Research project

How does the development of particle scale structure control river scale morphology?

Research groups:

Landscape Dynamics and Ecology
Lead researchers:

Professor Julian Leyland
Other researchers:

Professor David Sear
Status:

Not active

Project overview

The transport of sediments by rivers is a key process in the global geological cycle, a cornerstone of aquatic ecosystems and has a multi-billion pound impact on agricultural, industrial and urban, flood- and erosion-risk hazards. However, our ability to predict sediment entrainment and thus river bed stability was traditionally limited by our understanding of the factors that affect sediment movement. Grain size has typically accounted for, but other factors such as sediment structure (the way in which individual sediment grains are packed together in 3D) and the role of fine sediments in cementing grains together were not.

In this research we showed how the spatial pattern of erodibility plays an important role in controlling both the shape of the river bed, and how this shape changes under different flow conditions. For the very first time we quantified the development of 3D sediment structure in both a field and a laboratory environment using the Southampton high energy XCT-scanning facility (muvis). The CT images allowed us to develop a new 3D vector based model of grain entrainment and show how particle arrangement controls the critical shear stress required to move river grains, explaining how river morphology evolves under different conditions and the role of fine sediment in modulating transport.