urban Drainage Systems for Non-Conservative Contaminants

In the urban drainage sector, the problem of polluting discharges in sewers may act on the proper functioning of the sewer system, on the wastewater treatment plant reliability and on the receiving water body preservation. Therefore, the implementation of a chemical monitoring network is necessary to promptly detect and contain the event of contamination. Sensor location is usually an optimization exercise that is based on probabilistic or black-box methods and their efficiency is usually dependent on the initial assumption made on possible eligibility of nodes to become a monitoring point. It is a common practice to establish an initial non-informative assumption by considering all network…

Contaminant Intrusion through Leaks in Water Distribution System: Experimental Analysis

Abstract This paper presents the results of experimental tests on the intrusion of contaminant through pipe cracks in water distribution network resulting from low/negative pressures. The tests were carried out on a looped distribution network at the University of Enna and were performed first producing a pressure transient that causes negative pressures then reproducing intermittent supply. A soluble contaminant was added to the water volume in the network through a pipe crack. Sampling of water volume was carried out in two nodes of the network and the contaminant concentrations were measured. It was showed that: the contaminant was drawn in and transported, in the first set of tests; the…

Analysis of the impact of intermittent distribution by modelling the network-filling process

In many countries, users acquire private tanks to reduce their vulnerability to water scarcity. In such conditions, water managers often apply intermittent distribution in order to reduce the water volumes supplied to the users. This practice modifies the hydraulic behaviour of the network and determines competition among users that need to collect enough water resource for their uses. Intermittent distribution is thus responsible for the inequality that can occur among users: those located in advantaged positions of the network are able to obtain water resources soon after the service period begins, while others have to wait much longer, after the network is full. This paper analyses the i…

Uncertainty in urban stormwater quality modelling: The influence of likelihood measure formulation in the GLUE methodology

In the last years, the attention on integrated analysis of sewer networks, wastewater treatment plants and receiving waters has been growing. However, the common lack of data in the urban water-quality field and the incomplete knowledge regarding the interpretation of the main phenomena taking part in integrated urban water systems draw attention to the necessity of evaluating the reliability of model results. Uncertainty analysis can provide useful hints and information regarding the best model approach to be used by assessing its degrees of significance and reliability. Few studies deal with uncertainty assessment in the integrated urban-drainage field. In order to fill this gap, there ha…

Uncertainty in environmental and hydrological mathematical modelling

Engineers are increasingly called to deal with practical problems related to water resources management, risk analysis, environmental engineering and water pollution. Providing a way forward to solve the above questions requires setting up mathematical models that are affected by uncertainty, that in many cases is relevant. In fact, the theories that are employed for providing solutions to engineer’s problems are not exact sciences: even if it is methodologically rigorous, it is incapable of producing precise results, for the presence of inherent randomness that translates in indeterminacy and therefore uncertainty. To cope with uncertainty is a challenge for scientists and practitioners, t…

Stormwater Source Control as a Strategy for Sustainable Development: State of the Practice and Perceived Trends

The primary objective of the paper is to draw upon the experiences acquired in many parts of the world to provide an up-to-date summary of the state of the practice for source control techniques and approaches, in a sustainable development context. After a discussion of the prevailing context for urban drainage approaches, three main themes covering techniques and design criteria, institutional aspects and performance issues are discussed relative to source control implementation. The discussion is based on findings from the compilation and analysis of available literature, recently developed databases, the experience of the different members of the SOCOMA group and recent research on desig…

Le perdite apparenti e sottomisurazione

CARE – S: un sistema di supporto decisionale per le reti di drenaggio urbano

Evaluation of rehabilitation impact on hydraulic and environmental performance of sewer systems (WP3 CARE-S Project)

The research project CARE-S (Computer Aided RE-habilitation of Sewer Networks) deals with public sewer and storm water networks of any dimension. CARE-S aims to analyse the structural and functional reliability of wastewater networks at minimum cost and disturbance. The ultimate product will be a Decision Support System (DSS) that will enable municipal engineers to establish and maintain effective management of their sewer networks. The project work plan follows a logical structure for the necessary work. It is divided in 10 Work Packages (WP) and each WP is distributed among several partners. The present paper presents the structure and the final results of WP 3 .The work package aim is th…

Valutazione dell’incertezza di un modello integrato di drenaggio urbano.

Affidabilità dell’analisi prestazionale di un sistema di drenaggio urbano

THE IDENTIFIABILITY ANALYSIS FOR SETTING UP MEASURING CAMPAIGNS FOR INTEGRATED WATER QUALITY MODELLING

Identifiability analysis enables one the quantification of the number of model parameters that can be assessed by calibration with respect to a data set. Such a methodology is based on the appraisal of sensitivity coefficients of the model parameters by means of Monte Carlo runs. By employing the Fisher Information Matrix, the methodology is able to gain insights with respect to the number of model parameters that can be reliably assessed. The paper presents a study where identifiability analysis is used as a tool for the setting up of measuring campaigns for integrated water quality modelling. The analysis has been applied to a real case study characterized by a partially urbanized catchme…

Experimental Evidence of Leaks in Elastic Pipes

Several studies have been carried out in recent decades to establish a relationship between total head and leaks. In literature, the leakage governing equations have been analysed in light of pipe materials, water head, leak dimension or shape. Most of these contributions questioned the classical Torricelli equation, demonstrating through experimental evidence that the classical orifice law can give unsatisfactory results. Nevertheless, starting from the Torricelli equation, other exponential or linear governing equations have been proposed as mathematical models able to reproduce the leakages in water distribution systems (WDSs). To investigate the validity of the proposed governing equati…

Research in reduction of meters under registration: experience and results achieved in field tests and in laboratory in Palermo

Sistemi localizzati di riuso delle acque meteoriche in ambito urbano

A water demand model by means of the artificial neural networks method

Valutazione dell’impatto sui corpi idrici delle acque di pioggia: confronto tra un modello integrato fisicamente basato e uno semplificato

Nella nota viene presentato il confronto tra un modello complesso e uno semplificato, entrambi utilizzabili per la simulazione di un sistema integrato di drenaggio urbano

The effect of rainfall temporal resolution on urban drainage water quality modelling

Un modello previsionale della domanda idrica istantanea in condizioni di scarsità

Quantification of diffuse and concentrated pollutant loads at the watershed-scale: an Italian case study

In this study, diffuse and point source pollutant loads were evaluated using an Italian case study: the Nocella catchment, which has been subject to extensive monitoring. The Nocella catchment is located in Sicily (Italy) and has an area of about 60 km2. The river receives wastewater and stormwater from two urban areas drained by combined sewers. The two sewer systems, two wastewater treatment plants and a river reach were monitored during both dry and wet weather periods. Thereafter, an integrated catchment-scale model was applied to simulate point pollutant sources, i.e., pollution coming from the urban drainage system, and nonpoint pollutant sources, i.e., pollution coming from agricultu…

Modelling analysis of distribution network filling process during intermittent supply

The paper presents the modeling results of the filling process of a water distribution network subjected to intermittent supply. The local tanks built by users for reducing their vulnerability to intermittent supply increase user water demand at the beginning of the service period and the time required for completely fill the network. Such a delicate process is responsible of the inequalities taking part among users. Users located in advantaged positions can receive water resources soon after the beginning of the service period while disadvantaged users have to wait until the network is full. Such an highly dynamic process requires ad-hoc models to be developed in order to obtain reliable r…

Urban drainage performance analysis for flooding mitigation

Evaluation of the apparent losses caused by water meter under-registration in intermittent water supply

Apparent losses are usually caused by water theft, billing errors, or revenue meter under-registration. While the first two causes are directly related to water utility management and may be reduced by improving company procedures, water meter inaccuracies are considered to be the most significant and hardest to quantify. Water meter errors are amplified in networks subjected to water scarcity, where users adopt private storage tanks to cope with the intermittent water supply. The aim of this paper is to analyse the role of two variables influencing the apparent losses: water meter age and the private storage tank effect on meter performance. The study was carried out in Palermo (Italy). Th…

Receiving water body quality assessment: an integrated mathematical approach applied to an Italian case study

This study presents a basin-scale approach to the analysis of receiving water body quality considering both point and non-point pollution sources. In particular, this paper describes an extensive data gathering campaign carried out in the Nocella catchment, which is an agricultural and semi-urbanised basin located in Sicily, Italy. Two sewer systems, two wastewater treatment plants and a river reach were monitored during both dry and wet weather periods. A mathematical model of the entire integrated system was also created. Specifically, a detailed modelling approach was developed by employing three well known models: Storm Water Management Model, GPS-X and Soil and Water Assessment Tool. T…

Analisi integrata della qualità dei deflussi meteorici in un bacino naturale parzialmente urbanizzato

Planejamento existente e propostas para melhoria de gestao em Manaus

Valutazione delle perdite apparenti di un piccolo distretto della rete di distribuzione della città di Palermo: analisi sperimentale e modellistica

Catchment-scale modelling approach for a holistic urban water quality management

Urban drainage analysis for flooding mitigation

An Environmental Analysis of the Effect of Energy Saving, Production and Recovery Measures on Water Supply Systems under Scarcity Conditions

Water is one of the primary resources provided for maintaining quality of life and social status in urban areas. As potable water is considered to be a primary need, water service has usually been managed without examining the economic and environmental sustainability of supply processes. Currently, due to increases in energy costs and the growth of environment preservation policies, reducing water leakage, energy consumption and greenhouse gas (GHG) production have become primary objectives in reducing the environmental footprint of water service. The present paper suggests the implementation of some performance indicators that show the interdependence of water loss, energy consumption and…

Modelli di previsione del consumo idrico istantaneo

Urban drainage and sustainable cities: how to achieve flood resilient societies?

This paper tries to describe the main developments of urban flood forecasting and modelling. Currently, several new technologies are available for flood monitoring, modelling and mitigation and several paradigms suggest the adoption of greener approaches to urban storm water management. These tools and new approaches can be easily adaptable to new developments where the entire urban drainage system can be suited to follow a more sustainable way to drain storm water. The challenge for the future is instead aimed to apply this new philosophy to existing urban areas where the application of new tools and technologies requires high costs and such approaches have to be prepared by constructing a…

Evaluation of the water scarcity energy cost

Uncertainty estimation of a complex water quality model: The influence of Box–Cox transformation on Bayesian approaches and comparison with a non-Bayesian method

Abstract In urban drainage modelling, uncertainty analysis is of undoubted necessity. However, uncertainty analysis in urban water-quality modelling is still in its infancy and only few studies have been carried out. Therefore, several methodological aspects still need to be experienced and clarified especially regarding water quality modelling. The use of the Bayesian approach for uncertainty analysis has been stimulated by its rigorous theoretical framework and by the possibility of evaluating the impact of new knowledge on the modelling predictions. Nevertheless, the Bayesian approach relies on some restrictive hypotheses that are not present in less formal methods like the Generalised L…

In condizioni di scarsità delle risorse intervenire sulla domanda o sull'offerta

Implementation of a numerical model for the evaluation of potential apparent losses in a distribution network

The beneficial effect of local rain water reuse in urban areas: a long term modelling approach

Identification of Potential Locations for Run-of-River Hydropower Plants Using a GIS-Based Procedure

The increasing demand for renewable and sustainable energy sources has encouraged the development of small run-of-river plants. Preliminary studies are required to assess the technical and economic feasibility of such plants. In this context, the identification of optimal potential run-of-river sites has become a key issue. In this paper, an approach that is based on GIS tools coupled with a hydrological model has been applied to detect potential locations for a run-of-river plant. A great number of locations has been analyzed to identify those that could assure the achievement of different thresholds of potential power. The environmental and economic feasibility for small hydropower projec…

Uncertainty analysis of the influence of rainfall time resolution in the modelling of urban drainage systems

In urban drainage modelling, rainfall temporal variability can be considered as one of the most critical knowledge elements when dealing with rainfall–runoff models input data. The rainfall data temporal resolution usually available for practical applications is often lower than that requested for the rainfall–runoff simulation in urban areas, greatly compromising model accuracy. The present paper evaluates the influence of rainfall temporal resolution on the uncertainty of the response of rainfall–runoff modelling in urban environments. Analyses have been carried out using historical rainfall–discharge data collected for about 10 years in Parco d'Orleans experimental catchment (Palermo, It…

Impact of rainfall data resolution in time and space on the urban flooding evaluation

ABSTRACT Climate change and the modification of urban environment increase the frequency and the impact of flooding rising the interest of researchers and practitioners on this topic. Usually flooding frequency analysis in urban areas are indirectly carried out by adopting advanced hydraulic models to simulate long historical rainfall series or design storms. However their results are affected by a grade of uncertainty which has been much investigated in recent years. One of the most critical source of uncertainty inherent to hydraulic model results is linked to the imperfect knowledge of the rainfall input data both in time and space. Several studies show that hydrological modelling in urb…

Statistical analysis of uncertainty linked to flood risk evaluation

A composite indicator for water meter replacement in an urban distribution network

In water supply management, volumetric water meter are typically used to measure users' consumption. With water meters, utilities can collect useful data for billing, assess the water balance of the system, and identify failures in the network, water theft and anomalous user behaviour. Despite their importance, these instruments are characterised by intrinsic errors that cause so-called apparent losses. The complexity of the physical phenomena associated with metering errors in aging water meters does not allow meter replacement to be guided by single parameters, such as the meter age or the total volume passed through the meter. This paper presents a meter replacement strategy based on a c…

Comparison between storm tracking analysis techniques in urban area based on high resolution raingauge data

Experimental and modeling analysis of an apparent losses reduction device

Implementation of pressure reduction valves in a dynamic water distribution numerical model to control the inequality in water supply

The analysis of water distribution networks has to take into account the variability of users' water demand and the variability of network boundary conditions. In complex systems, e.g. those characterized by the presence of local private tanks and intermittent distribution, this variability suggests the use of dynamic models that are able to evaluate the rapid variability of pressures and flows in the network. The dynamic behavior of the network also affects the performance of valves that are used for controlling the network. Pressure reduction valves (PRVs) are used for controlling pressure and reducing leakages. Highly variable demands can produce significant fluctuation of the PRV set po…

Urban runoff modelling uncertainty: Comparison among Bayesian and pseudo-Bayesian methods

Urban stormwater quality modelling plays a central role in evaluation of the quality of the receiving water body. However, the complexity of the physical processes that must be simulated and the limited amount of data available for calibration may lead to high uncertainty in the model results. This study was conducted to assess modelling uncertainty associated with catchment surface pollution evaluation. Eight models were compared based on the results of a case study in which there was limited data available for calibration. Uncertainty analysis was then conducted using three different methods: the Bayesian Monte Carlo method, the GLUE pseudo-Bayesian method and the GLUE method revised by m…

Multi-stage Linear Programming Optimization for Pump Scheduling

This study presents a methodology based on Linear Programming for determining the optimal pump schedule on a 24-hour basis, considering as decision variables the continuous pump flow rates which are subsequently transformed into a discrete schedule. The methodology was applied on a case study derived from the benchmark Anytown network. To evaluate the LP reliability, a comparison was made with solutions generated by a Hybrid Discrete Dynamically Dimensioned Search (HD-DDS) algorithm. The cost associated with the result derived from the LP initial solution was shown to be lower than that obtained with repeated HD-DDS runs with differing random seeds. (C) 2013 The Authors. Published by Elsevi…

A robust estimation of sub-hourly ddf curves in partially urbanised catchments

Modelling urban drainage hydraulic performance

Bayesian inference analysis of the uncertainty linked to the evaluation of potential flood damage in urban areas.

Flood damage in urbanized watersheds may be assessed by combining the flood depth–damage curves and the outputs of urban flood models. The complexity of the physical processes that must be simulated and the limited amount of data available for model calibration may lead to high uncertainty in the model results and consequently in damage estimation. Moreover depth–damage functions are usually affected by significant uncertainty related to the collected data and to the simplified structure of the regression law that is used. The present paper carries out the analysis of the uncertainty connected to the flood damage estimate obtained combining the use of hydraulic models and depth–damage curve…

Reti bayesiane per l’indentificazione delle migliori strategie di gestione idraulica di un bacino urbano

Energy, water and environmental balance of a complex water supply system

The present paper describes the analysis of water and energy balance in a complex urban water supply system. The analysis was carried out employing Life Cycle Analysis (LCA) methodologies. The LCA approach was integrated with the analysis of the system energy and water balance. For a real size water supply system, based on the results of the individual LCAs, the current baseline was constructed highlighting the water, energy and environmental (in terms of CO2eq emissions in the atmosphere) costs of supplied water. Then, three different mitigation measures have been evaluated: the first is based on energy production by installation of photovoltaic systems; the second is based on energy recov…

Experimental Investigation for Local Tank Inflow Model

In the present paper the effect of private roof tanks and of the float valve characteristics on apparent losses due to water meter errors was investigated via an experimental study. The tests were carried out at the Environmental Hydraulic Laboratory of the University of Enna (Italy), on a high-density polyethylene (HDPE 100 PN16) looped distribution network. The experimental results showed that network pressure plays an important role in the characterisation of the floating ball valve emitter law, but the tank operating condition is the most relevant aspect to be considered mainly for water meter error evaluation. (C) 2014 The Authors. Published by Elsevier Ltd.

Mitigation of urban flooding: A simplified approach for distributed stormwater management practices selection and planning

The urbanization process and the hydraulic insufficiency of drainage systems are two of the most common causes of urban flooding. In some technical regulations, distributed stormwater management practices (DSMPs) are regarded as a solution for urban flooding problems. They can prevent the formation of runoff, dispose of it locally, or dampen its peak before it reaches the drainage system. Due to their diffuse localization and the wide number of available solutions, the evaluation of their efficiency in terms of flood reduction is very difficult. The methodology proposed in the present paper relies on the concept that the mitigation effects of DSMPs can be expressed as a function of the chan…

Uncertainty evaluation of design rainfall for urban flood risk analysis

A reliable and long dataset describing urban flood locations, volumes and depths would be an ideal prerequisite for assessing flood frequency distributions. However, data are often piecemeal and long-term hydraulic modelling is often adopted to estimate floods from historical rainfall series. Long-term modelling approaches are time- and resource-consuming, and synthetically designed rainfalls are often used to estimate flood frequencies. The present paper aimsto assess the uncertainty of such an approach and for suggesting improvements in thedefinition of synthetic rainfall data for flooding frequency analysis. According to this aim, a multivariate statistical analysis based on a copulameth…

Ability of Preissmann slot scheme to simulate smooth pressurisation transient in sewers

Urban drainage networks are generally designed to operate in a free-surface flow condition. However, as a consequence of heavy rainfall events or network malfunctioning, filling of sewers (pressurization) and network overflowing may occur. Several softwares are commonly used to simulate floods in drainage networks and their results are usually thought to be reliable and robust. However, no specific studies have been carried out on the behaviour of these softwares during the pressurization transient. Actually, mathematical models based on the momentum equation appear to be more suitable in correctly simulating the pressurization moving jump but models based on the energy equation are much mo…

Modeling of distribution network filling process during intermittent supply

Long Term Efficiency Analysis of Infiltration Trenches Subjected to Clogging

Abstract: In recent years, limitations linked to traditional urban drainage schemes have been pointed out and new approaches were developed introducing more natural methods for retaining and/or disposing of stormwater. Such practices include infiltration and storage tanks in order to reduce the peak flow and retain part of the polluting components. The impact of such practices on stormwater quantity and quality is not easily assessable because of the complexity of physical and chemical processes involved. In such cases, integrated urban drainage models may play a relevant role providing tools for long term analysis. In this study, the effect of the clogging phenomenon has been assessed by m…

Programmazione e gestione dei sistemi acquedottistici in condizioni di scarsità di risorsa

Uncertainty in urban flood damage assessment due to urban drainage modeling and depth – damage curve estimation

Comparison between a detailed and a simplified integrated model for the assessment of urban drainage environmental impact on an ephemeral river

The benefit of integrated analysis has been demonstrated in technical literature and it is also required by the EU Water Framework Directive 60/2000, which proposes a water-quality-orientated view of the whole urban drainage system and oversees new ways of assessing its performance. Integrated models, such as any complex modelling approach, often have prohibitive data availability requirements that reduce their applicability. Moreover, widely different approaches can be applied, ranging from simple conceptual models to complex physically based ones. In the present paper, two approaches have been compared using data from an experimental catchment in Bologna ( Italy), which consists of a part…

Controllo dell’inquinamento delle acque meteoriche e qualità dei corpi idrici ricettori: l’esperienza del bacino Nord di Palermo

Uncertainty in urban flood damage assessment due to urban drainage modelling and depth-damage curve estimation

Due to the increased occurrence of flooding events in urban areas, many procedures for flood damage quantification have been defined in recent decades. The lack of large databases in most cases is overcome by combining the output of urban drainage models and damage curves linking flooding to expected damage. The application of advanced hydraulic models as diagnostic, design and decision-making support tools has become a standard practice in hydraulic research and application. Flooding damage functions are usually evaluated by a priori estimation of potential damage (based on the value of exposed goods) or by interpolating real damage data (recorded during historical flooding events). Hydrau…

Stormwater infiltration trenches: a conceptual modelling approach.

In recent years, limitations linked to traditional urban drainage schemes have been pointed out and new approaches are developing introducing more natural methods for retaining and/or disposing of stormwater. These mitigation measures are generally called Best Management Practices or Sustainable Urban Drainage System and they include practices such as infiltration and storage tanks in order to reduce the peak flow and retain part of the polluting components. The introduction of such practices in urban drainage systems entails an upgrade of existing modelling frameworks in order to evaluate their efficiency in mitigating the impact of urban drainage systems on receiving water bodies. While s…

Uncertainty analysis in sewer systems performance evaluation

In recent years, in order to analyse complex urban drainage systems and to identify the most effective measures for improving their efficiency, many parameters, or indicators, have been defined and many methodologies have been proposed in order to quantify sewer systems performance in the most objective and general way. However, some uncertainty arises in these methodologies due to choices which the user has to take in applying the procedure. Thus, performance analysis results are affected by operator experience and they are mainly useful for comparison between different scenarios applied to the same system. In the present paper, a statistical analysis of sewer systems performance has been …

The influence of rainfall time resolution for urban water quality modelling

The objective of this paper is the definition of a methodology to evaluate the impact of the temporal resolution of rainfall measurements in urban drainage modelling applications. More specifically the effect of the temporal resolution on urban water quality modelling is detected analysing the uncertainty of the response of rainfall–runoff modelling. Analyses have been carried out using historical rainfall–discharge data collected for the Fossolo catchment (Bologna, Italy). According to the methodology, the historical rainfall data are taken as a reference, and resampled data have been obtained through a rescaling procedure with variable temporal windows. The shape comparison between ‘true’…

Pumps as turbines (PATs) in water distribution networks affected by intermittent service

A hydraulic model was developed in order to evaluate the potential energy recovery from the use of centrifugal pumps as turbines (PATs) in a water distribution network characterized by the presence of private tanks. The model integrates the Global Gradient Algorithm (GGA), with a pressure-driven model that permits a more realistic representation of the influence on the network behaviour of the private tanks filling and emptying. The model was applied to a real case study: a District Metered Area in Palermo (Italy). Three different scenarios were analysed and compared with a baseline scenario (Scenario 0 – no PAT installed) to identify the system configuration with added PATs that permits th…

Uncertainty assessment of an integrated urban drainage model

Over the last few years, the use of mathematical models has gained importance in urban drainage system management; indeed, such models enable the combined analysis of different components that constitute a drainage system; the sewer system, wastewater treatment plant and the receiving water body. The effectiveness of an integrated approach has been widely demonstrated in the past and is presented in the EU Water Framework Directive, which also introduces a new point of view regarding the water quality management of the whole system, requiring a global analysis at the river basin scale for pollutant sources. However, integrated urban drainage models introduce several uncertain factors that a…

Uncertainty estimation of a complex water quality model: GLUE vs Bayesian approach applied with Box – Cox transformation

In urban drainage modelling, uncertainty analysis is of undoubted necessity; however, several methodological aspects need to be clarified and deserve to be investigated in the future, especially in water quality modelling. The use of the Bayesian approach to uncertainty analysis has been stimulated by its rigorous theoretical framework and by the possibility of evaluating the impact of new knowledge on the modelling estimates. Nevertheless, the Bayesian approach relies on some restrictive hypotheses that are not present in less formal methods like GLUE. One crucial point in the application of Bayesian methods is the formulation of a likelihood function that is conditioned by the hypotheses …

Infiltration facilities design: comparison between simplified approaches and detailed physically based modelling

Assessment of data availability influence on integrated urban drainage modelling uncertainty

In urban water quality management, several models are connected and integrated for analysing the fate of pollutants from the sources in the urban catchment to the final recipient; classical problems connected with the selection and calibration of parameters are amplified by the complexity of the modelling approach increasing their uncertainty. The present paper aims at studying the influence of reductions in available data on the modelling response uncertainty with respect to the different integrated modelling outputs (both considering quantity and quality variables). At this scope, a parsimonious integrated home-made model has been used allowing for analysing the combinative effect of data…

Uncertainty analysis in urban flooding performance evaluation

Defining Uncertainties in Modelling of Urban Drainage Systems

Valutazione delle perdite idriche apparenti legate all’errata misurazione dei consumi residenziali

Modeling Hydraulic Performance Temporal Decline

Implementation of Pressure Reduction Valves in a dynamic water distribution system numerical model

The apparent losses due to metering errors: a proactive approach to predict losses and schedule maintenance

The effects of water meter age and private tanks on the apparent losses due to metering errors were evaluated by experimental and theoretical analyses. A monitoring campaign on a small district metered area (DMA) was carried out to determine the causes of apparent losses and implement a numerical model. Metering errors are affected by the flow rate passing through the meter, which is dependent on the network pressure and water level of the private tank. A node model that reproduces the effect of private tanks was coupled with EPANET and was applied to the DMA. The proposed modelling approach was used to identify where apparent losses are higher and to schedule maintenance. The model predict…

Il controllo distribuito dei deflussi meteorici in ambiente urbano: le esperienze brasiliane ed italiane, le problematiche e le prospettive.

A PERFORMANCE-BASED TOOL FOR PRIORITISING WATER METER SUBSTITUTION IN A URBAN DISTRIBUTION NETWORK

User water consumption is usually measured by volumetric water meters. Water meters also provide indispensable data used by the utilities for issuing bills, obtaining the system water balance, identifying failures in the network, water theft and anomalous user behaviour. Therefore, the utilities rely on such instruments for the technical and economic management of water systems. Despite their importance, water meters are characterised by relevant intrinsic errors that are responsible for a part of so-called apparent losses, i.e. water volumes reaching a final user without being accounted for. The aim of this paper is to provide a water meter management tool that analyses the meters performa…

Modelling urban stormwater impact mitigation by using bmps and storage tanks

The continuous growth of urban areas and the increasing public awareness about environmental impact of stormwater raised high interest on quality impact on the receiving water bodies. Indeed, in the last decades, large efforts have been provided for improving urban drainage systems in order to mitigate environmental impacts. In the present paper, a simplified modelling approach has been developed in order to evaluate the mitigation efficiency of different BMP schemes including infiltration and storage facilities and both considering possible distributed controls and centralised structures. The main goals of the research are the simulation of BMP efficiency in different operational condition…

Three-dimensional numerical simulations on wind- and tide-induced currents: The case of Augusta Harbour (Italy)

The hydrodynamic circulation in the coastal area of the Augusta Bay (Italy), located in the eastern part of Sicily, is analysed. Due to the heavy contamination generated by the several chemical and petrochemical industries active in the zone, the harbour was declared a Contaminated Site of National Interest. To mitigate the risks connected with the industrial activities located near the harbour, it is important to analyse the hydrodynamic circulation in the coastal area. To perform such analysis, a parallel 3D numerical model is used to solve the Reynolds-averaged momentum and mass balance, employing the k-e turbulence model for the Reynolds stresses. The numerical model is parallelized usi…

Catchment scale modeling approach for a holistic urban water quality management

Uncertainty assessment of sewer sediment erosion modelling

Urban stormwater quality modelling has become a fundamental issue in the evaluation of the receiving water bodies' quality state. Laboratory study as well as field campaigns have widely demonstrated that combined sewer sediments present cohesive-like properties which increase their resistance to erosion. However, only few models take sewer sediments into account considering their rheological properties. In the present paper different sewer sediment erosion models have been tested and their uncertainties have been assessed. The main goal was to discriminate the algorithms with respect to their robustness and the reduction of uncertainty. In order to accomplish such objective the GLUE methodo…

Controllo dell'inquinamento delle acque meteoriche e qualità dei corpi idrici ricettori

Il controllo distribuito dei deflussi meteorici in ambiente urbano: le esperienze brasiliane ed italiane, le problematiche e le prospettive. Atti del VIII Simpósio Ítalo Brasileiro de Engenharia Sanitária e Ambiental, VIII SIBESA

Estimation of sub-hourly ddf curves using scaling properties of hourly and sub-hourly data at partially-gaged site

Modelling of E. colidistribution in coastal areas subjected to combined sewer overflows

Rivers, lakes and the sea were the natural receivers of raw urban waste and storm waters for a long time but the low sustainability of such practice, the increase of population and a renewed environmental sensibility increased researcher interest in the analysis and mitigation of the impact of urban waters on receiving water bodies (RWB). In Europe, the integrated modelling of drainage systems and RWB has been promoted as a promising approach for implementing the Water Framework Directive. A particular interest is given to the fate of pathogens and especially of Escherichia coli, in all the cases in which an interaction between population and the RWB is foreseen. The present paper aims to p…

I grandi sistemi idrici in Sicilia

Impact of rainfall data resolution in time and space on the urban flooding evaluation.

Climate change and modification of the urban environment increase the frequency and the negative effects of flooding, increasing the interest of researchers and practitioners in this topic. Usually, flood frequency analysis in urban areas is indirectly carried out by adopting advanced hydraulic models to simulate long historical rainfall series or design storms. However, their results are affected by a level of uncertainty which has been extensively investigated in recent years. A major source of uncertainty inherent to hydraulic model results is linked to the imperfect knowledge of the rainfall input data both in time and space. Several studies show that hydrological modelling in urban are…

On the influence of rainfall time resolution for the analysis of urban drainage systems (with uncertainty)

Évaluation du colmatage de tranchées d'infiltration selon le type de sol : analyse à long terme

In recent years, limitations linked to traditional urban drainage schemes have been pointed out and new approaches were developed introducing more natural methods for retaining and/or disposing of stormwater. Such practices include infiltration and storage tanks in order to reduce the peak flow and retain part of the polluting components. The impact of such practices on stormwater quantity and quality is not easily assessable because of the complexity of physical and chemical processes involved. In such cases, integrated urban drainage models may play a relevant role providing tools for long term analysis of infiltration structures efficiency. In this study, the effect of the clogging pheno…

Assessing uncertainties in urban drainage models

The current state of knowledge regarding uncertainties in urban drainage models is poor. This is in part due to the lack of clarity in the way model uncertainty analyses are conducted and how the results are presented and used. There is a need for a common terminology and a conceptual framework for describing and estimating uncertainties in urban drainage models. Practical tools for the assessment of model uncertainties for a range of urban drainage models are also required to be developed. This paper, produced by the International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, is a contribution to the development of a harmonised framewor…

Bayesian approach for uncertainty quantification in water quality modelling: The influence of prior distribution

Summary Mathematical models are of common use in urban drainage, and they are increasingly being applied to support decisions about design and alternative management strategies. In this context, uncertainty analysis is of undoubted necessity in urban drainage modelling. However, despite the crucial role played by uncertainty quantification, several methodological aspects need to be clarified and deserve further investigation, especially in water quality modelling. One of them is related to the “a priori” hypotheses involved in the uncertainty analysis. Such hypotheses are usually condensed in “a priori” distributions assessing the most likely values for model parameters. This paper explores…

Uncertainty propagation throughout an integrated water-quality model

In integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating sewer system, wastewater treatment plant and receiving water body), uncertainty produced in one sub-model propagates to the following ones depending on the model structure, the estimation of parameters and the availability and uncertainty of measurements in the different parts of the system. Uncertainty basically propagates throughout a chain of models in which simulation output from upstream models is transferred to the downstream ones as input. The overall uncertainty can differ from the simple sum of uncertainties generated in each sub-model, dep…

Multivariate statistical analysis for water demand modelling: implementation, performance analysis, and comparison with the PRP model

Water demand is the driving force behind hydraulic dynamics in water distribution systems. Consequently, it is crucial to accurately estimate the actual water use to develop reliable simulation models. In this study, copula-based multivariate analysis was proposed and used for demand prediction for a given return period. The analysis was applied to water consumption data collected in the water distribution network of Palermo (Italy). The approach produced consistent demand patterns and could be a powerful tool when coupled with water distribution network models for design or analysis problems. The results were compared with those obtained using a classical water demand model, the Poisson re…

Uncertainty in water quality modelling: The applicability of Variance Decomposition Approach

Quantification of uncertainty is of paramount interest in integrated urban drainage water quality modelling. Indeed, the assessment of the reliability of the results of complex water quality models is crucial in understanding their significance. However, the state of knowledge regarding uncertainties in urban drainage models is poor. In the case of integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating the sewer system, wastewater treatment plant and receiving water body), uncertainty produced in one sub-model propagates to the following ones in a manner dependent on the model structure, the estimation of …

Modellazione dell’impatto dei deflussi urbani sui corpi idrici ricettori attraverso un approccio integrato

Water and Energy Saving in Urban Water Systems: The ALADIN Project

The ALADIN project was aimed at contributing to environmental and energy sustainability of the urban water system by means of a decision support tool able to allow an evaluation of the energy impact related to each different macro-sectors of urban water cycle highlighting the main energy flows and to assess the system energy balance and identify the possible energy-efficient solutions. Moreover the tool suggests the most efficient actions in reducing water losses. In the present paper the main features of the developed tool are presented. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

Integrated Urban Water Modeling with Uncertainty Analysis

In the last 20th years, the scientific world has got particular care towards the problems that involve the respect of the environment. According to this point, several researches were developed to describe the phenomena that take place during both wet and dry period and to increase the knowledge in this field. In particular, the attention was addressed towards the problems linked with the pollution of the water body because of the pollution carried by rainfall waters in the urban environment. In order to obtain a good description of the problem, it is important, of course, to analyze both quantity and quality aspects connected with all the transformation phases that characterize the urban w…

Flood frequency analysis for an urban watershed: comparison between several statistical methodologies simulating synthetic rainfall events

To obtain the flooding frequency distribution for an urban watershed, different methods based on simulations of synthetic rainfall events were compared with an empirical analysis of the flooding data and with the results of long-term simulations. A copula-based multivariate statistical analysis of the main hydrological variables was proposed to generate synthetic hyetographs. Two different approaches were adopted to assess a temporal pattern to the synthetic rainfall: one analyses all available historical rainfall patterns, and another adopts the cluster analysis in three different variants to reduce the computational effort of the analysis. To test the methodology reliability, the analysis…

Analisi e previsione dei consumi idrici urbani attraverso l’applicazione di modelli a rete neurale

Comparison of different stochastic models for urban water demand forecasting in drought conditions

Incertezza nella valutazione del danno da allagamento in ambiente urbano

Uncertainty in urban stormwater quality modelling: The effect of acceptability threshold in the GLUE methodology

Uncertainty analysis in integrated urban drainage modelling is of growing importance in the field of water quality. However, only few studies deal with uncertainty quantification in urban drainage modelling; furthermore, the few existing studies mainly focus on quantitative sewer flow modelling rather than uncertainty in water quality aspects. In this context, the generalised likelihood uncertainty estimation (GLUE) methodology was applied for the evaluation of the uncertainty of an integrated urban drainage model and some of its subjective hypotheses have been explored. More specifically, the influence of the subjective choice of the acceptability threshold has been detected in order to ga…

Water quality monitoring campaign design based on integrated modelling identifiability analysis.

Identifiability analysis for pressure sensors positioning

The identifiability analysis is investigated as sampling design method aimed to the leakage detection in looped water distribution networks. The preliminary ranking of the candidate nodes for the pressure sensors positioning is performed by running several hydraulic simulations and calculating sensitivity functions. The reduced subset of nodes and their sensitivities are then used to perform the identifiability analysis by calculating the collinearity index which provides the maximum number of sensors and their location into the network. The index selects the nodes according to their sensitivities to several leakages scenarios, simulated in EPANET by changing the emitter coefficient of the …

Modèles intégrés par drainage urbain : propagation d'incertitude et identifiabilité de paramètres

Colloque avec actes et comité de lecture. Internationale.; International audience

Generazione di ietogrammi sintetici per l’analisi di frequenza degli allagamenti in ambiente urbano

Impact of diffusion and dispersion of contaminants in water distribution networks modelling and monitoring

Abstract In recent years, there has been a need to seek adequate preventive measures to deal with contamination in water distribution networks that may be related to the accidental contamination and the deliberate injection of toxic agents. Therefore, it is very important to create a sensor system that detects contamination events in real time, maintains the reliability and efficiency of measurements, and limits the cost of the instrumentation. To this aim, two problems have to be faced: practical difficulties connected to the experimental verification of the optimal sensor configuration efficiency on real operating systems and challenges related to the reliability of the network modelling …

Role of Modeling Uncertainty in the Estimation of Climate and Socioeconomic Impact on River Water Quality

AbstractClimate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty and the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based…

The identifiability analysis for setting up measuring campaigns in integrated water quality modelling.

Abstract Identifiability analysis enables the quantification of the number of model parameters that can be assessed by calibration with respect to a data set. Such a methodology is based on the appraisal of sensitivity coefficients of the model parameters by means of Monte Carlo runs. By employing the Fisher Information Matrix, the methodology enables one to gain insights with respect to the number of model parameters that can be reliably assessed. The paper presents a study where identifiability analysis is used as a tool for setting up measuring campaigns for integrated water quality modelling. Particularly, by means of the identifiability analysis, the information about the location and …

Definition of performance indicators for urban water distribution systems in drought conditions

Emission standards versus immission standards for assessing the impact of urban drainage on ephemeral receiving water bodies

In the past, emission standard indicators have been adopted by environmental regulation authorities in order to preserve the quality of a receiving water body. Such indicators are based on the frequency or magnitude of a polluted discharge that may be continuous or intermittent. In order to properly maintain the quality of receiving waters, the Water Framework Directive, following the basic ideas of British Urban Pollution Manual, has been established. The Directive has overtaken the emission-standard concept, substituting it with the stream-standard concept that fixes discharge limits for each polluting substance depending on the self-depurative characteristics of receiving waters. Stream-…

“Modellazione dell’impatto dei deflussi urbani sui corpi idrici ricettori attraverso un approccio integrato”. La tutela idraulica ed ambientale dei territori urbanizzati. Atti dei seminari. Parma (5-6 febbraio 2004) e Cosenza (13-15 dicembre 2004)

In condizioni di scarsità delle risorse intervenire sulla domanda o sull’offerta

Investigations into under-registration of costumers meters in Palermo (Italy) and the effect of introducing unmetered flow reducers

Analisi modellistica dello stato di contaminazione delle acque di falda e degli interventi di messa in sicurezza d’emergenza

Assessment of data and parameter uncertainties in integrated water-quality model

In integrated urban drainage water quality models, due to the fact that integrated approaches are basically a cascade of sub-models (simulating sewer system, wastewater treatment plant and receiving water body), uncertainty produced in one sub-model propagates to the following ones depending on the model structure, the estimation of parameters and the availability and uncertainty of measurements in the different parts of the system. Uncertainty basically propagates throughout a chain of models in which simulation output from upstream models is transferred to the downstream ones as input. The overall uncertainty can differ from the simple sum of uncertainties generated in each sub-model, dep…

Procedures for the redaction of flood risk maps based on the derivation of proper specific indexes for urban areas

CONTROLLO DELL’INQUINAMENTO DELLE ACQUE METEORICHE E QUALITÀ DEI CORPI IDRICI RICETTORI: L’ESPERIENZA DEL BACINO NORD DI PALERMO

Estimation of sub-hourly DDF curves using scaling properties of hourly and sub-hourly data at partially gauged site

Abstract In urban drainage systems, knowledge of short-duration rainfall events can be considered as one of the most critical elements when their hydrological behaviour wants to be investigated. The temporal resolution of rainfall data usually available for practical applications is often lower than the data requested for the design procedures or mathematical models application, greatly affecting their reliability. Moreover, when high resolution rain gauges are available in the catchment, the registration period cannot be sufficiently long for obtaining practically usable statistical analyses. The present study proposes a method for estimating the distribution of sub-hourly extreme rainfall…

Comparison of different uncertainty techniques in urban stormwater quantity and quality modelling

Abstract Urban drainage models are important tools used by both practitioners and scientists in the field of stormwater management. These models are often conceptual and usually require calibration using local datasets. The quantification of the uncertainty associated with the models is a must, although it is rarely practiced. The International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, has been working on the development of a framework for defining and assessing uncertainties in the field of urban drainage modelling. A part of that work is the assessment and comparison of different techniques generally used in the uncertainty assessm…

Tecniche di mitigazione dell'impatto delle acque di dilavamento da aree industriali

Urban drainage impact assessment on receiving water body: long-term simulation and statistical analysis

Performance of membrane bioreactor (MBR) systems for the treatment of shipboard slops: Assessment of hydrocarbon biodegradation and biomass activity under salinity variation

In order to prevent hydrocarbon discharge at sea from ships, the International Maritime Organization (IMO) enacted the MARPOL 73/78 convention in which any oil and oil residue discharged in wastewater streams must contain less than 5. ppm hydrocarbons. Effective treatment of this petroleum-contaminated water is essential prior to its release into the environment, in order to prevent pollution problem for marine ecosystems as well as for human health. Therefore, two bench scale membrane bioreactors (MBRs) were investigated for hydrocarbon biodegradation. The two plants were initially fed with synthetic wastewater characterised by an increasing salinity, in order to enhance biomass acclimatio…

Effect of network pressure on apparent losses due to meters under-registration