View source for Tidal Characteristic Numbers of Eff. Bed Shear Stress Action

[[category: Tidal Characteristic Numbers]]
[[de: Tidekennwerte der Wirkung der effektiven Bodenschubspannung]]

A graphic sketch for the definition of the various tidal characteristic numbers of effective bed [[shear stress]] is not available.
 
==Motivation==

The calculation as well as the graphic visualization of various tidal characteristic numbers of the effective bed [[shear stress]] contributes 
to an improved understanding of the impact of tidal flow on the bed as well as on [[bed load]] [[sediment transport]] for areas like coastal seas and 
estuaries as well.

* As the analysis is performed separately for the individual periods of ebb- and [[flood]]-current it can be demonstrated that the impact of the flow on the bed can differ significantly. This can be related to locally varying [[flood]]-ebb   asymmetries for either ebb and [[flood]] current velocities or otherwise differences between [[flood]] and ebb   current duration. Asymmetries may contribute significantly to residual ebb- or [[flood]]-oriented [[sediment transport]].

An automatic analysis of all tidal characteristic numbers of effective bed [[shear stress]] is carried through by 
the computer programs [[TDKLF]] and [[NCANALYSE]]. 

==Definitions for the Tidal Characteristic Numbers of Effective Bed Shear Stress==

===Program [[NCANALYSE]]===

====Flood Current====

=====Maximum eff. Bed Shear Stress due to Flood Current=====

Maximum value of effective bed [[shear stress]] during [[flood]] current. Vector quantity. <br />
<!-- [[Example figures: maximum effective bed shear stress during flood current]]. -->

=====Mean eff. Bed Shear Stress due to Flood Current=====

Mean value (computed from magnitude) of effective bed [[shear stress]] during [[flood]] current. Vector quantity.
The magnitude corresponds to the mean value computed from the magnitude of all individual vectors (given for different dates).
Mean direction follows from vectorial addition of the individual vectors. <br />
<!-- [[Example figures: mean effective bed shear stress during flood current]]. -->

=====Residual eff. Bed Shear Stress due to Flood Current=====

Residual effective bed [[shear stress]] during [[flood]] current. Vector quantity.
Magnitude as well as (mean) direction follow from vectorial addition of the individual vectors (given for different dates).
In case all individual vectors point into the same direction mean and residual value are identical.
The residual can never be larger than the mean value. <br />
<!-- [[Example figures: residual effective bed shear stress during flood current]]. -->

====Ebb Current====

=====Maximum eff. Bed Shear Stress due to Ebb Current=====

Maximum value of effective bed [[shear stress]] during ebb current. Vector quantity. <br />
<!-- [[Example figures: maximum effective bed shear stress during ebb current]]. -->

=====Mean eff. Bed Shear Stress due to Ebb Current=====

Mean value (computed from magnitude) of effective bed [[shear stress]] during ebb current. Vector quantity.
The magnitude corresponds to the mean value computed from the magnitude of all individual vectors (given for different dates).
Mean direction follows from vectorial addition of the individual vectors. <br />
<!-- [[Example figures: mean effective bed shear stress during ebb current]]. -->

=====Residual eff. Bed Shear Stress due to Ebb Current=====

Residual effective bed [[shear stress]] during ebb current. Vector quantity.
Magnitude as well as (mean) direction follow from vectorial addition of the individual vectors (given for different dates).
In case all individual vectors point into the same direction mean and residual value are identical.
The residual can never be larger than the mean value. <br />
<!-- [[Example figures: residual effective bed shear stress during ebb current]]. -->

====Tidal Cycle====

=====Mean eff. Bed Shear Stress within a Tidal Cycle=====

Mean value (computed from magnitude) of effective bed [[shear stress]] during a tidal cycle (here this
corresponds to the period between two subsequent ebb slacks). Scalar quantity.
Magnitude corresponds to the mean value computed from the magnitude of all individual vectors (given for different dates).<br />
<!-- [[Example figures: mean effective bed shear stress within a tidal cycle]]. -->

=====Residual eff. Bed Shear Stress within a Tidal Cycle=====

Residual (computed from vectorial addition) of effective bed [[shear stress]] during a tidal cycle (here this
corresponds to the period between two subsequent ebb slacks). Vector quantity.
Magnitude and direction are computed from vectorial addition of the individual vectors (given for different dates).<br />
<!-- [[Example figures: residual effective bed shear stress within a tidal cycle]]. -->

=====Ratio of mean eff. Bed Shear Stress during Flood Current : mean eff. Bed Shear Stress during Ebb Current=====

Quotient computed from the magnitude of mean eff. bed [[shear stress]] during [[flood]] current and mean eff. bed [[shear stress]] during ebb current.<br />
<!-- [[Example figures: Quotient for mean eff. bed shear stress flood current vs. ebb current]]. -->

=====Ratio of maximum eff. Bed Shear Stress during Flood Current : maximum eff. Bed Shear Stress during Ebb Current=====

Quotient computed from the magnitude of maximum eff. bed [[shear stress]] during [[flood]] current and maximum eff. bed [[shear stress]] during ebb current.<br />
<!-- [[Example figures: Quotient for maximum eff. bed shear stress flood current vs. ebb current]]. -->

=====Ratio of mean eff. Bed Shear Stress during Flood Current : mean eff. Bed Shear Stress during Tidal Cycle=====

Quotient computed from the magnitude of mean eff. bed [[shear stress]] during [[flood]] current and mean eff. bed [[shear stress]] during the tidal cycle.<br />
<!-- [[Example figures: Quotient for mean eff. bed shear stress flood current vs. tidal cycle]]. -->

=====Ratio of mean eff. Bed Shear Stress during Ebb Current : mean eff. Bed Shear Stress during Tidal Cycle=====

Quotient computed from the magnitude of mean eff. bed [[shear stress]] during ebb current and mean eff. bed [[shear stress]] during the tidal cycle.<br />
<!-- [[Example figures: Quotient for mean eff. bed shear stress ebb current vs. tidal cycle]]. -->

=====Ratio of maximum eff. Bed Shear Stress during Flood Current : mean eff. Bed Shear Stress during Tidal Cycle=====

Quotient computed from the magnitude of maximum eff. bed [[shear stress]] during [[flood]] current and mean eff. bed [[shear stress]] during the tidal cycle.<br />
<!-- [[Example figures: Quotient for maximum eff. bed shear stress flood current vs. tidal cycle]]. -->

=====Ratio of maximum eff. Bed Shear Stress during Ebb Current : mean eff. Bed Shear Stress during Tidal Cycle=====

Quotient computed from the magnitude of maximum eff. bed [[shear stress]] during ebb current and mean eff. bed [[shear stress]] during the tidal cycle.<br />
<!-- [[Example figures: Quotient for maximum eff. bed shear stress ebb current vs. tidal cycle]]. -->

===Program [[TDKLF]]===

====Flood Current====

=====Action of Effective Bed Shear Stress due to Flood Current=====

Time integral of effective bed [[shear stress]] over [[flood]] current duration.

====Ebb Current====

====Action of Effective Bed Shear Stress due to Ebb Current====

Time integral of effective bed [[shear stress]] over ebb current duration.

====Tidal Cycle====

=====Residual Action of the Effective Bed Shear Stress=====

If the action of effective bed [[shear stress]] during [[flood]] current duration is equal but in opposite direction
of the ebb current related action this will result in a zero residual action of the effective bed [[shear stress]].

=====Ratio between Flood- and Ebb-Current induced Action of the Effective Bed Shear Stress=====

[[Flood]] to ebb ratio for the respective action of the effective bed [[shear stress]].

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