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Research Project Title: Mixing in Channels with Patchy Vegetation

The management of water quality in river networks is essential for ecological and human well-being. Predicting the effects of management strategies requires knowledge of the hydrodynamic processes covering spatial scales of a few millimetres (turbulence) to several hundred kilometres (catchments), with a similarly large range of timescales from milliseconds to weeks. Predicting underlying water quality processes and their human and ecological impact is complicated as they are dependent on contaminant concentration.

Current water quality modelling methods for large scale river networks employ one-dimensional (1D) time dependent models, for economic, fast, easy-to-use applications within highly complex situations in river catchments. In these models, the water quality processes, such as BOD and organic chemical degradation, are often described by rate coefficients. These rate coefficients are governed by the channel characteristics and the exchange processes at channel boundaries and interfaces, such as around vegetation patches. To estimate the rate coefficients within a reach an understanding of the mixing mechanisms is required.

Spatial variations in channel characteristics, which could be caused by vegetation, results in 3D variations in the velocity field and hydrodynamics. One challenge is how to incorporate the effects of such 3D variations into 1D models. This proposal focusses on the effect of different configurations of vegetation patches, in affecting the travel time and mixing characteristics within a channel reach.

Interests: Environmental Hydraulics, Water Quality Modelling, Pollution Control

Supervisors

Ian Guymer and Virginia Stovin