What is a detention basin?
What is a catchment?
How does Council know what works will help reduce the impacts of flooding?
- emergency response plans based on detailed understanding of flood behaviour
- building new structures that collect and carry stormwater into drains or creeks, such as detention basins and swales, or improving existing ones to better manage stormwater and floods
- land zoning that says what can and can’t be built on flood-prone land
- voluntary purchase of houses built in high flood risk areas
What did the Fairy and Cabbage Tree Creek catchment flood study find?
Why do we need a detention basin in this area?
This detention basin will help protect houses, roads and land from flooding by storing water that flows from the steep land of the escarpment to the west, and releasing it slowly onto flatter land to the east.
What information do you want people to share with you?
What will happen to the trees if you build a detention basin here?
Will the basin be safe?
It’s being designed to prevent dam break during extreme storms by releasing water the basin can’t hold over a spillway, at a point that has the least impact on surrounding properties. During heavy rain, detention basins can quickly fill with fast-flowing water, so it’s safest to stay away from them when it’s raining. There’ll be warning signs at the basin to let people know this.
Who will maintain the basin?
What is run-off?
What are peak flows?
Why doesn’t Council clear out creeks?
In many cases, vegetation in watercourses can help reduce flood risk by slowing down the flow of stormwater, and preventing it from arriving all at once in areas where the creek bed flattens out or where several creeks join up. This effect is very important because it helps prevent serious dangers like properties or roads being flooded by fast-flowing water in a short amount of time.
As well as helping prevent the most serious flood hazards, appropriate creek vegetation adds beauty to our city, and provides vital habitat. It helps to manage water quality by filtering pollutants, regulates temperatures in urban areas and reduces erosion that can generate debris, or damage land, buildings, or roads.
We are continuing to work in the creeks on public land across our city, to reduce infestation by problematic creek vegetation such as weeds, and replace it with stable, low-maintenance vegetation. This enhances the many functions of our urban creeks without increasing flood risk.
What other work have you done to reduce the risk from flooding in this area?
There’s another detention basin in Foothills Road, Mount Ousley:
This basin is similar to what we’re proposing for this site. There are also some debris control structures to reduce the risk of blockage during storm events. We can’t prevent flooding, so we use planning controls to make sure that new developments are built in a way that minimises flood risk. Council also buys some high-risk properties under the Voluntary Purchase Scheme.
What can I do around my yard to help keep watercourses clean?
- Be careful not to dispose of grass clippings and other garden cuttings in or near watercourses and remove any obstructions that may cause blockages or divert flood waters.
- Be aware of any drainage easements or overflow paths that affect your property. Seek Council approval before altering your driveway or footpath levels, as this may cause water to flow off the road and down your driveway.
- Take care when planting trees near drainage pipes. Certain species with aggressive root systems e.g. Jacaranda, Poplar, Willow, Fig, Camphor Laurel and Rubber Trees can cause pipes to become blocked or cracked.
- Don’t lay any pipes, construct a bridge or divert a watercourse without first consulting Council. Unapproved work can increase flooding for both you and your neighbours.
- Don’t fill low-lying areas of your yard without seeking Council approval, as this may cause water to pond and increase flooding potential on your and your neighbours’ properties.
- Keep drainage inlets on your property clear of any rubbish or blockages. Remember, large paved areas will increase runoff, so you may need extra drainage.