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Updated: Jul 30, 2025

Design and Construction of an Urban Runoff Research Facility
Published on: August 8, 2014
Assessing the characteristics of different-sized particles in the first flush of roof runoff
Wei Zhang1, Peizhen Qu2, Huichao Sun2
1Key Laboratory of Urban Stormwater System and Water Environment, Ministry of Education, Beijing University of Civil Engineering and Architecture, Beijing 100044, China E-mail: weizhang021@163.com; Beijing Engineering Research Center of Sustainable Urban Sewage System Construction and Risk Control, Beijing University of Civil Engineering and Architecture, Beijing 100044, China; Beijing Energy Conservation & Sustainable Urban and Rural Development Provincial and Ministry Co-construction Collaboration Innovation Center, Beijing 100044, China.
Abstract:
The first flush occurs during urban runoff events. In this study, we aimed to assess the characteristics of different-sized particles in the first flush of roof runoff, and runoff was collected from an asphalt roof (AR), metal roof (MR), and cement roof (CR) for analysis. There were no clear patterns in the particle size distributions in the runoff from the three roofs and were affected by several factors. The strength of the first flushes differed significantly for particles in different size categories in AR, MR, and CR runoff and were very different from suspended solids (SS). The comparison showed that it would be possible to meet the SS control design expectation required by the Chinese national standard for runoff pollution control (VFF = 3 mm) for particles <45 μm but not for particles >45 μm. The methods presented provide an alternative for assessing the ability to control the transport of different-sized particles in runoff.
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