Flood level enquiries

A guide to obtaining computer generated flood levels on a valley-wide basis.

Flood level enquiries

Council is able to provide approximate flood level heights and/or depths for following design flood events:

Average Exceedance Probability (AEP) Comments Average Recurrence Interval (ARI)
20% A hypothetical flood or combination of floods with a 20% chance of occurring in any given year. 1 in 5 year
5% A hypothetical flood or combination of floods with a 5% chance of occurring in any given year. 1 in 20 year
2% A hypothetical flood or combination of floods with a 2% chance of occurring in any given year. 1 in 50 year
1% A hypothetical flood or combination of floods with a 1% chance of occurring in any given year. 1 in 100 year
Extreme/PMF flood events A hypothetical flood or combination of floods which represent an extreme scenario. >1 in 1000 year flood

Flood heights are given as metres Australian Height Datum (AHD) and flood depths refer to actual water depth in metres over the subject property. AHD is the single reference point adopted by the National Mapping council of Australia to relate all vertical measurements throughout Australia and is based on Mean Sea Level.

To obtain approximate flood height levels and/or depths visit Council’s Online Mapping and follow the step-by-step instructions here. This mapping is based on computer generated flood levels on a valley-wide basis. Actual floods behave differently on each occasion due to variability of rainfall and other factors. It is not possible to accurately predict exact future flood levels for any location and the level given is indicative only.

Please note that while these maps can indicate depth of flooding they do not include floor levels of your building/s. Before making any decision to purchase, sell or do anything on, at or to that property and to determine the depth of flood water over the subject property you should engage a qualified consultant and/or surveyor to assess how a flood level affects your property. Whilst every effort has been made to ensure the accuracy of the flood information, Council accepts no responsibility for any errors or omissions.

Flood Planning Levels and Floor Heights

Minimum Habitable Floor Level for Dwelling Houses

Locality Habitable Floor Level
North Grafton 6.4m* AHD
SouthGrafton 7.1m* AHD
Heber Street Catchment (map of this area on page 55 of Council’s Residential Zone Development Control Plan) 8.0m* AHD
Remaining Clarence Floodplain (Mountain View to Iluka/Yamba) 500mm above 1% flood level contours as detailed on Council’s Online Maps
Glenreagh 500mm above 1% flood level contours as detailed on Council’s Online Maps
Wooli 500mm above 1% flood level contours on page 191 of Council’s Residential Zone Development Control Plan.
Copmanhurst 23.2m AHD
Other Flood Prone Areas Assessed by Council’s Building Surveyor

*These levels are based on historical flood records. The latest BMT-WBM ‘Lower Clarence Flood Model Update 2013’ study indicated that these levels are not always above the 1% flood level plus 500mm. Council recommend the applicant proceed with the proposed floor level at the higher level. A review of the flood planning levels for Grafton/South Grafton is in the Operational Plan for 2017/18.

Floor heights - Records Search

Council has the floor level for some properties in Records if the information was previously submitted with a Development Application. In order to access the relevant records on file, an “GIPA Informal Request For Access” form needs to completed and submitted to Council’s front counter or council@clarence.nsw.gov.au. If available, the requested information will then be available for viewing at one of Council’s main offices at Grafton and Maclean or can be emailed to the Applicant. There is no fee for information provided by email, fees apply for copying or printing.

Other flood information sources

Historical information from previous floods may be available by contacting the NSW State Emergency Service (SES) Regional Office at Induna Street, South Grafton, telephone 6641 6900. Nearby property owners may also have some knowledge of previous flood levels on their property.

 

Other Websites