Flood studies and projects
Flood projects Property flood reports Flood risk management
Flood studies provide detailed information for policy making, planning and development.
Studies are produced in line with the NSW Government's guidelines and have been publicly exhibited and adopted by Council.
Floodplain risk management - studies and plans
South Murwillumbah Floodplain Risk Management Study and Plan (2019)
Tweed Valley Flood Study (2009)
A study into the flood behaviour of the Tweed River and its major tributaries, from Boat Harbour and Byangum upstream of Murwillumbah to the river mouth at Tweed Heads.
The study area includes Murwillumbah, Condong, Tumbulgum, Chinderah, Kingscliff, Fingal Head, Banora Point, Tweed Heads, Tweed Heads South and Tweed Heads West.
The addendum provides scenarios for potential impacts of climate change (sea level rise and increased rainfall intensity).
Tweed Valley Flood Study 2009(PDF, 6MB)
Tweed Valley Flood Study 2009 - Climate Change(PDF, 3MB)
Tweed-Byron Coastal Creeks Flood Study (2009)
A study into the flood behaviour of four coastal creeks: Cudgen, Cudgera, Mooball and Marshalls Creeks.
A joint study between Tweed and Byron Shire Councils (reflecting the cross-boundary flooding between Mooball and Marshall Creek).
The study area includes South Kingscliff, Cabarita - Bogangar, Hastings Point, Pottsville, Burringbar, Mooball, Crabbes Creeks, Wooyung, South Golden Beach, Billinudgel, New Brighton and Ocean Shores.
The study provided model scenarios for possible future changes in land use (e.g. agricultural change from sugar cane production) and potential impacts of climate change (sea level rise and increased rainfall intensity).
Coastal Creeks Flood Study(PDF, 10MB)
Coastal Creeks Flood Study flood maps addendum(PDF, 14MB)
Climate change and flooding
In 2008 the NSW Government issued guidelines for councils to include climate change variables into flood studies.
Since then all our flood studies have included climate change modelling that considers:
- a sea level rise of 0.91 m
- an increase in rainfall intensity of 10%
Climate impact maps
Maps of climate change scenarios are available in our flood studies above. In 2010 Council adopted these climate change maps as appendices to our Development Control Plan.
The maps are applied as design flood levels for large scale greenfield residential subdivisions, such as Cobaki, Kings Forest and West Kingscliff.
Flood terms explained
Flood terms and definitions
Common terms used in relation to flooding:
- Annual Exceedance Probability (AEP): The probability of a flood event of a given size occurring in any one year, usually expressed as a percentage annual chance.
- Average Recurrence Interval (ARI) Similar to AEP. The long-term average number of years between the occurrence of a flood as big as (or larger than) the selected event. This is an average (a ‘1 in 100 Year’ ARI event last year does not mean a flood that big will not occur for another 99 years).
- Design Flood Level: A hypothetical flood representing a specific likelihood of occurrence. For residential property in Tweed Shire, the peak of the modelled 1% AEP (100 Year ARI) flood is the Design Flood Level.
- Freeboard: A safety factor typically used to set minimum floor levels. In Tweed Shire, the minimum habitable floor level (or Flood Planning Level) is based on the 1% AEP flood event plus 0.5 metres of freeboard.
- Floodplain: Refers to all flood prone areas in the Tweed catchment.
- Metres above Australian Height Datum (m AHD): The reference level for defining ground levels in Australia. The level of 0.0m AHD is approximately mean sea level.
- Minimum Habitable Floor Level: The minimum level in metres AHD at which habitable areas of development (generally including bedrooms, living rooms, kitchen, study, family and rumpus rooms) must be constructed. In Tweed Shire, this is Design Flood Level plus 0.5m of freeboard.
- Probable Maximum Flood (PMF): An extreme flood, considered the largest flood that could occur at a specific location. Generally it’s not physically or economically possible to provide complete protection against this flood event, but it should be considered for emergency response.
The probable maximum flood defines the extent of the Tweed’s flood prone land (floodplain).
Voluntary house purchase
Voluntary House Purchase was a recommendation of Council’s Floodplain Risk Management Studies completed in 2014 and 2015.
The scheme aims to permanently remove at-risk people from high flood hazard areas (areas with high flood depths and velocities) by buying their houses. The properties are then back-zoned for more flood compatible uses, such as parkland or farming.
The NSW Government has approved Voluntary House Purchase in the high flood hazard areas of South Murwillumbah, Bray Park, Burringbar and Mooball.
Under the scheme, the price paid for a home (compensation) is determined by an independent valuer with the Office of Environment and Heritage paying two-thirds of the price and Council picking up the remainder.
Council has identified individual homes for the scheme and will speak with home owners to see if they are interested in selling.
The scheme will take many years to roll out and relies on funding from the NSW State Government (Council has to apply for funding each financial year).
Media release: State okays Council to buy high flood risk homes (2018)
Voluntary House Purchasing Scheme plans
These plans were publicly exhibited and adopted by Council in August 2019:
Express an interest
To express an interest in the voluntary house purchase scheme email your property and contact details to firstname.lastname@example.org or write to PO Box 816 Murwillumbah NSW 2484.
Voluntary House Raising Scheme
The Tweed has many flood prone houses. The economic and social burden of flooding on the community can be reduced by raising these dwellings to increase their flood immunity.
Council's Voluntary House Raising Scheme aims to reduce flood damage to houses by raising the habitable floor level of individual buildings.
Both the Tweed Valley and Tweed Coastal Creeks Floodplain Risk Management Plans recommended a house raising scheme.
The State Government's Department of Planning, Industry and Environment will provide two-thirds of the eligible cost of raising a house. The house owner will be responsible for providing the other third. Council will manage and administer the scheme.
Benefits of the scheme include:
- less flood damage to houses and their contents
- reduced personal loss, stress and post-flood trauma
- reduced frequency of household disruption
- reduced clean up after floods.
The draft Tweed Voluntary House Raising Scheme was on exhibition in June 2020 and then adopted by Council.
The document outlines a process for eligible property owners. A list of properties will not be published (this information is confidential) but eligible property owners will receive a letter from Council about the scheme.
Am I eligible?
To check eligibility for the scheme contact our Flooding and Stormwater Engineer on 02 6670 2400.