Calibration of the high-pressure cohesive strength meter (CSM)

S. Vardy, J. E. Saunders, T. J. Tolhurst, P. A. Davies, D. M. Paterson

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    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 (Nm-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.

    Original languageEnglish
    Pages (from-to)1190-1199
    Number of pages10
    JournalContinental Shelf Research
    Volume27
    Issue number8
    DOIs
    Publication statusPublished - 1 May 2007
    Event3rd Workshop on the Comparison of Laboratory and in situ Measuring Devices, and the Extrapolation of Flume and Erosion Device Data to the Field - Venice International University, Venice, Italy
    Duration: 1 Aug 2004 → …

    Keywords

    • in-situ
    • erosion threshold
    • cohesive strength meter
    • intertidal sediment stability
    • intertidal sediments
    • stability
    • calibration
    • CSM
    • erosion shear-stress

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