Estimating present day extreme total water level exceedance probabilities around the Australian coastline

The occurrence of extreme water level events along low-lying, highly populated and/or developed coastlines can lead to devastating impacts on coastal infrastructure. Therefore it is very important that the probabilities of extreme water levels are accurately evaluated to inform flood and coastal management and for future planning. The aim of this study was to provide estimates of present day extreme total water level exceedance probabilities around the whole coastline of Australia, arising from combinations of mean sea level, astronomical tide and storm surges generated by both extra-tropical and tropical storms, but exclusive of surface gravity waves. The study has been undertaken in two main stages. In the first stage, a high-resolution (~10 km along the coast) hydrodynamic depth averaged model has been configured for the whole coastline of Australia using the Danish Hydraulics Institute’s Mike21 modelling suite of tools. The model has been forced with astronomical tidal levels, derived from the TPX07.2 global tidal model, and meteorological fields, from the US National Center for Environmental Prediction’s global reanalysis, to generate a 61-year (1949 to 2009) hindcast of water levels. This model output has been validated against measurements from 30 tide gauge sites around Australia with long records. At each of the model grid points located around the coast, time series of annual maxima and the several highest water levels for each year were derived from the multi-decadal water level hindcast and have been fitted to extreme value distributions to estimate exceedance probabilities. Stage 1 provided a reliable estimate of the present day total water level exceedance probabilities around southern Australia, which is mainly impacted by extra-tropical storms. However, as the meteorological fields used to force the hydrodynamic model only weakly include the effects of tropical cyclones the resultant water levels exceedance probabilities were underestimated around western, northern and north-eastern Australia at higher return periods. Even if the resolution of the meteorological forcing was adequate to represent tropical cyclone-induced surges, multi-decadal periods yielded insufficient instances of tropical cyclones to enable the use of traditional extreme value extrapolation techniques. Therefore, in the second stage of the study, a statistical model of tropical cyclone tracks and central pressures was developed using histroic observations. This model was then used to generate synthetic events that represented 10,000 years of cyclone activity for the Australia region, with characteristics based on the observed tropical cyclones over the last ~40 years. Wind and pressure fields, derived from these synthetic events using analytical profile models, were used to drive the hydrodynamic model to predict the associated storm surge response. A random time period was chosen, during the tropical cyclone season, and astronomical tidal forcing for this period was included to account for non-linear interactions between the tidal and surge components. For each model grid point around the coast, annual maximum total levels for these synthetic events were calculated and these were used to estimate exceedance probabilities. The exceedance probabilities from stages 1 and 2 were then combined to provide a single estimate of present day extreme water level probabilities around the whole coastline of Australia.

SWIRLnet : portable anemometer network for wind speed measurements of land-falling tropical cyclones

Wind speed measurement systems are sparse in the tropical regions of Australia. Tropical cyclone wind speeds impacting communities are often ‘guestimated’ from analyzing damaged structures. A re-locatable anemometer system is required to enable measurements of wind speeds. This paper discusses design criteria of the tripods and tie down system, proposed deployment of the anemometers, instrumentation, and data logging. Preliminary assessment of the anemometer response indicates a reliable system for 1 second response, however, it is noted that the Australian building code and wind loading standard uses a moving average time of approximately 0.2 seconds for its wind speed design criteria.

Wind speed measurements of land-falling tropical cyclones using SWIRLnet, a portable anemometer network

Wind speed measurement systems are sparse in the tropical regions of Australia. Given this, tropical cyclone wind speeds impacting communities are seldom measured and often only ‘guestimated’ by analysing the extent of damage to structures. In an attempt to overcome this dearth of data, a re-locatable network of anemometers to be deployed prior to tropical cyclone landfall is currently being developed. This paper discusses design criteria of the network’s tripods and tie down system, proposed deployment of the anemometers, instrumentation and data logging. Preliminary assessment of the anemometer response indicates a reliable system for measuring the spectral component of wind with frequencies of approximately 1 Hz. This system limitation highlights an important difference between the capabilities of modern instrumentation and that of the Dines anemometer (around 0.2 seconds) that was used to develop much of the design criteria within the Australian building code and wind loading standard.

Extreme water level exceedance probabilities around Australia

The potential impacts of extreme water level events on our coasts are increasing as populations grow and sea levels rise. To better prepare for the future, coastal engineers and managers need accurate estimates of average exceedance probabilities for extreme water levels. In this paper, we estimate present day probabilities of extreme water levels around the entire coastline of Australia. Tides and storm surges generated by extra-tropical storms were included by creating a 61-year (1949-2009) hindcast of water levels using a high resolution depth averaged hydrodynamic model driven with meteorological data from a global reanalysis. Tropical cyclone-induced surges were included through numerical modelling of a database of synthetic tropical cyclones equivalent to 10,000 years of cyclone activity around Australia. Predicted water level data was analysed using extreme value theory to construct return period curves for both the water level hindcast and synthetic tropical cyclone modelling. These return period curves were then combined by taking the highest water level at each return period.

Queensland floods anniversary : Brian Willmett

"In today's story we hear from Postmans Ridge helicopter pilot, Brian Willmett, and how he and his neighbours worked together to rescue four people, including Kevin and Eileen Lees, from the inland tsunami which swept down the Lockyer Valley during last year's Queensland floods. It was a ten metre high wave that swept through Postmans Ridge that day, ripping houses from their foundations and sweeping two people to their deaths. Brian Willmett was at home when he suddenly ran to rescue neighbours who were in danger. To mark the anniversary of the floods in Queensland, ABC Open has compiled Aftermath, an extensive look at the Queensland floods as well as floods in NSW, Victoria and remote Western Australia, Cyclone Yasi and the 2009 Victorian 'Black Saturday' bushfires. Australia certainly has been hit by a few disasters in the past two or so years. The site has a timeline showing content from these six disasters, with links to about 40 people effected by these disasters. If you go to that site you will be able to choose a person to watch videos about them."

Queensland floods anniversary : Angela Emmerson

"We're marking the anniversary of the destructive floods that hit Queensland a year ago this week with our series of interviews from survivors. Today's story is from Helidon teenager and university student Angela Emmerson, who tells Amanda Gearing how she and her sister scrambled to the roof to escape the dangerous flash flood which suddenly engulfed their house on the 10th of January last year. Tomorrow we'll hear from Grantham resident Rob Wilkin who rescued 31 local people using his car and boat. He helped them escape to safety as 138 houses in the town were destroyed. To mark the anniversary of the floods in Queensland, ABC Open has compiled Aftermath, an extensive look at the Queensland floods as well as floods in NSW, Victoria and remote Western Australia; Cyclone Yasi and the 2009 Victorian 'Black Saturday' bushfires. Australia certainly has been hit by a few disasters in the past two or so years. The site has a timeline showing content from these six disasters, with links to about 40 people effected by these disasters. If you go to that site you will be able to choose a person to watch videos about them."

Queensland floods anniversary : Rob Wilkin

"This week, we have been marking the anniversary of the destructive floods that hit Queensland a year ago this week with a series of interviews from survivors. Today's story comes from Grantham resident Rob Wilkin who helped save 31 people in the flash flood disaster on the 10th of January last year. 23 people in Toowoomba and the Lockyer Valley died and 138 houses in the town were destroyed.. To mark the anniversary of the floods in Queensland, ABC Open has compiled 'Aftermath', an extensive look at the Queensland floods as well as floods in NSW, Victoria and remote Western Australia, Cyclone Yasi and the 2009 Victorian 'Black Saturday' bushfires. Australia certainly has been hit by a few disasters in the past two or so years. The site has a timeline showing content from these six disasters, with links to about 40 people effected by these disasters. If you go to that site you will be able to choose a person to watch videos about them."

La Niña : we knew it was coming, and it’s not going away

"The major La Niña climate event responsible for record flooding in Queensland  - and the largest ever cyclone to hit Australia in Yasi  —  is not over yet according to a senior climatologist at Britain’s Met office."

Making stories matter: Using participatory new media storytelling and evaluation to serve marginalised and regional communities

In this chapter, we draw on our experiences facilitating community storytelling workshops in regional Queensland in partnership with the Queensland branch of Oral History Association of Australia (OHAA Qld) in order to develop a best practice model for promoting creative approaches to recording oral narratives using digital tools, informed by creative writing practice and embedded evaluation (Klaebe 2012 & 2013). These experiences offer an insight into how creative approaches to training can facilitate the sharing and preservation of stories in regional communities.

Partisipasi masyarakat dalam pengayaan koleksi elektronik warisan dokumenter

This paper discusses documentary heritage collection enrichment programs run with community participation. Two library programs at the State Library of Queensland (SLQ) are explored as examples. The programs are the Flood and Cyclone Mosaic and Pitch in! The challenges for the implementation of such programs in Indonesia are also discussed in the last section of the paper. This paper provides better understanding of documentary heritage collection enrichment strategies conducted by a public library in Queensland, Australia. It is expected that this paper will inspire public libraries in Indonesia to maximise their documentary collection enrichment strategies with community participation. This paper can also help the National Library of Indonesia (PNRI) in designing their documentary heritage collections enrichment strategies in its role as the Web portal provider of the national documentary heritage repository. Tulisan ini membahas program pengayaan koleksi warisan dokumenter yang dilaksanakan dengan partisipasi masyarakat. Dua program perpustakaan di the State Library of Queensland (SLQ) dieksplorasi sebagai contoh. Program-program yang dibahas adalah Flood and Cyclone Mosaic dan Pitch In! Tantangan yang harus dihadapi untuk penerapan program semacam di Indonesia juga dibahas di bagian akhir tulisan. Tulisan ini memberikan pemahaman mengenai strategi pengayaan koleksi warisan dokumenter yang dilakukan oleh sebuah perpustakaan umum di Queensland, Australia. Diharapkan tulisan ini dapat menjadi inspirasi bagi perpustakaan umum di Indonesia untuk dapat memaksimalkan strategi pengayaan koleksi dokumenter mereka dengan melibatkan partisipasi masyarakat. Tulisan ini juga dapat membantu Perpustakaan Nasional Republik Indonesia (PNRI) dalam merancang strategi pengayaan koleksi warisan dokumenter mereka dalam perannya sebagai penyedia portal Web repositori warisan dokumenter bangsa.

Environmental context for late Holocene human occupation of the South Wellesley Archipelago, Gulf of Carpentaria, northern Australia

A 2400 year record of environmental change is reported from a wetland on Bentinck Island in the southern Gulf of Carpentaria, northern Australia. Three phases of wetland development are identified, with a protected coastal setting from ca. 2400 to 500 years ago, transitioning into an estuarine mangrove forest from ca. 500 years ago to the 1940s, and finally to a freshwater swamp over the past +60 years. This sequence reflects the influence of falling sea-levels, development of a coastal dune barrier system, prograding shorelines, and an extreme storm (cyclone) event. In addition, there is clear evidence of the impacts that human abandonment and resettlement have on the island's fire regimes and vegetation. A dramatic increase in burning and vegetation thickening was observed after the cessation of traditional Indigenous Kaiadilt fire management practices in the 1940s, and was then reversed when people returned to the island in the 1980s. In terms of the longer context for human occupation of the South Wellesley Archipelago, it is apparent that the mangrove phase provided a stable and productive environment that was conducive for human settlement of this region over the past 1000 years.

Fatigue capacity of cold-formed steel roof battens under cyclic wind uplift loads

Steel roofs made of thin cold-formed steel roof claddings and battens are widely used in low-rise residential and industrial buildings all around the world. However, they suffer from premature localised pull-through failures in the batten to rafter connections during high wind events. A recent study proposed a suitable design equation for the pull-through failures of thin steel roof battens. However, it was limited to static wind uplift loading. In contrast, most cyclone/storm events produce cyclic wind uplift forces on roofs for a significantly long period, thus causing premature fatigue pull-through failures at lower loads. Therefore, a series of constant amplitude cyclic load tests was conducted on small and full scale roof panels made of a commonly used industrial roof batten to develop their S-N curves. A series of multi-level cyclic tests, including the recently introduced low-high-low (LHL) fatigue loading test, was also undertaken to simulate a design cyclone. Using the S-N curves, the static pull-through design capacity equation was modified to include the effects of fatigue. Applicability of Miner’s rule was evaluated in order to predict the fatigue damage caused by multi-level cyclic tests such as the LHL test, and suitable modifications were made. The combined use of the modified Miner’s law and the S-N curve of roof battens will allow a conservative estimation of the fatigue design capacity of roof battens without conducting the LHL tests simulating a design cyclone. This paper presents the details of this study, and the results.