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Fluvial terraces in the upper Hunter catchment, southeastern Australia provide a long-term record of river activity in response to climate change in the late Quaternary. Single-grain optically stimulated luminescence (OSL) dating of quartz was applied in this study to investigate the timing of the formation of three fluvial terraces in the upper Hunter catchment. A detailed examination of luminescence properties of individual quartz grains revealed some correlation between their OSL decay rates, intrinsic brightness and dose saturation characteristics. Some quartz grains containing a higher proportion of non-fast components exhibit low brightness in OSL signals and high dose saturation levels. Some grains with slow OSL decays pass the standard rejection criteria, but are likely to yield underestimated equivalent doses (Des) because of a higher contribution of non-fast components, which are shown to have low thermal stability. Different rejection criteria, including the fast ratio, the dose saturation level and the OSL sensitivity criteria, were tested on the single-grain Deresults. Application of a fast ratio rejection criterion is able to successfully identify thermally unstable grains. A new rejection criterion based on dose saturation property was also applied to improve the age of one sample with a large De. Our dating results identify multiple phases of river valley aggradation in the upper Hunter catchment since late Marine Isotope Stage (MIS) 6; at ∼ 138 ka, ∼90-94 ka, ∼65 ka, ∼26 ka and ∼18 ka. The aggradational episodes of the terraces in the upper Hunter catchment are correlated with glacial or stadial periods since MIS 6. These phases of valley-floor aggradation are inferred to be a function of increased sediment supply during the cold periods resulting from strong periglacial activities in the adjacent Australian highlands.

Fluvial terraces in the upper Hunter catchment, southeastern Australia provide a long-term record of river activity in response to climate change in the late Quaternary. Single-grain optically stimulated luminescence (OSL) dating of quartz was applied in this study to investigate the timing of the formation of three fluvial terraces in the upper Hunter catchment. A detailed examination of luminescence properties of individual quartz grains revealed some correlation between their OSL decay rates, intrinsic brightness and dose saturation characteristics. Some quartz grains containing a higher proportion of non-fast components exhibit low brightness in OSL signals and high dose saturation levels. Some grains with slow OSL decays pass the standard rejection criteria, but are likely to yield underestimated equivalent doses (Des) because of a higher contribution of non-fast components, which are shown to have low thermal stability. Different rejection criteria, including the fast ratio, the dose saturation level and the OSL sensitivity criteria, were tested on the single-grain Deresults. Application of a fast ratio rejection criterion is able to successfully identify thermally unstable grains. A new rejection criterion based on dose saturation property was also applied to improve the age of one sample with a large De. Our dating results identify multiple phases of river valley aggradation in the upper Hunter catchment since late Marine Isotope Stage (MIS) 6; at ∼ 138 ka, ∼90-94 ka, ∼65 ka, ∼26 ka and ∼18 ka. The aggradational episodes of the terraces in the upper Hunter catchment are correlated with glacial or stadial periods since MIS 6. These phases of valley-floor aggradation are inferred to be a function of increased sediment supply during the cold periods resulting from strong periglacial activities in the adjacent Australian highlands.

Human disturbance induces significant geomorphic changes to river systems. In eastern Australia, land-use practices such as clearance of forests and riparian vegetation, and removal of wood from channels in the 19th and 20th centuries induced widespread geomorphic impacts. However, since the 1970s, there has been a noticeable shift in the geomorphic condition of many rivers in eastern New South Wales (NSW). This transition to a recovery trajectory reflects a reduction in land-use pressures and improved farming practices on the one hand and adoption of recovery enhancement approaches to river conservation and rehabilitation by management authorities on the other. Monitoring and tracking changes in condition by state government agencies involves identifying when geomorphic recovery is occurring so that decision-support frameworks can determine whether river management is required, where, when, and how much to intervene to enhance river recovery and when to opt-out of management because the system requires little (or no) intervention. Here, we document procedures that are used to manage process-based, recovery enhancement in NSW. Following a brief review of river change in eastern NSW since European settlement, we outline an approach to identify and measure key geomorphic indicators of river recovery for different river types. We use case studies to demonstrate examples of geomorphic river recovery, prior to showing how state government agencies in NSW are monitoring trajectories and rates of recovery. Broader implications of this 'good news story' are discussed.