The role of floodplains in attenuating contaminated sediment fluxes in formerly mined drainage basins
Article first published online: 29 DEC 2008
Copyright © 2008 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 34, Issue 3, pages 453–466, 15 March 2009
How to Cite
Dennis, I. A., Coulthard, T. J., Brewer, P. and Macklin, M. G. (2009), The role of floodplains in attenuating contaminated sediment fluxes in formerly mined drainage basins. Earth Surf. Process. Landforms, 34: 453–466. doi: 10.1002/esp.1762
- Issue published online: 18 FEB 2009
- Article first published online: 29 DEC 2008
- Manuscript Accepted: 22 SEP 2008
- Manuscript Revised: 1 SEP 2008
- Manuscript Received: 2 SEP 2007
- University of Wales, Aberystwyth, the UK Department for Environment, Food and Rural Affairs. Grant Number: Research and Development Grant SP 0525
- UK Engineering and Physical Sciences Research Council (jointly with NERC, the Joint Defra/EA Flood and Coastal Erosion Risk Management R&D programme, the Scottish Executive, the Rivers Agency (Northern Ireland) and UK Water Industry Research) as part of the Flood Risk Management Research Consortium. Grant Number: EPSRC Grant Number GR/S76304/01
- metal contamination;
- historical mining;
- sediment budget;
- tributary storage;
- floodplain storage.
Many upland river catchments in the UK have been historically mined for metals such as lead (Pb) and zinc (Zn), and as part of the mining process large quantities of metal contaminated sediment were released into the river system. The levels of sediment associated heavy metal contamination in river systems are largely controlled by the volumes of contaminated sediment released into the river and fluvial processes (e.g. erosion and deposition). As a consequence, the contamination patterns are often highly variable, which can make it difficult to create accurate assessments of the volumes of contaminated sediment remaining within the system. This paper uses a combination of techniques to establish the volumes of metal contaminated sediment remaining within the River Swale, UK. Firstly, using detailed field sampling and a geographical information system (GIS), it estimates the volumes of sediment remaining within one formerly mined tributary (Gunnerside Beck) which is then extrapolated to represent the contaminant volumes on other tributaries of the River Swale. Secondly, combining fresh field data with a range of existing data, volumes of contaminated sediment on the main stream of the River Swale are established. This two tier approach shows that significant volumes of contaminated sediment remain within the River Swale, with over 32 000 tonnes of Pb within the mined tributaries and 123 000 tonnes within the main channel belt of the River Swale itself. This represents approximately 28% of the Pb produced in the Swale catchment. Given these volumes and present day rates of removal, it may take over 5000 years for all of the metal rich sediment to be removed from the catchment. If the contaminated sediment is used as a tracer, present day rates of reworking of floodplain sediment can be calculated to be 0·02% per year. Copyright © 2008 John Wiley & Sons, Ltd.