Implications of climate and urban development on the design of sustainable urban drainage systems (SUDS)

This paper explores the implications of climate change and urban development on the design of sustainable urban drainage systems (SUDS) using the example of ponds and raingardens in Auckland, New Zealand. Many of Auckland's coastal and freshwater receiving environments have been degraded due to stormwater inflows and are potentially at further risk due to continued urbanisation and climate change. SUDS have been suggested as a possible means of adapting to those risks. However, there is little guidance available on how they should be designed for future conditions. Response-curves which relate changes in SUDS sizing to both climate change and imperviousness are presented as a means of displaying a range of possible future design needs. It is suggested that they could aid in the selection of adaptation strategies. The methodology followed is based on publicly available guidance material to provide a real world example of the design issues facing stormwater managers. An incremental adaptation strategy, whereby construction is staggered over time, is recommended for ponds which vary greatly in size depending on the projected climate and imperviousness. In contrast, adapting raingardens at the time of construction is pragmatic as the change in size, with even the maximum projected climate change, is modest.