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Amendments to Flood Hazard Area Mapping

FAQ'S

During 2010/2011, prolonged and extensive rainfall, which fell over large parts of Queensland, coupled with already saturated catchments, lead to flooding of historic proportions affecting more than 78 per cent of the state, the loss of thirty-three lives and in excess of $5 billion in damages.
 
Following the floods, the Queensland Government established the Queensland Flood Commission of Inquiry on 17 January 2011 to investigate matters relating to the floods.
 
The Commission’s findings were publicly released in March 2012, which amongst many other things, highlighted the lack of flood risk mapping across the state and recommended that action be taken to address this deficiency.
 
The majority of Council’s existing adopted flood studies were undertaken in the period prior to 2010 and represented the best available data and modelling practices at the time, however, significant improvements have since been gained in both flood modelling software and practices and detailed ground level data to better define flood impacts at property scale.
 
Council is committed to undertaking an ongoing strategic programme to:
•    Improve the detail and accuracy of existing flood modelling; and
•    Undertake flood modelling for areas which have no existing flood risk information.
The State Government requires Councils to prepare a planning scheme to help sustainably manage growth and development. The planning scheme shapes how our region grows by ensuring the right development occurs in the right places.
 
A planning scheme is a legal document prepared by a local Council to regulate the use and development of land in a way that achieves outcomes that the community has identified as desirable, e.g. well-designed buildings, prevents incompatible land uses from establishing near one another and protecting the environment. The planning scheme identifies land uses, e.g. house, shop, industry, and types of development, e.g. new buildings, extensions to existing buildings and advertising signs that require Council approval and the standards that development applications must meet to be approved, e.g. building setbacks and height, noise levels, car parking.
 
Land use and development within the Fraser Coast Regional Council is regulated by the Fraser Coast Planning Scheme 2014
For most people, changes to the Planning Scheme to reflect the revised flood hazard area will have little to no impact because it only applies to new development.  
 
This means it only affects you if you wish to further develop your land.  This could include building works (including extensions), changing a use (e.g. residential to commercial), subdividing a property and filling or excavating your property.
 
The planning scheme does not affect existing development or development that has been lawfully established or already has approval, but has not commenced.
 
Existing lawfully established dwellings are not required to be altered to address changes to the flood hazard area mapping.
 
Refer to FAQ 3 if you have existing buildings on your property and are not developing building, otherwise click here for more information.
When looking at managing flooding from a land use planning perspective, it’s important to understand the difference between flood hazard and flood risk.  
 
Flood hazard is the hazard which exists due to specific flood dynamics ie. that is, how deep, fast and wide the water spreads. It’s one of the factors used to determine flood risk. 
 
Flood risk is how flooding might affect people, buildings, land, roads and the natural environment.  
 
For many parts of Queensland and in our region, areas of natural floodplain have a lower flood risk than areas where people and buildings are concentrated. Flood risk is harder to manage where development, or the right to develop, already exists. Flood risk to existing infrastructure is usually reduced through improvements to protection as part of any upgrade. However, there are basically three ways of managing flood risk to reduce the consequences of flooding: by modifying flood behaviour, property modification or community response.

None of these measures is a stand-alone solution for addressing flood issues. The preferred option is usually a combination of flood, response and property modification measures to reduce risk to an acceptable level and to manage the remaining risk appropriately.
Reasons why the flood maps may be different to your own experiences may be because:
 
  • The flood event that is represented in the Flood Hazard Mapping has not occurred during the time you have lived on the property. 
  • Your property may be impacted by localised drainage constraints which can contribute to property flooding during rainfall events, even if your property is not identified as being impacted by catchment scale flood risk.
  • Blockages to drainage systems and restrictions to the flow of water can result in flooding in areas which are not generally subject to flooding if the natural flow path is unobstructed. 
  • A property may be within a natural overland flow path. Minor scale overland flow paths are not expected to be defined or represented in the catchment scale flood risk assessment.   Major overland flow paths are being captured and defined within new flood risk studies and will be represented in the Flood Hazard Overlay Map. 
  • It is important to note that the risk that a property might flood existed before the risk was identified and confirmed in any detailed flood study.
The adopted Flood Hazard Area represents the most detailed flood risk information available to Council at the present time. Updates and revisions to flood risk information across the Fraser Coast region will be on ongoing process, resulting in revision to the adopted Flood Hazard Area over time.  
 
Being outside the flood hazard area does not guarantee that your property will; 
 
  • never flood, 
  • will not be impacted by future revision to the adopted Flood Hazard Area or
  • is not subject to localised constraints which may cause drainage or flood related impact.

The storm tide level is only shown if that flood type is identified to impact on the property. Refer to FAQ 4 which explains the building requirement differences between a defined flood level (DFL) and a defined storm tide event (DSTE) level. 

The new flood studies are based on a 100 year Average Recurrence Interval (ARI) flood event). ARI can be interpreted in terms of years (frequency). ARI can also be described as an Annual Exceedence Probability (AEP) which can be interpreted as the percentage chance of a flood of this magnitude occurring in any one year. A 100 year ARI flood event corresponds to a 1% AEP or a Q100 Flood Event.  
 
For example, the Bureau of Meteorology explains that for each and every year, there is a 1% chance (a 1 in 100 chance) that the defined event will be equalled or exceeded (once or more than once).
 
Probabilities of experiencing a given size flood once or more in a lifetime. 
 

Chance of a flood of a particular size being exceeded in any one year

Chance of experiencing a flood in a 70 year period

At least once

At least twice

1% (1 in 100 odds)

50.3%

15.6%

(an excerpt from Understanding Floods: Q&A, The State of Queensland 2011)

 

A 100 Year ARI flood does not mean that it is a flood that only occurs once in 100 years, which can only occur once in 100 years, or occurred 100 years ago.

All affected property owners in the following catchments (Tooan Tooan Lowlands, Pulgul, Eli, Glenwood, Aldershot and Bunya System) have been sent a flood information pack that includes flood heights on their properties. 
 
If you haven’t received a notice from Council, your property is likely to not be affected by the changes to the Flood Hazard Area. 
 
You can still submit a flood search application or check Council’s Flood Hazard Area Amendment mapping via the following links:
 
 
Please note that flood models do not include information on existing building levels or the extent of potential flooding to physical structures eg. houses.  This is because Council does not hold information on built levels of all properties across the region.  Landholders who would like to confirm their built levels of existing structures will need to engage a suitably qualified person (e.g. Surveyor or Building Certifier) to confirm their property and building levels, for comparison against the defined flood level(s) provided. 

Flood levels vary according to the flood profile across the catchment. Variations in topography, locations of structures and flood mitigation measures can all impact the flood level and natural overland flow path as flood extends across the catchment. The flood level, depths, velocity and hazard can vary from individual property to property, depending on the local topography, location of structures and flood mitigation measures in place. 

In-line with industry best practice, national design standards and recommendations from the Queensland Flood Commission of Inquiry, Council has incorporated climate change consideration, including increased rainfall intensity, cyclone intensity and sea levels, in all new flood risk studies within the Fraser Coast region.
 
Inclusion of such considerations is critical to the forward planning of areas within the region, due to the coastal location, significant extent of foreshore frontage and low-lying adjacent land, in addition to the major river systems and other high flood risk areas located within the Fraser Coast region.
Questions regarding changes to your insurance schedule should be directed to your insurance provider. Insurers do their own flood risk assessments and risk mapping, independent of local government. 
 
Insurance companies spend time and resources researching areas of Australia to map flood prone areas and assign risk estimates to each area.  Insurance companies use data from a range of sources, including flood mapping (where available), terrain data and independent hydrologist reports. Industry bodies such as the Insurance Council of Australia often complete this on behalf of insurance companies, and then each company considers how to adjust premiums to reflect how likely it is that an individual property might flood.
 
Fraser Coast Regional Council will forward on the amended flood hazard mapping and related data to the Queensland Government’s FloodCheck interactive mapping service for the purpose of providing the public and private sector (including the insurance industry) accurate local flood data. 
 
The Insurance Council of Australia recommends that consumers shop around if they are dissatisfied with their current cover.
 
For more information about flood insurance visit the Floodplain Management Australia webpage at www.floods.org.au/site/flood-insurance-fact-sheets
 
Local governments use statutory land valuations as a basis to calculate rates. Valuations are just one of many factors taken into account when Council frames its annual budgets and determines rates.
 
The Valuer-General (a State Government role) provides land valuations for all rateable properties in Queensland, which are issued annually to local governments.  Adverse natural events, such as flooding, occur regularly in some parts of Queensland and the Valuer-General may review valuations based on the impacts of these events.  
 
For more information, please visit the Queensland Government’s website at www.qld.gov.au/environment/land/title/valuation 
 
Note: Fraser Coast Regional Council will provide the updated flood hazard area mapping and related data to the Queensland Government’s Valuer-General for their consideration in future statutory land valuations.

Property values can vary markedly depending on factors such as global financial markets, interest rates, or development nearby.  Ultimately, it is the property market that determines the value. 

Compensation is not available on the basis of flood hazard information being updated.

Existing development that has occurred in accordance with the current Planning Scheme was approved based on the information of flooding risk available at the time.

With the availability of more recent hydrological and other data about flood behaviour and extents, Council is updating the planning scheme to reflect new data and to help better manage our region’s flood risk.
These maps relate specifically to disaster management and are for the limited purpose of providing historical or predicted flood maps, for disaster management and evacuation preparation purposes.
 
The disaster management mapping is different to the flood hazard area map contained in the Planning Scheme and it should be noted that disaster management mapping is not intended to be used for individual property risk assessment.  
 

Subdivision of a property (Reconfiguring a lot) always requires an application to Council, regardless if it is or isn’t in a flood area.  In addition to the standard reconfiguring a lot criteria, the proposal will be assessed against the Flood Hazard Overlay Code which is part of the Planning Scheme.  The purpose of the Code is to ensure that development protects people and avoids or mitigates the potential adverse impacts of flood on property, economic activity and the environment.

Australian Height Datum (AHD) is the survey height datum adopted by the National Mapping Council as the datum to which all vertical control for mapping is to be referred.  
0.00metres AHD approximates to mean sea level. 
 
Average Recurrence Interval (ARI) is the probability of experiencing a flood of a particular magnitude. ARI can be interpreted in terms of years (frequency). 
A 100 year ARI flood event corresponds to a 1% Annual Exceedance Probability (AEP) or a Q100 Flood Event. AEP can be interpreted as the percentage chance of a flood of this magnitude occurring in any one year.  For example, the Bureau of Meteorology explains that for each and every year, there is a 1% chance (a 1 in 100 chance) that the defined event will be equalled or exceeded (once or more than once).
 
Defined Flood Level (DFL) means the flood level calculated for the 100 Yr ARI design flood event and adopted for the purpose of the Fraser Coast Planning Scheme.
Example - the defined flood level (DFL) is 5.00m (AHD). 
 
Defined Storm Tide Event (DSTE) Level is an inundation level adopted by Council that represents the flood level of a 100 year ARI storm tide event and adopted for the purpose of the Fraser Coast Planning Scheme.
 
Flood Hazard Area is an area designated by Council as a flood hazard area for the purpose of the Fraser Coast Planning Scheme 2014, section 13(1)(b) of the Building Regulation 2006 and Queensland Development Code MP3.5 – Construction of Buildings in Flood Hazard Areas.
  
Freeboard means a height above the defined flood level that must be included in the calculation to set the minimum habitable floor level, to provide additional protection for flood immunity of the finished floor level. 
 
Minimum Habitable Floor Level (MHFL) means the level of the uppermost surface of a finished floor for habitable structures (not including any floor covering).
Council has utilised the latest LiDAR imagery (captured 2015) for new catchment models, where such data is held.
 
For catchments where the 2015 LiDAR is not held, the previous LiDAR data was utilised (2011 data). LiDAR - (light detection and ranging) is an optical remote-sensing technique that uses laser light to densely sample the surface of the earth, producing highly accurate x,y,z measurements (ground level data)
The LiDAR provides a snap shot of ground levels across the catchment, at a certain point in time. It is expected that over time, individual properties which undertake ground works and properties which are developed as part of estates will be subject to changes in their ground level due to operational works or other works which significantly modify the natural ground level of the land.
 
This can result in new or significantly modified properties being included in the flood mapping, when in fact their modified ground levels actually achieve flood immunity or otherwise change the flood outcome on the property.
 
Where this occurs, the changes to the property will be reflected in the next modelling run for that specific catchment. Due to the scale, complexity and high cost of the catchment modelling, running updates to capture individual property scale changes will not be pursued.
 
Properties which change as a result of individual landholder works can utilise the Defined Flood Level provided on a Flood Search Report, along with their confirmed property ground levels to determine whether or not their property is still affected by flooding after the ground works.
 
Properties which are created as part of a development estate can use the above method, as well as confirmation from Council that the estate met the required flood immunity conditions of their development approval.
 
The onus of identifying and confirming property specific ground levels is on the landholder.

The flood duration is unique to each flood event, dependent on a variety of factors including rainfall intensity, tidal conditions, local topography and stormwater pipe network arrangements. A 100 Year ARI Flood Event can be triggered by high-intensity rainfall occurring over a very short period of time (ie. 25 minutes) or by lower intensity rainfall occurring over a longer duration (ie. 72 hours). The new flood modelling has analysed the full suite of flood durations to identify which flood duration resulted in the worst flood impacts in each sub-catchment area.

 

The resulting outcomes reflect the peak flood impacts across the whole catchment area, for the flood duration event which resulted in the worst flood impacts for each sub-catchment area.

 

Therefore, some areas are subject to worse impacts in high intensity, short duration rainfall events, while others can accommodate those short duration events better but are subject to worse impacts in lower intensity, longer duration rainfall events.

Visit the Queensland Government's website for more information: https://getready.qld.gov.au/natural-disasters/flood/

Reasons:

  1. Notification packages will only be sent to affected property owners. If the flood hazard area extents/depths/velocities have not changed for your property, you will not be notified; or 
  2. Council will send notification packages between 8-22 May, 2019. There may be a delay between posting of a letter and it being delivered; or
  3. There is a 4-6 week gap before Council receives new owner information from the Department of Natural Resources, Mines and Energy and so the notification may have been sent to previous owners of the property. Council will regenerate our mailing/emailing list on 9 May and resend the notifications to the new owners on 29 May 2019.

The amendments are based on the studies undertaken by specialist engineers and incorporate the latest data and modelling techniques. Under the Planning Act 2016 Council is required to give notice to every property owner affected by the planning change about the meaning of the change and how to obtain further advice.  The notification process is distinctly different from standard planning scheme amendment “public consultation” in that it is purely intended to inform and does not seek submissions on the change. 


In the 2019/20 financial year, Council will engage an external consultant to undertake a fit-for-purpose flood risk assessment which will inform planning scheme amendments and mitigation measures, including infrastructure upgrade solutions, for future consideration of Council.  Community consultation will be undertaken as part of the project.