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  • 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

  • Floods are Australia's most expensive natural hazard with the average annual cost of floods estimated at AUD$377 million (BITRE 2008). This figure is likely to have risen following the widespread and devastating floods across eastern Australia that occurred over the summer of 2010-11. The development of tools to support the identification and analysis of flood risk is an important first step in reducing the cost of floods in the community. The Australian Government through Geoscience Australia (GA) has been leading the development of tools which assist in flood intelligence, modelling and damage assessment. An overview of three of these tools will be provided in this presentation. Note: Rest of abstract is too long for space provided.

  • 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.

  • 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.

  • 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.

  • 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.

  • The datasets created to produce the emergency mapping support products which contributed to fulfilling GA's arrangements in supporting the outcomes sought by the Australian Government during disaster events.

  • In this study, various hydrochemical approaches were used to understand recharge processes in shallow (<120m) unconsolidated alluvial sediments in a 7,500 km2 area of the Darling River floodplain. Pore fluids were extracted from sediments from 60 sonic-cored bores, and together with surface and groundwater samples, provided a hydrochemical dataset with over 1600 samples and 25 analytes. Major ion chemistry highlights a mixing signature between river waters, the shallow unconfined aquifer and the underlying semi-confined Calivil Formation aquifer. These represent the fresh groundwater resources near the river and are Na-(Ca-Mg)-HCO3-Cl waters. Away from the influence of river leakage, the regional groundwater is more saline and sodic with an evolved Na-Cl-SO4 watertype. The mixing associated with river leakage is also supported by age dating. Stable isotope data show that recharge is episodic and linked to high-flow flood events rather than continuous river leakage, as demonstrated by hydrographic monitoring. The combination of surface water and groundwater sampling, the pore fluid analyses and fuzzy-k means (FCM) cluster analysis, provides a novel, relatively simple but powerful tool to assist with interpretation of groundwater processes. The FCM cluster analysis used analytes that were present in at least 60% of samples and resulted in samples being classified into eight classes (or hydrochemical facies). Pore fluids and groundwater with the greatest affinity to the surface water samples were easily identified. In this way, sites with significant active recharge, principally by river leakage, were mapped. Downhole plots of the pore fluid FCM classes provided additional insights into groundwater processes. Comparing the FCM classification of pore fluids within the target (semi)confined aquifer with those from the overlying clay aquitard and shallow aquifer allowed the assessment of vertical inter-aquifer leakage.