http://www.sealevelrise.info/

NCCARF 2014

Steve George

Canute: The Sea Level Calculator

Online Decision Support Tool

Impact of (varying) sea-level on the coastal environment. Geographical

quantification of:

• Storm surge (floods)• Soft shoreline recession• Wave activity

Canute: The Sea Level Calculator

Online Decision Support Tool

Impact of (varying) sea-level on the coastal environment. Geographical

quantification of:

• Storm surge (floods)• Soft shoreline recession• Wave activity• (others not discussed, or in development)

• Steady climate variability• Additional impacts due to climate change

Canute Output

Storm Surge

Storm Surge: Likelihood of flooding

What has been done previously?

• Find your nearest decent tide- gauge (what’s happened previously)

• Fit a distribution to the extremes & extrapolate

• Calculate risk you are willing to take. e.g. Melbourne Water requires that any new development is protected in the 1 in 100 year flood event.

Storm Surge: What of the future?

Sea-level is rising, so can no longer just look to the past for what will happen in the future.

One options is to choose an arbitrarily large height (above which you are allowed to build)• This can be expensive, and

prevents a planner from performing a comprehensive risk analysis.

Alternatively, provide a localised calculation of flood likelihood.• Uncertainty in past• Uncertainty in future

Canute Output: Storm Surge

Canute Output: Storm Surge

AEP vs. ARI

ARI (years) AEP

1 0.632

2 0.393

5 0.181

10 0.095

20 0.049

50 0.020

100 0.010

ARI

AEP1

exp1

Canute Output: Storm Surge

Number of Events

The EP gives the probability of one or more events. The expected number of events at a certain level is possibly more relevant:

Recent Addition

)exp(exp1 NARI

TEP

Canute Output

Coastal Setbacks

Canute Output: Coastal Setback

How far back from the sea should I build my beach house?

• S1: Allowance for short term storm erosion (storm demand)• S2: Allowance for ongoing underlying recession• S3: Allowance for recession due to future sea level rise (SLR)• S4: Allowance for beach rotation• S5: Allowance for dune stability

Canute Output: Coastal Setback

How far back from the sea should I build my beach house?

• S1: Allowance for short term storm erosion (storm demand)• S2: Allowance for ongoing underlying recession• S3: Allowance for recession due to future sea level rise (SLR)• S4: Allowance for beach rotation• S5: Allowance for dune stability

Canute Output: Coastal Setback

Beach Modelling

•Results of Modelling by Water Research Laboratory

•Forced by storm surge high water levels (tide gauge), and significant wave height(CSIRO)

•Regionally specific

Regionally specific beach types modelled under localised storm-surge conditions

Coming soon:

• S1: Allowance for short term storm erosion• S5: Allowance for dune stability

Canute Output

Wave Activity

Canute Output: Wave Activity

Sea-level is more than just the still-water level

• Wave setup is the superelevation of mean water level caused by wave action (total water depth being the sum of still-water depth and wave setup).

• Wave runup is the maximum elevation of wave uprush above still-water level: it is the sum of the setup and incident wave runup.

Canute Output: Wave Activity

Present day variability: developing tool

• First version required user to provide location specific data on offshore wave climatology (e.g., from sparse network of Waverider buoys).

• Latest version provides full coverage around the Australian coast by utilising results from NOAA WAVEWATCH III ocean wave model.

• Development system has access to assorted model datasets (e.g., ECMWF and CSIRO wave data).

• Future system will incorporate results from XBeach modelling.

Canute

...and finally

Canute: The Sea Level Calculator

Online Decision Support Tool

Impact of (varying) sea-level on the coastal environment. Geographical

quantification of:

• Storm surge (floods)• Soft shoreline recession• Wave activity• (others not discussed, or in development)

• Steady climate variability• Additional impacts due to climate change

Canute: Usage

Users who have completed the training

http://www.sealevelrise.info/http://staff.acecrc.org.au/~segeorge