School of Geography, Earth and Atmospheric Sciences - Research Publications
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ItemComparison of Regionalisation Techniques for Peak Streamflow Estimation in Small Catchments in the Pilbara, Australia(MDPI, 2022-10)Arid and semi-arid regions typically lack high-resolution river gauging data causing difficulties in understanding rainfall-runoff patterns. A common predictive method for discharge estimation within ungauged catchments is regional flood frequency estimation (RFFE), deriving peak discharge estimates from similar, gauged catchments and applying them to the catchment of interest. The majority of RFFE equations are developed for larger catchments where flow events may be larger and of greater interest. We test a series of RFFE methods derived for the Pilbara region, applying them to new ungauged small catchments under 10 km2. Rainfall values are derived from a guideline Australian design rainfall database, Australian Rainfall and Runoff 2019 (ARR2019) which was recently updated with an additional 30 years of rainfall data. RFFE equations are compared to a direct rainfall model to evaluate their performance within small catchments, identifying key limitations and considerations when modelling small headwater catchments.
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ItemUsing Structure-from-Motion Photogrammetry to Improve Roughness Estimates for Headwater Dryland Streams in the Pilbara, Western Australia(MDPI, 2022-02)There are numerous situations where engineers and managers need to estimate flow resistance (roughness) in natural channels. Most estimates of roughness in small streams come from humid areas. Ephemeral streams in arid and semi-arid areas have different morphology and vegetation that leads to different roughness characteristics, but roughness in this class of stream has seldom been studied. A lack of high-resolution spatial data hinders our understanding of channel form and vegetation composition. High resolution structure-from-motion (SfM)-derived point clouds allow us to estimate channel boundary roughness and quantify the influence of vegetation during bankfull flows. These point clouds show individual plants at centimetre accuracy. Firstly, a semi-supervised machine learning procedure called CANUPO was used to identify and map key geomorphic features within a series of natural channels in the Pilbara region of Western Australia. Secondly, we described the variation within these reaches and the contribution of geomorphic forms and vegetation to the overall in-channel roughness. Channel types are divided into five reach types based on presence and absence of geomorphic forms: bedrock; alluvial single channel (≥cobble or sand dominated); alluvial multithread; composed of either nascent barforms or more established; stable alluvial islands. Using this reach classification as a guide, we present estimates of Manning’s roughness within these channels drawing on an examination of 650 cross sections. The contribution of in-channel vegetation toward increasing channel roughness was investigated at bankfull flow conditions for a subset of reaches. Roughness within these channels is highly variable and established in-channel vegetation can provide between a 35–55% increase in total channel roughness across all channel types. This contribution is likely higher in shallow flows and identifies the importance of integrating vegetation and geomorphic features into restorative practices for these headwater channels. These results also guide Manning’s selection for these semi-arid river systems and contribute to the vegetation-roughness literature within a relatively understudied region.
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ItemRules of reengagement: integrating geomorphology into river diversion designs(River Basin Management Society, 2020)There are many river diversions around mining pits in Australia. Poor performance of these diversions has led to stricter guidelines for their design, including better appreciation of geomorphic context. The Pilbara region in Western Australia is an area with many open-pit mines and river diversions. There is a poor understanding of the regional watercourses and limited guidelines for the incorporation of geomorphic and environmental elements into river diversion designs. We developed a series of hydrogeomorphic guidelines for headwater channels in the Eastern Pilbara, Western Australia. We undertook a large-scale regional geomorphic analysis of headwater streams, before focusing on the variability in river reach form. Using Structure-from-Motion photogrammetry (SfM), the presence and distribution of channel features were mapped. The result was a high resolution ‘recipe’ or classification of features for a river addressing the natural morphology, roughness contribution and character of natural rivers within the Pilbara. Direct rainfall modelling provided appropriate rainfall flood frequency estimation for these small ungauged catchments. This knowledge was integrated to produce a series of guideline hydraulic criteria for the various headwater channels. These guideline hydraulic criteria can be used to design river diversions, in addition to helping us understand more about the complexity and variability of headwater channels within the Eastern Pilbara. These criteria can also help to set ‘closure criteria’ which specify the conditions that mine owners have to meet to return the mine to public ownership.
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ItemRivers, relocation and ruin: the history and legacy of mining river diversions in Victoria(Australasian Mining History Association, 2019)Eager to strike gold and make their fortunes, the 1850s influx of miners was to have a dramatic impact on the demography, the economy and the environment of Victoria. The proportion of alluvial gold coming from Victoria was extremely high by world standards, and much of the initial mining effort concentrated on the uncovering of alluvial gold deposits that lay within the bed and banks of river channels, or the adjacent floodplains, and the flow of the water within river channels was a key resource for mining success. The procurement and subsequent control of water resources was essential for success within alluvial mining and for settler hegemony. However, Australia is notorious for its seasonal, and often unreliable water supply, with rivers experiencing some of the greatest flow variability in the world. Subsequently, the gold mining rush within Australia caused a vast growth of population and unforeseen expansion and alteration to the waterways of the continent.