What is the purpose of the Floodplain Risk Management Study?

During periods of heavy rainfall across the Woy Woy Peninsula, there is potential for water to overwhelm the stormwater drainage system and/or overtop the banks of creeks and drainage canals and inundate adjoining properties. Following the completion of the flood study in 2010, Central Coast Council has been seeking financial assistance to prepare a Floodplain Risk Management Plan. Council secured funding from the NSW Floodplain Grants Program.

The floodplain risk management study aims to identify, assess and compare various risk management options. Through the study, a strategic assessment considers social, ecological and economic factors relating to flood risk.

One of the most important sources for floodplain risk management studies is community input as many residents would have lived through past flood events. These views will be integrated to the decision making process in the flood management plan, seen in the chart below.

For more information about the process used to manage flood liable land, a copy of the floodplain development manual developed by the NSW government may be viewed by clicking here

flood-risk-management-process-diagram_v2

What is overland flooding?

 

Overland flooding is caused by excess rainfall runoff which flows across the land before it enters a creek or stream. A combination of factors lead to excess rainfall runoff including:

  • Inadequate drainage

  • A build-up of impervious surfaces overtime (such as concrete surfaces)

  • The ability of the ground to absorb water

 

Overland flow flooding tends to affect localised areas rather than the whole city at once.

What are the past flood events which have affected the Woy Woy Peninsula?

Flooding has been experienced across the Peninsula on a number of occasions. Significant flooding events identified by the community included: August 1972; May 1974; March 1986;  April 1988; February 1990; March 1991; February 1992;  May 1998; April 1999 and June 2007.

Who is the project being supported by?

The Woy Woy Peninsula Floodplain Risk Management Study and Plan is jointly supported by Central Coast Council and the NSW Government under the flood management grant scheme. Assistance provided under the program is usually $2 from the NSW government for every $1 provided by the applicant (Council).

What is a 1 in 100 year flood event?

A 1 in 100 year flood event is a statistical event occurring on average once every 100 years. That is, there is a 1% chance of a flood of this size or greater occurring in any given year. This type of flood event is generally used to limit flood exposure and damage to standard residential development. This event is also referred to as a 1% AEP Event.