COASTAL HAZARD

Byron Shire Council’s Staff Report (October 2021) on the Planning Proposal states:
The location of the 7(f1) Coastal Lands zone was originally based on The Byron Bay – Hastings Point coastal hazard report, prepared in the late 1970s. The zone was intended to identify land subject to the most immediate coastal risks and is a very restrictive zone that does not permit permanent development.
To address coastal hazard on the site, the proponents commissioned a detailed Coastal Hazard Assessment of the property, which provides contemporary probabilistic modelling to establish the predicted location of the erosion escarpment in years 2050, 2070, 2100 and 2120 (Attachment 2).
The modelling approach, which includes allowance for sea-level rise and climate change, was agreed by staff of the Department of Planning, Industry and Environment Coastal Division, and forms a sound basis for the hazard assessment. 
For the purposes of the planning proposal, the seaward extent of the E4 Environmental Living zone is set at the year 100 (2120) 1% exceedance line.  
This is where the model predicts the coastal erosion escarpment to be in 100 years’ time. The 1% exceedance means there is 1% chance that the line could be further landward – i.e. there is 99% certainty that the line will not be further landward in 100 years.
The location of this contemporary 100 year hazard line is shown by the dashed green line on the existing zoning diagram above.
It is located approx. 135m seaward of the previously mapped 100 year hazard line, which was used as the basis of the 7(f1) Coastal Land zoning and associated DCP Part J erosion precincts. 
The contemporary modelling demonstrates that the area within the site that is subject to coastal hazard is far smaller than previously understood.
Council resolved (Res. 20-470, Part 3) that the current 7(f1) Coastal Land zoning remain in place for the part of the site located seaward of the contemporary 100 year hazard line, pending completion of the Coastal Management Program, at which time it can be reviewed.
Through further consultation with the applicant and agencies an E2 zone has instead been applied. This was to ensure that this part of the future lots to be created retained the integrity of the hazard line without development being place on it. 
The landowner has agreed to the application of an E2 Environmental Conservation zone on the part of the property seaward of the contemporary line, and E zones have been applied in accordance with the state government’s ‘Northern Councils E Zone Review Final Recommendations Report’.  
The combination of the E4 and E2 zones will allow the subdivision of this cleared part of the property but ensure that all future development within the lots is located outside of the coastal hazard area. The application of a minimum lot size will restrict the subdivision potential of the land to a maximum of 9 lots.
The coastal hazard modelling was only applied to the cleared parts of the property. It was not extended for the full length of the property, and therefore cannot be used to ‘fix’ a zoning line north-west of the cleared area.  
As such, it is recommended that the existing zoning of 7(f1) Coastal Lands remain outside of the area that was subject of the probabilistic modelling. 
A combination of E2 Environmental Conservation and E3 Environmental Management is proposed over the remaining undeveloped and vegetated parts of the site, outside of the coastal hazard areas. The SP3 Tourist zone will remain over the existing resort.
The E3 Environmental Management area fringes the existing resort, where asset protection zones are required to be maintained in accordance with bush fire approvals”.

Royal HaskoningDHV, the coastal management experts who undertook the study, also undertake work for Byron Shire Council and many other NSW coastal councils. Their methodology was peer reviewed and agreed to by both Council staff and staff from the Department of Planning, Industry and Environment Coastal Division. The results were also peer reviewed and accepted by all parties. There is no conjecture, no disagreement or grey area about the findings of the coastal hazard assessment.

The results are consistent with the Byron Shire Coastline Hazards Assessment Update prepared by BMT WBM for Byron Shire Council in 2013. The findings of this study have not yet been included in any updated coastal hazard planning controls for Byron Shire. Planning controls remain based on the 42 year old 1978 Byron Bay – Hastings Point Erosion Study. The 1986 DCP is also based on this 1978 work. Recent aerial photography also supports the findings of the 2013 and 2019 studies.

The Royal HaskoningDHV study use probabilistic modelling, which is widely accepted to be the best practice approach to understanding future coastal hazard. The parameter values are randomly sampled one million times and combined repeatedly as a means of predicting the shoreline position (extent of coastal hazard) at particular times in the future. The study used a 2020 (100 year) horizon and a 1% exceedance factor. This is the most conservative position and has been adopted in the planning proposal.

Subject site showing 1988 coastal hazard line and updated coastal hazard lines from 2013 and 2019 studies