Evaluation of roofing materials emissions at the city scale: Statistical approach for computing roofing area distribution

International audienceRoofing materials are considered as a major source of urban runoff contamination. Today, in the context of the European Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required at the city scale, and therefore the development of assessment tools is needed. However, at the city scale, the important diversity of roofing materials represents a difficult task. In fact, the most restrictive step when estimating contaminant flows for large-scale territories is the estimation of the roofing materials surfaces area, for which no direct data exists. This paper aims to describe the proposal statistical approach for computing roofing materials area distribution. This method is based on two steps. The first one is the sampling theory which aims to define the required size of the selected sample which represents the proportion R (%) from any total urban area surface. The second step is based on applying the estimation theory. In fact, after determining the proportion R (%), we estimate the unknown distribution of roofing materials in an urban area by performing a sample representing R (%) from the total urban area surface. The reliability of the methodology has been proved for tow different urban areas with known roofing materials distribution. Results obtained showed that a sample representing R=4% of the zone area should be randomly generated

A new method for modelling roofing materials emissions on the city scale: Application for zinc in the City of Créteil (France)

International audienceToday, urban runoff is considered as an important source of environmental pollution. Roofing materials, in particular, the metallic ones, are considered as a major source of urban runoff metal contaminations. In the context of theEuropean Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required on thecity scale, and therefore the development of assessment tools is needed. However, on this scale, there is an important diversity of roofing materials. In addition, given the size of a city, a complete census of the materials of the different roofing elements represents a difficult task. Information relating roofing materials and their surfaces on an urban district do not currently exist in urban databases. The objective of this paper is to develop a new method of evaluating annual contaminant flow emissions from the different roofing material elements (e.g., gutter, rooftop) on the city scale. This method is based on using and adapting existing urban databases combined with a statistical approach. Different rules for identifying the materials of the different roofing elements on the city scale have been defined. The methodology is explained through its application to the evaluation of zinc emissions on the scale of the city of Créteil

Modelling the Zn emissions from roofing materials at Créteil city scale - Defining a methodology

11 p.International audienceToday, urban runoff is considered as an important source of environment pollution. Roofing materials, in particular the metallic ones are considered as a major source of urban runoff contamination. An accurate evaluation of contaminant flows from roofs is thus required at the city scale. This paper aims to describe the definition of an appropriate methodology for evaluating the zinc emission at the city scale. This methodology is based on combining two different methods. The first one is an automatic classification and the second one is a theoretical urban study site. In order to obtain representative data, the choice of the study site was based on the diversity of land use and the urban and social context. Finally some results and future works will be presented

Evaluation of roofing materials emissions at the city scale: Statistical approach for computing roofing area distribution

International audienceRoofing materials are considered as a major source of urban runoff contamination. Today, in the context of the European Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required at the city scale, and therefore the development of assessment tools is needed. However, at the city scale, the important diversity of roofing materials represents a difficult task. In fact, the most restrictive step when estimating contaminant flows for large-scale territories is the estimation of the roofing materials surfaces area, for which no direct data exists. This paper aims to describe the proposal statistical approach for computing roofing materials area distribution. This method is based on two steps. The first one is the sampling theory which aims to define the required size of the selected sample which represents the proportion R (%) from any total urban area surface. The second step is based on applying the estimation theory. In fact, after determining the proportion R (%), we estimate the unknown distribution of roofing materials in an urban area by performing a sample representing R (%) from the total urban area surface. The reliability of the methodology has been proved for tow different urban areas with known roofing materials distribution. Results obtained showed that a sample representing R=4% of the zone area should be randomly generated

Evaluation of gutter and valley materials emissions at the city scale: Statistical approach for computing gutter and valley lengths

International audienceRoofing materials are considered as a major source of urban runoff contamination. Today, in the context of the European Water Directive (2000/60 CE), an accurate evaluation of contaminant flows from roofs is thus required at the city scale, and therefore the development of assessment tools is needed. However, at the city scale, the important diversity of roofing materials represents a difficult task for the quantification. In fact, the most restrictive step when estimating contaminant flows for large-scale territories is the estimation of the roofing materials surfaces area, for which no direct data exists. This study focuses on describing the method to evaluate gutter and valley lengths at the city scale. The proposed approach relies uses a statistical framework. The city was divided into homogenous urban areas. Then, a stratified random sampling technique was employed. The reliability of the methodology has been proved for three different urban areas (drained by sewer system) with known roofing materials distribution and known gutter and valley lengths. The obtained results show that a sample representing R=4% of the urban area leads to an absolute error less than 2% for gutter and valley length values

The TERRACES project – A collaborative work to understand the role of vegetative green roof in refreshing the urban ambiances

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