What is the study area included in the catchment?

    The Lurline Bay, Matraville, Malabar and Yarra Bay Catchment covers an area of 9.6 km2 and includes parts of the suburbs of South Coogee, Malabar, Matraville, Chifley, Phillip Bay, Little Bay and La Perouse. 

    Why does Council study flooding?

    Councils are required to follow the NSW Flood Prone Land Policy, which outlines how Councils should manage flooding to reduce the risk to people and properties.

    What are Councils doing to manage flood risk?

    Councils prepare Flood Studies and Risk Management Plans according to the NSW Government's Floodplain Development Manual (2005). The recommendations are to be implemented with the technical and financial assistance of NSW Government and key stakeholders through the Flood Prone Land Policy.

    How are flood affected properties identified?

    Council’s flood modelling determines the extent of flooding throughout the catchment and the identification of properties partially or fully impacted by flooding. When Council is in possession of reliable information regarding flooding, it is obliged to provide that information when asked. This consultation is one way for Council to advise affected property owners and residents of flood affectation. Council is also required to notate S10.7 Planning Certificates for properties that are identified as flood prone.

    What is the Flood Planning Area?

    The flood planning area is the area within which developments may be conditioned with flood related development controls. The flood planning area is calculated as the area below the Flood Planning Level.

    What is the Flood Planning Level?

    The Flood Planning Level (FPL) is a height used to set floor levels for property development in flood prone areas. It is generally defined as the 1% AEP flood level plus an appropriate freeboard (see explanation of ‘freeboard’ below). This level may be higher for vulnerable land uses (e.g. hospitals or schools).

    What is a Freeboard?

    A freeboard is a height above the 1% AEP flood level that is included in the Flood Planning Level to account for factors such as wind, waves, unforeseen blockages and other localised hydraulic effects. Freeboard is usually 0.5m above a flood level.

    What is a “1 in 100 year” flood?

    A 1 in 100 year flood is a flood event that has the probability of occurring on average once every 100 years, i.e. there is a 1% chance of a flood of this size occurring at a particular location in any given year. This does not mean that if a location floods one year that it will not flood for the next 99 years. Nor, if it has not flooded for 99 years that it will necessarily flood the next year. Some parts of Australia have experienced more than one ‘1 in 100 year’ floods within a decade of each other.

    What is the Probable Maximum Flood?

    The Probable Maximum Flood (PMF) combines a range of extreme conditions and probabilities to calculate the largest flood that could possibly occur within a catchment. It is extremely rare and is calculated to aid in the design of critical facilities such as hospitals, nursing homes, schools and emergency service facilities. 

    Have impacts from future changes in climate been included in existing flood levels?

    Climate change has been considered. Rainfall data is used to develop the flood study model. The model will be reviewed periodically as changes occur to rainfall patterns and guidelines are established. Sea level rise causes very little impact on flood levels within this catchment.

    What is the difference between a Flood Study and a Floodplain Risk Management Plan?

    Flood Studies identify flood behaviour including the areas flooded, water depth, hazard categories and the likelihood of flooding within the catchment. Floodplain Risk Management Studies and Plans assess potential management approaches to reduce the impact of flooding (e.g. drainage upgrades, development controls, community awareness and emergency response arrangements).

    What should I do in the event of a flood?

    If the situation is life threatening you should call 000. For other assistance during an emergency such as flood, storm or tsunami, please contact the NSW State Emergency Service (SES) on 132 500 or visit their website at www.ses.nsw.gov.au.

    It is best to be prepared for any flood. The State Emergency Service provides advice on how to manage your flood risk at https://www.ses.nsw.gov.au/floodsafe/what-floodsafe-means-for-you/floodsafe-for-urban-areas/