The influence of stress history on the stability of graded sediment beds.

Lead Research Organisation: University of Glasgow
Department Name: School of Engineering

Abstract

European and national legislation is increasingly being imposed on river management practice in the UK. Successful implementation requires detailed understanding of the interaction between flow and sediment transfer within river systems. Environmental organisations are calling for research aimed at accurately predicting the instant at which sediment motion begins and improving our understanding of the mechanics of sediment transport. This is because predictive sediment transport models are essential tools for engineers and scientists whose responsibility it is to plan and manage river regulation, restoration and re-alignment. However, existing models do not perform well. Improving the accuracy of these models is of immediate importance in predicting the sensitivity of sediment transport to changing flow patterns resulting from climate change and catchment modification. To date, it has been widely assumed that the stability of sediment comprising a river bed is only affected by high flows capable of sediment transport. Yet, there is clear evidence that the period of low flow between two flood events is actually a very important control on the point at which sediment is mobilised during a subsequent high flow event. Whilst, sediment transport occurs at lower shear stresses following short inter-flood periods, it is delayed until a higher shear stress when floods are separated by a longer inter-flood period. Accepting, quantifying and understanding the influence of antecedent low flows (termed the stress history ) on river bed stability are crucial if sediment transport predictions are to be improved. As such, detailed, systematic investigations aim to quantify the effect that stress history has on the stability of graded sediment beds, determine the mechanisms responsible and develop a practical method for integrating a stress history variable into sediment transport relationships. Whilst this new area of experimental research will significantly benefit the active international research community at a fundamental level, the motivation for this research is firmly rooted in its application to improving sediment transport models imperative to civil engineers, councils, consultants, water companies, reservoir managers, fisheries and the environment agencies directly involved in implementing the EC Water Framework Directive in areas such as river regulation, river restoration and flood risk.

Publications

10 25 50
 
Description Carnegie Trust for Scotland Large Research Award
Amount £40,000 (GBP)
Organisation Carnegie Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 09/2011 
End 08/2013
 
Description Scottish Natural Heritage: Research Award
Amount £1,000 (GBP)
Organisation Scottish Natural Heritage 
Sector Public
Country United Kingdom
Start 05/2008 
End 04/2009
 
Description The Nuffield Foundation's Awards to Newly Appointed Lectures in Science, Engineering and Mathematics
Amount £5,000 (GBP)
Funding ID NAL/32517 
Organisation Nuffield Foundation 
Sector Charity/Non Profit
Country United Kingdom
Start 06/2006 
End 05/2008
 
Description H R Wallingford Ltd 
Organisation HR Wallingford Ltd
Country United Kingdom 
Sector Private 
Start Year 2007
 
Description Scottish Environment Protection Agency 
Organisation Scottish Environment Protection Agency
Country United Kingdom 
Sector Charity/Non Profit 
Start Year 2007