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Mathematical interpretation of pollutant wash-off from urban road surfaces using simulated rainfall

Egodawatta, Prasanna K. and Thomas, Evan C. and Goonetilleke, S. Ashantha (2007) Mathematical interpretation of pollutant wash-off from urban road surfaces using simulated rainfall. Water Research 41(13):pp. 3025-3031.

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Abstract

In the context of stormwater quality modelling, an in-depth understanding of underlying physical processes and the availability of reliable and accurate mathematical equations which can replicate pollutant processes are essential. Stormwater pollutants undergo three primary processes, namely, build-up, wash-off and transport, before accumulating into receiving waters. These processes are expressed mathematically by equations in stormwater quality models. Among the three processes, wash-off is the least investigated. This paper presents the outcomes of an in-depth investigation of pollutant wash-off processes on typical urban road surfaces. The study results showed that a storm event has the capacity to wash-off only a fraction of pollutants available and this fraction varies primarily with rainfall intensity, kinetic energy of rainfall and characteristics of the pollutants. These outcomes suggest that the exponential equation commonly used for mathematically defining pollutant wash-off would need to be modified in order to incorporate the wash-off capacity of rainfall. Consequently, the introduction of an additional term referred to as the ‘capacity factor’ CF is recommended. CF primarily varies with rainfall intensity. However, for simplicity three rainfall intensity ranges were identified where the variation of CF can be defined. For rainfall intensities less than 40mm/hr, CF varies linearly from 0 to 0.5. For rainfall intensities from 40 to around 90mm/hr, CF is a constant around 0.5. Beyond 90mm/hr CF varies between 0.5 and 1.

Item Type:Journal Article
Status:Published
Keywords:pollutant wash-off, urban water quality, rainfall simulation
Subjects:290000 Engineering and Technology > 290800 Civil Engineering > 290802 Water and Sanitary Engineering
300000 Agricultural, Veterinary and Environmental Sciences > 300100 Soil and Water Sciences > 300105 Applied Hydrology (Drainage, Flooding, Irrigation, Quality, etc.)
290000 Engineering and Technology > 291100 Environmental Engineering > 291101 Environmental Engineering Modelling
ID Code:8736
Deposited By:Goonetilleke, Ashantha
Deposited On:23 July 2007
Alternative Locations:http://dx.doi.org/10.1016/j.watres.2007.03.037
Copyright Owner:Copyright 2007 Elsevier
Copyright Statement:Reproduced in accordance with the copyright policy of the publisher.