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Sustainable Flood Management

Council is committed to protecting our city against flooding. Flood mitigation plays an important role in our city's long term sustainability and safety.

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Potential flood risks on the Gold Coast

The Gold Coast is subject to existing, future and residual flood risks and has experienced more than 45 floods since 1925. Past flood events caused moderate to extensive damage to private property, community buildings, bridges and roads.

Since 1970’s the City of Gold Coast has been monitoring and mapping flood extent to support community resilience to flood risk.

Flood maps

The City recognises that residents are interested in potential flood inundation of their property.

Flood overlay maps identify properties where future development will need to meet the provisions of the Flood overlay code.

The City Plan Interactive Mapping tool is designed to address the statutory needs of local government with respect to development assessment by identifying hazard areas that are subject to flood, and act as a trigger for development assessment.

Flood overlay maps reflect the impact of a one in 100 year ARI (Average Recurrence Interval) rainfall.

The City has recently updated existing flood overlay mapping which will commence as part of City Plan Version 6 on 20 September 2018.

The updated mapping considers future changes to climate, incorporating the projected increase in sea level of 0.8m above present day levels by 2100 established by the State Government in 2015. The updated mapping also includes the State Governments projected 10 per cent storm tide intensity and 10 per cent rainfall intensity, based on advice from industry representatives.

Find out more about the updated mapping and provide feedback.

Find Frequently Asked Questions below.

Flood level search

A flood search system is in place to provide detailed peak flood levels which can then be compared with the resident's information about their property. It is recommended that a licensed surveyor be engaged to accurately determine property and floor levels.

Obtain a flood search report

The outcome of a flood search is the Designated Flood Level, which is reported in metres AHD (Australian Height Datum), the nationally adopted datum or standard to which all elevation for mapping is to be referred. As a general guide, 0.0 metres AHD is close to the mean sea level. Therefore 1.5 metres AHD is approximately equivalent to 1.5 metres above Mean Sea Level. It is to be noted that tide information is not on this datum.

The Designated Flood Levels are used as the basis for determining floor levels for specific service facilities, general utilities and residential properties.

To enhance future safety for residents, the City requires that habitable floor levels are a minimum of 300 millimetres above the designated flood level.

Flood search results are associated with riverine or regional flooding only, not local flooding. Regional flooding is caused by long duration rainfall over a whole catchment or number of catchments. Local flooding is caused by high intensity and short duration rainfall over a local drainage catchment.

A flood the size of a 100 year ARI has one chance in 100 (one per cent) of occurring in any one year. However, the rainfall events which cause floods are random and there is no guarantee when such a flood will occur, that it won't be much larger, or that it will only occur once in any year.

Download an example of a flood search report.

How do I request a flood search report?

Complete and submit the Search request form below.

An administrative fee applies for undertaking the search and forwarding the results. Fees can be found in the Register of fees and charges.

Please visit our Lodging a search request page for more information about options available for lodgement and payment of search requests.

History

The former Albert Shire and Gold Coast Councils used to provide flood levels collected during past flood events for properties if records were available at or nearby the property. In 1996, historical flood levels in the Nerang River system downstream of the Pacific Highway were substituted with computer generated flood levels from the then Department of Primary Industries for the 100 year ARI flood event.

After the amalgamation of the two local authorities, initiatives were taken to streamline the flood search process and provide peak flood levels derived from computer-based hydraulic modelling.

In 1999, the flood search system was created, which combined both computer modelled data and historical data. The result is a standardised citywide flood level database which is updated periodically.

If your property level is below the Designated Flood Level, your property may be affected by a 100 year ARI flood. If your property is above the Designated Flood Level, your property may not be affected.

Diagram of houses and flood levels

Designated Flood level - Surveyed Floor level = Depth of flooding

Further information

For further information, contact us.

Related information

Jump to key information
  • What is flooding in the City Plan?

    Flooding is generally understood as the inundation of land from rivers breaking their banks usually the result of rainfall. Elevated sea levels and extreme tides because of storms can also result in land being inundated by water.

    The City of Gold Coast’s flood overlay maps only show the impacts of these types of inundation. Rainfall that cannot be drained away quickly enough or flows over the surface of the land (overland flow path) to waterway or drainage systems can also result in inundation, but this has not been reflected in the City Plan Flood Overlay Map.

  • What is flood overlay mapping?

    Flood overlay mapping identifies which properties may be affected by a designated flood event and acts as a trigger for development assessment.

    The maps reflect the impact of a rain event that has 1 per cent chance of occurrence in any given year (1 per cent AEP) coinciding with a storm-tide for the majority of areas. These maps by themselves do not show flood risk in its totality with areas outside of the flood map not necessarily immune from flooding. Infrequent or local floods can affect any property.

  • How do I obtain flood levels?

    The City Plan online interactive mapping tool has been updated to include flood planning levels and flood depths for land in the current City Plan Flood overlay maps. You can also apply to City of Gold Coast for a formal Flood Search Report.

  • I was affected by the recent flood but my property is not shown as being affected on the new mapping?

    1. City Plan flood maps are based on a rain event that has 1 per cent change of occurrence in a given year. There is always a possibility of having rarer rainfalls that may overwhelm our protection measures.
    2. There may be small creeks on higher grounds that are not fully included in our models yet. These creeks may experience flash flooding, causing short term overland flooding.
    3. Blockages to drainage systems and restrictions to the flow of water in waterways can result in flooding.
    4. A property may be on an overland flow path which is yet to be included in the City Plan Flood Overlay Map.
  • Was the recent flood event comparable to the defined flood event as shown on the City Plan maps?

    In relation to the most recent flooding on the Gold Coast (Cyclone Debbie, March 2017), in limited areas the flood level was close to or higher than the flood planning level reflected in the City Plan. In the majority of areas it was below the flood planning level.

  • My property is within the new flood map. Will this affect insurance premiums?

    Insurance companies use various means to determine flood risk for individual properties. Some companies may have developed their own flood information while others may seek information from the applicant, which may include the results of a flood search.

    The new flood overlay map identifies the extent of flooding that can occur across the city having regard to climate conditions up to and include the year 2100. Developments that are built above Designated Flood Levels can include measures to reduce the potential for flooding to damage property. Council cannot predict or influence how commercial insurance companies will use this information in setting flood insurance premiums. The information provided by Council aids property owners in decisions to manage their flood risk.

  • I want to do a development and my property has triggered the flood overlay map. What does this mean?

    If your development application is on land that is within the flood overlay map, you will need to undertake further assessment by reviewing the necessary provisions in the flood overlay code.

  • Why have flood levels changed?

    The maps were developed utilising a more robust software platform, up-to-date flood related topographic, land use, technological and hydrological data.

    The updated mapping considers:

    • Future changes to climate, incorporating the projected increase in sea level of 0.8m above present day levels by 2100 established by the State Government in 2015.
    • State Government projected 10 per cent increase in storm tide intensity by year 2100. Storm tide intensity is an indicator of the power of the cyclone.
    • An increase of 10 per cent in rainfall intensity, based on advice from industry representatives. Rainfall intensity is the measure of the amount of rain that falls within a unit of time.
    • Vast areas of the city were void of flood information in the past due to lack of predictive models or historical information. The City is now in possession of new models that cover large sections of the city. Therefore, there are properties that did not have any flood information in the past and now they have relevant flood information to the property, as reflected in the City Plan Flood overlay map.
    • Council’s old flood map was informed solely by historical flood data for some areas. This data reflected a flood level with an unknown return period. We now model for these areas and have generated flood levels that have 1 per cent chance of occurrence in any given year. As a result flood information for some properties is now more accurate.
  • Why is my property highlighted on the map now?

    Change in policies, increased accuracy due to enhanced data, inputs and technological advances and an increase in the extent of the models has resulted in a change to the flood overlay mapping. Some areas within the city have been removed from flood overlay mapping while other areas have now been included.

  • How do I know if my property is on the flood map?

    The City Plan interactive mapping tool provides a flood overlay option that indicates whether a property is flood affected.

  • What is the difference between local, riverine and regional flooding?

    Local flooding: An intense burst of rainfall over a short period of time may cause excessive run-off that builds up in a confined area and causes localised flooding. Inundation is expected to last only for a limited period of time until the run-off is able to drain away.

    Regional flooding: Continuous heavy rainfall across a number of river catchments is likely to cause inundation across an extensive area. It may take a number of days for these floodwaters to subside.

    Riverine flooding: Riverine flooding occurs when excessive rainfall over an extended period of time causes a river to exceed its capacity, flood water spill over the river banks and inundate the river floodplain.

    During both riverine and regional floods, areas which normally experience local flooding are also likely to experience higher flood levels compared to those recorded in the main drainage paths such as creeks, canals, lakes and rivers.

  • What is a flood search report?

    A flood search system is in place to provide Designated Flood Levels which can then be compared with the resident's information about their property. It is recommended that a licensed surveyor be engaged to accurately determine property and floor levels.

    Please note, flood levels provided through flood search reports reflect a rainfall that has 1 per cent chance of occurrence in a given year (Designated Flood Level) for most areas of the city. Rarer flood level will be higher than the report flood level through the flood search system.

  • Do I need a flood search report?

    A flood search report should be obtained from Council when development is proposed on land in the flood overlay maps. Should you require further information regarding a flood search report please contact the City of Gold Coast on (07) 5582 8809.

  • Is there a fee associated with a flood search?

    All searches undertaken by the City of Gold Coast attract a fee for processing. Refer to the Register of fees and charges for the current fee for flood level information. The written report may prove valuable when purchasing a property, building a home or when applying for flood insurance. (The fee excludes the cost of collecting the data and producing the computer flood models.)

  • Does City of Gold Coast produce general flood maps for residents to view?

    The City Plan interactive mapping tool has been updated to include flood planning levels and flood depths for land in the current City Plan flood overlay maps.

    A formal flood search system is also in place to provide Designated Flood Level (in AHD - Australian standard unit of elevation) which can then be compared with the resident's information about their property. It is recommended that a licensed surveyor be engaged to accurately determine property and floor levels.

    As shown in the diagram, some parts of the property may be below the Designated Flood Level and therefore may be inundated during a 100 year ARI flood event.

  • What is AHD?

    AHD refers to Australian Height Datum. This is the standard elevation reference for mapping purposes adopted by the National Mapping Council of Australia. As a general guide, 0.0m AHD is approximately equal to mean sea level.

  • What are the one in 100 year ARI and 1 per cent AEP?

    They are the same thing. They reflect a flood generated by a rainfall that has 1 per cent chance of occurrence in any given year.

  • What are flood planning levels?

    Flood planning levels are obtained from the Council’s flood search system. Properties should be built above flood planning levels. Designated Flood Level is a reflection of the impact of a rainfall with 1 per cent probability of occurrence in any year for most areas of the city.

  • Is the 1 per cent AEP the largest flood we are likely to experience?

    No. It is possible that floods of a much greater magnitude could occur.

    The one in 100 year ARI flood or 1 per cent event is the minimum standard used by City of Gold Coast in determining the Designated Flood Level for habitable floors. The Designated Flood Level is applied when assessing development applications to ensure that habitable rooms in homes are built to a certain minimum level.

    Many other councils throughout Australia have also adopted the 100 year ARI flood event for the same purpose.

  • Does City of Gold Coast allow for future development in its floodplain planning?

    Yes, but in a controlled way as articulated in the City’s flood code. The main aim of this control is to ensure that development in a flood plain does not cause any adverse flood impact on any other properties, on the city as a whole and on the City's capacity to exercise its responsibilities with respect to flood emergency management.

  • What are flood models?

    Flood models are used to inform and refine the flood map. A flood model is a computer simulation of a river or floodplain system to determine the magnitude, extent and depth of flooding; how fast floodwaters rise; and the implications for flood damage and emergency planning.

  • Can I get insurance against flood damage?

    Yes, some insurance companies offer flood insurance either as part of their home and contents policies or as an optional extra. Check your policy or speak with your insurance company to determine whether you are covered and 'exclusions' apply.

    The Insurance Council of Australia has produced a brochure 'Flood Insurance: Are You Covered?' that can be downloaded form their website www.ica.com.au.

  • Does the City of Gold Coast provide advice to insurance companies about flood risk to individual properties or areas?

    Insurance companies have their own means of determining flood risk for individual properties. Some companies have developed their own flood information while others seek information from the applicant, which may include the results of a flood search.

    Individuals can lodge an application for a flood search for a specific property with the City for an administrative fee. Current fees for flood level information can be found in the City's Register of fees and charges.

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