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FloodAUS: Detailed Australian Riverine Flood Loss Model

Riverine flooding is one of the most costly perils in Australia. The 2023 normalisation of the Insurance Council of Australia Disaster Loss list has riverine flooding contributing over 22% of the loss for natural disasters in Australia. The National Flood Information Database (NFID) shows that over one million addresses have some level of flood risk in Australia.

With climate change the risk from riverine flooding is likely to exacerbate. The frequency and intensity of heavy rainfall events are expected to increase, leading to more frequent and severe flooding. This will have a significant impact on property values and insurance premiums, as well as the cost of rebuilding after a flood.

Risk Frontiers’ riverine flood model, FloodAUS, provides high resolution riverine flood modelling and data to determine the return period of floodwater depth at individual addresses in Australia for over 500,000 unique simulated events. Building on our recognised expertise in developing and managing the National Flood Information Database (NFID) for the Insurance Council of Australia, peer reviewed research and on-the-ground post-event surveys, FloodAUS 4.0 has national coverage for modelling the impact of floods on property and businesses.

 

FloodAUS Model Overview

FloodAUS is Risk Frontiers’ riverine flood loss model for Australian property exposures that incorporates the latest flood studies, research and expertise.

It is a probabilistic loss model which incorporates high resolution flood modelling and data to represent the hazard as the average annual probability of floodwater depth at individual addresses in hazard as the average annual probability of floodwater depth at individual addresses in Australia. The data source for the hazard is the NFID, which is described below. Risk Frontiers’ internal flood data collection and handling is used to supplement NFID where required. Catchment correlations are incorporated using over 100 years of historical rain gauge data. For the vulnerability a semi-empirical approach has been used, using a combination of empirical derived vulnerability curves from engineering studies and insurance claims data.

FloodAUS Features

NFID/FEZ

Risk Frontiers Flood Australia Pty Ltd and Willis Re Australia have been developing the National Flood Information Database (NFID) for the ICA. NFID is fundamentally a database of flood risk information at street address resolution. The current version of NFID contains around 8.3 million addresses out of 15.2 million addresses in Australia and includes data on the main at-risk areas of Australia. For the remaining addresses, Risk Frontiers has developed a methodology that takes into consideration the critical flood hazard attributes of catchments and determines Flood Exclusion Zones (FEZs) for addresses that lie beyond the Probable Maximum Flood extent. FEZ addresses count for a further 5.1 million addresses meaning the model scope covers roughly 13.4 million addresses in total.

Catchment Correlations

Regional rainfall patterns dictate that the incidence of flooding cannot be treated as independent between catchments. As one catchment floods, there is a conditional probability that another catchment will also flood to a similar, or different, magnitude. To account for these inter-dependencies, a set of cross-catchment flood event correlations is used in FloodAUS. Specifically, these are used to estimate the probability of occurrence (and magnitude) of a flood event in a catchment given the occurrence of an event in another catchment during a time window of one week.

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 FloodAUS?

Insurers/ReInsurers

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Local Government

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Federal Government

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FloodAUS Technical Specifications

Hazard Resolution

Better than 0.01%

Exposure Resolution

Location Address Level

Event Catalogue

50,000 years of stochastic flood data derived from NFID and Risk Frontiers’ own aggregation and acquisition of definitive flood data

Line of Business

Residential|Commercial|Industrial

Business Interruption

ALE|Commercial|Industrial

Coverage

All properties on mainland Australia and Tasmania. Utilises G-NAF|Geoscape and/or Geovision
Risk Frontiers Chief Geospatial Scientist

James O’Brien, Chief Geospatial Scientist

Learn More About FloodAus

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


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