Flooding has the potential to cause considerable damage and disruption to a community. In addition to tangible damage, floods also impose high levels of intangible damage such as increased levels of stress on affected communities. Council is undertaking this study to consider a range of options and measures to manage the flood risk.

Council is investigating and managing the natural flooding caused by significant catchment rainfall resulting in overland flow.

Flooding occurs when runoff after rain exceeds the capacity of the drainage system including the creeks, built pipes and channels. Local overland flows during heavy rains which take the ‘path of least resistance’ on the way to drains or watercourses can also cause localised flooding. Urbanisation and an increasing number of hard surfaces have impacted flow because they reduce ground absorption of rainfall and cause run-off to reach catchments faster than before areas were developed. Urbanisation can also lead to a redirection of these natural overland flowpaths.

The dominant cause of creek and overland flooding is intense rainfall, while foreshore flooding from the Harbour and the Pacific Ocean can be driven by elevated ocean conditions (tide and storm surge), and local wind waves. This study will focus on flooding of creeks and overland flow paths caused by heavy rainfall, and will consider the influence of downstream water levels in the Harbour and the Pacific Ocean on this local catchment flooding.

A Floodplain Risk Management Study utilises the information from the preceding Flood Study to identify, assess and compare various flood risk management options and consider opportunities for environmental enhancements as part of flood mitigation works.

The management study provides information and tools to allow strategic assessment of the impacts of management options for existing, future and continuing flood risk on flood behaviour and hazard. It also allows for a robust assessment of the social, economic, environmental and cultural issues and costs and benefits of all options.

A Floodplain Risk Management Plan is the key outcome of the preceding Floodplain Risk Management Study. The Floodplain Risk Management Plan offers preferred options to mitigate flood risk within a study area; balancing the social, economic, environmental and cultural interests in the floodplain with the resultant flood hazard. 

In NSW, the roles and responsibilities for the management of flood prone land are stated in the NSW Government’s 2005 Floodplain Development Manual. These are shared across Council and the state government including some of their agencies. Roles for each are listed below:

Council's roles and responsibilities include:

• preparation of Floodplain Risk Management Plans
• flood education
• emergency response and public infrastructure
• post flood data collection and reviews
• preparation of Local Environment Plans (LEPs) and Development Control Plans (DCPs)
• local development under Part 4 of the EP&A Act including exempt development; complying development; and development requiring consent
• planning certificates
• asset management.

Through relevant government bodies such as the Department of Planning, Industry and Environment (DPIE), the state government's roles and responsibilities include:

• support of policy through legislation
• definition of broad policy objections
• provision of technical advice
• provision of financial assistance
• provision of emergency management including recovery, collection and reviews.

The State Emergency Service acts as the lead agency for coordinating evacuation and welfare during flood events.

If it is a life threatening situation call 000.

In the event of floods, storms or tsunamis, please contact the State Emergency Service (SES) on 132 500 or visit their website at www.ses.nsw.gov.au.

The State Emergency Service has a useful website providing advice on how to manage flood risk. Visit www.floodsafe.com.au for more information.

Flood related development controls can be found in the Manly Local Environment Plan (Clause 6.3) and the Manly Development Control Plan (Clause 5.4.3), which can be viewed at https://www.northernbeaches.nsw.gov.au/planning-an...

To check if, or the part of your property that is affected by flood related development controls, go to: https://services.northernbeaches.nsw.gov.au/icongis/index.html, search your address and turn on the NBC Flood Hazard Map at the bottom of the Overlay Maps drop-down box.