What is sea level rise?
In simple terms, sea level rise raises the average water level of oceans and estuaries. As the average water level rises, so too will high and low tide levels affecting the natural processes responsible for shaping our coastline.
The basis for sea level rise benchmarks
The NSW Government released the NSW Sea Level Rise Policy Statement in 2009. This document stated, “The best national and international projections of sea level rise along the NSW coast are for a rise relative to 1990 mean sea levels of 40cm by 2050 and 90cm by 2100”.
The State Government has now removed the state-wide sea level rise planning level. Instead, they recommend that local government adopt a regionally relevant sea level rise planning level, providing flexibility for council to consider local conditions when determining future hazards.
On 10 March 2015, council adopted a medium sea level rise benchmark with localised sea level rise projections of 0.2m by 2050 and 0.74m by 2100. A medium sea level rise benchmark is considered a balanced and reasonable approach by council.
Current coastal zone management and flood risk management plans now reflect these localised sea level rise projections.
Table 1: Medium local sea rise projection
||Projection (based on RCP 8.5)
For the absolute projected sea level elevation relative to AHD, a further 0.08m should be added to the above values.
Why does council have to adopt a planning level for sea level rise?
Council is responsible for planning for future development in Gosford, for managing the natural environment, and for the wellbeing of residents. Planning and development decisions taken now will still be on the ground in 50 to 100 years.
The adopted rate for sea level rise allows councillors, council staff and the community to develop policies, carry out more detailed studies and make planning and development decisions that are suitable for the changed conditions.
What is council doing to plan for the impact of sea level rise?
Planning for an uncertain future, where the trends of the past cannot be relied upon, is an emerging issue for council. In undertaking this complex planning, council will, in many instances, be breaking new ground.
Planning for sea level rise and, more broadly, climate change is, and will be over the coming years, very challenging and demanding for council.
The consideration of a planning level for sea level rise and the exhibition of sea level rise mapping in September/October 2009 was an initial step that assists council to work with its community through this complex and multi-faceted problem.
Gosford City Council has a relatively strong tradition in planning for hazards such as coastal erosion and flooding through the development of coastal management plans, estuary management plans and floodplain risk management plans.
These have provided our community with information and guidance regarding local flooding and coastal erosion issues that already exist.
As the changes to climate manifest themselves over time, it is likely the extent of hazards such as these will change, and this planning tradition will assist with meeting the challenges we will face.
To enable this to happen, climate change parameters such as sea level rise planning level are considered in these strategic processes.
It is equally important that a sea level rise planning level is a consideration in all asset management and capital works project planning. The process for doing this is best described in the graphic below:
Sea level rise mapping
A set of maps were produced to provide an initial indication of the areas that may be potentially impacted by increases in sea levels, this information is available on the Sea Level Rise Mapping Page.