Earth and Environmental Science

Inselbergs, such as Uluru in central Australia, are iconic landscape features of semi-arid and deeply denuded continental interiors. These islands of rock are commonly skirted by steep, overhanging cliffs (flared slopes) at ground level. The weathering processes responsible for formation of flared slopes and steep-sided inselbergs in flat, planated landscapes are enigmatic. One model emphasizes sub-surface weathering followed by denudation and excavation of saprolite to expose the unweathered bedrock while other models advocate slope development under subaerial conditions at ground level. We present a new hypothesis that identifies wildfire as a primary agent of flared slope development via fire-induced rock spalling around the periphery of inselbergs. Widespread fire-spalling following the 2019–2020 Australian fires illustrates that this is a common form of physical weathering in fire-prone environments but its effects are particularly evident in semi-arid regions where lateral fir...

Successful placement of sediment traps requires an understanding of how hillslope morphology influences erosion. Following the 2007 Mount Bold wildfire, in South Australia, a 1 in 5 year rainfall event resulted in the failure of many sediment traps due to substantial sediment movement within the reservoir reserve. This study assesses how hillslope morphology can influence post-fire surface erosion and the subsequent appropriate placement of sediment traps. Erosion pins and sediment traps were used at five different sites to measure hillslope surface change and trapped sediment volumes. Terrestrial laser scanning was used to model surface change where slope gradients are 1:2 or greater. Surface change was assessed in relation to slope gradient, slope length, cross-slope curvature, hillslope position and fire severity. The results suggested a threshold for substantial increased sediment yield at slope gradients of 1:2. The findings also suggested that concave cross-slope curvatures we...

The fire regime in eucalypt forest and woodland in Australia has changed over the last 200 years from being characterized by frequent low intensity burns, to generally less frequent but higher intensity fires. Spatial variability in the transfer of sediment, organic matter and leaf litter was monitored on 10 plots for 6 months following fires of high, moderate and low intensity. Sediment and organic matter movement was substantially higher on intensely and moderately burnt areas than on unburnt (low fire intensity) areas. Leaf litter was recorded in largest amounts on moderately burnt areas where additional post-fire leaf fall from singed vegetation occurred following strong winds. Fire intensity is important in contributing to spatial variability in the post-fire transfer of sediment, organic matter and leaf litter. Burnt vegetation may be temporarily retained in on-slope litter dams and subsequently incorporated into bench or flood plain deposits within channels.

Post-fire soil erosion is a great concern to land managers due to the potential adverse effects on water quality, the alteration to soil profiles and the detrimental impacts on human communities. To reduce the potential adverse effects of post-fire erosion mitigation actions have been instigated following severe wildfires. Various programs of prescribed burning have been initiated to reduce the risk of wildfires. In order to predict and manage post-fire erosion a clear understanding is needed of the influential environmental variables, associated processes and whether mitigation actions will be effective. In the Southern Mount Lofty Ranges there is a paucity of post-fire erosion data from which to generate evidence-based predictive models and management recommendations. This thesis has the overarching goal of developing evidence-based options for managing post-fire sediment movement in the Southern Mount Lofty Ranges. Evidence-based management of sediment movement from both prescrib...

A flood exceeding the 100 year average recurrence interval in November 2005 led to the failure of an upland peat bog in Waterfall Gully. The area is prone to severe bushfire and flood events and the control dam at the base of First Falls was filled with sediment sourced from Wilson Bog. A resistant quartzite bar at Fourth Falls has formed a natural constriction point against which burnt logs and debris have collected following previous fire events forming a natural dam resulting in sediment/peat accumulation upstream. The failure of the bog was inevitable as the vegetative material in the log-jam progressively weakened and rotted. Intense flooding triggered the failure but it was augmented by the build up of a critical mass of sediment upstream of the restriction point. The downstream force of the flood waters and the weight of the saturated bog sediments was enough to overcome the basal frictional forces resulting in slumping and headward erosion. LiDAR data clearly shows an erosio...

A flood exceeding the 100 year average recurrence interval in November 2005 led to the failure of an upland peat bog in Waterfall Gully. The area is prone to severe bushfire and flood events and the control dam at the base of First Falls was filled with sediment sourced from Wilson Bog. A resistant quartzite bar at Fourth Falls has formed a natural constriction point against which burnt logs and debris have collected following previous fire events forming a natural dam resulting in sediment/peat accumulation upstream. The failure of the bog was inevitable as the vegetative material in the log-jam progressively weakened and rotted. Intense flooding triggered the failure but it was augmented by the build up of a critical mass of sediment upstream of the restriction point. The downstream force of the flood waters and the weight of the saturated bog sediments was enough to overcome the basal frictional forces resulting in slumping and headward erosion. LiDAR data clearly shows an erosio...

ABSTRACT The relevance of cars in relation to changing climates seems indisputable: scientific evidence points out the significant contribution of cars globally in causing greenhouse gas emissions. Despite higher levels of general public understanding and concern about climate change, this has not generally resulted in decreased car use. This paper outlines how a spatial perspective drawing on a cultural economy approach may provide insights into the paradox of the environmental ‘value action gap’ by focusing on suburban belongings, passions and anticipations derived from driving. Drawing on insights from Burraneer Bay, an affluent Sydney suburb, the paper illustrates how habituated and embodied knowledge of driving props up class envy, the spatial bordering of the city and the transformation of a love of driving into driving as love, underpinned as much by a desire to consume as by the performance of an identity. The implications for urban policy are considered that look beyond culture as attitudes.