After a wetter than average start to 2023, and almost three years of La Nina conditions, we started shifting towards a warmer and drier period with El Nino predicted to influence our seasons over the coming years. Rainfall observations for Adelaide closely reflect this transition and although it seems we have exceeded our annual average rainfall across the hills and plains, winter and spring rainfall was significantly less. The downpour on 28 November, and bursts of rain in June and December, have certainly put WSUD assets to the test, enabling much of that stormwater to be captured, treated or infiltrated in streets and parks, and helping to mitigate the impacts of urban catchment flooding.
On 28 November, water sensitive urban design features across Adelaide stormwater catchments worked over time to slow fast moving water, capture pollutants and attenuate floodwaters as rainfall peaked.
Just like this stormwater channel in the Adelaide Park Lands. The City of Adelaide recently upgraded the channel from an eroded ditch to a WSUD swale with detention basin and gross pollutant trap, with funding support from a Green Adelaide Water Sustainability Grant.
Hard-working WSUD assets in Angas Street, Channel 16, Victoria Park. Source: Adelaide City Council
Gauges in the Brown Hill Keswick Creek catchment n the Mitcham foothills recorded 75mm in 24 hours with a heavy burst of rain at 7am providing much of the downstream flows through Keswick and West Torrens. The mean annual rainfall for the month of November is usually 36.2mm.
How well did your WSUD work?
We often take a nice photo at the installation of a WSUD feature, but recording it in action is just as important.
Please send us your photos of raingardens, tree pits, swales, wetlands and creeks that are working hard to keep stormwater clean in these recent deluges.