Before a flood occurs, it is important to be aware of flood warnings which might be issued before and during a flood. In South Australia there are a number of different types of warnings issued by different agencies. These include warnings from the Bureau of Meteorology, the Department for Environment and Water (DEW), the State Emergency Service and Alert SA.
Bureau of Meteorology
The Bureau of Meteorology provides warnings for severe weather for all areas of the state and flood warnings for some rivers. Warning types are:
- Flood Watch
- Flood Warning for the Gawler, Torrens and Onkaparinga Rivers
- Severe Weather Warning (which can include advice for heavy rainfall and flash flooding)
- Severe Thunderstorm Warning
The Bureau of Meteorology is currently developing flood warning services for the Angas and Bremer Rivers catchment, and the Light and Wakefield Rivers catchment.
Flood warnings for the Gawler, Torrens and Onkaparinga River catchments identify the likely timing, location and severity of flooding and are issued as ‘minor’, ‘moderate’ and ‘major’ flood warnings, as described below (from the Bureau of Meteorology):
Minor flooding: Causes inconvenience. Low-lying areas next to watercourses are inundated which may require the removal of stock and equipment. Minor roads may be closed and low-level bridges submerged.
Moderate flooding: In addition to the above, the evacuation of some houses may be required. Main traffic routes may be covered. The area of inundation is substantial in rural areas requiring the removal of stock.
Major flooding: In addition to the above, extensive rural areas and/or urban areas are inundated. Properties and towns are likely to be isolated and major traffic routes likely to be closed. Evacuation of people from flood affected areas may be required.
These warnings are issued on the Bureau of Meteorology website, televised weather reports and on radio updates.
More Information about these services and warnings can be found at the Bureau of Meteorology website:
http://www.bom.gov.au/australia/flood/otherlinks.shtml
The Department for Environment and Water
The Department for Environment and Water (DEW) issues Flow Advice, High Flow Advice and Flood Warning Advice for the River Murray within South Australia. The corresponding flow rate and type of warning issued is shown in the table below:
| Flow at Border | SA River Murray | Shack Areas only downstream of Cadell
(Excluding River Murray towns) |
| 200,001 ML/day or more | Major Flood | Major Flood |
| 130,001 to 200,000 ML/day | Moderate Flood | Moderate Flood |
| 100,001 to 130,000 ML/day | Minor Flood | Minor Flood |
| 60,001 to100,000 ML/day | High Flow | Minor Flood |
| 40,001 to 60,000 ML/day | High Flow |
| 40,000 ML/day or below | Normal Flow Range, no warnings |
These warnings are issued on a weekly basis or more frequently as necessary on the Water Connect website, radio or television.
High Flow Advice is issued when the river water levels exceeds 40,000 ML/day downstream of the South Australian border. High Flow Advice provides information about the potential hazards to river users of high flows in the River Murray.
Flood Warning Advice is issued when water flows in the River Murray downstream of the South Australian border are expected to exceed 100,000ML/day, or 60 000 ML/d for shack areas. These warnings are classified as minor, moderate and major and provide advice on the likely impacts and advised action to take for each flood level.
In the River Murray system, water takes a long time to travel from the upstream states to the Lower Murray in South Australia. Due to this, there is often a long time available to issues flood warnings in South Australia. Warnings for major floods can be issued up to a month in advance. While floods of this magnitude are too large to be mitigated by locks and weirs, early warnings can assist in communities preparing for a flood event and can help to lessen impacts.
State Emergency Service (SES)
The SES can issue flood advice and warnings. The SES can also re-issue advice and warnings produced by other agencies such as the Bureau of Meteorology and DEW.
The SES may choose to issue a flood advice or warning via Emergency Alert. Emergency Alert is a national telephone warning system which sends voice messages to landline telephones and text messages to mobile telephones. Emergency Alert is not used in all circumstances, so you should use a range of information to stay aware of local conditions.
For more information on the Emergency Alert system visit: emergencyalert.gov.au
Alert SA
The Alert SA website brings together social media messages from South Australia's emergency services and the Bureau of Meteorology via Twitter, Facebook and RSS in one place.
The AlertSA website is:
http://alert.sa.gov.au/
Other types of messages
Messages are increasingly being issued other means such as, via social media, Twitter and Facebook. Messages may be through informal channels from person to person or sites may be set up spontaneously during a disaster. Increasingly, emergency services are utilising this way of communication and establishing sites on social media before an event. Social media can provide an accurate and rapid way to transmit information on impacts occurring, although is not always provided by an authorised source and may be second or third hand information, subsequently it may be worth checking the source of information to ensure accuracy.
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