Volcanic ash represents a serious hazard to communities living in the vicinity of active volcanoes in developing countries like Indonesia. Geoscience Australia, the Australia-Indonesia Facility for Disaster Reduction (AIFDR) and the Indonesian Centre for Volcanology and Geohazard Mitigation (CVGHM) have adapted an existing open source volcanic ash dispersion model for use in Indonesia. The core model is the widely used volcanic ash dispersion model FALL3D. A python wrapper has been developed, which simplifies the use of FALL3D for those with little or no background in computational modelling. An application example is described here for Gunung Ciremai in West Java, Indonesia. Scenarios were run using eruptive parameters within the acceptable range of possible future events for this volcano, granulometry as determined through field studies and a meteorological dataset that represented a complete range of possible wind conditions expected during the dry and rainy seasons for the region. Implications for varying degrees of hazard associated with volcanic ash ground loading on nearby communities for dry versus rainy season wind conditions is discussed. Communities located on the western side of Gunung Ciremai are highly susceptible to volcanic ash ground loading regardless of the season whereas communities on the eastern side are found to be more susceptible during the rainy season months than during the dry. This is attributed to prevailing wind conditions during the rainy season that include a strong easterly component. These hazard maps can be used for hazard and impact analysis and can help focus mitigation efforts on communities most at risk.

Severe wind has major impacts on exposed human settlements and infrastructure, while climate change is expected to increase the severe wind hazard in many regions of Australia. The Risk and Impact Analysis Group (RIAG) in Geoscience Australia (GA) has developed a series of techniques to analyse the impact of severe wind imposed on the residential buildings under current and future climate. The process includes four components: hazard, exposure, vulnerability and risk. Severe wind hazard represents site specific wind speed values for different return periods (e.g. 500-year, 2000-year return periods), which may be derived by the wind loading standard (AS/NZS 1170.2), or be a result of modelling for current or future climates. GA has developed a National Exposure Information System (NEXIS), a repository of spatial and structural information of infrastructure exposed and vulnerable to natural hazards. NEXIS has also been extended to consider the number of future residential structures by utilising simple spatial relationships. Using an expert evaluation process, GA has developed a series of fragility curves which relate wind speed to the expected level of damage to residential buildings (measured as a percentage of the total replacement cost) in specific regions in Australia. These curves include consideration of factors such as building location, age, roof material, wall material, and so on. Given a certain intensity of severe wind imposed on a certain type of residential building in a specific region, the physical impact to a community can be determined in terms of the economic loss and casualties. By applying above concepts and procedures, based on sample data from the selected cities, we have integrated these three components (hazard, residential buildings exposure and vulnerability) within a computational framework to derive severe wind risk under both current climate and for a range of climate scenarios. These processes will be utilised for the assessment of climate change adaptation strategies concerning structural wind loading.

The term "Smartline" refers to a GIS line map format which can allow rapid capture of diverse coastal data into a single consistently classified map, which in turn can be readily analysed for many purposes. This format has been used to create a detailed nationally-consistent coastal geomorphic map of Australia, which is currently being used for the National Coastal Vulnerability Assessment (NCVA) as part of the underpinning information for understanding the vulnerability to sea level rise and other climate change influenced hazards such as storm surge. The utility of the Smartline format results from application of a number of key principles. A hierarchical form- and fabric-based (rather than morpho-dynamic) geomorphic classification is used to classify coastal landforms in shore-parallel tidal zones relating to but not necessarily co-incident with the GIS line itself. Together with the use of broad but geomorphically-meaningful classes, this allows Smartline to readily import coastal data from a diversity of differently-classified prior sources into one consistent map. The resulting map can be as spatially detailed as the available data sources allow, and can be used in at least two key ways: Firstly, Smartline can work as a source of consistently classified information which has been distilled out of a diversity of data sources and presented in a simple format from which required information can be rapidly extracted using queries. Given the practical difficulty many coastal planners and managers face in accessing and using the vast amount of primary coastal data now available in Australia, Smartline can provide the means to assimilate and synthesise all this data into more usable forms.

In 1994, the United Nations Regional Cartographic Conference for Asia and the Pacific resolved to establish a Permanent Committee comprising of national surveying and mapping agencies to address the concept of establishing a common geographic information infrastructure for the region. This resolution subsequently led to the establishment of the Permanent Committee for GIS Infrastructure for the Asia and Pacific (PCGIAP). One of the goals of the PCGIAP was to establish and maintain a precise understanding of the relationship between permanent geodetic stations across the region. To this end, campaign-style geodetic-GPS observations, coordinated by Geoscience Australia, have been undertaken throughout the region since 1997. In this presentation, we discuss the development of an Asia Pacific regional reference frame based on the PCGIAP GPS campaign data, which now includes data from 417 non-IGS GPS stations and provides long term crustal deformation estimates for over 200 GPS stations throughout the region. We overview and evaluate: our combination strategy with particular emphasis on the alignment of the solution onto the International Terrestrial Reference Frame (ITRF); the sensitivity of the solution to reference frame site selection; the treatment of regional co-seismic and post-seismic deformation; and the Asia-Pacific contribution to the International Association of Geodesy (IAG) Working Group on "Regional Dense Velocity Fields". The level of consistency of the coordinate estimates with respect to ITRF2005 is 6, 5, 15 mm, in the east, north and up components, respectively, while the velocity estimates are consistent at 2, 2, 6 mm/yr in the east, north and up components, respectively.

The development of the Indian Ocean Tsunami Warning and mitigation System (IOTWS) has occurred rapidly over the past few years and there are now a number of centres that perform tsunami modelling within the Indian Ocean, both for risk assessment and for the provision of forecasts and warnings. The aim of this work is to determine to what extent event-specific tsunami forecasts from different numerical forecast systems differ. This will have implications for the inter-operability of the IOTWS. Forecasts from eight separate tsunami forecast systems are considered. Eight hypothetical earthquake scenarios within the Indian Ocean and ten output points at a range of depths were defined. Each forecast centre provided, where possible, time series of sea-level elevation for each of the scenarios at each location. Comparison of the resulting time series shows that the main details of the tsunami forecast, such as arrival times and characteristics of the leading waves are similar. However, there is considerable variability in the value of the maximum amplitude (hmax) for each event and on average, the standard deviation of hmax is approximately 70% of the mean. This variability is likely due to differences in the implementations of the forecast systems, such as different numerical models, specification of initial conditions, bathymetry datasets, etc. The results suggest that it is possible that tsunami forecasts and advisories from different centres for a particular event may conflict with each other. This represents the range of uncertainty that exists in the real-time situation.

Abstract for AMSA Conference

Nuclear Magnetic Resonance (NMR) tools have been used for decades by the oil industry to study lithological properties in consolidated sedimentary materials. Recently, slimline NMR borehole logging systems have been developed specifically for the study of near-surface (<100m) groundwater systems. In this study of unconsolidated fluvial sediments in the Darling River floodplain, data were acquired downhole every 0.5 m using a Javelin NMR tool. A total of 26 sonic cored bores were logged to a depth of ~70 m. Hydraulic conductivity (KNMR) can be estimated from the NMR measurements using the Schlumberger-Doll Research Equation: KNMR = C x -2 x T2ML2, where is the NMR porosity, T2ML is the logarithmic mean of the T2 distributions, and C is a formation factor related to tortuosity. To this end, the NMR data were classified into five hydraulic classes ranging from clay to gravely-coarse sand using the core, geophysical, mineralogical, and hyperspectral logs. Borehole slug tests were conducted to provide constraints on the K and T of the aquifers. Least-squares inversion was used to solve for the optimum C values versus the slug test derived T for the aquifer material (medium to gravely sand). Laboratory permeameter measurements helped constrain the C values of fine textured sediment. Comparisons between the geophysics derived KNMR and slug test KSlug indicated correspondence within two orders of magnitude. Investigations were also carried out to compare measurements of water content between laboratory determinations (oven drying of wet sediment at 105 oC) and that derived from NMR bore log data. A systematic decrease in ratio between the NMR total water and gravimetric water with fining of texture is observed. This is in part due to the inter-echo spacing of the NMR instrument (2.5 ms), which may be too large to detect hydroscopic moisture. Differences observed between NMR free water and gravimetric water within the sands requires further investigation, including the potential influence of iron phase coating of grains on fast relaxation responses. Overall, the borehole NMR method provides logging of near-continuous variations in K through a saturated sedimentary sequence, providing useful K estimates at increments not achievable using traditional aquifer testing, as well as K estimates for aquitard material.

The Murray River is known to display great complexity in surface-groundwater interactions along its course, with 'gaining' sections of the river identified as sites of regional saline groundwater system discharge to the river and the adjacent floodplain. 'Losing' reaches of the river occur where river water infiltrates through the base of the river and recharges underlying aquifers and/or where adjacent aquifers are recharged through lateral bank infiltration. Recent studies have shown that recharge is not-steady state, with surface-groundwater processes promoted after river bank scouring during major flood events. 'Losing' reaches of rivers are hard to identify hydrochemically, while only airborne electromagnetic (AEM) methods provide 3D spatial mapping of salinity and hydrostratigraphy at depth beneath the river and across the floodplain. In 2007 a regional airborne electromagnetic (AEM) survey (24,000 line km @ 150m line-spacing in a 20 km-wide swath) was acquired along a 450 km reach of the Murray River in Victoria from Gunbower Island in the east to near the South Australian border. The AEM survey was calibrated and validated by drilling and complementary field mapping, and lithological and hydrogeochemical investigations. Holistic inversions of the AEM data were used to map key elements of the hydrogeological system and salinity extent in the shallow sub-surface (top 20-50 m). The survey successfully mapped key elements of the hydrogeological system including previously unmapped salinity discharge zones and significant losing 'flush' zones. Significant 'flush' zones to depths of 25m and up to 1.5 km in width have been identified at Turrumbarry Weir, with other significant zones identified in parts of Gunbower Forest, and between Liparoo and Robinvale. Elsewhere, flush zones are smaller, and occur at depths of 5-10m in narrower zones associated with locks, weirs and irrigation districts. Salt mobilisation associated with the flush zones at weir pools may be an issue in terms of salt load delivery to the River Murray and floodplain. Reaches of the river where the flush zones are absent and /or significantly constricted, and similar zones in tributary creeks in the adjacent floodplain, are at higher risk of saline groundwater inflows.

The lower Darling Valley contains Cenozoic shallow marine, fluvial, lacustrine and aeolian sediments including a number of previously poorly dated Quaternary fluvial units associated with the Darling River and its anabranches. New geomorphic mapping of the Darling floodplain that utilises a high resolution LiDAR dataset and SPOT imagery, has revealed that the Late Quaternary sequence consists of scroll-plain tracts of different ages incised into a higher more featureless mud-dominated floodplain. Samples for OSL (Optically-Stimulated Luminescence) and radiocarbon dating were taken in tractor-excavated pits, from sonic drill cores and from hand-auger holes from a number of scroll-plain and older floodplain sediments in the Menindee region. The youngest, now inactive, scroll-plain phase, associated with the modern Darling River, was active in the period 5-2 ka. A previous anabranch scroll-plain phase has dates around 20ka. Indistinct scroll-plain tracts older than the anabranch system, are evident both upstream and downstream of Menindee and have ages around 30ka. These three scroll-plain tracts intersect just south of Menindee but are mostly separated upstream and downstream of that point. Older dates of 50 ka, 85 ka and >150 ka have been obtained from lateral-migration sediments present beneath the higher mud-dominated floodplain. Establishing a chronology for the Quaternary fluvial landscape has been important for groundwater investigations in the Darling River floodplain area. More specifically, this has assisted in constraining the 3D mapping of floodplain units, helped constrain conceptual models of surface-groundwater interaction, and aided in the assessment of managed aquifer recharge options.

In this study, 3D mapping using airborne electromagnetics (AEM) was used to site a monitoring bore network in the Darling River floodplain corridor. Pressure loggers were installed in over 40 bores to monitor groundwater levels primarily in the shallow unconfined Coonambidgal Formation aquifer, deeper (semi)confined Calivil Formation and confined Renmark Group aquifers. In 2010-11, the network provided the opportunity to monitor the groundwater response to flooding of the Darling River and the replenishment of the Menindee Lakes storages, following a period of prolonged drought. In this event, the Darling River at Menindee (Weir 32) rose from 1.59m in October 2010 and peaked at 7.16m in March 2011. A synchronous rise in groundwater levels varying between 0.5-3.4m was observed in the shallow unconfined aquifer near the river. Shallow groundwater levels also declined following the flood peak. Near-river groundwater levels in the Calivil aquifer rose between 0.2-1.3m and also by 4.0 m at a site near Lake Menindee. The latter confirms lake leakage into the aquifer at this particular site, as previously inferred by the AEM data. There was also a pressure response of 0.1-0.9m evident in certain Renmark aquifer bores near the river. The monitoring confirms the importance of episodic flood events to the recharge of the alluvial aquifers, as supported by groundwater chemistry and stable isotope data. Although some of the confined aquifer response may relate to transient hydraulic loading associated with the flood, the inference is that in places there is a degree of hydraulic connectivity between the aquifers.