Interim Flood Planning Levels

The Development Control Plans have been updated to implement the interim Flood Planning Levels for the Clarence River floodplain, which is based on Council’s recently adopted Lower Clarence Flood Model Update 2022.

The DCP amendments also update Wooli controls to the recently adopted Wooli Wooli River Flood Planning Levels.

The flood planning levels mean that new habitable floors need to be constructed 500mm above the new flood levels, which includes a mid range projection for climate change.

The Glenreagh controls are not changing, with mapping to include the 500mm freeboard in the Flood Planning Area.

Habitable floor area in a residential development includes: a living or working area, such as a lounge room, dining room, rumpus room, kitchen, bedroom, or workroom.

For new industrial or commercial development this includes: an area used for offices or to store valuable possessions susceptible to flood damage in the event of a flood.

The Lower Clarence Flood Model Update 2022 is for the Clarence River catchment from Mountain View to the mouth of the river at Yamba and Iluka. These changes will affect Grafton, South Grafton, Southgate, Ulmarra, Lawrence, Maclean, Yamba and Iluka and the rural areas in between.

The Wooli Wooli River Floodplain Risk Management Plan 2022 impacts Wooli only.

There are changes to the Glenreagh DCP controls, however this will not impact Flood Planning Levels (floor levels).

See the Flood Planning Area maps as APPENDICES to the Development Controls plans here: https://www.clarence.nsw.gov.au/Building-and-planning/Development-applications/Our-LEP-and-DCPs

Flood Planning Levels are available for individual properties on Council’s online mapping system.  

The DCP changes will commence on 1 January 2025. That means that if a Development Application is lodged on the Planning Portal on or after this date, it will be required to comply with the interim Flood Planning Levels. If a Development Application is lodged prior to this date, it will be assessed against the current Flood Planning Levels.

No, the Flood Planning Levels applicable before 1 January 2025 will continue to apply as the development control.

Applicants are encouraged to consider the latest information and meet the updated Flood Planning Levels when possible.  

The Wooli controls are updated to refer to the adopted Wooli Wooli River Flood Planning Level, being the 1% AEP event 2100 Climate Change scenario plus 500mm freeboard, which are derived from the Wooli Wooli River Floodplain Management Study and Plan 2022.

The Floor Height Controls in Part V of the Residential Zones DCP and in Part N of the Environmental Protection, Recreation and Special Use Zones DCP will be updated to refer to this Flood Planning Level. In addition, the existing maps will be removed and replaced with an improved map, showing the revised flood extent.

The Wooli Wooli River Floodplain Management Study and Plan was completed in 2022.  At its September 2023 meeting council resolved to adopt the Wooli River Flood Study and to exhibit the draft Wooli Floodplain Risk Management Study and Plan, with the Study and Plan to be adopted if there were no submissions changing their intent.  No submissions were received during the public exhibition which changed the intent of the Wooli Floodplain Risk Management Study and Plan, and at its meeting of 18 March 2024 Council’s Floodplain Risk Management Committee endorsed the Flood Study and Plan as exhibited.

You can view how this will impact your land on Council’s online mapping system.

The Flood Planning Level for Glenreagh remains unchanged at the 1% AEP flood level plus 500mm freeboard, consistent with the current Glenreagh Floodplain Risk Plan 2018. However, the mapped area now includes the 500mm freeboard for improved clarity. Previously, the 500mm freeboard was added at the Development Application stage, in accordance with the DCP requirements.

Changes to Part R Glenreagh Village Controls within the Residential Zones DCP are required to update definitions for consistency with the updated Dictionary. In addition, the existing map will be removed (Map R4) and replaced with an up-to-date Flood Planning Area map.

Part O Controls for Precincts Close to Glenreagh Village in the Rural Zones DCP will also be amended to reflect the above changes.

You can view how this will impact your land on Council’s online mapping system.

A Flood Planning Level is the minimum level that new developments are typically required to be built above.

‘Flood Planning Level’ (FPL) is defined as ‘The combination of the flood level from the Defined Flood Event and freeboard selected for flood plain risk management purposes’ in the NSW Government’s Flood risk management manual: The policy and manual for the management of flood liable land, published 30 June 2023.

For the purpose of Clarence Valley Council’s interim Flood Planning Levels:

1. the Defined Flood Event (DFE) is the 1% Annual Exceedance Probability (AEP) Flood Event (i.e. 1 in 100 year flood) with a mid range Climate Change scenario (RCP 4.5) to the year 2090
2. the ‘Freeboard’ is 500mm.

The DFE is derived from the Lower Clarence Flood Model Update 2022 (2022 Flood Model). Council adopted the 2022 Flood Model on 27 June 2023 (Resolution 06.23.009) and resolved to adopt the interim Flood Planning Levels for on 25 June 2024 (Resolution 07.24.093).

The interim Flood Planning Levels are to replace current Flood Planning Levels for the Clarence River Floodplain.

Generally, the Flood Planning Levels increase in all cases, more in Grafton and surrounds, and lesser in the Lower River. This is because the updated Flood Planning Levels include greater climate change assumptions than the current 2013 Flood Model.

The existing Flood Planning Levels are based on the 1% AEP Defined Flood Event derived from the 2013 Lower Clarence Flood Model Update (2013 Flood Model) + 500mm freeboard. The 2013 Flood Model includes conservative assumptions about sea level rise associated with climate change.

The interim Flood Planning Levels are based on the 1% AEP Flood Event with a Climate Change scenario (RCP 4.5) to the year 2090, as derived form the latest 2022 Flood Model, + 500mm freeboard. The ‘RCP 4.5’ is the Representative Concentration Pathway 4.5, which is a mid-range climate change projection. The 2022 Flood Model includes up-to-date assumptions about sea level rise and increases in rainfall and runoff associated with climate change. 

The FPL for north Grafton is to be in accordance with the Lower Clarence Flood Model Update 2022 – 1% AEP with the mid range Climate Change Scenario plus freeboard of 500mm.

However, in June 2024 Council resolved that the draft DCPs allow for the consideration of floor levels in Grafton for infill development to be reduced to no lower than the revised 1% AEP plus 500mm freeboard, that is, without the inclusion of the Climate Change scenario levels. This has been included as an option for applicants as there is currently an option to vary the FPL in Grafton with justification.

This will only be considered where an applicant can demonstrate that the new FPL for the development is not feasible or practical due to the resident’s accessibility requirements, the unreasonable impacts on neighbouring properties resulting from earthworks/filling, the building construction cost no longer being feasible, or the unreasonable impacts on heritage values. The controls will still require all building components below the interim FPL to be flood compatible regardless of the floor level approved.

Freeboard is a factor of safety typically used in relation to the setting of minimum floor levels and is added in addition to a defined flood event like a ‘buffer’ to allow for other factors, such as wave and wind action.

Freeboard aims to provide reasonable certainty that the risk exposure selected in deciding on a specific event for development controls or mitigation works is achieved, and is typically set at 500mm across NSW. 

The interim Flood Planning Levels are to apply to all development to which the current Flood Planning Levels apply, which is typically residential development and other development that includes habitable rooms.

Council’s current planning controls in the Development Control Plans (DCPs) typically require habitable floor levels to be above the Flood Planning Level.

Our DCPs define Habitable Floor area as:

• in a residential situation: a living or working area, such as a lounge room, dining room, rumpus room, kitchen, bedroom or workroom;
• in an industrial or commercial situation: an area used for offices or to store valuable possessions susceptible to flood damage in the event of a flood.

The interim Flood Planning Levels will apply to all new development applications within the Flood Planning Area.

All new and recently submitted development applications that propose earthworks and/or filling of flood prone land will be required to demonstrate compliance with the flood planning controls in the of the Clarence Valley Local Environmental Plan 2011 and relevant DCP. Flood impact assessments will be required to be undertaken against the latest 2022 Flood Model.

Including climate change in Flood Planning Levels is “best practice” and must be considered, as required by the NSW Government’s current flood planning policy and guidelines.   

The RCP4.5 climate change scenario chosen is the mid-range scenario that aligns with Council’s adopted Disaster Resilience Framework. RCP4.5 is a middle-of-the-road greenhouse gas emission scenario where some mitigation of green house gas emissions occurs.

The climate change scenario is to 2090 (RCP 4.5), which is a commonly adopted planning horizon for climate change predictions. This scenario aligns with minimum timeframes for residential building and infrastructure life. 

An ‘interim’ Flood Planning Level is to quickly incorporate the most up-to-date flood planning information from the 2022 Flood Model into our planning controls. 

An ‘interim’ Flood Planning Level is also required because the way Flood Planning Levels are set has recently been changed by the NSW Department of Planning and Environment (DPE).

Currently, the Flood Planning Levels and a Flood Planning Area map are included in our Clarence Valley Local Environmental Plan 2011 (CVLEP). Recent advice from the DPE indicates that the standardised Local Environmental Plan used across NSW will no longer include definitions for a Flood Planning Level or a Flood Planning Area, meaning the CVLEP cannot be updated to reflect the new Flood Planning Levels. The standardised Local Environmental Plan now uses the definitions in the Flood Risk Management Manual 2023 to define Flood Planning Levels.

What this change of approach means is that the Flood Risk Management Manual 2023 generally requires that Flood Planning Levels are determined through a Floodplain Risk Management Study and incorporated into a Floodplain Risk Management Plan. Council has commenced preparation of a new Floodplain Risk Management Study and Plan for the Clarence River floodplain which is expected to take 18-24 months.

For these reasons, Council has resolved to adopt the interim Flood Planning Levels, which will be in effect until a new Floodplain Risk Management Plan is adopted. 

The interim Flood Planning Levels are a planning control and will only apply to new development where habitable rooms are proposed. As such, the updated levels would apply to developments such as extensions with habitable rooms or an additional new dwelling. The interim Flood Planning Levels do not affect the use of existing homes or buildings. 

The future dwelling on the lot will need to have the primary habitable floor areas above the interim Flood Planning Levels. This may require the use of elevated floor levels using piers, posts, suspended slab and/or fill pad dwelling designs to achieve compliance. 

The purpose of the interim Flood Planning Levels is to increase the habitable floor height of houses and other buildings to reduce flood risk, and this may be done by using a range of design methods.

Where filling of a site is proposed, it is possible that the interim Flood Planning Levels will result in higher fill pads. If filling is proposed, the applicant must demonstrate to Council that the planning controls in the Clarence Valley Local Environmental Plan 2011 and the relevant Development Control Plan are met, including demonstrating no detrimental flooding impacts on other developments or properties.