Urban Traffic Characteristics and Urban Stormwater Quality: A Methodology to Measure Traffic Generated Water Pollutants

Introduction

Current urban development practices are creating increasing pressure on water resources due to high pollutant loads created by anthropogenic activities. Therefore, it is necessary to adopt innovative urban development strategies to minimise water pollution. These strategies should be based on sound theoretical understanding of the principal drivers of urban water pollution, both now and into the future.

The Australian Bureau of Statistics (ABS) (2008) reported that there has been a 3% average annual vehicle registration growth over the last five years in Australia. As a result, the concentration of traffic generated pollutants in the atmosphere and on road surfaces is increasing (AATSE, 1997). This increase causes not only direct impacts such as air pollution, but also indirect impacts such as stormwater pollution and the accumulation of these pollutants in receiving waters. Road surfaces are the most significant pollutant contributor to urban stormwater as they generate key pollutants such as heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) (Sartor and Boyd, 1972). Additionally, as urban roads cover a considerable land area and are impervious, they generate a significant volume of stormwater runoff and, consequently, large pollutant loads.

It has been predicted that Australia will face some degree of climate change over the next 30 to 50 years (CSIRO 2007; RAGODEH 2005). The effects of traffic growth due to urbanisation, and rainfall changes due to the effects of climate change, may combine dynamically in the future, causing significant impacts on urban stormwater quality. However, the ability to predict these impacts is currently limited due to the lack of understanding of urban pollutant loads with key traffic and climate variables. The sustainability of urban waterways requires the formulation and adoption of appropriate stormwater management measures to meet these future challenges. However, this is reliant on the accurate estimation of key pollutant loads to urban stormwater from expected traffic growth and climate change. Therefore, the development of a suitable methodology is required to predict traffic generated pollutant loads under future traffic growth and climate change scenarios.

This chapter describes an experimental research methodology formulated to predict traffic generated key pollutant loads to urban road surfaces and, subsequently, to receiving waters. A detailed discussion of traffic generated key pollutants is presented followed by a discussion on traffic generated pollutant processes and the likely effect of climate change on these processes. The key steps in the research methodology are then presented. Finally, the selection of sampling and testing methods is presented.