This book presents new findings on intrinsic variability in pollutant build-up and wash-off processes by identifying the characteristics of underlying process mechanisms, based on the behaviour of various-sized particles. The correlation between build-up and wash-off processes is clearly defined using heavy metal pollutants as a case study. The outcome of this study is an approach developed to quantitatively assess process uncertainty, which makes it possible to mathematically incorporate the characteristics of variability in build-up and wash-off processes into stormwater quality models. In addition, the approach can be used to quantify process uncertainty as an integral aspect of stormwater quality predictions using common uncertainty analysis techniques. The information produced using enhanced modelling tools will promote more informed decision-making, and thereby help to improve urban stormwater quality.

This book discusses the physicochemical changes (transformations) that metals deposited on urban road surfaces undergo during dry weather periods, in order to provide insights into their potential impacts on stormwater quality. Based on extensive field experiments, and laboratory and data analyses, it examines transformation characteristics of metals with respect to the particle size of road dust, antecedent dry days and land uses. Further, it proposes a new risk-assessment methodology, improving the original human health-risk indices based on the transformation characteristics and potential bioavailability of metals in order to evaluate the risks posed by metals in stormwater. This book is of interest to researchers and decision-makers developing appropriate pollution mitigation measures to enhance the quality of stormwater, targeting the effective reuse of stormwater in urban areas.