Channelization in England and Wales : downstream consequences for the channel morphology and aquatic vegetation
Channelization in England and Wales : downstream consequences for the channel morphology and aquatic vegetation
River channelization, a term previously confined to the North American literature, may be defined as the modification of river channels for the purposes of flood control, land drainage, navigation and the prevention of erosion. Channelization in England and Wales includes capital works and major improvement schemes such as resectioning, lining and embanking, and routine maintenance activities such as weed cutting, tree clearance and the removal of rubbish from urban channels. The extent and character of channelization has been assessed by collating data obtained from the annual reports of water authorities and from records held by engineers in water authority offices. There were 8504 kms of major or capital works undertaken in the period 1930 to 1980 and 35,500 kms is main river which is regularly maintained.The range of impacts that channelization may have on river morphology and aquatic vegetation are identified at a total of 57 sites located in a variety of physical and hydrological environments in England and Wales. Particular attention is focused upon the downstream consequences and two basic groups of effect are identified. First there are those impacts arising at the time of construction when sediment may be released to the downstream reaches as a result of disruption to the bed and banks. The second group of effects are those which occur in the long-term, in response to increased flows arising from the works. Erosional adjustments are identified at upland gravel-bed river sites by methods such as the remeasurement of water authority cross-sections, the reconstruction of eroded banklines and the technique of space-time substitution. Morphological changes and recovery of the aquatic vegetation are also assessed for the modified reaches of the nationally located sites. Finally, a multivariate equation is developed which should enable engineers and scientists to predict the magnitude of downstream morphological adjustment by incorporating easily measured independent variables. Two sets of guidelines for the minimisation of the downstream consequences are also presented.
University of Southampton
1983
Brookes, Andrew
(1983)
Channelization in England and Wales : downstream consequences for the channel morphology and aquatic vegetation.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
River channelization, a term previously confined to the North American literature, may be defined as the modification of river channels for the purposes of flood control, land drainage, navigation and the prevention of erosion. Channelization in England and Wales includes capital works and major improvement schemes such as resectioning, lining and embanking, and routine maintenance activities such as weed cutting, tree clearance and the removal of rubbish from urban channels. The extent and character of channelization has been assessed by collating data obtained from the annual reports of water authorities and from records held by engineers in water authority offices. There were 8504 kms of major or capital works undertaken in the period 1930 to 1980 and 35,500 kms is main river which is regularly maintained.The range of impacts that channelization may have on river morphology and aquatic vegetation are identified at a total of 57 sites located in a variety of physical and hydrological environments in England and Wales. Particular attention is focused upon the downstream consequences and two basic groups of effect are identified. First there are those impacts arising at the time of construction when sediment may be released to the downstream reaches as a result of disruption to the bed and banks. The second group of effects are those which occur in the long-term, in response to increased flows arising from the works. Erosional adjustments are identified at upland gravel-bed river sites by methods such as the remeasurement of water authority cross-sections, the reconstruction of eroded banklines and the technique of space-time substitution. Morphological changes and recovery of the aquatic vegetation are also assessed for the modified reaches of the nationally located sites. Finally, a multivariate equation is developed which should enable engineers and scientists to predict the magnitude of downstream morphological adjustment by incorporating easily measured independent variables. Two sets of guidelines for the minimisation of the downstream consequences are also presented.
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Published date: 1983
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Local EPrints ID: 460102
URI: http://eprints.soton.ac.uk/id/eprint/460102
PURE UUID: 91eb1a86-28dc-4a1b-be9a-4f0711c38c64
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Date deposited: 04 Jul 2022 17:52
Last modified: 04 Jul 2022 17:52
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Author:
Andrew Brookes
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