Impact of Escherichia colifrom stormwater drainage on recreational water quality: an integrated monitoring and modelling of urban catchment, pipes and lake

Frédéric Charles Soulignac
SPRINGER HEIDELBERG, 2020
Journal paper

Abstract

In recent years, recreational waterbodies are increasingly favoured in urban areas. In spite of the growing concerns for maintaining the required bathing water quality, the impacts of stormwater drainage are still poorly controlled. In this context, this study originally develops an integrated urban catchment-pipes-lake monitoring and modelling approach to simulate the impacts of microbial quality from stormwater drainage on recreational water quality. The modelling system consists of three separated components: the urban catchment component, the 3D lake hydrodynamic component and the 3D lake water quality component. A series of processes are simulated in the model, such as rainfall-discharge, build-up, wash-off ofEscherichia coli(E. coli) on urban surfaces, sewer flows, hydrothermal dynamics of lake water and transport and mortality ofE. coliin the lake. This integrated model is tested for an urban catchment and its related recreational lake located in the Great Paris region. Continuous monitoring and samplings were performed at the stormwater drainage outlet and three different sites in the lake. Comparing the measured data with simulation results over 20 months, the modelling system can correctly represent theE. colidynamics in the stormwater sewer systems and in the lake. Although uncertainties related to parameter values, pollution sources andE. colimortality processes could be further discussed, the good performance of this modelling approach emphasizes a promising potential for urban bathing water quality management.

Official source

https://infoscience.epfl.ch/record/280096?ln=en

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related concepts

Related publications

Frédéric Charles Soulignac
SPRINGER HEIDELBERG, 2020
Journal paper

Abstract

Official source

https://infoscience.epfl.ch/record/280096?ln=en

About this result

Related concepts (12)

Related concepts

Related publications (6)

Related publications

Probabilistic risk assessment of urban stormwater discharge

David Andrew Barry, Nathalie Chèvre Rossi, Luca Rossi

Urban stormwater is an important source of detrimental impacts for receiving waters. Discharges from separated or combined sewer systems are recognized as a major contamination input to the environment. Moreover, these discharges may impact the morphological aspect of receiving waters, like rivers and streams. But these impacts are difficult to handle. First, precipitation is the main driving force of the problem and has stochastic features, which must be taken into account. Second, some variables and parameters of the urban and receiving water systems are difficult to measure or to estimate (e.g., riverbed characteristics, number of inhabitants in a watershed, imperviousness, etc.) and therefore cannot be determined exactly. Finally, factors involved in the cause-effect relationship between urban stormwater discharges and the receiving water ecosystem, i.e., the assessment criteria, are difficult to describe with a linear relationship. To tackle this problem, we developed a new impact-based approach in Switzerland to allow engineers to plan adequately treatment devices and technical solutions. To support this approach, a probabilistic software tool has been proposed to assess impacts of urban drainage to receiving waters based on new impact-based criteria. The software includes probabilistic modeling facilities (Monte Carlo simulation routine) and sensitivity analysis to focus the data acquisition on the most important parameters. Long-term simulations (10-year duration) are performed using historical rain data from different Swiss locations for the simulation of an urban watershed, upstream watershed, and the receiving water’s hydrology and water quality. This long period allows us to account for variability in precipitation. The computation typically runs 200-500 iterations. Most variables and parameters’ uncertainties are taken into consideration by generating random values of a given multivariate distribution. The results, after sorting, are plotted as a cumulative distribution function that represents the probability (on the Y-axis) complying with a criterion (on the X-axis). The guidelines and the software were proposed to authorities and to experts active in the field of urban wet-weather and ecosystem management. This new approach was accepted by the majority of the experts, even if the complexity of the planning procedure generated skepticism from some users. The concepts of uncertainty and variability were well understood by users. In fact, they are commonly used in urban wet-weather and water ecosystem management, even if not explicitly presented. For example, the definition of watershed imperviousness, the choice of rain series, the initial rain losses, the impacts of chemicals on aquatic species, etc., are parameters that are commonly estimated in a given range of reliabilities. Examples of applications and presentations of scenarios were the best way to illustrate the benefits of using the new approach. Nevertheless, the interpretation of results is quite difficult and a communication strategy, such as organization of workshops and courses is a need for the acceptance of the methodology.

2010

Lake mesoscale processes have no secrets for artists, they have some for scientists and policy-makers. In the introduction to this dissertation, we saw that poets and painters depict the lake with rich variability. This vision conflicts with conventional approaches inferring the lake's bio-physical status from a few in-situ measurements with limited spatio-temporal coverage. Yet it reflects upon true physical processes, capable of disrupting the misleading lentic nature of lakes, the essential ecosystem services they provide, and even citizens' safety. Recent overarching policies now aim at securing those services, using novel approaches like numerical simulations and remote sensing observations. Harnessing the potentiality of in-situ, remote sensing data and model simulations, this thesis developed an end-to-end framework delivering reliable synoptic lake information, at high spatial and temporal resolution. In lakes, three-dimensional hydrodynamic models are the only information source capable of resolving transport and mixing, and forecasting their dynamics. However, they still rely on large observational datasets for their complex parameterizations and for constraining their uncertainties. This thesis addressed such challenges by (i) implementing an automated model calibration framework alleviating the need for expert knowledge, and by (ii) developing a data assimilative scheme capable of reducing and quantifying model uncertainties by incorporating satellite and in-situ data. Both yielded remarkable results: the former returned parametric values diminishing models Root Mean Square Error by up to 47 %, while the latter cut it further down by 54 %. Furthermore, the data assimilation enhanced the spatial coherence and magnitude of imperfectly resolved physical processes, and provided system uncertainties. Finally, this thesis delivered a practical outcome of its findings by developing an online pre-operational three-dimensional lake monitoring and forecasting system: meteolakes.ch. For two years, Meteolakes has been disseminating spatially explicit real-time lake information and data products to more than hundred thousand end-users. This pioneering platform has been featured in numerous media (newspapers, radio, television), public events, museum exhibitions, and benefited scientific, lake professionals, and public communities. A pinnacle of this research has been its early-warning and forecasting capabilities, which anticipated numerous mesoscale physical phenomena in Lake Geneva, such as upwellings, gyres, and strong currents. Two of those events, which impacted public and commercial activities, are illustrated in this dissertation. From observations and models to societal benefit, we created here a long value chain for water management. At the crossroads of scientific, computational and observational advances, this research paves the route for understanding lakes' delicate imbalance. By producing data society can use, it opens novel frontiers for interdisciplinary research on previously elusive lake physical processes, and their implications on the everyday life of people.

EPFL2019

Development and application of a numerical simulation system to evaluate the impact of anthropogenic heat fluxes on urban boundary layer climate

Andrea Krpo

Increasing economic development, and growing population, generated during the last decades a very important growth of cities. Urban regions include nowadays more than half of the global population and, by 2030, this proportion is forecasted to increase to three quarters. A consequent more and more extensive use of natural resources, together with increasing anthropogenic activities such as emissions from traffic and factories, or heating from air-conditioning facilities, modify local climate in many different ways, leading to a progressive degradation of life quality in urban areas. Taking these facts into account, there is nowadays a real need for efficient urban planning guidelines and sustainability policies in order to improve life quality in urban areas. Different points should be considered including urban warming, air pollution, human health, economic, and cooling energy needs. The present work goes in this direction, aiming at developing a simulation system for the study of the complex interactions between buildings and the atmosphere. The system of equations describing atmospheric flows is highly non linear and it is common to employ numerical techniques in order to solve them. Moreover, the representation of urban canopy climate, and related air pollution problems, requiree taking the interaction between urban scale (tens of kilometers), and mesoscale (hundreds of kilometers) processes into account. At first, starting from previous studies, a mesoscale meteorological model has been developed as part of this work. Urban induced processes have been considered by implementing inside the model a detailed urban parameterization scheme developed in a previous work. The scheme is able to capture different urban processes, and reproduces the effects of cities in a more accurate way than traditional methods usually used in mesoscale models. However, the heat generated in buildings, and the way this heat is exchanged with the exterior, was not explicitly resolved. In particular, recent studies indicated that anthropogenic heat from air-conditioning facilities can play an important role and should be taken into account for more complete urban climate studies. To this purpose, a Building Energy Model (BEM) has been developed, and coupled to the Urban Canopy Parameterisation (UCP). This building model takes into account the diffusion of heat through walls, roofs, and floors, the natural ventilation, the generation of heat from occupants and equipments, and the consumption of energy through air conditioning systems. Comparisons with other programs indicate that BEM is able to accurately simulate the basic heat transfer phenomena, and to reproduce the heat fluxes exchanged between buildings and the atmosphere. In a second part of the work, the simulation system composed by the Mesoscale Model (MM), UCP, and BEM is tested with respect to one, and two-dimensional configurations. In particular, the impact of BEM on the meteorological variables is analyzed, as well as the efficiency of different urban warming countermeasures, and cooling energy demands control strategies. Two-dimensional results are then utilized as guidance for the application of MM-UCP-BEM over the realistic configuration including the city of Basel and the surrounding areas. At first, comparisons of urban and rural simulated temperatures with measures provided by the BUBBLE project (Basel Urban Boundary Layer Experiment), have shown that the model could reasonably well reproduce the variations in outdoor air temperature. In a second time, the simulations considered for the two-dimensional configuration are applied to the case of Basel. Numerical results confirm that anthropogenic fluxes from air-conditioning facilities can have a non negligent impact on the urban meteorology. Typically, they modify the outdoor temperature and increase the Urban Heat Island (UHI) phenomenon. In the last part of the study, the applicability of the model in performing urban warming countermeasures, and cooling energy demands control strategies, is evaluated. In this purpose in mind, a sensitivity analysis is carried out indicating that appropriate physical properties of built materials, efficient air-conditioning systems, and the application of simple energy saving policies, can lead to very important cooling energy savings. In general, the application of BEM inside the UCP allows computing the heat released into the atmosphere by air-conditioning facilities, as well as the corresponding feedbacks produced on the different meteorological variables. It also increases the capability of the urban parameterisation to provide more detailed studies of urban warming countermeasures, and cooling energy demands in real cities.

EPFL2009