Legacy product - no abstract available

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. This paper focuses specifically on differing lake level management practices in order to assess associated environmental impacts. In western NSW, two Eucalyptus species, River Red Gum (E. camaldulensis) and Black Box (E. largiflorens) have well documented tolerances and both are located on the fringes of lakes in the Menindee Lakes Storage Water scheme. Flows to these lakes have been controlled since 1960 and lake levels monitored since 1979. Pre-regulation aerial photos indicate a significant change to the distribution of lake-floor and fringing vegetation in response to increased inundation frequency and duration. In addition, by coupling historic lake water-level data with a Landsat satellite imagery, spatial and temporal vegetation response to different water regimes has been observed. Two flood events specifically investigated are the 2010/11 and 1990 floods. Results from this analysis provide historic examples of vegetation response to lake regulation including whether recorded inundation duration and frequency resulted in positive or negative impacts, the time delay till affects become evident, duration of observed response and general recovery/reversal times. These findings can be used to inform ongoing water management decisions.

Legacy product - no abstract available

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.

Integrating surface water and groundwater sampling with pore fluid analysis of cored sediments, combined with fuzzy-k means (FCM) cluster analysis, provides a novel, relatively simple but powerful tool to interpret groundwater processes. This methodology has been applied to a study of shallow (<120m) alluvial aquifers in the Darling River floodplain, Pore fluids were extracted from sediments from 100 sonic-cored bores, and together with surface and groundwater samples, provided a hydrochemical dataset with over 1600 samples and 25 analytes. 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 groundwaters 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. The FCM cluster analysis also assigns indices to each sample as indicators of how well it relates to each of the eight classes. A simple recharge index was calculated from these FCM indices. This novel approach has provided invaluable new insights into groundwater processes and has assisted greatly with assessing groundwater resources and managed aquifer recharge options.

Legacy product - no abstract available

Legacy product - no abstract available

Progress report for Milestone 8 of Palaeovalley Groundwater project. Report prepared by Geoscience Australia for delivery to National Water Commission.