The use of remote sensing as a tool to further understanding of suspended sediment dynamics in the Bristol Channel
The use of remote sensing as a tool to further understanding of suspended sediment dynamics in the Bristol Channel
Seventeen cloud-free Landsat MSS virtually instantaneous images of the Bristol Channel turbidity maximum have been examined, but the severe problems of working in a highly dynamic environment preclude the acquisition of adequate synchronous seatruth data. The behaviour of the cohesive suspended sediments is governed by the semidiurnal and spring-neap tidal cycles, so it is therefore possible to match non-synchronous sediment concentrations data to satellite data provided both are obtained at identical stages of the two tidal cycles. A linear relationship is shown between band 5 (600-700 nm) and loge surface suspended sediment concentrations (SSCs). Unexpectedly for a well-mixed estuary, the relationship comprises two statistical populations, designated Class I and Class II. Image analysis techniques are used to separate them. Differences in mineralogical composition of the suspensions may explain this phenomenon. An algorithm is developed using the two liner relationships to produce surface SSC maps. These are compared with the equivalent Kirby (1986) SSC maps and used to enhance them and the understanding of cohesive suspended sediment behaviour. Bridgwater Bay is shown to behave as a separate entity from the main Channel. Its sediment circulation pattern is described. Further light is shed on problems of entrainment, advection and settling. The presence of a vertical sediment front with higher concentrations of the English side of the Channel, is confirmed. The possible application of remote sensing techniques in the construction of a Severn Tidal Barrage is discussed, and other possibilities for the future are indicated.
University of Southampton
1989
Lees, Barbara Joan
(1989)
The use of remote sensing as a tool to further understanding of suspended sediment dynamics in the Bristol Channel.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Seventeen cloud-free Landsat MSS virtually instantaneous images of the Bristol Channel turbidity maximum have been examined, but the severe problems of working in a highly dynamic environment preclude the acquisition of adequate synchronous seatruth data. The behaviour of the cohesive suspended sediments is governed by the semidiurnal and spring-neap tidal cycles, so it is therefore possible to match non-synchronous sediment concentrations data to satellite data provided both are obtained at identical stages of the two tidal cycles. A linear relationship is shown between band 5 (600-700 nm) and loge surface suspended sediment concentrations (SSCs). Unexpectedly for a well-mixed estuary, the relationship comprises two statistical populations, designated Class I and Class II. Image analysis techniques are used to separate them. Differences in mineralogical composition of the suspensions may explain this phenomenon. An algorithm is developed using the two liner relationships to produce surface SSC maps. These are compared with the equivalent Kirby (1986) SSC maps and used to enhance them and the understanding of cohesive suspended sediment behaviour. Bridgwater Bay is shown to behave as a separate entity from the main Channel. Its sediment circulation pattern is described. Further light is shed on problems of entrainment, advection and settling. The presence of a vertical sediment front with higher concentrations of the English side of the Channel, is confirmed. The possible application of remote sensing techniques in the construction of a Severn Tidal Barrage is discussed, and other possibilities for the future are indicated.
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Published date: 1989
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Local EPrints ID: 461327
URI: http://eprints.soton.ac.uk/id/eprint/461327
PURE UUID: 8a849a5a-4603-4e1e-a5b0-cfa38be8a877
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Date deposited: 04 Jul 2022 18:43
Last modified: 04 Jul 2022 18:43
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Author:
Barbara Joan Lees
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