The Australian National Coastal Vulnerability Assessment (NCVA) has been commissioned by the Federal Government (Department of Climate Change) to assess the risk to coastal communities from climate related hazards including sea-level rise, storm surge and severe wind from tropical cyclones. In addition to an understanding of the impact/risk posed by the current climate, we have also examined the change in risk under a range of future climate scenarios considering a number of periods up to the end of the 21st century. In collaboration with state and local governments and private industry, this assessment will provide information for application to policy decisions for, inter alia, land use, building codes, emergency management and insurance applications. The understanding of coastal vulnerability and risk is derived from a number of factors, including: the frequency and intensity of the hazard(s); community exposure and the relationship with stressors; vulnerability related to socio-economic factors; impacts that result from the interaction of those components; and capacity of communities, particularly vulnerable communities and groups, to plan, prepare, respond and recover from these impacts. These factors and resulting impacts from hazard events are often complex and often poorly known, but such complexity and uncertainty is not an excuse for inaction. Given these limitations, the NCVA has been undertaken using the best information available to understand the risk to coastal areas on a national scale, and to prioritise areas that will require more detailed assessment.

The current study has developed a national methodology for assessing the hazard that peak wind gusts pose to Australian communities. The key components of the hazard assessment model include the regional wind hazard and the hazard modification multipliers. The local effects on return period regional wind speeds were determined utilising remote sensing techniques, digital elevation data, and formulae presented in the wind loadings standard AS/NZS 1170.2 [1]. The estimation of the local wind speeds was evaluated by combining the local wind multipliers (terrain/height, shielding and topographic) for eight cardinal directions with the return period regional wind speeds (from [1]) on a 25 metre grid across the areas examined for each region. Here we seek to use the 500 year return period wind gust hazard from the Australian/New Zealand wind loadings standard (AS/NZS 1170.2) [1], which is a building design document that seeks to 'envelope' possible wind effects, as a proxy for the regional hazard. Arthur et al. [2] provide a new hazard assessment for the Australian continent, which we plan to utilise in future updates. Tanh and Letchford [3] compared current US, Australian/New Zealand, European and Japanese wind standards and reported that the treatment of topographic effects in these design standards is on the whole conservative. Holmes [4] proposed adjustments to remove the conservatism from the methods in the Australian wind loading standard to assess risk. These proposals and several other initiatives were adopted to improve various components of the model from its initial steps [5] towards a reliable nationally consistent wind hazard assessment for Australia.

This user guide describes the important instructions for using the Tasmanian Extreme Wind Hazard Standalone Tool (TEWHST). It aims to assist the Tasmanian State Emergency Service (SES) to view the spatial nature of extreme wind hazard (and how it varies depending on the direction of the extreme wind gusts). This information indicates detailed spatial texture for extreme hazard, which can provide guidance for understanding where the local-scale hazard (and impact) is expected to be the greatest for any particular event depending on the intensity and directional influence of the broad-scale severe storm. The tool provides spatial information at the local scale (25 metre resolution) of the return period extreme wind hazard (3-second gust at 10 metre height; variation with direction) where the broad-scale regional hazard is provided by the Australian and New Zealand Wind Loading Standard (AS/NZS 1170.2, 2002).

Geoscience Australia's Risk & Impact Analysis Group has developed a statistical model of wind hazard utilising the Generalised Pareto Distribution (GPD). The model calculates the return period of severe winds based on daily maximum wind gust observations. The model utilises an automated procedure to partition the data into the hazard constituents (thunderstorms, synoptic winds, tornadoes, etc) based on the World Meteorological Observation Codes 3-hourly coded observations. This observational data set records the archived and present weather at the station site. The model fits the GPD to the station data (daily maximum wind gust) by automating the selection of the appropriate threshold above which data is included in the extreme value distribution. This threshold <em>u</em> is selected as the maximum of all feasible return period values obtained by fitting the GPD. Published comparative findings, including same region results, demonstrate the model can produce similar results in a more efficient, fully computational way. Confidence intervals for return periods are calculated automatically to allow wind analysts to distinguish regions of greater reliability.

A model to assess severe wind hazard using climate-simulated wind speeds have been developed at Geoscience Australia (Sanabria and Cechet, 2010a). The model has a num-ber of advantages over wind hazard calculated from observational data: Firstly the use of climate-simulated data makes it possible to assess wind hazard over a region rather than at a recording station. Secondly climate-simulated data allows wind analysts to calculate wind hazard over a long climatology and, more importantly, to consider the impact of cli-mate change on wind hazard. In this paper we discuss model sensitivity to two IPCC scenarios: scenario B1, a low emissions scenario, and scenario A2, a high emissions scenario. Current and future climate is considered. Currently we deal only with gusts associated with synoptic winds (mid-latitude weather systems) as the climate model only provides mean winds at a resolution of 14 km, which does not resolve thunderstorms. MODEL DESCRIPTION The model involves three computationally processes: - Calculation of return period (RP) for gust wind speed using a statistical model; - Extraction of wind speeds from a high resolution climate model; and - A Monte Carlo method to generate synthetic gust speeds based on a convolution of modelled mean speeds and empirical gust factor measurements.

Knowledge of the degree of damage to residential structures expected from severe wind is used to study the benefits from adaptation strategies developed in response to expected changes in wind severity due to climate change, inform the insurance industry and provide emergency services with estimates of expected damage. A series of heuristic wind vulnerability curves for Australian residential structures has been developed for the National Wind Exposure project. In order to provide rigor to the heuristic curves and to enable quantitative assessment to be made of adaptation strategies, work has commenced by Geoscience Australia in collaboration with James Cook University and JDH Consulting to produce a simulation tool to quantitatively assess damage to buildings from severe wind. The simulation tool accounts for variability in wind profile, shielding, structural strength, pressure coefficients, building orientation, component self weights, debris damage and water ingress via a Monte Carlo approach. The software takes a component-based approach to modelling building vulnerability. It is based on the premise that overall building damage is strongly related to the failure of key components (i.e. connections). If these failures can be ascertained, and associated damage from debris and water penetration reliably estimated, scenarios of complete building damage can be assessed. This approach has been developed with varying degrees of rigor by researchers around the world and is best practice for the insurance industry. This project involves the integration of existing Australian work and the development of additional key components required to complete the process.