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CyclAUS: Detailed Australian Tropical Cyclone Loss Model

Tropical cyclones are a regular threat to Australia, with an average of 11 cyclones developing over Australian waters each year and around 4 of these crossing the coast. The official tropical cyclone season runs from November 1st to April 30th, potentially impacting more than two thirds of Australian coastlines.
Tropical cyclones are accompanied by a combination of hazards leading to significant damage, including:

  • Strong winds, causing widespread damage to property and infrastructures.
  • Heavy rainfall, leading to flash-flooding, riverine flooding and landslides.
  • Storm surge, which is an anomalous rise in sea-level increasing the risk of coastal inundation and erosion.

In recent years, Australia has experienced a number of severe tropical cyclone landfalls with devastating consequences. According to the Insurance Council of Australia, 3 of the top 10 most costly natural disasters were tropical cyclones, including cyclone Debbie (2017), cyclone Yasi (2011) and cyclone Tracy (1974) each resulting in multi-billion-dollar insured losses.
In the context of climate change, tropical cyclones will continue to threaten Australian communities. Warming ocean temperatures will increase the severity of cyclones and extend their path further south, where larger Australian coastal communities are located.

CyclAUS Model Overview

CyclAUS builds on 16 years of development consisting of 3 modelling modules: genesis, tracking and wind modeling. Each component has been carefully calibrated against the Australian Bureau of Meteorology Tropical Cyclone database. The model domain extends 600 km from the coast of Australia covering all tropical cyclone affected areas.

CyclAUS simulates a unique event set of more than 300,000 tropical cyclones over 50,000 years Tropical cyclones are generated in the genesis module on genesis gates or in genesis cells around Australia. The tracking module then models the cyclone’s path by propagating the storm within the model domain and varying its intensity. Finally, maximum open and local wind gust (10s) speeds are calculated in the wind modelling module for each unique path, every 15 minutes, at the centroids of an orthogonal Variable Resolution Grid (VRG) refined with increasing exposure and proximity to the coastline.

Translating wind hazard into loss is done through a combination of vulnerability curves for specific building types, height, age and location, allowing location level intelligence. Vulnerability models were empirically derived from historical Australian insurance claims data.

 

CyclAUS Features

Resolution where needed

CyclAUS boasts an extremely high spatial resolution, able to resolve the steep gradients in wind speed as cyclones move inland as well as the local terrain conditions. The wind speed is calculated every 15 minutes at the centroids of an Variable Resolution Grid (VRG) refined with increasing exposure and proximity to the coastline. 

Calibrated with historical cyclones

CyclAUS was developed using more than 50 years of historical cyclone tracks impacting Australia provided by the Bureau of Meteorology. This ensures that tropical cyclone risk output is representative of the characteristics of Australian cyclones which are very different to other parts of the world.

Vulnerability Functions

Risk Frontiers has a suite of flood vulnerability functions which are used to determine the damage from a riverine flood event. These detailed curves use empirical curves and insurance claims data to best represent the insured loss. There are vulnerability functions for different lines of business, building types, and building, contents or business interruption covers.

Who can utilise CyclAUS?

Insurers/ReInsurers

CyclAUS can assist both insurance and reinsurance companies in setting premiums for insurance and re-insurance policies associated with tropical cyclones. This understanding applies to the individual policy level as well as the whole of portfolio.

Banks

Financial institutions can use CyclAUS as a tool to better understand the vulnerability of any given real-estate portfolio to tropical cyclone risk and guide them in managing their assets on both short and long term timeframes.

Governments

CyclAUS can provide critical insights for any government departments in evaluating and managing policies in regions heavily exposed to cyclone risks. This can be applied to a variety of topics from housing/insurance affordability to long-term policy development to mitigate impacts of climate change.

CyclAUS Technical Specifications

Hazard Resolution

Variable resolution, down to 90m

Exposure Resolution

Location Address Level

Event Catalogue

50,000 years of stochastic tropical cyclones

Wind and Exposure Parameters

Local gust wind speed at 10m elevation (3s average), wind regions, building age, building height.

Line of Business

Residential / Commercial / Industrial

Business Interruption

Residential ALE / Commercial / Industrial

Coverage

All Properties on mainland Australia and Tasmania. 100% GNAF / Geoscape / Geovision

Learn More About CyclAUS

Get the opportunity to speak with the team who developed the CyclAUS model.


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