How flooding occurs on the Central Coast
Coastal Flooding Infographic (click to zoom)
Coastal Flooding
Overland flooding
River and creek flooding
Flooding in built up urban environments
To understand the potential impacts of flooding on your property, use our online flood risk tools.
Flooding comes in different types, sizes and durations:
1) Catchment flooding
Catchment flooding occurs from prolonged or intense rainfall (e.g. severe storms and East Coast Lows) that can lead to:
- Breaking the banks of creeks and rivers - Hawkesbury River, Erina Creek, Narara Creek, Ourimbah Creek, Wyong River, and many others.
- Filling coastal lakes and lagoons - Tuggerah Lakes, Wamberal lagoon, Terrigal Lagoon, Avoca Lake, Cockrone Lagoon, Pearl Beach Lagoon.
- Water flowing across normally dry land in both urban and rural areas on its way to waterways, due to the inability for the ground to absorb additional water.
2) Coastal flooding
Coastal flooding normally occurs when dry and low-lying land is submerged by seawater, often caused by tidal or storm-driven coastal events, including storm surge and wind-induced waves in coastal waterways.
Areas on the Central Coast that can be impacted by coastal flooding include:
- Brisbane Water and the lower reaches of Narara Creek and Erina Creek
- Coastline foreshores areas
3) Combination flooding
Catchment and coastal flooding can occur simultaneously. The impacts will vary depending on factors such as catchment characteristics and the specifics of the weather event.
4) Flash Flooding
Flash flooding is caused by sudden local or nearby heavy rainfall generally peaks within six hours of the onset of rain.
Flood duration
Areas that are affected by coastal flooding, such as foreshore communities in Brisbane Water, may experience flooding which can typically last only 2 hours associated with a high tide.
Land adjacent to creeks and rivers can be flooded for a day or more; foreshore land around Tuggerah Lakes can be flooded for up to four days.
Normal and Flooded Lake Infographics (click to zoom)
Flooded lake
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Australian Warning System (floods)
The NSW State Emergency Service uses the Australian Warning System for flood warnings.
The Australian Warning System is a national approach to information and warnings during emergencies like bushfire, flood, storm, extreme heat and severe weather. The System uses a nationally consistent set of icons, like those below, designed to make warnings clearer and lead people to take action ahead of severe weather events.
- ADVICE (yellow): An incident has started. Stay up to date in case the situation changes.
- WATCH AND ACT (orange): Conditions are changing and you need to start taking action now to protect you and your family.
- EMERGENCY WARNING (red): The highest level of warning. You may be in danger and need to take action immediately.
Australian Flood Warning Levels
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Bureau of Meteorology Flood Warning Service
The Bureau of Meteorology provides flood forecasting and warning services for most major rivers in Australia.
The Bureau issues a Flood Watch to provide early advice of a developing situation that may lead to flooding. A Flood Watch is not a warning of imminent flooding. A Flood Watch provides information about a developing weather situation including forecast rainfall totals, catchments at risk of flooding, and indicative severity where required. Although there is uncertainty attached to a Flood Watch, its early dissemination can help individuals and communities to be better prepared should flooding eventuate.
Flood Warnings are issued by the Bureau to advise that flooding is occurring or expected to occur in a geographical area based on defined criteria.
Flood Classifications: The Bureau uses a three-tiered classification scheme that defines flooding as minor, moderate or major at key river height stations. Each classification is defined by the water level that causes certain impacts upstream and downstream of the station. These levels have been determined based on standard descriptions of flood effects (see below), historical data and relevant local information