Suspended sediment dynamics and distribution in the Solent using Landsat MSS data
Suspended sediment dynamics and distribution in the Solent using Landsat MSS data
The suspended sediment regime for the Solent has been studied by field observations and the application of Landsat MSS data. The field surveys, performed on an almost monthly basis from January to December 1980 for a travese across the West Solent, show the spatial variability as well as the seasonal variation in the sediment concentration. Seasonal effects such as those caused by winds, rainfalls and the river discharge are also investigated. Observations over a tidal cycle at two positions have indicated the close relation between fluctuations of the surface concentration and tidal velocities. In addition to the determination of suspended sediment concentrations, the water samples collected were analysed for the organic contents for the two periods, viz. the winter and the summer. Brief analyses for the sediment composition and size distribution reveal the spatial and temporal consistency in composition of the bimodal mixture of silt size particles.Synoptic distributions and patterns of suspended sediment has been obtained by analyses of Landsat imagery using the Plessey IDP 3000 Image Processor. Band 5 imagery are found to give best manifestation of the surface sediment. Interpretation of the colour sliced images obtained at various portions of a tidal cycle has shown the correspondence between the sediment patterns and tidal circulation within the area. Although these images were acquired for the period 1975 to 1980, there is nonetheless a consistency in the distribution patterns from scene to scene. Valuable information relating to suspended sediment behaviour is evidenced including the possible source in the adjacent Christchurch Bay west of the Solent. An attempt is made to quantitatively correlate the satellite radiance values with suspended sediment concentrations. Previous studies concerning this are also discussed. A direct calibration is carried out for a Landsat overpass for which simultaneous sediment data was collected. In addition an indirect approach is undertaken based entirely on the histograms showing the radiance level frequencies of seven historical images, and the knowledge of suspended sediment distribution observed in 1980. A linear fit is applied for both cases. The two relationships are found to be closely related. The test of the two algorithms by comparing the predictions of the sediment concentrations from radiance values to limited sea truth observations has indicated an error in estimation that could range from 4% to 18%. Their application to the nine images obtained over a period of the six-year time span used in the study yield reasonable estimations of the concentration range appropriate to the seasonal conditions obtaining. The agreement between the estimated ranges and those observed in the field indicates the practicability of the algorithms to different frames provided that the atmospheric correction is allowed for. The band-S colour sliced images can thus become the quantitative expressions (colour maps) of the spatial and temporal distributions of suspended sediment for the region.
University of Southampton
1982
Srisaengthong, Darasri
(1982)
Suspended sediment dynamics and distribution in the Solent using Landsat MSS data.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The suspended sediment regime for the Solent has been studied by field observations and the application of Landsat MSS data. The field surveys, performed on an almost monthly basis from January to December 1980 for a travese across the West Solent, show the spatial variability as well as the seasonal variation in the sediment concentration. Seasonal effects such as those caused by winds, rainfalls and the river discharge are also investigated. Observations over a tidal cycle at two positions have indicated the close relation between fluctuations of the surface concentration and tidal velocities. In addition to the determination of suspended sediment concentrations, the water samples collected were analysed for the organic contents for the two periods, viz. the winter and the summer. Brief analyses for the sediment composition and size distribution reveal the spatial and temporal consistency in composition of the bimodal mixture of silt size particles.Synoptic distributions and patterns of suspended sediment has been obtained by analyses of Landsat imagery using the Plessey IDP 3000 Image Processor. Band 5 imagery are found to give best manifestation of the surface sediment. Interpretation of the colour sliced images obtained at various portions of a tidal cycle has shown the correspondence between the sediment patterns and tidal circulation within the area. Although these images were acquired for the period 1975 to 1980, there is nonetheless a consistency in the distribution patterns from scene to scene. Valuable information relating to suspended sediment behaviour is evidenced including the possible source in the adjacent Christchurch Bay west of the Solent. An attempt is made to quantitatively correlate the satellite radiance values with suspended sediment concentrations. Previous studies concerning this are also discussed. A direct calibration is carried out for a Landsat overpass for which simultaneous sediment data was collected. In addition an indirect approach is undertaken based entirely on the histograms showing the radiance level frequencies of seven historical images, and the knowledge of suspended sediment distribution observed in 1980. A linear fit is applied for both cases. The two relationships are found to be closely related. The test of the two algorithms by comparing the predictions of the sediment concentrations from radiance values to limited sea truth observations has indicated an error in estimation that could range from 4% to 18%. Their application to the nine images obtained over a period of the six-year time span used in the study yield reasonable estimations of the concentration range appropriate to the seasonal conditions obtaining. The agreement between the estimated ranges and those observed in the field indicates the practicability of the algorithms to different frames provided that the atmospheric correction is allowed for. The band-S colour sliced images can thus become the quantitative expressions (colour maps) of the spatial and temporal distributions of suspended sediment for the region.
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Published date: 1982
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Local EPrints ID: 460236
URI: http://eprints.soton.ac.uk/id/eprint/460236
PURE UUID: c11a8251-0443-4127-ade5-0f3987b5edd1
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Date deposited: 04 Jul 2022 18:14
Last modified: 04 Jul 2022 18:14
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Author:
Darasri Srisaengthong
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