Council has updated its coastal hazard mapping as part of the Our Cairns Coast project, assisted by funding from the QCoast2100 program. This refined mapping identifies areas along the Cairns coast that are likely to be affected by current and future coastal hazards being coastal erosion, storm tide inundation and sea level rise from climate change. This mapping has been prepared for planning horizons 2020, 2040, 2060, 2080 and 2100.
The attached maps are for the purpose of engagement on the project, and indicate the extent of coastal hazards for each area at 2020, 2040, 2060, 2080 and 2100.
Erosion Hazard Area Maps
The updated Erosion Hazard Area mapping indicatively shows the landward extent of the coast that is potentially vulnerable to coastal erosion (short term and/or longer term coastal processes) and assumes no adaptation action is undertaken. This mapping is for the purpose of obtaining feedback and is updated from the current State Erosion Prone Area at the year 2100. In some cases, this mapping aligns with or is less than the area identified on the current State mapping and does not encroach as far landward.
The areas indicated on the map are indicative only and do not represent a shoreline position or where land may be lost to coastal processes. The mapping incorporates erosion controls such as bedrock and engineered seawalls. The mapping does not consider any other features that may limit the extent of erosion such as roads or buildings.
Storm Tide Inundation Maps
The Storm Tide Inundation mapping identifies those areas of the coast potentially affected by temporary inundation from the sea during a tropical cyclone (or other severe weather event) and assumes no adaptation action is undertaken. The mapping does not include riverine or waterway flooding caused by rainfall.
The 1% AEP* storm tide has been mapped for five planning horizons: 2020, 2040, 2060, 2080 and 2100 and identifies water depths and inundation extents. The mapping includes an allowance for wave processes that occur near the coastline.
Mapping is indicative only and has a statistical basis. It does not represent the storm tide inundation associated with a single tropical cyclone or severe weather event.
*Annual Exceedance Probability (AEP) is the likelihood or probability of a threshold being exceeded in any given year. For the 1% AEP storm tide, this means ‘on average’ there is a 1% chance of the coastal water level and associated inundation of this size or larger, occurring in any one year.
Sea Level Rise Maps
The sea level rise mapping indicates areas that will potentially form part of the intertidal zone and assumes no adaptation action is undertaken.
Consistent with the State’s requirements, the updated mapping includes an allowance of 0.8m sea level rise by the year 2100, due to the impact of climate change. Mapping has been prepared for each planning horizon and is based on present day Highest Astronomical Tide (HAT) plus a sea level rise allowance for each planning horizon out to the year 2100. Mapping is indicative only and does not represent a shoreline position or where land may be lost to coastal processes.
The approach to identifying coastal hazard areas along the Cairns coast is consistent with the Queensland Government’s Coastal Hazard Technical Guide for determining coastal hazards (DEHP 2013) and follows leading practice methodologies in the QCoast2100 Minimum Standards and Guidelines (LGAQ 2016).