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Measuring instruments for estuaries

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This article is a summary of sub-section 5.3.3 of the Manual Sediment Transport Measurements in Rivers, Estuaries and Coastal Seas[1]. This article describes which instruments are available to measure several aspects of sediment management in estuaries.

Instruments for estuaries

Table 1, 2 and 3 present the available instruments (and accuracies involved) for measuring:

  • bed load transport,
  • suspended sediment concentrations and transport rates
  • particle sizes and fall velocities,

The order of preference in the Tables is based on the overall sampling accuracy. Simple mechanical instruments such as the bottle-type and the trap-type samplers are not attractive because of the very short sampling times involved. Accuracy cannot be improved by increasing number of samples due to time-variation of sediment concentrations within the tidal cycle.

Point-samples should be taken over the entire water column in strong tidal flows as the sediments will be mixed over the water column by turbulent eddies. Data sampling can be confined to the bottom region in weak tidal flows. Flocculation often is a dominant process in muddy estuaries. The LISST-ST which is an in-situ Laser diffraction instrument in combination with a settling tube offers a powerful solution to measure particle sizes, concentrations and densities of the individual particles as well as the flocculated aggregates (low concentrations <150 mg/l) in on-line mode. This instrument (LISST-ST) is not yet suitable for long-term, stand-alone measurements due to insufficient robustness, relatively low concentration range (<150 mg/l) and biological fouling problems (see also Optical Laser diffraction instruments (LISST)).

Table 1 and 2: Instruments to measure bed load and suspended load
Table 3: Instruments to measure particle size and fall velocity


See also

Summaries of the manual

Other internal links

External links

References

  1. Rijn, L. C. van (1986). Manual sediment transport measurements. Delft, The Netherlands: Delft Hydraulics Laboratory
The main author of this article is Rijn, Leo van
Please note that others may also have edited the contents of this article.


The main author of this article is Roberti, Hans
Please note that others may also have edited the contents of this article.