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David M. Paterson - One of the best experts on this subject based on the ideXlab platform.

  • Calibration of the high-pressure Cohesive Strength meter (CSM)
    Continental Shelf Research, 2007
    Co-Authors: S. Vardy, James E. Saunders, Trevor Tolhurst, Peter A. Davies, David M. Paterson
    Abstract:

    Abstract Coastal erosion is an immense economic and social problem that has been receiving increased attention in recent years. A number of devices have been developed to determine the sediment stability in coastal areas: laboratory and field flumes; a range of different erosion devices; shear vanes and fall cone penetrometers. The Cohesive Strength meter (CSM) erosion device was developed to determine in situ the temporal and spatial variations in the erosion threshold of muddy intertidal sediments. Technological developments have enabled considerable improvements to be made to the original design over the last 15 years. This paper describes modifications to the CSM system that extend the range of eroding pressures the device can generate, to enable measurements to be made on very stable and consolidated sediments such as saltmarshes. A recalibration of the modified device found inconsistencies in the calibration for CSM devices presently in use, therefore a completely new calibration method is presented. This calibrates the CSM jet pressure to the pressure on the surface sediment (henceforth termed the “stagnation pressure”). The stagnation pressure when erosion is detected is assumed to be a relative (but not absolute) measure of the erosion threshold. The application of the device using the new calibration under laboratory conditions on muddy sediment is also presented. The following calibration equations were generated for the individual CSM models, where y=stagnation pressure at the sediment surface (N m−2) and x=jet exit pressure (kPa): Mark IV (high pressure): y=22.652x; Mark IV (prototype): y=8.528x; and Mark III: y=15.844x.

  • measuring the in situ erosion shear stress of intertidal sediments with the Cohesive Strength meter csm
    Estuarine Coastal and Shelf Science, 1999
    Co-Authors: T J Tolhurst, K S Black, S A Shayler, S Mather, I Black, K Baker, David M. Paterson
    Abstract:

    The shear resistance of muddy sediments directly governs the susceptibility of the sediment to erosion by tidal and wave induced currents. Measurements of the natural erosion shear stress are important in modelling estuarine systems and in determining the possible impact of human disturbance. A second-generation erosion instrument the Cohesive Strength Meter (CSM) designed to measure the critical erosion shear stress (τoCr) of intertidal sediments in situ is described. The CSM allows measurements of small-scale spatial and temporal variation of sediment stability to be made on a scale and rapidity previously unachievable. New features of specialized hardware are described and the instrument is empirically calibrated in terms of an equivalent horizontal bed shear stress using quartz sand. Some example results from recent field trials on the Konigshafen (Sylt-Romo Bight) are presented. The erosion characteristics of this intertidal flat varied on a cm scale due to the presence of patchy diatom biofilms. Areas with a diatom biofilm were more stable than those without, giving a biostabilization index of 6·2.

Geraldene Wharton - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of critical shear stress from Cohesive Strength meter‐derived erosion thresholds
    Limnology and Oceanography: Methods, 2010
    Co-Authors: Robert C. Grabowski, Ian G. Droppo, Geraldene Wharton
    Abstract:

    Measures of Cohesive sediment erodibility, such as erosion thresholds and rates, are essential for the development of accurate sediment transport models. In situ devices for erodibility quantification are increasingly being used to capture the high spatial and temporal variability in erodibility found in natural Cohesive sediments. The Cohesive Strength meter (CSM) is a small, hand-held, commercially available device that has been used extensively in recent years to measure in situ erosion thresholds. However, the device is primarily used for relative measures of erosion thresholds, due to a difficulty in comparing the vertical forces generated by the CSM with horizontal bed shear stress. In this article, we describe the development of a methodology for the estimation of horizontal bed shear stress from CSM-derived erosion thresholds. The approach used Cohesive sediment mixtures with varying clay contents to create sediments with a range of erodibilities and tested them using the CSM and a laboratory annular flume. A calibration is proposed based on a comparison of mean erosion thresholds from each device per clay treatment. This study is the first successful inter-comparison between CSM- and flume-derived erosion thresholds. Significant differences in erosion thresholds were noted between CSM routines, so it is recommended that the empirical calibration be applied only to erosion thresholds estimated using the Sand 1 routine, and ranging from 40-90 Pa stagnation pressure. The calibration allows the conversion of CSM-derived erosion thresholds into critical shear stress, a form that permits incorporation into sediment transport models.

  • estimation of critical shear stress from Cohesive Strength meter derived erosion thresholds
    Limnology and Oceanography-methods, 2010
    Co-Authors: Robert C. Grabowski, Ian G. Droppo, Geraldene Wharton
    Abstract:

    Measures of Cohesive sediment erodibility, such as erosion thresholds and rates, are essential for the development of accurate sediment transport models. In situ devices for erodibility quantification are increasingly being used to capture the high spatial and temporal variability in erodibility found in natural Cohesive sediments. The Cohesive Strength meter (CSM) is a small, hand-held, commercially available device that has been used extensively in recent years to measure in situ erosion thresholds. However, the device is primarily used for relative measures of erosion thresholds, due to a difficulty in comparing the vertical forces generated by the CSM with horizontal bed shear stress. In this article, we describe the development of a methodology for the estimation of horizontal bed shear stress from CSM-derived erosion thresholds. The approach used Cohesive sediment mixtures with varying clay contents to create sediments with a range of erodibilities and tested them using the CSM and a laboratory annular flume. A calibration is proposed based on a comparison of mean erosion thresholds from each device per clay treatment. This study is the first successful inter-comparison between CSM- and flume-derived erosion thresholds. Significant differences in erosion thresholds were noted between CSM routines, so it is recommended that the empirical calibration be applied only to erosion thresholds estimated using the Sand 1 routine, and ranging from 40-90 Pa stagnation pressure. The calibration allows the conversion of CSM-derived erosion thresholds into critical shear stress, a form that permits incorporation into sediment transport models.

T J Tolhurst - One of the best experts on this subject based on the ideXlab platform.

  • measuring the in situ erosion shear stress of intertidal sediments with the Cohesive Strength meter csm
    Estuarine Coastal and Shelf Science, 1999
    Co-Authors: T J Tolhurst, K S Black, S A Shayler, S Mather, I Black, K Baker, David M. Paterson
    Abstract:

    The shear resistance of muddy sediments directly governs the susceptibility of the sediment to erosion by tidal and wave induced currents. Measurements of the natural erosion shear stress are important in modelling estuarine systems and in determining the possible impact of human disturbance. A second-generation erosion instrument the Cohesive Strength Meter (CSM) designed to measure the critical erosion shear stress (τoCr) of intertidal sediments in situ is described. The CSM allows measurements of small-scale spatial and temporal variation of sediment stability to be made on a scale and rapidity previously unachievable. New features of specialized hardware are described and the instrument is empirically calibrated in terms of an equivalent horizontal bed shear stress using quartz sand. Some example results from recent field trials on the Konigshafen (Sylt-Romo Bight) are presented. The erosion characteristics of this intertidal flat varied on a cm scale due to the presence of patchy diatom biofilms. Areas with a diatom biofilm were more stable than those without, giving a biostabilization index of 6·2.

Robert C. Grabowski - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of critical shear stress from Cohesive Strength meter‐derived erosion thresholds
    Limnology and Oceanography: Methods, 2010
    Co-Authors: Robert C. Grabowski, Ian G. Droppo, Geraldene Wharton
    Abstract:

    Measures of Cohesive sediment erodibility, such as erosion thresholds and rates, are essential for the development of accurate sediment transport models. In situ devices for erodibility quantification are increasingly being used to capture the high spatial and temporal variability in erodibility found in natural Cohesive sediments. The Cohesive Strength meter (CSM) is a small, hand-held, commercially available device that has been used extensively in recent years to measure in situ erosion thresholds. However, the device is primarily used for relative measures of erosion thresholds, due to a difficulty in comparing the vertical forces generated by the CSM with horizontal bed shear stress. In this article, we describe the development of a methodology for the estimation of horizontal bed shear stress from CSM-derived erosion thresholds. The approach used Cohesive sediment mixtures with varying clay contents to create sediments with a range of erodibilities and tested them using the CSM and a laboratory annular flume. A calibration is proposed based on a comparison of mean erosion thresholds from each device per clay treatment. This study is the first successful inter-comparison between CSM- and flume-derived erosion thresholds. Significant differences in erosion thresholds were noted between CSM routines, so it is recommended that the empirical calibration be applied only to erosion thresholds estimated using the Sand 1 routine, and ranging from 40-90 Pa stagnation pressure. The calibration allows the conversion of CSM-derived erosion thresholds into critical shear stress, a form that permits incorporation into sediment transport models.

  • estimation of critical shear stress from Cohesive Strength meter derived erosion thresholds
    Limnology and Oceanography-methods, 2010
    Co-Authors: Robert C. Grabowski, Ian G. Droppo, Geraldene Wharton
    Abstract:

    Measures of Cohesive sediment erodibility, such as erosion thresholds and rates, are essential for the development of accurate sediment transport models. In situ devices for erodibility quantification are increasingly being used to capture the high spatial and temporal variability in erodibility found in natural Cohesive sediments. The Cohesive Strength meter (CSM) is a small, hand-held, commercially available device that has been used extensively in recent years to measure in situ erosion thresholds. However, the device is primarily used for relative measures of erosion thresholds, due to a difficulty in comparing the vertical forces generated by the CSM with horizontal bed shear stress. In this article, we describe the development of a methodology for the estimation of horizontal bed shear stress from CSM-derived erosion thresholds. The approach used Cohesive sediment mixtures with varying clay contents to create sediments with a range of erodibilities and tested them using the CSM and a laboratory annular flume. A calibration is proposed based on a comparison of mean erosion thresholds from each device per clay treatment. This study is the first successful inter-comparison between CSM- and flume-derived erosion thresholds. Significant differences in erosion thresholds were noted between CSM routines, so it is recommended that the empirical calibration be applied only to erosion thresholds estimated using the Sand 1 routine, and ranging from 40-90 Pa stagnation pressure. The calibration allows the conversion of CSM-derived erosion thresholds into critical shear stress, a form that permits incorporation into sediment transport models.

K Baker - One of the best experts on this subject based on the ideXlab platform.

  • measuring the in situ erosion shear stress of intertidal sediments with the Cohesive Strength meter csm
    Estuarine Coastal and Shelf Science, 1999
    Co-Authors: T J Tolhurst, K S Black, S A Shayler, S Mather, I Black, K Baker, David M. Paterson
    Abstract:

    The shear resistance of muddy sediments directly governs the susceptibility of the sediment to erosion by tidal and wave induced currents. Measurements of the natural erosion shear stress are important in modelling estuarine systems and in determining the possible impact of human disturbance. A second-generation erosion instrument the Cohesive Strength Meter (CSM) designed to measure the critical erosion shear stress (τoCr) of intertidal sediments in situ is described. The CSM allows measurements of small-scale spatial and temporal variation of sediment stability to be made on a scale and rapidity previously unachievable. New features of specialized hardware are described and the instrument is empirically calibrated in terms of an equivalent horizontal bed shear stress using quartz sand. Some example results from recent field trials on the Konigshafen (Sylt-Romo Bight) are presented. The erosion characteristics of this intertidal flat varied on a cm scale due to the presence of patchy diatom biofilms. Areas with a diatom biofilm were more stable than those without, giving a biostabilization index of 6·2.