Legacy product - no abstract available

Legacy product - no abstract available

In many areas of the world, vegetation dynamics in semi-arid floodplain environments have been seriously impacted by increased river regulation and groundwater use. With increases in regulation along many rivers in the Murray-Darling Basin, flood volume, seasonality and frequency have changed which has in turn affected the condition and distribution of vegetation. Floodplain vegetation can be degraded from both too much and too little water due to regulation. Over-regulation and increased use of groundwater in these landscapes can exacerbate the effects related to natural climate variability. Prolonged flooding of woody plants has been found to induce a number of physiological disturbances such as early stomatal closure and inhibition of photosynthesis. However, drought conditions can also result in leaf biomass reduction and sapwood area decline. Depending on the species, different inundation and drought tolerances are observed. Identification of groundwater-dependent terrestrial vegetation, and assessment of the relative importance of different water sources to vegetation dynamics, typically requires detailed ecophysiological studies over a number of seasons or years as shown in Chowilla, New South Wales [] and Swan Coastal Plain, Western Australia []. However, even when groundwater dependence can be quantified, results are often difficult to upscale beyond the plot scale. Quicker, more regional approaches to mapping groundwater-dependent vegetation have consequently evolved with technological advancements in remote sensing techniques. Such an approach was used in this study. LiDAR canopy digital elevation model (CDEM) and foliage projected cover (FPC) data were combined with Landsat imagery in order to characterise the spatial and temporal behaviour of woody vegetation in the Lower Darling Floodplain, New South Wales. The multi-temporal dynamics of the woody vegetation were then compared to the estimated availability of different water sources in order to better understand water requirements.

Groundwater monitoring around the CO2CRC Otway Project CO2 injection site aims to (1) establish baseline aquifer conditions prior to CO2 injection, and (2) enable detection monitoring for CO2 leakage, in the unlikely event any should occur in the future. The groundwater composition was monitored at 24 bores around the site for nearly 2 years before injection started. The water samples were analysed for standard bulk properties, and inorganic chemical and isotopic compositions. In addition to sampling, standing water levels were monitored continuously in 6 of the bores using barometric loggers. The shallow groundwaters have compositions typical of carbonate aquifer-hosted waters, being fresh (EC 800-4000 S/cm), dominated by Ca2+, Na+, HCO3- and Cl-, cool (T 12-23°C), and near-neutral (pH 6.6-7.5). Most of the deep groundwater samples are fresher (EC 400-1600 S/cm), also dominated by Ca2+, Na+, HCO3- and Cl-, cool (T 15-21°C), but are more alkaline (pH 7.5-9.5). Time-series reveal that most parameters measured have been relatively stable over the sampling period, although some bores display changes that appear to be non-seasonal. Groundwater levels in some of the shallow bores show a seasonal variation with longer term trends evident in both aquifers.

Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

Water security in extensive arid parts of Australia is reliant upon groundwater resources to meet the requirements of remote towns, isolated Aboriginal communities, the pastoral and mining industries and the environment. Greater understanding and predictability of groundwater resources in these regions is imperative for future sustainable water supplies, particularly where mining activities are increasing. Hydrogeological investigations in diverse geologic provinces in Western Australia, South Australia and the Northern Territory have been undertaken in frontier areas to assess palaeovalleys and associated groundwater systems. This work, funded by the Australian Federal Government, appraised various methodologies for regional reconnaissance of arid zone palaeovalley aquifers. Demonstration studies were conducted in large regions, spread across an area comparable in size to Europe. Permian glacial valleys, ancient fluvial valleys and Cenozoic basin-and-range lake settings were investigated. Mapping of buried palaeovalley networks beneath dunefields was a particular focus. Investigations in these little-known regions included integrated application of innovative landscape analysis, geophysics - including Airborne Electromagnetic and ground-based gravity surveys - drilling, bore installation and monitoring and hydrochemical analysis. The depths of the infilled valleys, their geographic extents and stratigraphy, and their groundwater resources were assessed. Substantial heterogeneity of palaeovalley aquifers was revealed. Neotectonism appears to have influenced palaeovalley evolution in some regions. Groundwater quality is variable and aquifer volumes and interconnectivity are yet to be established. A key finding has been the widespread presence of palaeowaters; 14C groundwater ages reveal residence times up to 30,000 years, with only limited, infrequent and localised recharge due to proximity to cyclonic trajectories and topographic position. This multidisciplinary approach to meet regional-scale groundwater resource challenges is applicable in desert lands in other Gondwanan sub-continents and arid to semi-arid zones elsewhere, particularly for reconnaissance investigations in 'greenfield' regions where major groundwater abstractions are required.

Legacy product - no abstract available

Legacy product - no abstract available