G. Becciu
Politecnico di Milano, DICA, Faculty Member
The paper discusses the efficiency, in terms of the reduction of both water volumes and pollution loads discharged to receiving water bodies, of first flush storage tanks in stormwater runoff networks of urban drainage systems, depending... more
The paper discusses the efficiency, in terms of the reduction of both water volumes and pollution loads discharged to receiving water bodies, of first flush storage tanks in stormwater runoff networks of urban drainage systems, depending on their specific capacity, their kind (transit or capture) and their position inside networks collecting multiple subcatchments (one single tank downstream the whole system rather than multiple tanks, i.e. one per each subcatchment, in series or just in parallel). The numerically achieved results show that the distance between two confluences has a very slight influence on the amount of both water volumes and pollution loads washed off in wet weather from the catchment surfaces. On the contrary, as expected and as already known in literature, the capacity of the tanks has the most relevant role on annual basis in terms of both overflow volumes and discharged pollution loads, while a very smaller influence is related to their position. Moreover, it ...
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Il libro affronta gli argomenti del Corso di Costruzioni Idrauliche del Politecnico di Milano, fornendo, accanto agli indispensabili richiami alle basi teoriche, un ausilio per la corretta comprensione delle procedure e dei calcoli di... more
Il libro affronta gli argomenti del Corso di Costruzioni Idrauliche del Politecnico di Milano, fornendo, accanto agli indispensabili richiami alle basi teoriche, un ausilio per la corretta comprensione delle procedure e dei calcoli di pratico interesse per l’ingegnere. La scelta degli argomenti e degli esercizi proposti riflette il desiderio di coniugare la complessità della pratica professionale con l’esigenza didattica di rendere evidenti i concetti ed i criteri di base delle Costruzioni Idrauliche. I principali argomenti trattati riguardano: i canali e le condotte a pelo libero, gli alvei fluviali e i canali erodibili, le condotte in pressione, i serbatoi di compenso, gli impianti di sollevamento, gli acquedotti, la stima delle portate di piena, le fognature, i sifoni e gli scaricatori di piena, gli invasi di laminazione, la verifica statica delle dighe a gravità, gli scarichi di superficie e di fondo delle dighe, le vasche di dissipazione. Gli argomenti sono presentati in forma quanto più possibile sintetica, con talune semplificazioni e schematizzazioni, allo scopo di mettere in luce in modo efficace gli aspetti fondamentali e significativi dei problemi e sviluppare una “forma mentis” che permetta poi di ben esercitare nella professione
Nature-based solutions (NBS) are very popular techniques to solve several problems in urban areas. These techniques proved several benefits such as stormwater management, heat island reduction, air and water quality improvement, and... more
Nature-based solutions (NBS) are very popular techniques to solve several problems in urban areas. These techniques proved several benefits such as stormwater management, heat island reduction, air and water quality improvement, and biodiversity enhancements. Among these techniques, are green roofs, green walls, grid permeable pavement, bio-retention basins, constructed wetlands, and infiltration trenches. Although the benefits of these techniques are significant, their use is still limited and not widespread because the hydraulic characteristics of the materials involved in their construction are often unknown. Most of these NBS has the soil, or any porous media, as the main layer. In this way, the definition of the hydraulic properties of the porous media involved in the construction will help designers, researchers, and practitioners to choose the best materials for the purpose. In this way, this study will explore the main methods to define the hydraulic properties of a porous m...
The paper discusses the concept of critical events from the point of view of runoff pollution from the urban catchment surfaces in wet weather. It comes out that such critical events are quite frequent in a normal rainfall regime, with a... more
The paper discusses the concept of critical events from the point of view of runoff pollution from the urban catchment surfaces in wet weather. It comes out that such critical events are quite frequent in a normal rainfall regime, with a return period of just few months or sometimes even few weeks. The here proposed procedure, allows to generate, for a given return period of interest (that for this kind of phenomena is usually intended to be expressed in months), a conventional synthetic rainfall having a rectangular shape and being able to simulate the same effects (in terms of probabilistic level of washed off mass during a rainfall) produced by the series of build-up and wash-off phases for the real rainfall events which are the base of the probability distribution of the mean intensity of rainfall events in the catchment area. This definition of a single simple synthetic critical rainfall event gains the relevant advantage of having the possibility to run, both in the current si...
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The traditional approach of stormwater management in urban areas frequently affected by floods has proven to be unsustainable for the growing urbanization scenario as well as not adapted to provide climate change resilience. In the spirit... more
The traditional approach of stormwater management in urban areas frequently affected by floods has proven to be unsustainable for the growing urbanization scenario as well as not adapted to provide climate change resilience. In the spirit of water sensitive cities, a stormwater management change is necessary, moving from pipe-based conveyance system to solutions able to manage at its source by small scale structures sprawled over the entire watershed, in a collection of systems and practices known as SuDs (Sustainable Urban Drainage Systems). These techniques provide several benefits not only related to risk mitigation but also to water quality and ecosystem services enhancement that make cities resilient also in terms of climate change. Currently stormwater and land use regulations mostly define a flow-limit to reduce discharge on the sewer systems. In this way, however, the search for further benefits is not encouraged. Flow-limit restrictions are obtained through storage control ...
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Research Interests: Stormwater, Urban And Regional Planning, Probability and statistics, Stormwater management, Probabilistic Analysis, and 8 moreWater Storage Structures, rainwater Management, Rainwater, Stormwater Storage Tank, Stormwater Drainage System, Water Storage Tanks, Sustainable Storm Water Management , and stormwater control measure
Sustainable Urban Drainage Systems (SuDS) gatherer effective strategies and control systems for stormwater management especially in highly urbanized areas characterized by large impervious surfaces that increase runoff peak flow and... more
Sustainable Urban Drainage Systems (SuDS) gatherer effective strategies and control systems for stormwater management especially in highly urbanized areas characterized by large impervious surfaces that increase runoff peak flow and volume. The main goal is to restore the natural water balance by increasing infiltration, evapotranspiration and promoting rainwater reuse. This paper proposes an analytical probabilistic approach for the modelling SuDS applicable to different structures and goals. Developed equations allow to estimate the probability of overflow and the probability of pre-filling at the end of dry periods, to evaluate the efficiency of the storage in rainwater management and its ability to empty between consecutive events. A great advantage of the proposed method is that it allows to consider a chain of rainfall events; this aspect is particularly important for control systems SuDS characterized by low outflow rates which storage capacity is often not completely availab...
Green roofs can be an effective tool for sustainable urban drainage, since they reduce and retain runoff by delaying its peak. Most studies analysing the retention capacity of green roofs are usually referred to a specific place and roof... more
Green roofs can be an effective tool for sustainable urban drainage, since they reduce and retain runoff by delaying its peak. Most studies analysing the retention capacity of green roofs are usually referred to a specific place and roof condition and do not consider the possibility that the roof could be partially pre-filled from previous rainfalls at the beginning of the given event. The aim of this paper is to develop an analytical probabilistic approach to evaluate green roof performance for stormwater control in terms of runoff that could be applied for different sites and climate conditions. To this end, the possibility that the green roof retention capacity could not be completely available owing to pre-filling from previous rainfall events has been considered and equations for an optimum green roof design, relating the runoff average return interval to the water retention capacity, have been proposed. The influence of parameters affecting the runoff process has been examined...
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Detention ponds are important for stormwater control. Insufficient design of these facilities may have significant impact in terms of flood and environmental safety. Although continuous simulation is sometimes used, often design... more
Detention ponds are important for stormwater control. Insufficient design of these facilities may have significant impact in terms of flood and environmental safety. Although continuous simulation is sometimes used, often design procedures are based on the single-event approach and pre-filling possibility is neglected. This can lead to underestimation of pond insufficiency risk. Pre-filling probability is here analyzed for different pond management rules and some direct relationships are proposed. An application to a real case is also presented.
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Detention ponds are important for stormwater control. Insufficient design of these facilities may have significant impact in terms of flood and environmental safety. Although continuous simulation is sometimes used, often design... more
Detention ponds are important for stormwater control. Insufficient design of these facilities may have significant impact in terms of flood and environmental safety. Although continuous simulation is sometimes used, often design procedures are based on the single-event approach and pre-filling possibility is neglected. This can lead to underestimation of pond insufficiency risk. Pre-filling probability is here analyzed for different pond management rules and some direct relationships are proposed. An application to a real case is also presented.
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ABSTRACT of Hydraulic, Environmental and Survey Engineering of the Politecnico di Milano. For five of these streams the measured daily discharges were available, while for the other ones they had been estimated by means of the PRMS model... more
ABSTRACT of Hydraulic, Environmental and Survey Engineering of the Politecnico di Milano. For five of these streams the measured daily discharges were available, while for the other ones they had been estimated by means of the PRMS model of the USGS. The regression equation may be simplified through the analysis of the observed significance of each of the variables. The paper proposes and two very simple forms of the equation, one including i and P, the other only P, also discussing their forecasting capability. For the environmental factor, the equation FA=1+N+Q+M+R is presented, in which each of the four terms at the right side ranges between the values 0 and 0.25, so that the factor FA may vary between 1 and 2. The four terms take into account respectively: the degree of naturalness of the fluvial ecosystem; the water quality (through the Extended Biotic Index); the pool percentage in the river bed; the administrative constraints and the possibility of recreational, touristic and fishing uses. The relevant criteria for the choice of the values of these terms are presented.
Research Interests: Engineering, Environmental Science, Stormwater, Probability and statistics, Multidisciplinary, and 11 moreUrban Drainage, sustainable urban drainage systems (SUDS), Stormwater management, Probabilistic Analysis, rainwater Management, Rainwater, Hydraulic Retention Time, Stormwater Storage Tank, Stormwater Drainage System, Elsevier, and Mean Retention Time
In recent decades, Best Management Practices (BMPs) for runoffs and water pollution control have gained considerable recognition and acceptance . I addition to downstream runoff control by detention storages source control with... more
In recent decades, Best Management Practices (BMPs) for runoffs and water pollution control have gained considerable recognition and acceptance . I addition to downstream runoff control by detention storages source control with infiltration basins has proved to be very effective in reducing the risk of drainage network overload and of polluted spills in receiving water bodies. Infiltration basins collect runoffs from impermeabl e surfaces like roofs, parking lots, streets and temporarily store rainwater volume to allows its in filtration into the soil even under conditions of low permeability. A key aspect for infiltration bas in design is sizing the storage volume. Traditional approaches are based on the resolution of the continuity equation, which represents the balance of inflows and outflows from the filter med ium, coupled with the Darcy's law to estimate the infiltration capacity. Despite these methods ar e quite robust, they can lead to underestimation of the probability ...
Research Interests: Geology()
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The fate of particulate matter (PM) and associated pollutants in unit operations and processes (UOP) for highway drainage clarification are subject to the size hetero-dispersivity of PM coupled with unsteady flow rates. This study applied... more
The fate of particulate matter (PM) and associated pollutants in unit operations and processes (UOP) for highway drainage clarification are subject to the size hetero-dispersivity of PM coupled with unsteady flow rates. This study applied multiphase computational fluid dynamics (CFD) validated with physical model results to simulate a screened hydrodynamic separator (HS) and a granular media radial cartridge filter (RCF). Coupled with controlled physical modeling examining UOP mechanisms, CFD predictions of PM fate are in good agreement with measured effluent concentrations, particle size distribution (PSD), as well as head loss for steady flow loadings for the RCF and the HS. CFD modeling was successfully extended to model a real-time rainfall-runoff event with coupled transient hydrodynamics and particle transport. In the study post-processing results with physical model validation provided in-depth insight into the mechanistic behavior of the UOPs by means of three dimensional hy...
Green roofs can be an effective tool for sustainable urban drainage, since they reduce and retain runoff by delaying its peak. Most studies analysing the retention capacity of green roofs are usually referred to a specific place and roof... more
Green roofs can be an effective tool for sustainable urban drainage, since they reduce and retain runoff by delaying its peak. Most studies analysing the retention capacity of green roofs are usually referred to a specific place and roof condition and do not consider the possibility that the roof could be partially pre-filled from previous rainfalls at the beginning of the given event. The aim of this paper is to develop an analytical probabilistic approach to evaluate green roof performance for stormwater control in terms of runoff that could be applied for different sites and climate conditions. To this end, the possibility that the green roof retention capacity could not be completely available owing to pre-filling from previous rainfall events has been considered and equations for an optimum green roof design, relating the runoff average return interval to the water retention capacity, have been proposed. The influence of parameters affecting the runoff process has been examined...
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Research Interests: Water quality, Urban And Regional Planning, Water Pollution, Probability and statistics, Probabilistic Modeling, and 10 moreStorage Tank, Urban Drainage, sustainable urban drainage systems (SUDS), Stormwater management, rainwater Management, Water Quality, Rainwater, Retention Time, Water Pollution Controll, and stormwater control measure
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Research Interests: Stormwater, Urban And Regional Planning, Probability and statistics, Stormwater management, Probabilistic Analysis, and 8 moreWater Storage Structures, rainwater Management, Rainwater, Stormwater Storage Tank, Stormwater Drainage System, Water Storage Tanks, Sustainable Storm Water Management , and stormwater control measure
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Research Interests: Engineering, Civil Engineering, Human Geography, Rainwater Harvesting, Stormwater, and 10 moreUrban Water, Urban Drainage, sustainable urban drainage systems (SUDS), Stormwater management, Probabilistic Analysis, Domestic Rainwater Harvesting, Rainwater, Probabilistic Desgin, Rainwater Tanks, and stormwater control measure
The feasibility of hydroelectric plants depends on a variety of factors: water resource regime, geo-graphical, geological and environmental context, available technology, construction cost and eco-nomic value of produced energy. Choices... more
The feasibility of hydroelectric plants depends on a variety of factors: water resource regime, geo-graphical, geological and environmental context, available technology, construction cost and eco-nomic value of produced energy. Choices about the building or renewal of hydroelectric plants should be based on the forecast of the future trend of these factors at least during the project life of the system. Focusing on the economic value of the produced energy this paper examines its influ-ence on the feasibility of hydroelectric plants. Analysis, referred to Italian case, were based on three different phases: i) the economic sustainability of small-scale hydroelectric plants under a minimum price guaranteed to the hydroelectric operator; ii) the estimate of the incentives to reach the thresholds of "acceptability" and "bankability" of the investment; iii) the analysis of results ob-tained in the previous phases using a model of the evolution of the electricity pric...
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The implementation of green roofs as sustainable urban drainage systems provides benefits for stormwater control and the environment and is more and more encouraged. A model for the estimation of the probability of vegetation survival... more
The implementation of green roofs as sustainable urban drainage systems provides benefits for stormwater control and the environment and is more and more encouraged. A model for the estimation of the probability of vegetation survival without irrigation is proposed. The model, developed through a probabilistic analytical derivation procedure, can also consider the effects of chained rainfall events, without the need of continuous simulation of hydrological processes. The model equations can be useful in the design of green roofs, allowing to determine the growing medium thickness in terms of an assumed risk of vegetation withering in dry periods. The proposed model is also able to identify the optimal thickness of the growing medium, over which the survival performances can be increased only with irrigation. Model performances were tested by the application to two case studies in Italy. Comparison between the probabilities and the cumulative frequencies from a continuous simulation ...
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The traditional approach for the optimization of water distribution networks (WDNs) does not always lead to consistent solutions from an operational point of view. The latest optimization algorithms identify solutions that are “the best... more
The traditional approach for the optimization of water distribution networks (WDNs) does not always lead to consistent solutions from an operational point of view. The latest optimization algorithms identify solutions that are “the best solutions” in mathematical terms but that can be less than robust against changes in operating conditions, resulting in the worst case in hydraulically infeasible configurations. Thus, this paper aims to provide a methodology that can synthesize the network performance capabilities under the change in operating conditions with two convergent strategies. The first consists of the implementation of new performance indices (PIs), the demand deficit and the pressure range, and the evaluation of their ability to criticality highlight in operating conditions. The second is the introduction of a new approach to weight the infeasible solutions in the final result, which are those inconsistent with the real hydraulic network performances. The analysis shows t...
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The current approach to stormwater management should focus on dealing with water on its source. The Sustainable Urban Drainage Systems (SuDS) promotes runoff peak flow and volume attenuation, load removal while providing amenites and... more
The current approach to stormwater management should focus on dealing with water on its source. The Sustainable Urban Drainage Systems (SuDS) promotes runoff peak flow and volume attenuation, load removal while providing amenites and biodiversities but can be difficult to apply in developed urban centers. An infiltration-exfiltration system (IES) placed on road gutters can function on receiving runoff from roads and directing them to the sewers system reducing peak flow and volume. This research follows up a full-scale test of an IES installed in São Paulo, Brazil. The IES has 49 × 1880 m dimension and a cross-section of 49 × 30 cm with a pervious concrete surface layer. The pervious concrete showed mechanical results acceptable for a low vehicular traffic and infiltration rate that allows water infiltration. Rainfall-runoff modeling showed that the proposed IES had a low effect on runoff peak flow and volume attenuation. A deeper gravel layers depth and outlet flow restrictor would...
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Purpose – The purpose of this paper is to study the transformation of some macropollutants including hydrocarbons, surfactants and metals in Milan west sewer basin. The study is part of a wider research (named SWARMNET and proposed by... more
Purpose – The purpose of this paper is to study the transformation of some macropollutants including hydrocarbons, surfactants and metals in Milan west sewer basin. The study is part of a wider research (named SWARMNET and proposed by Politecnico di Milano and Metropolitana Milanese S.p.A and has been classified as fundable by the Ministry of Education, University and Research of Italy), aiming at installing a monitoring system for measurement of accidental discharge of pollutants from industrial activities and real-time protection of the wastewater treatment plant (WWTP) by avoiding dangerous discharges entering the sewers. Good effluent and waste sludge quality allow safe agricultural reuse of both streams. Other objectives include food safety, lower treatment costs and reduction of pollution of soil, surface and groundwater. Design/methodology/approach – The west basin of Milan sewer network, discharging to San Rocco WWTP was considered. Among 700 industries, 16 have been selecte...