EPSRC Project
Numerical Simulation of Bank Erosion and Channel Migration in Meandering Rivers
River meanders are recognised as features with great elegance and natural beauty. River meanders are in fact one of the most important components of the fluvial landscape, and are features whose geomorphological significance cannot be underestimated. River meanders are observed in all natural rivers across the globe, at high and low latitudes, and in rivers flowing through coarse and fine sediments. Meanders are intrinsically dynamic features. Flow impingement concentrates fluvial attack at the outer banks of meander bends, which retreat across and down the valley. Eroded bank material is transported downstream to the next point bar, where outer bank erosion is balanced by bar deposition and advance. Through these systematic spatial differences in zones of erosion and deposition, meanders migrate across floodplains, reworking floodplain sediments and creating and destroying floodplain features in a relentless cycle that promotes diversity of ecological habitat. The forms that are created often have a startling regularity, even across a range of spatial scales and environmental boundary conditions. The meandering planform, and the startling regularity of that sinuous shape, have led scientists to wonder about the factors responsible for shaping river meanders. In addition, the tendency of natural river meanders to actively migrate across floodplains in dynamic equilibrium, coupled with the tendency for floodplains to be densely populated, cultivated and otherwise exploited, has often led to conflict between nature and humankind.
This EPSRC project involves work on the numerical modelling of bank erosion and channel migration in river meanders. This interdisciplinary project is directed by Dr Stephen Darby and is undertaken in close collaboration with Delft Hydraulics. The research aims to contribute to effective river engineering and management by developing an improved tool for predicting river bank erosion and channel migration for natural river channels with cohesive bank materials. Globally and nationally, lateral channel migration impacts floodplain dwellers and users through erosion and sedimentation. Understanding and predicting the processes and mechanisms of channel change is fundamental to the sustainable management of river environments.
This project aims to address two limitations associated with existing numerical models of river bank erosion and channel migration. First, the research utilises an advanced boundary-fitted gridding system that enables the complex shapes associated with natural rivers to be simulated. Existing models without this feature are constrained to simulate idealised meander planforms. Second, width adjustments will be accounted for using a mechanistic analysis of cohesive bank erosion which accountes for the geotechnical stability of each bank. This represents an advance over existing models wherein meander migration is simulated assuming constant channel width.
Improvements in the ability to predict rates of bank erosion and channel migration of meandering rivers will have considerable potential economic and environmental benefits because accurate assessment of the cause, extent, and severity of problems caused by river bank erosion underpins implementation of succesfull countermeasures. The research is therefore expected to have a significant international scientific impact, providing software and data for the international scientific and river engineering communities.
Further information about the project, which started in August 1999 and ended in February 2001, can be found by following the links on the right.
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