The aim of this document is to * outline the information management process for inundation modelling projects using ANUGA * outline the general process adopted by Geoscience Australia in modelling inundation using ANUGA * allow a future user to understand (a) how the input and output data has been stored (b) how the input data has been checked and/or manipulated before use (c) how the model has been checked for appropriateness

Widespread flooding and associated damage in south-east Queensland during January and February, 2011 have demonstrated the importance of flood risk assessment. Flood risk assessment requires knowledge of the hazard, nature of properties exposed and their vulnerability to flood damage. Flood risk assessment can addresses different aspects of flood risk, i.e., hydrological, structural, economic and social aspects. This report presents the results of work undertaken by Geoscience Australia during 2011-2012 to further the understanding of the vulnerability of Australian buildings to inundation. The work consists of three parts: 1. Development of vulnerability curves for inundation, without velocity, of residential homes of the types encountered during surveys following the January, 2011 flooding in south-east Queensland. 2. Development of vulnerability curves for inundation, without velocity, of building types typical of the Alexandria Canal area of the inner south of Sydney. 3. Development of vulnerability curves for inundation with velocity (storm surge) of residential homes of the types encountered during surveys following TC Yasi, February, 2011.

User Manual - Australian Flood Studies Database Search

An integrated multi-scale approach has been used to map and assess shallow (<100m) aquitards in unconsolidated alluvial sediments beneath the Darling River floodplain. The study integrated a regional-scale (7,500km2) airborne electromagnetics (AEM) survey with targeted ground electrical surveys, downhole lithological and geophysical (induction, gamma and nuclear magnetic resonance (NMR)) logging, hydraulic testing and hydrogeochemistry obtained from a 100 borehole (7.5km) sonic and rotary drilling program. Electrical conductivity mapping confirmed a relatively continuous lacustrine Blanchetown Clay aquitard, mostly below the water table. The Blanchetown Clay is typically 5-10m thick with a maximum thickness of 18m but, importantly, can also be absent. Variations (up to 60m) in the elevation of the aquitard top surface are attributed partly to neotectonics, including warping, discrete fault offsets, and regional tilting. Hydrograph responses in overlying and underlying aquifers, laboratory permeameter measurements on cores, and hydrogeochemical data demonstrate where the Blanchetown Clay acts as an effective aquitard. In these areas, the AEM and induction logs can show an electrical conductivity (EC) decrease towards the centre of the clay rich aquitard, contrary to the typical response of saturated clays. Even though the aquitard centre is below the watertable, core moisture data and NMR total water logs indicate very low water content, explaining the relatively low EC response. The NMR logs also indicate that the clay aquitard is partially saturated both from the top and the bottom. This suggests very low hydraulic conductivities for the aquitard resulting in negligible vertical leakage in these areas. This is supported by core permeameter measurements of less than 10-12 m/s.

The satellite images below show the dramatic effect on the land of recent heavy rain, causing floodwaters to inundate south-west Queensland. This area is known as the Channel Country and has an extensive braided river system which includes the Georgina River, the Diamantina River and Cooper Creek. Excess water from this area generally feeds into the Lake Eyre system which is a vast drainage basin in Australia's arid interior. Flooding of the magnitude visible on the satellite images can cause Lake Eyre to fill up - something which occurs very rarely.

The Australian Flood Risk Information Portal (the portal) is an initiative of the Australian Government, established following the devastating floods across Eastern Australia in 2011. The portal is a key component of the National Flood Risk Information Project (NFRIP), and aims to provide a single point of access to Australian flood information. Currently much of Australia's existing flood information is dispersed across disparate sources, making it difficult to find and access. The portal will host data and tools that allow public discovery, visualisation and retrieval of flood studies, flood maps, satellite derived water observations and other related information, all from a single location. The portal will host standards and guidelines for use by jurisdictions and information custodians to encourage best practice in the development of new flood risk information. While the portal will initially host existing flood information, the architecture has been designed to allow the portal content to grow over time to meet the needs of users. The aim is for the portal to display data for a range of scenarios from small to extreme events, though this will be dependent on stakeholder contributions. Geoscience Australia's Australian Flood Studies Database is the portal's data store of flood study information. The database includes metadata created through a purpose-built data entry application, and over time, information harvested from state-operated catalogues. For each entry the portal provides a summary of the flood study, including information on how the study was done, what data was used, what flood maps were produced and for what scenarios, as well as details on the custodian and originating author. If the study included an assessment of damage, details such as estimates of annual average damage, or the number of properties affected during a flood of a particular likelihood will also be included. During the last phase of development downloadable flood study reports and their associated flood maps have been added to the portal where available. As the portal is populated it will increasingly host mapped flood data, or link to flood data and maps held in authoritative databases hosted by State and Territory bodies. Mapping data to be made accessible through the portal will include flood extents and to a lesser degree information on water depths. The portal will also include water observations obtained from Geoscience Australia's historic archive of Landsat imagery. This data will show whether a particular location was 'wet' at some point during the past 30 years. While this imagery does not necessarily represent the peak of a flood or show water depth, the data will support the validation and verification process of hydrologic and hydraulic flood modelling. This work will prove useful particularly in rural areas where there is little or no flood information. The portal also provides flood information custodians with the ability to either upload mapped data directly to the portal or to make this data accessible via web services. Data management tools and standards, developed through NFRIP, will enable data custodians to map their data to agreed standards for delivery through the portal. A portal framework and supporting principles has been developed to guide the maintenance and development of the portal.

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.

In this study, a 1 m resolution LiDAR Digital Elevation Model (DEM) has been used for predictive flood modelling and flood-risk assessment that will inform recharge studies. To produce accurate predictions of flood inundation and calculations of flood volume, the DEM was initially levelled to the Darling River floodplain by subtracting interpolated floodplain elevation trend surface from the DEM. This produces a de-trended floodplain surface. Secondly, the levelled DEM surface was adjusted to the water level reading at the Darling River gauging station (Site 425012), upstream of Weir 32, 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 were extracted from the NSW Office of Water real time river data website. 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. Predicted flood extents have been validated by comparisons to satellite images from the 1990 floods, and photographs of inundation from recent 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. These included (1) examination of the extent of flooding at the highest historical level; (2) determination of the river level required to completely inundate the Coonambidgal Formation scroll plain in the GWMAR1 study area (probable maximum recharge potential) and (3) an assessment of flood impacts in 0.5 m increments from 5.5 to 7 m of river level rise at the Site 425012 gauging station. In summary, this flood modelling methodology has been used to predict the extent and depth of water coverage across the Darling floodplain under different scenarios.

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.

With the average annual cost of floods estimated at $377 million, floods are Australia's most expensive natural hazard. As a result, considerable expenditure is made by government and industry to define flood areas in an effort to reduce the impacts of floods. This work typically involves the creation of reports describing the methodology used, data sources and results of hydrological and hydraulic modelling and damage assessments. While numerous reports are developed each year, there was no centralised record of what studies had been undertaken in Australia at a state/territory or national level until the development of the Australian Flood Studies Database in 2004. In 2009 Geoscience Australia reviewed the Australian Floods Studies Database via an online questionnaire. Opinion of the database was sought in three key areas including database functionality and content, and updating the database. The respondents confirmed the usefulness of the existing database content including hydrology and hydraulic scenarios, historical flood events used in the calibration, terrain and floor level surveys, damage assessments, inundation and hazard scenarios, information on what has occurred since a study's completion and related studies. Recurring themes highlighted by the survey respondents include the ability to be able to access the flood study reports and GIS flood layers via the database and be able to input data. Over 170 people completed the survey; 90% of whom were from local government. While only 20% of respondents had used the database, 72% of all respondents to the survey indicated that they would use the database in the future, whether or not they had used the database in the past. Three main recommendations can be concluded from the survey responses. The first recommendation is that the Australian Flood Studies Database is updated and that the lead agency for floodplain management in each State/Territory be responsible for that update on at least an annual basis. The second recommendation is that the database's existing functionality and content is maintained and further enhanced. The final recommendation is that the database is further publicised.