flood
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<div>The A1 poster incorporates 4 images of Australia taken from space by Earth observing satellites. The accompanying text briefly introduces sensors and the bands within the electromagnetic spectrum. The images include examples of both true and false colour and the diverse range of applications of satellite images such as tracking visible changes to the Earth’s surface like crop growth, bushfires, coastal changes and floods. Scientists, land and emergency managers use satellite images to analyse vegetation, surface water or human activities as well as evaluate natural hazards.</div>
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The increasing availability of high-resolution digital elevation models (DEMs) is leading to improvements in flood analysis and predictions of surface-groundwater interaction in floodplain landscapes. To produce accurate predictions of flood inundation and calculations of flood volume, a 1m resolution LiDAR DEM was initially levelled to the Darling River floodplain by subtracting interpolated floodplain elevation trend surface from the DEM. This produces a de-trended flood-plain surface. Secondly, the levelled DEM surface was adjusted to the water-level reading at the Darling-River gauging station (Site 425012) at the time when the LiDAR was acquired. Flood extents were derived by elevation slicing of the adjusted levelled DEM up to any chosen river level. River-level readings from historical and current events utilised NSW Office of Water real-time river data. The flood-depth dataset is an inverted version of the flood-extent grid. Predicted flood depth and extent were classified by depth/elevation slice ranges of the adjusted de-trended DEM with 25 and 50 cm increments. In summary, the extent and depth of water inundation across the Darling floodplain have been predicted under different flooding scenarios, and validated using satellite data from historical (1990) and recent (2010/11) flood events. In all cases imagery and photo validation proved that predicted extents are accurate. The flood-risk predictions were then applied to a number of river-level scenarios. The flood risk predictions maps have been used as an input into developing recharge potential maps, and are being employed in flood-hazard assessments and infrastructure planning.
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There are a number of factors which influence the direct consequence of flooding. The most important are depth of inundation, velocity, duration of inundation and water quality. Though computer modelling techniques exist that can provide an estimate of these variables, this information is seldom used to estimate the impact of flooding on a community. This work describes the first step to improve this situation using data collected for the Swan River system in Perth, Western Australia. Here, it is shown that residential losses are underestimated when stage-damage functions or the velocity-stage-damage functions are used in isolation. This is because the functions are either limited to assessing partial damage or structural failure resulting from the movement of a house from its foundations. This demonstrates the need to use a combination of techniques to assess the direct economic impact of flooding.
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11-5519 Metropolitan Manilla (Philippines). Philippine GIS data-sets should arrive from the source on the 15th of July, 2011. GAV will process the data, and produce a short movie. The movie will reveal the 17 town halls of the greater metro Manilla; and outline the fault line, as well as earthquake affected areas, flood affected areas and cyclone affected areas. This movie is for the Philippine Govt. via Ausaide, and will include photographs of Philippine nationals assisting in disaster reduction work. The aquired data-sets will be stored on the GA data store, where access can be gained through communication with Luke Peel - GEMD National Geographic Information Section, Geoscience australia.
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The Risk Research Group at Geoscience Australia (GA) in Canberra is a multidisciplinary team engaged in the development of risk models for a range of natural hazards that are applicable to Australian urban areas. The Group includes hazard experts, numerical modellers, engineers, economists, and a specialist researching social vulnerability. The risk posed by riverine flooding to residential buildings is an important component of the work undertaken by the Group and is the focus of this paper. In 1975 researcher Richard Black published a report titled Flood Proofing Rural Residences as part of a multidisciplinary investigation of flood risk management in the USA. Black's research produced a number of curves describing combinations of water depth and velocity theoretically required to move a flooded house from its foundations. These so-called 'Black's Curves' have been referenced by numerous researchers worldwide since their publication. The houses used in Black's study are small by modern standards, and construction materials used in Australia can differ from those used in Black's research.
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ACRES acquired SPOT 2 satellite images over the Namoi River, between the towns of Walgett and Wee Waa in December 1997 and November 2000. The November 2000 image consists of 12 scenes in which floodwaters, peaking at 8 metres, inundating the region are visible as green and light blue. Extensive flooding is evident. The December 1997 image shows the area of the Namoi River without floodwaters. The Namoi River catchment area is more than 350 kilometres long and stretches from Walcha in the east to Walgett in the west. Other river systems in the region include the Gwydir, Castlereagh, Hunter, Macquarie, Macleay, Manning, Culgoa and Condamine. You can find these rivers on Geoscience Australia's interactive Map of Australia.
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The Swan River is the main river through Perth, the capital city of Western Australia. Direct tangible economic losses to residential dwellings in Perth was based on hydraulic modelling using the one dimensional unsteady flow model HEC-RAS, geographical information systems, a building exposure database and synthetic stage-damage curves. Eight flood scenarios ranging from the 10 year average recurrence interval (ARI) to the 2000 year ARI event were examined. The combined structure and contents flood losses ranged from A$17 million to A$659 million for insured structures and A$14 million to A$583 million for uninsured structures. This equates to an average annual damage of A$9.6 million and A$7.9 million respectively. The results reinforce the need to consider a wide range of varying magnitude flood events when assessing losses due to the temporal and spatial variation between flood scenarios.
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In this paper a new benchmark for tsunami model validation is pro- posed. The benchmark is based upon the 2004 Indian Ocean tsunami, which provides a uniquely large amount of observational data for model comparison. Unlike the small number of existing benchmarks, the pro- posed test validates all three stages of tsunami evolution - generation, propagation and inundation. Specifically we use geodetic measurements of the Sumatra{Andaman earthquake to validate the tsunami source, al- timetry data from the jason satellite to test open ocean propagation, eye-witness accounts to assess near shore propagation and a detailed inundation survey of Patong Bay, Thailand to compare model and observed inundation. Furthermore we utilise this benchmark to further validate the hydrodynamic modelling tool anuga which is used to simulate the tsunami inundation. Important buildings and other structures were incorporated into the underlying computational mesh and shown to have a large inuence of inundation extent. Sensitivity analysis also showed that the model predictions are comparatively insensitive to large changes in friction and small perturbations in wave weight at the 100 m depth contour.
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Floods are Australia's most expensive natural hazard with annual average damages estimated at $377 million. Modelling flood hazard and potential flood impact is therefore an important first step in reducing the cost of floods to the community. The availability of a rigorously tested free software modelling tool for flooding would assist in meeting this objective. ANUGA is a collaborative effort of Geoscience Australia and the Australian National University and has gained increasing interest as an open source two-dimensional flood model. The development of ANUGA for flood modelling purposes has been guided and furthered through close consultation with a number of local government and consulting engineers. This paper highlights case studies where ANUGA has been used for both hydrological and hydraulic modelling. This paper also makes two broad recommendations. The first recommendation is for further model validation against historical flood events. Additional model comparison is also needed, particularly against other two-dimensional models. ANUGA should also be validated against a suite of hydraulic tests to provide confidence in ANUGA's ability to be used as a general purpose hydraulic model. The second broad recommendation is that the ANUGA software is further developed to make it comparable with other two-dimensional flood models. Priorities for this development include the ability to model structures (culverts, pipes and bridges), the addition of a kinematic viscosity term and the inclusion of discharge as an inflow boundary condition. The ability to incorporate variable bed elevation in models, account for water storage in buildings and consider spatially and depth varying Manning's friction 'n' are also important. The development of a graphical (geographical information systems) user interface would make ANUGA more accessible.
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This paper introduces the work of the National Flood Risk Advisory Group in providing advice and guidance on the management of flood risk in Australia, in particular its work on the development of a set of national guidelines. The guidelines are included as an appendix and they highlight that communities utilise the support and cooperation of departments and agencies across all levels of government to effectively access the broad range of skills and the funding essential to implement flood risk management solutions. The paper discusses the more important flood risk considerations embodied in the guidelines.