Types of flooding
Brisbane is located on the Brisbane River floodplain and contains more than 4000 km of waterways. The South/North Pine Rivers and Moreton Bay also influence flooding in the Brisbane Local Government Area (LGA).
Before searching for a property on Brisbane City Council’s Flood Awareness Map, it is important to understand the four types of flooding in Brisbane.
Depending on property locations, residents may experience flooding from four different sources including:
All floods are different and may occur from one or a combination of these four sources. Floodwater may rise very slowly and be slow-moving. This is normally associated with Brisbane River flooding, which occurs after prolonged periods of heavy rain across the whole catchment. Floodwater can also rise quickly and be very fast-moving, and then recede quickly. This is normally associated with creek flooding and overland flow.
You can also view this video on Council's YouTube channel.
Video transcript
Video transcript
This is a video transcript of the Types of flooding in Brisbane video hosted on Brisbane City Council's YouTube channel. This video is 1 minutes and 45 seconds long.
>>Female voice: The Brisbane Local Government Area contains more than 4000 kilometres of waterways.
Brisbane experiences flooding from four sources and it’s important to understand these and to be prepared. This will help you stay safe, confident and ready for flood.
Creek flooding in Brisbane occurs when there is prolonged rainfall over a creek catchment. Intense rainfall, over an already saturated catchment, during the summer storm season could also result in Creek flooding.
River flooding occurs when the river reaches capacity and excess water flows over its banks or backs up through the drainage system as backflow. This happens when there is widespread and prolonged rainfall over the upper catchments of the Brisbane River and can lead to floods in adjacent creeks. River flooding can occur hours after the rain has stopped.
Overland flow is the most common type of flooding during the summer storm season in Brisbane and can be unpredictable. It is the stormwater run-off that travels over the land when there are heavy rainfall events. It’s fast-moving and generally lasts for a short duration.
Storm tide flooding happens when there are higher than normal sea levels caused by a storm surge and is more likely to occur when there is high tides or king tides. This type of flooding affects low-lying areas close to tidal waterways and foreshores.
Use Brisbane City Council’s Flood Awareness Map to view a property and understand the likelihood of flooding from these flood sources on a property or in a suburb.
Council’s Flood Information Online can help residents and visitors stay safe, confident and ready.
Creek flooding
Creek flooding happens when intense rain falls over a creek catchment. Run-off from houses and streets also contributes to creek flooding. The combination of heavy rainfall, run-off and the existing water in the creek causes creek levels to rise. Floodwater from creek flooding can rise quickly and be very fast moving, and then recede quickly.
Creek flooding map example
Creek flooding map example
River flooding
River flooding happens when widespread, prolonged rain falls over the catchment of a river. As the river channel reaches capacity, excess water flows over its banks causing flooding. River flooding downstream can occur hours or days after the rainfall has finished. River flooding may coincide or exacerbate flooding in adjacent creeks and tributaries and may itself be exacerbated by higher than normal high tide conditions. Unlike creek or overland flow flooding, floodwater may rise very slowly and be slow-moving. It usually occurs after prolonged periods of heavy rain across the whole catchment.
River flooding map example
River flooding map example
Overland flow flooding
Overland flow is run-off that travels over the land during heavy rainfall events.
Overland flow can be unpredictable because it is affected by localised rainfall and urban features such as stormwater pipes, roads, fences, walls and other structures. The actual depth and impact of overland flow varies depending on local conditions, but it generally occurs quickly and for short durations. It is a common occurrence during Brisbane's summer storm season.
Overland flow map example and diagram
Overland flow map example and diagram
Storm tide/high tide flooding
Storm tide flooding happens when a storm surge creates higher than normal sea levels. A storm surge is caused when a low-pressure system or strong onshore winds force sea levels to rise above normal levels. The impact of a storm tide or storm surge is increased during high tides and king tides and can affect low-lying areas close to tidal waterways and foreshores.
Tidal flooding is the temporary inundation of low-lying areas and streets during high tide events, such as at full and new moons. The highest tides of the year may be known as king tides. Areas connected to the foreshore and tide-affected areas of the river, tidal creeks and other waterways are susceptible.
Find out more about tides in Brisbane.
Storm tide flooding map example
Storm tide flooding map example
