Effects of changing rainfall patterns on WSUD in Australia

Bioretention basins and permeable pavements are two widely implemented water sensitive urban design (WSUD) technologies. While their applications are extensive, their effectiveness as a result of changes in rainfall patterns is an emerging and important research question. This paper describes how these systems behave under varying rainfall conditions in Australian cities. To illustrate this, two design parameters, namely emptying times for permeable pavements and scour velocities for bioretention systems, were investigated. The study revealed that there are two groups of cities displaying almost similar peak flow characteristics – high (Darwin, Cairns, Brisbane, Townsville and Sydney) and low (Alice Springs, Hobart, Melbourne, Perth and Adelaide). It was shown that selection of an optimal storage size to ensure appropriate emptying times for permeable pavements requires a balance between managing dry periods, reuse demand and economic considerations. Increase of high flows increases the risk of scouring in bioretention basins, which is particularly significant for the first group of cities. Finally, the paper describes the importance of peak flow estimation method and appropriate selection of modelling time step for sustainable implementation of WSUD in Australia.