2nd International Conference on GeoComputation

Modelling Hydraulic, Sediment Transport and Slope Processes, at a Catchment Scale, using a Cellular Automaton Approach.

T.J. Coulthard, M.J. Kirkby & M.G. Macklin

School of Geography, University of Leeds
Leeds, LS2 9JT, United Kingdom
Tel: +44(0)113 2333326, Fax: +44(0)113 2333308

Email: T.Coulthard@geog.leeds.ac.uk

Presented at the second annual conference of GeoComputation 97 & SIRC 97, University of Otago, New Zealand, 26-29 August 1997

Abstract

There have been recent advances in the numerical model-ling of hydraulic and sediment transport processes at a fine scale, but the ability to extrapolate these advances to a larger scale is rarely realised. Existing approaches have been based upon linked cross sections, giving a quasi 2-d view, which is able to effectively simulate sediment trans-port for a single river reach. A catchment represents a whole discrete dynamic system within which there are channel, floodplain and slope processes operating over a wide range of space and time scales. A Cellular Automaton (CA) approach has been used to overcome some of these difficulties, in which the landscape is represented as a se-ries of fixed size cells. At every model iteration, each cell acts only in relation to the influence of its immediate neigh-bours in accordance with appropriate rules.

The model presented here takes approximations of exist-ing flow and sediment transport equations, and integrates them, together with slope and floodplain approximations, within a cellular automaton framework. This method has been applied to the Catchment of Cam Gill Beck (4.2 km 2 ) above Starbotton, upper Wharfedale, a tributary of the River Wharfe, North Yorkshire, UK.

This approach provides for the first time a workable model of the whole catchment at a meso scale (1m). Preliminary results show the evolution of bars, braids, terraces and alluvial fans which are similar to those observed in the field, and indicates the emergence of significantly non-linear behaviour.