Are the current On-site Stormwater Detention (OSD) policies the best solution for source control stormwater management? A case study of Australian and Brazilian cities

In recent decades On-site Stormwater Detention (OSD) systems have been implemented in many cities around the world. However, a few studies have evaluated the effectiveness of OSD policies. Therefore, this paper compared the use of OSD in Australian and Brazilian cities, evaluating aspects of regulations, technical details and management matters. The results showed that Australian OSD design guidelines are a few steps ahead of Brazilian manuals. However, it is not possible to affirm that the catchment-based approach, adopted by most Australian councils, is better than the site-based approach, embraced by Brazilian cities, since neither is supported by monitoring data of real OSD performance. In general, all municipalities have the same management problems. There is no control over the number of OSDs built in the cities or even the conditions of the systems. Thus, the authors proposed some directions on how OSD policies could be improved.