A predictive model of weathering intensity or the degree of weathering has been generate over the Australian continent. The model has been generated using the Random Forest decision tree machine learning algorithm. The algorithm is used to establish predictive relationships between field estimates of the degree of weathering and a comprehensive suite of covariate or predictive datasets. The covariates used to generate the model include satellite imagery, terrain attributes, airborne radiometric imagery and mapped geology. The weathering intensity model is an estimate of the degree of surface weathering only. The interpretation of the weathering intensity is different for in-situ or residual landscapes compared with transported materials within depositional landscapes. In residual landscapes, weathering process are operating locally whereas in depositional landscapes the model is reflecting the degree of weathering either prior to erosion and subsequent deposition, or weathering of sediments after being deposited. The degree of surface weathering is particularly important in Australia where variations in weathering intensity correspond to the nature and distribution of regolith (weathered bedrock and sediments) which mantles approximately 90% of the Australian continent. The weathering intensity prediction has been generated using the Random Forest decision tree machine learning algorithm. The algorithm is used to establish predictive relationships between field estimates of the degree of weathering and a comprehensive suite of covariate or predictive datasets. The covariates used to generate the model include satellite imagery, terrain attributes, airborne radiometric imagery and mapped geology. Correlations between the training dataset and the covariates were explored through the generation of 300 random tree models. An r-squared correlation of 0.85 is reported using 5 K-fold cross-validation. The mean of the 300 models is used for predicting the weathering intensity and the uncertainty in the weathering intensity is estimated at each location via the standard deviation in the 300 model values. The predictive weathering intensity model is an estimate of the degree of surface weathering only. The interpretation of the weathering intensity is different for in-situ or residual landscapes compared with transported materials within depositional landscapes. In residual landscapes, weathering process are operating locally whereas in depositional landscapes the model is reflecting the degree of weathering either prior to erosion and subsequent deposition, or weathering of sediments after being deposited. The weathering intensity model has broad utility in assisting mineral exploration in variably weathered geochemical landscapes across the Australian continent, mapping chemical and physical attributes of soils in agricultural landscapes and in understanding the nature and distribution of weathering processes occurring within the upper regolith. <b>Value: </b>Weathering intensity is an important characteristic of the earth's surface that has a significant influence on the chemical and physical properties of surface materials. Weathering intensity largely controls the degree to which primary minerals are altered to secondary components including clay minerals and oxides. In this context the weathering intensity model has broad application in understanding geomorphological and weathering processes, mapping soil/regolith and geology. <b>Scope: </b>National dataset which over time can be improved with additional sites for training and thematic datasets for prediction.

The impact of seismic surveys on the catchability of marine fish is a contentious issue, with claims that seismic surveys may negatively affect catch rates. However little empirical evidence exists to quantify the impacts or determine potential causes. In this study, we used a 2-D seismic survey in the Gippsland Basin, Bass Strait, Australia in April 2015 as an opportunity to quantify fish behaviour (field-based) and commercial fisheries catch (desktop study) across the region before and after airgun operations. Three species found in abundance (gummy shark, swell shark, tiger flathead) were acoustically tagged and released within one of two acoustic arrays (experimental and control zone) and monitored before, during and after the seismic survey. In the field study, only 35% of the gummy sharks and 30% of the swell sharks were subsequently detected two days after release, although various individuals returned sporadically over the period of monitoring including during the seismic survey operations. Behaviour consistent with a possible response to the seismic survey operations was restricted to flathead which increased their swimming speed during the seismic survey period and changed their diel movement patterns after the survey. We also investigated the potential impacts of the seismic survey on catch rates using Commonwealth fisheries logbook data from Jan 2012 – Oct 2015. Fifteen species and two gear types (Danish seine, gillnet) were modelled to examine differences in catch rates before and after the seismic survey. The catch rates in the six months following the seismic survey were different than predicted in nine out of the 15 species examined, with six species (tiger flathead, goatfish, elephantfish, boarfish, broadnose shark and school shark) showing increases in catch following to the seismic survey, and three species (gummy shark, red gurnard, sawshark) showing reductions. Overall, we found little evidence consistent with behavioural or catch rate changes induced by the seismic survey in the targeted species, although behavioural data were limited because many sharks left the acoustic receiver array prior to the commencement of the seismic survey. <b>Citation:</b> Barry Bruce, Russ Bradford, Scott Foster, Kate Lee, Matt Lansdell, Scott Cooper, Rachel Przeslawski, Quantifying fish behaviour and commercial catch rates in relation to a marine seismic survey,<i> Marine Environmental Research</i>, Volume 140, 2018, Pages 18-30, ISSN 0141-1136. https://doi.org/10.1016/j.marenvres.2018.05.005.

Tropical Cyclone (TC) Tracy impacted Darwin early on Christmas Day, 1974. The magnitude of damage was such that Tracy remains deeply ingrained in the Australian psyche. Several factors contributed to the widespread damage, including the intensity of the cyclone and construction materials employed in Darwin at the time. Since 1974, the population of Darwin has grown rapidly, from 46,000 in 1974 to nearly 115,000 in 2006. If TC Tracy were to strike Darwin in 2008, the impacts could be catastrophic. We perform a validation of Geoscience Australia's Tropical Cyclone Risk Model (TCRM) to assess the impacts TC Tracy would have on the 1974 landscape of Darwin, and compare the impacts to those determined from a post-impact survey. We then apply TCRM to the present-day landscape of Darwin to determine the damage incurred if a cyclone identical to TC Tracy impacted the city in 2008. In validating TCRM against the 1974 impact, we find an underestimate of the damage at 36% of replacement cost (RC), compared the survey estimate of 50-60% RC. Some of this deficit can be accounted for through the effects of large debris. Qualitatively, TCRM can spatially replicate the damage inflicted on Darwin by the small cyclone. The northern suburbs suffer the greatest damage, in line with the historical observations. For the 2008 scenario, TCRM indicates a nearly 90% reduction in the overall loss (% RC) over the Darwin region. Once again, the spatial nature of the damage is captured well, with the greatest damage incurred close to the eye of the cyclone. Areas that have been developed since 1974 such as Palmerston suffer very little damage due to the small extent of the severe winds. The northern suburbs, rebuilt in the years following TC Tracy, are much more resilient, largely due to the influence of very high building standards put in place between 1975 and 1980. Article published in the Australian Journal of Emergency Management

<div>To set out how Geoscience Australia is meeting its vision for the Exploring for the Future program, we have summarised the ways our scientific activities, outputs and intended outcomes and impacts are linked, using the Impact Pathway diagram. This updated brochure includes program impact infographics.</div>

<div>The Severe Wind Hazard Assessment for Queensland arose as a project to better understand the potential impacts of tropical cyclones (TCs) on population centres and elements of critical infrastructure in Queensland. The rationale for the project was reinforced by lessons from Severe Tropical Cyclone (STC) Debbie, the direct and indirect impacts of which affected a significant area of Queensland, stretching from Bowen to the City of Gold Coast and Northern New South Wales between 28 March and 7 April 2017, resulting in 14 mostly flood associated deaths, and more than A$3.5 billion in direct losses. The intent of the project is to explore and assess a range of scenarios that extend beyond the contemporary recollection of severe events in order to challenge decision making for rarer but higher-consequence events. The scenarios described in the report can be used to improve planning for severe tropical cyclone (TC) events and their impacts. This includes developing a better understanding of how the capabilities of emergency services and supporting elements may be impacted in actual events.&nbsp;</div><div><br></div><div>Scenarios were selected from the catalogue of synthetic events (i.e. events that did not actually occur but whose occurrence was as probable as those that did occur) generated for the 2018 Tropical Cyclone Hazard Assessment (TCHA; Arthur, 2018), in consultation with Queensland Fire and Emergency Services (QFES) and those local governments involved within the project. Two TC events were modelled for each location for this project – a Category 3 and a Category 5 TC -with ‘favourable’ tracks for impact analysis. In all scenarios, consideration was given to regional historical analogues for the selected synthetic tracks to better relate the scenario outputs to known or “lived” events. These categories were chosen as they represent events with a moderate and very low likelihood with respect to intensity, based on historical observations. This also accounts for the future climate of less TCs but more intense occurrences, highlighting the different impacts arising from different events. It is important to emphasise and understand that each individual TC event will be different and lead to different impacts.&nbsp;</div><div><br></div>

Severe TC Vance was one of the most intense cyclones to impact mainland Australia. The observed damage to buildings could be explained in terms of structural performance of those buildings. Combining the structural vulnerability of housing with an estimate of the maximum wind gusts, we can explore the possible impacts that a repeat of Vance would cause in Exmouth, and compare the outcomes with what occurred in 1999. The analysis of the impacts of TC Vance on present-day Exmouth shows that very few houses would be completely destroyed. Not surprisingly, older houses (pre-1980’s construction era, excluding the US Navy block houses) would dominate those destroyed, and most likely the timber-framed style houses, many of which were substantially damaged in TC Vance. Published in the Australian Journal of Emergency Management July 2019 edition

The Severe Wind Hazard Assessment project aims to provide DFES with intelligence on the scale of impacts that could arise from major tropical cyclone events in communities along the northwest and western coast of WA. We simulated category 3 and 5 scenarios in the northwest, and category 1 and 3 scenarios down the west coast. Simulations included translating the local-scale wind fields into the level of damage to residential housing, through the application of vulnerability models applied to residential buildings which had been categorised on the basis of attributes such as construction era, roof type, wall type and location. Some scenarios produce impacts that are comparable to past events (e.g. the category 5 scenario for Exmouth is similar to TC Vance). Other scenarios are catastrophic, such as the category 3 scenario for Geraldton, where nearly all residential buildings in the city are extensively or completely damaged. The different outcomes for communities arises because of the different profiles of residential buildings in each community. Geraldton lies outside the cyclonic regions defined in AS/NZS 1170.2, so houses are not explicitly designed cope with to the extreme winds that can arise in TCs, hence major impacts were found there in our analysis. DFES used these scenarios to guide planning and preparations for events, such as TC Veronica in March 2019, guiding decisions on preparations and recovery options, which are explored in a companion paper. Abstract presented at the 2020 Australian Meteorological and Oceanographic Society 2020 National Conference (http://amos-2020.w.amos.currinda.com/)

The National Hazard Impact Risk Service for Tropical Cyclone Event Impact provides information on the potential impact to residential separate houses due to severe winds. The information is derived from Bureau of Meteorology tropical cyclone forecast tracks, in combination with building location and attributes from the National Exposure Information System and vulnerability models to define the level of impact. Impact data is aggregated to Statistical Area Level 1, categorised into five qualitative levels of impact.

<div>Ask a Queenslander where tropical cyclones (TCs) occur, and the inevitable response will be North Queensland. Whilst most of the tropical cyclones have made landfall north of Bundaberg, the cascading and concurrent effects are felt much further afield. The major flooding following TC Yasi in 2011 and TC Debbie in 2017, are just two examples where impacts were felt across the State, and of course, the wind impacts to the banana plantation following TC Larry (2006) was felt nationally.&nbsp;</div><div> &nbsp;</div><div>South East Queensland has not been forgotten when it comes to tropical cyclone impact with an event crossing Coolangatta in 1954. There was also the more recent TC Gabrielle which tracked offshore on its path southwards to New Zealand.&nbsp;&nbsp;</div><div>&nbsp;</div><div>Acknowledging that climate is influencing the intensity and frequency of more intense severe weather hazards, understanding how tropical cyclone hazard varies under future climate conditions is critical to risk-based planning in Queensland. With this climate influence, along with increasing population and more vulnerable building design in South East Queensland (relative to northern Queensland), there is an urgent need to assess the wind risk and set in place plans to reduce the impacts of a potential tropical cyclone impact in South East Queensland. <b>Citation:</b> Sexton, J., Tait, M., Turner, H., Arthur, C., Henderson, D., Edwards, M; Preparing for the expected: tropical cyclones in South East Queensland.<i> AJEM</i> 38:4, October 2023, pages 33-39.

The region of coastal South East Queensland (SEQ) represents a large concentration of population, business activity and infrastructure important to the economy of Queensland and Australia. The region is also subject to severe storms that can generate damaging winds, particularly as a result of thunderstorm and tropical cyclone activity. Older residential homes have historically been the most damaged in such storms, contributing disproportionately to community risk, and recent storm damage in Western Australia has indicated that there are issues with modern SEQ homes also. This risk posed by severe wind is not well understood, nor are the optimal strategies for managing and potentially reducing this risk. Previous work has provided insights into the potential impacts of rare storm events in the SEQ region and the vulnerability of residential homes that contribute to them. The Severe Wind Hazard Assessment for Queensland (SWHAQ) project (Arthur, et al., 2021) provided valuable insights on the potential impacts of rare tropical cyclones making landfall in the region. The SWHA-Q project included two storms impacting the Gold Coast that highlighted that credible cyclone events in South East Queensland generating no more than design level wind gusts can have challenging consequences. Five tropical cyclone scenario events were selected by the project partners and modelled to provide a demonstration of the residential housing damage outcomes that could result from plausible storms that could impact South East Queensland. Four storms generated category 3 winds (gusts over 165 km/h) on landfall and were essentially design level events for ordinary residential structures. The fifth (Scenario 3) generated category 4 winds (gusts over 225 km/h) at landfall but was still quite a credible storm for the region. The events highlighted, as did the previous SWHA-Q work, that rare cyclone events of this kind affect all parts of the study region and produce very significant consequences. One design level event (Scenario 2) was found to inflict moderate or greater damage to 39% of the homes in the region, representing a major need for temporary accommodation. One of the events was used as the evidence-based scenario that underpinned Exercise Averruncus – A SEQ Tropical Cyclone Impact held in Brisbane on 15 June 2022 that explored critical issues around preparation for, response to, and initial recovery from the event. It is noted that the scale of impacts from any scenario is contingent on the characteristics of the TC itself (size, intensity, landfall location) and on the landscape in which buildings are located. However, while each scenario is unique, the suite of scenario impacts provide a useful resource for EM planning by local government, emergency services and other agencies with a role in disaster recovery.