Stormwater harvesting and WSUD frequent flow management: a compatibility analysis

Harvesting stormwater from urban catchments provides a supplementary water resource and, due to the physical abstraction of polluted water, also leads to environmental benefits. These benefits include the reduction of frequent ecosystem disturbance during small storms and less waterway erosion; hydrological impacts which are currently addressed by Water Sensitive Urban Design guidelines for stormwater frequent flow management (FFM). Although FFM and stormwater harvesting share the same store-release behaviour, they have a very different underlying basis to their design and operation. This paper explores the level of compatibility between these two systems and hence the potential for their integration. It was found by water balance analysis that the harvesting storage required to maximise most yields is similar to the recommended storage volume for FFM. This analysis was performed for a temperate-climate location in South East Queensland under historically low rainfalls. Environmental benefits associated with runoff quantity and pollutant load reductions are highest when the capture storage is rapidly emptied after storms.