Tidal Characteristic Numbers of Suspended Sediment Transport

graphical representations of the characteristic numbers of salinity

Motivation

The calculation as well as the graphic visualization of various tidal characteristic numbers of suspended sediment concentration and also for the advective transport of suspended sediment contributes to an improved understanding of tidally dominated transport processes in estuaries. Spatial variations of suspended sediment concentration, advective transport of suspended sediment by means of flood and ebb currents can be highlighted for areas like coastal seas and estuaries as well.

• As the calculations are performed separately for the durations of ebb- and flood-current it can be shown that transport paths can differ significantly for the two tidal phases. From this one can get additional insight with respect to the relevant transport mechanisms dominated by the tidal currents. This can be related to locally varying flood-ebb asymmetries for ebb volume and flood volume. Also the presence of horizontal gradients can contribute to this effect.
• The variation of suspended sediment concentration resulting from the local maximum as well as the local minimum of suspended sediment concentration can be quite large. This is a consequence of the different availability of suspended sediments, e. g. inside or outside of the turbidity maximum. The value for the local suspended sediment concentration variation is mainly the result of the product between the horizontal suspended sediment concentration gradient and the lagrangian drift of a water particle during a complete tidal cycle, but also effected by the strong spatial variation of deposition and erosion of suspended sediments throughout the estuary.

An automatic analysis of all tidal characteristic numbers of suspended sediment transport is carried through by the computer programs TDKSF and NCANALYSE.

Definitions for the Tidal Characteristic Numbers of Suspended Sediment Transport

Program NCANALYSE

Flood Current

Advective Flood Transport of Suspended Load

Exact amount of suspended load (with exception of roundoff) which passes a certain cross section during flood current due to advection. This quantity makes use of the normal flow of suspended load only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).

Diffusive Flood Transport of Suspended Load

Exact amount of suspended load (with exception of roundoff) which passes a certain cross section during flood current due to (turbulent) diffusion. This quantity makes use of the normal flow of suspended load only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT).

Advective Flood Transport-Rate of Suspended Load

Exact transport rate of suspended load (with exception of roundoff) which passes a certain cross section during flood current due to advection. This quantity makes use of the normal flow of suspended load only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT). On tidal flats this quantity is computed for the period of inundation only.

Diffusive Flood Transport-Rate of Suspended Load

Exact transport rate of suspended load (with exception of roundoff) which passes a certain cross section during flood current due to (turbulent) diffusion. This quantity makes use of the normal flow of suspended load only, which is orthogonal to the flow face. Reconstruction of the total vector by means of projection is left to visualization programs (e. g. NCPLOT). On tidal flats this quanmtity is computed for the period of inundation only.

Mean Suspended Load Flood Current

Mean value of suspended load during flood current duration of a tide.
Data analysis: NCANALYSE.

Ebb Current

Mean Suspended Load Ebb Current

Mean value of suspended load during ebb current duration of a tide.
Data analysis: NCANALYSE.

Tidal Cycle

Maximum Suspended Load

Maximum value of suspended load during a full tidal cycle (period between two subsequent slack water times of ebb current).
Data analysis: NCANALYSE.

Minimum Suspended Load

Minimum value of suspended load during a full tidal cycle (period between two subsequent slack water times of ebb current).
Data analysis: NCANALYSE.

Mean Suspended Load

Average value of suspended load during a full tidal cycle (period between two subsequent slack water times of ebb current).
Data analysis: NCANALYSE.

Tidal Variation of Suspended Load

Difference between maximum and minimum values of suspended load during a full tidal cycle (period between two subsequent slack water times of ebb current).
Data analysis: NCANALYSE.

Mean Suspended Load Flood Current : Mean Suspended Load

Ratio between mean suspended load during flood current and mean suspended load during the full tidal cycle.
Data analysis: NCANALYSE.

Mean Suspended Load Ebb Current : Mean Suspended Load

Ratio between mean suspended load during ebb current and mean suspended load during the full tidal cycle.
Data analysis: NCANALYSE.

Mean Suspended Load Flood Current : Mean Suspended Load Ebb Current

Ratio between mean suspended load during flood current and mean suspended load during ebb current.
Data analysis: NCANALYSE.

Tidal Variation of Suspended Load : Mean Suspended Load

Ratio between tidal variation of suspended load and mean suspended load during the tidal cycle.
Data analysis: NCANALYSE.

Maximum Suspended Load : Mean Suspended Load

Ratio between maximum suspended load and mean suspended load during the tidal cycle.
Data analysis: NCANALYSE.

Minimum Suspended Load : Mean Suspended Load

Ratio between minimum suspended load and mean suspended load during the tidal cycle.
Data analysis: NCANALYSE.

Program TDKSF

Flood Current

Advective Flood Transport of Suspended Sediment

Suspended sediment mass, which is transported by means of flood current through a cross section
Example: not available.

Ebb Current

Advective Ebb Transport of Suspended Sediment

Suspended sediment mass, which is transported by means of ebb current through a cross section
Example: not available.

Tidal Cycle

Maximum Suspended Sediment Concentration

Maximum value of suspended sediment concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Minimum Suspended Sediment Concentration

Minimum value of suspended sediment concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Mean Suspended Sediment Concentration

Average value of suspended sediment concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Tidal Variation of Suspended Sediment Concentration

Difference between the extreme values of suspended sediment concentration during a complete tidal cycle (period between two subsequent slack water times of ebb current)
Example: not available.

Advective Residual Transport of Suspended Sediment

Residual suspended sediment mass which is transported by means of ebb and flood currents through a cross section (the different transport directions are taken into account). If the advective transport by means of flood current is equal but in opposite direction of the ebb current transport this will result in a zero advective residual transport of suspended sediment.
Example: not available.

Advective Suspended Sediment Transport, Flood-Ebb-Ratio

Flood to ebb ratio for the suspended sediment volumes which are transported by means of flood and ebb currents
Example: not available.

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Overview