Urbanisation and Stormwater

The traditional process of urbanisation increases impermeable areas, provides piped drainage for stormwater, increases flood risk and causes pollution in rivers. This chapter covers the effects of urbanisation on stormwater management and examines simple ways of determining the capacity required for various elements of drainage systems. An awareness of flood risk and other negative impacts of conventional piped drainage has led to the use in some urban areas of approaches to drainage that make use of semi-natural drainage features that increase infiltration and storage. The chapter discusses the problems associated with drainage systems, and the issue of sewer flooding. Apart from the risk of flooding, another effect of urbanisation on stormwater relates to its quality, which is also discussed in the chapter. Simple methods for designing drainage components, including storage, are also described.