BOM flood warnings
The Bureau of Meteorology (BOM) issues severe weather warnings for all areas of the state and flood warnings for some rivers.
BOM issues the following flood warnings.
A Flood Watch notifies the community in specific regions of a potential flood threat from a developing weather situation. It is generally issued 24-36 hours before any likely flooding to give the public a heads up that flooding is possible. If a Flood Watch is issued and you are living, camping or working along rivers or streams, you should regularly check weather forecasts, rainfall totals and river levels and be ready to take action.
A Flood Warning is issued when flooding is about to or is already occurring for the Gawler, Torrens and Onkaparinga rivers. BOM predicts the flood size (minor, moderate or major) and estimates the time that the river height will reach certain river gauges. When flood warnings are issued, people in low-lying areas prone to flooding need to activate their flood emergency plan immediately.
Severe weather warning
A Severe Weather Warning is issued when heavy rainfall and flash flooding is expected.
River flood terms
BOM uses the following flood warnings terms. It is important to know what they mean.
When a Minor Flood Warning is issued, the following may be expected:
- water levels reach the top of the river banks
- low lying areas along the waterway are inundated by flood water
- minor roads may be closed and low level bridges submerged
- livestock and equipment along the waterways are moved to higher ground.
In addition to the above, the following may be expected when a Moderate Flood Warning is issued:
- water levels overtop river banks and inundate low lying areas
- flood water starts to approach buildings and infrastructure
- some properties may be inundated by rising flood water, requiring evacuation
- caravan parks on waterways may be inundated
- main traffic routes may be closed by flood water.
In addition to all of the above, the following may be expected when a Major Flood Warning is issued:
- water levels overtop river banks and cause extensive inundation on the floodplain
- farmland is inundated, stock and equipment losses may occur
- residential and commercial properties are inundated
- properties and towns may be isolated
- major traffic routes may be closed
- evacuations may be required.
Used where intense rainfall could be expected to cause high runoff in limited areas local to the rainfall, but not necessarily leading to significant rises in main streams.
Flooding occurring in less than 6 hours of rain, usually the result of intense local rain and characterised by rapid rises in water levels. They are difficult to predict accurately and give little time for effective preventive action.
Terms for river heights
Flood warnings also refer to terms for river heights that include:
Peak: the highest height at which the river is expected to rise to
Reach: the height a river is expected to rise to at a certain time. There may be further rises above this height in the future
Exceed: A height the river is expected to rise to at a certain time and then rise further above this height.
Access BOM flood warnings
Warnings are issued on the BOM website, televised weather reports and on radio updates.
From the South Australian Weather and Warnings page - www.bom.gov.au/sa/ follow the links (when activated) to:
Use the recorded message phone weather warning service for SA on 1300 659 215 (charges apply).