Know the warnings
The Bureau of Meteorology and the SES use different flood terms in their alerts and updates. It is important to know what each term means, how they are related and what you need to do in each situation according to the risk of flooding and your flood plan.
The Bureau of Meteorology (BOM) classifies riverine flooding into three classes – minor, moderate and major – based on its potential severity and impact on communities.
Minor Flooding
Minor Flooding causes inconvenience. Low-lying areas next to water courses, including some backyards, buildings below floor level, and bicycle and pedestrian paths, are inundated. Minor roads may be closed, and low-level bridges may be submerged. In rural areas, removal of stock and equipment may be required.
Moderate Flooding
Moderate Flooding can affect main traffic routes, buildings above the floor level, and the areas listed above. With the area of inundation more substantial, evacuation of flood-affected areas may be required, as is the removal of stock in rural locations.
Major Flooding
Major Flooding can affect buildings above the floor level, causing properties and towns to be isolated and major rail and traffic routes to be closed. In addition to moderate flooding, extensive rural and/or urban areas are inundated, requiring possible evacuation of flood-affected areas. Utility services may also be impacted.
For Lismore, the BOM may issue warnings for the Wilsons River such as:
- Flood levels: Minor: 4.20 Moderate: 7.20 Major: 9.70 (Wilsons River at Lismore AHD gauge).
Once the BOM’s classification has been issued, the NSW SES follows the Australian Warning System (AWS) to issue one of three warnings – advice, watch and act, or emergency – based on expected consequences and the actions the community should take.
The level of threat posed to the community determines the level of warning.
Advice (Yellow)
An incident has started. There is no immediate danger. Stay up to date in case the situation changes.
Watch and Act (Orange)
There is a heightened level of threat. Conditions are changing and you need to start taking action now to protect you and your family.
Emergency Warning (Red)
This is the highest level of warning. You may be in danger and need to take action immediately. Any delay now puts your life at risk.