Types of infrastructure
Wetlands help remove nutrients from stormwater by providing a habitat for water-loving reeds, grasses and trees which use the nutrients to grow. They remove sediments by reducing the speed of water flows caused by run-off. Wetlands attract a large diversity of wildlife, like birds and frogs, as well as providing opportunities for recreation and the enjoyment of nature.
Ponds settle fine sediments by reducing the speed of water flows caused by run-off. They also provide temporary storage so stormwater can be reused. Ponds attract birdlife, reduce water-borne pathogens through UV sterilisation and offer a place for people to play, explore and learn. They work best towards the end of a catchment after coarse sediments and gross pollutants (litter) have been removed.
Rain gardens (also known as bio-retention systems), look like a garden on the surface but have a storage and filtration structure underground that reduces nutrients from stormwater before it enters the drainage system. They have a small footprint and are suited to highly urbanised environments and smaller catchment areas.
Stormwater, when captured, can be used for irrigation. This puts nutrients contained in run-off back into the soil, benefiting plant life. Re-using and recyling stormwater reduces the demand on high-quality mains water supplies.
Creek restoration is really about adapting and revegetating waterways. Once a creek is restored to suit changed water flows, run-off is slowed down and filtered, nutrient and sediment levels are lowered and erosion is reduced. Creek restoration also creates new habitats for native plants and animals.
Channel reconnection involves reconnecting part of a creek that has become disconnected, either naturally by flood or by engineered drainage works, from the primary creek line. The disconnection may form a wetland. Reconnecting the channel to the creek allows more water to be diverted into the wetland and treated through the wetland process.
Swales are shallow, elongated depressions that collect and convey stormwater. Swales are lined with grass or other plants which trap and remove sediments as stormwater passes through them.
Gross pollutant trap
Gross pollutant traps are structures designed to remove a range of pollutants from waterways, including rubbish, coarse sediments, litter and some types of oil. They are often the important ‘first line of defence’ in treating stormwater, particularly in areas of high litter. If carefully designed, they can be integrated into the waterscape.