A web tool for adapting to rising sea levels

With 85% of Australia’s population living in coastal areas, understanding the risks to infrastructure and private property is important for urban areas. Accurate sea level projections are vital for planning in coastal areas, with some analyses projecting sea-level rises of almost a metre by 2100.

“Planning for sea-level rise would seem simple at first glance; in reality it requires regular data points and sophisticated modelling techniques for analysis,” said Sven Rand, pitt&sherry.

To adapt to rising sea levels, scientists have developed a calculator that can guide coastal planners on the height and positioning necessary for infrastructure to avoid inundation and erosion as sea levels rise. Canute - Sea Level Calculator is a web tool that provides estimates for probability of inundation for infrastructure at various elevations on hard shorelines. In the case of soft shorelines, it assists with estimating the distance infrastructure needs to be set back from the existing shoreline to avoid the impact of shoreline recession.

Canute was developed by Dr Steve George and Dr John Hunter of the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), a business partner with pitt&sherry. The scientists looked at data from tide gauges and modelled storm surge at 12,000 points roughly every 2.5 km around the Australian coast to develop the tool, which assesses the likelihood of inundation from the sea based on two parameters.

“We have developed a statistical technique that combines the uncertainty of how often a storm surge or very high tide may occur with the uncertainty of the extent of future sea-level rise. This technique combines those into a single likelihood,” said Dr George.

“The beauty of Canute is that it now has a suite of calculators that allow coastal planners to estimate a range of factors, such as waves and tropical cyclones, which can impact on the positioning of infrastructure.”

In addition to current tide information, Canute enables users to select a climate change or greenhouse gas emissions scenario. The tool can then calculate the combined probability of the tide event and also the sea level rise due to the selected scenario.

To use the inundation calculator, users select the location on a Google Maps interface before selecting a greenhouse gas emission scenario and the timeframe for assessment, which is generally the lifetime of the asset. Two graphs are generated - one showing coastal flooding probability under a rising greenhouse gas scenario, the other projecting the probability if sea level remained where it is today.

“pitt&sherry routinely uses sea-level inundation calculations in infrastructure asset design as well as in planning processes where consideration of coastal vulnerability is required,” said Rand.

“We have used Canute in a range of coastal vulnerability assessments such as the Bicheno golf course development project, Georges River floodplain and Georges Bay, St Helens inundation assessments and the assessment of potential impacts on rail bridge development at Turners Beach Tasmania - it’s a versatile tool in the planning and design of coastal assets.”

Canute also provides users with estimates of potential erosion that may occur on soft coastlines typical of a range of representative beach types around Australia.

Estimates of the probability of inundation can be generated for projected sea level rise as a result of greenhouse gas emissions at any year between now and the end of the century throughout Australia.