Types of flooding
Storms and flooding are a natural part of living in Brisbane during summer months. Brisbane's subtropical climate makes it prone to weather that can cause flooding from rivers, creeks, storm tide and overland flow. Find out what types of flooding may affect your property, including creek, river and tidal, and how you can be better prepared.
Overland flow flooding
Overland flow is excess rainfall runoff from homes, driveways and other surfaces. Overland flow flooding is water that runs across the land after rain, either before it enters a creek or stream, or after rising to the surface naturally from underground. Overland flow flooding tends to affect localised areas rather than the whole city at once.
What you can do to manage overland flow flooding
Overland flow flooding can be unpredictable and its severity will depend on the amount of rainfall.
You can understand overland flow flooding by looking at the natural overland flow path through your property and taking appropriate steps to prepare and protect yourself and your home. Consider these natural flows when you are looking to renovate, build a fence or put in a shed. Remember where water will flow.
Creek flooding happens when rain runoff from homes flows along streets, to local stormwater drains, then flows into our creeks, the river and ultimately Moreton Bay.
Causes of creek flooding
During rainfall, water from roofs, driveways, parks, footpaths and other surfaces makes its way to the underground stormwater pipe network. The rain runoff exits the stormwater pipe network into our creeks and waterways.
The combination of rainfall, rain runoff and the existing water in the creek causes creek levels to rise. How high the creek level rises depends on the amount and duration of rainfall. Heavy rainfall can cause the creek level to exceed its capacity. This is when creek flooding occurs. Floodwaters may flow over the banks into properties, roads and parks. Storm surge can also cause creek levels to rise.
Creek flooding is difficult to forecast, as floodwaters can rise and fall quickly without warning. It is important that properties near creeks are prepared at all times.
River flooding happens when widespread, prolonged rain falls over the catchment area of the river. As the river reaches capacity, excess water flows over its banks, causing flooding.
River flooding downstream can occur hours after the rain has finished. The level of flooding depends on the speed and volume of water carried in the river.
The frequency of river flooding depends on the severity of the weather. The impact on homes depends on how close they are to the river and how high the property is built above ground level.
Storm tide flooding
Storm tide flooding happens when a storm surge creates higher than normal sea levels. A storm surge is caused when a low atmospheric pressure meteorological system and strong on-shore winds force sea levels to rise above normal levels.
Flooding can also occur from king tides. King tides occur regularly throughout the year and are noticeably higher than regular tides. The highest king tides are typically in the mornings over a few days in January each year. Similar tides occur at other times during the year but are at night. King tide information is predictable and readily available in tide books.
Brisbane, the Bayside and low lying parts of nearby suburbs can be susceptible to storm tide flooding. Areas connected to the foreshore and tide-affected areas of the river, tidal creeks and other waterways are also susceptible.
What you can do to be prepared for flooding
You can minimise the impacts of flooding to your home by:
- keeping furniture, fittings, wiring and electrical items above possible flood levels
- placing valuables such as photographs, passports and other important documents in high places away from possible flood waters
- moving your car to higher ground if your carport or garage is likely to flood
- securing outdoor furniture, garden equipment and children's toys to prevent them from becoming potential debris or flood hazards.
Purchasing flood insurance
Many home and content policies do not cover flood damage or have specific limitations on the definition of a flood. Read your insurance policy carefully or contact your insurer to discuss home and contents insurance.
Reporting flood hazards to Council
Flood management is a community-wide responsibility. You can assist Council in reducing the risk of flooding by reporting hazards such as:
- blocked or damaged drains, grates (the metal grills in the gutter)
- blocked stormwater pipes
- water pooling around the kerb and gutters
- illegal piping.
To report flood hazards, contact Council.
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