Stormwater in urban areas is rainwater that flows across outside surfaces into stormwater drains and gutters in the street. Traditionally, the water that goes into stormwater drains is not treated and usually flows directly to creeks, rivers, lakes and oceans.

In order to protect the native plants and animals that live in these receiving waters, we need to ensure our urban stormwater does not contain excessive levels of pollutants such as heavy metals, hydrocarbons (ie. fuel, oils and grease), leaf litter, trash, detergents and soil particles.

As an added bonus, keeping our stormwater clean maximises our opportunities for stormwater harvesting and reuse

Stormwater as a Resource.

It should be noted that “rainwater” generally means water that runs off the roof of a building. Urban stormwater usually contains plenty of rainwater too, but if you can collect rainwater before it travels over the ground and becomes “urban stormwater” (like you do with a rainwater tank), then you can possibly use this water for even more uses.

How does Stormwater fit into “Water Sensitive Urban Design (WSUD)”?

The SA MDB NRM Board has been a key player in the Water Sensitive Urban Design (WSUD) project led by the Department of Planning and Local Government (previously known as Planning SA), which seeks to ensure that WSUD becomes the norm in Greater Adelaide, rather than the exception.

The board is very proud of its involvement in this critical project, which we hope can be rolled out in all urban areas across the state as soon as possible. We also continue to monitor the level of achievement of the project’s key objectives:

• Improving the quality of stormwater entering Gulf St Vincent,
• Diversifying Adelaide’s water sources to reduce reliance on the River Murray (ie. maximising opportunities for “fit for purpose” water use),
• Reducing demand for water on a per person basis,
• Reducing the risk of flooding in urban areas,
• Preventing erosion of waterways, and
• Protecting the ecological, scenic and landscape values of streams.

One very important part of this project was to agree on a definition of WSUD for South Australia, because there were so many different opinions on what it meant. So after much consultation and discussion, this is what the project arrived at:

Water Sensitive Urban Design (WSUD) is an approach to urban planning and design that integrates the management of the total water cycle into the urban development process. It includes:

• Integrated management of groundwater, surface runoff (including stormwater), drinking water and wastewater to protect water related environmental, recreational and cultural values,
• Storage, treatment and beneficial use of runoff,
• Treatment and reuse of wastewater,
• Using vegetation for treatment purposes, water efficient landscaping and enhancing biodiversity, and
• Utilising water saving measures within and outside domestic, commercial, industrial and institutional premises to minimise requirements for drinking and non drinking water supplies.

So stormwater is a big part of WSUD, as shown by the 1st, 2nd and 4th dot points in the definition above.

The above illustration shows how the local water cycle can change due to urban development, with bigger arrows representing higher flows. Among other things, WSUD seeks to minimise and manage the adverse impacts of the change illustrated above. These potential adverse impacts include:

• Increased flooding risk,
• Increased erosion risk;
• Increased pollutant loads; and
• Reduced groundwater recharge.

For more information on WSUD in the SA Murray-Darling Basin, visit our webpage on the topic.