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University of Bristol (2005)

Investigating the effects of hillslope-channel coupling on sediment transport in semi-arid areas

Martin, Gareth James

Titre : Investigating the effects of hillslope-channel coupling on sediment transport in semi-arid areas

Auteur : Martin, Gareth James.

Université de soutenance : University of Bristol

Grade : Doctor of Philosophy (Ph.D.) : 2005

Résumé
Hillslope-channel coupling has been found to be of great importance in controlling the supply of water and sediment in semi-arid areas. Despite this importance the spatial and temporal linkages between hillslopes and floodplains, and their effect on hydrological and sediment response, has lain relatively unexplored. A discrete particle based model which uses flow hydraulics to predict the forces acting on a particle, and determine particle transport, was developed to investigate the effects of coupling upon sediment transport in semi-arid areas. The model dynamically accounts for variations in topography and surface hydrologic characteristics, as well as variations in particle diameter and density. The model was parameterised using field data collected from a semi-arid catchment in southern Spain. A sensitivity analysis was undertaken using a range of parameters to investigate the importance of each parameter in controlling sediment transport, while allowing the influence of coupling upon sediment transport to be assessed. The results of this analysis showed that coupled slopes allowed direct transmission of sediment to the channel, although this was complicated by other factors such as slope profile. Decoupled slopes were found to buffer the sediment transport from the hillslope, preventing sediment from reaching the channel. Most sediment was deposited at the interface between the hillslope and floodplain, with analyses suggesting that the change in slope angle between the hillslope and floodplain is the major control on sediment deposition and storage. Furthermore, spatial variability in output was found to exert an important control on sediment transport for both coupled and decoupled slopes.

Présentation : EThOS (UK)

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