The Forgotten Legacy: Sediment From Historical Gold Mining Greatly Exceeds all Other Anthropogenic Sources in SE Australian Rivers

Rutherford, Ian and Davies, P and Macklin, Mark and Grove, J R (2016) The Forgotten Legacy: Sediment From Historical Gold Mining Greatly Exceeds all Other Anthropogenic Sources in SE Australian Rivers. In: AGU.

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Item Type:Conference or Workshop contribution (Presentation)
Item Status:Live Archive

Abstract

Coarse and fine sediment has been a major pollutant of Australian rivers and receiving waters since European settlement in 1788. Anthropogenic sediment budget models demonstrate that catchment and channel erosion has increased background sediment delivery by 10 to 20 times across SE Australia, but these estimates ignore the contribution of historical gold mining. Detailed historical records allow us to reconstruct the delivery of coarse and fine sediment (including contaminated sediment) to the fluvial system. Between 1851 and 1900 alluvial gold mining in the state of Victoria liberated between 1.2 billion and 1.4 billion m3 of coarse and fine sediment into streams. Catchment scale modelling demonstrates that this volume is at least twice the volume of all anthropogenic (post-European) erosion from hillslopes, river banks, and gullies. We map the deposition and remobilization of these contaminated legacy mining sediments down selected valleys, and find that many contemporary floodplains are blanketed with mining sediments (although mercury contamination is present but low), and discrete sediment-slugs can be recognized migrating down river beds. Overall, the impact of gold mining is one of the strongest indicators of the Anthropocene in the Australian landscape, and the level of impact on rivers is substantially greater than recognized in the past. Perhaps of most interest is the rapid recovery of many river systems from the substantial impacts of gold mining. The result is that these major changes to the landscape are largely forgotten.

Keywords:1625 Geomorphology and weathering, GLOBAL CHANGEDE: 1803 Anthropogenic effects, HYDROLOGYDE: 1825 Geomorphology: fluvial, HYDROLOGYDE: 1862 Sediment transport, HYDROLOGY
Subjects:F Physical Sciences > F841 Maritime Geography
F Physical Sciences > F840 Physical Geography
F Physical Sciences > F810 Environmental Geography
Divisions:College of Science > School of Geography
ID Code:33630
Deposited On:19 Oct 2018 10:20

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