Difference between revisions of "Longshore current"
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==Notes== | ==Notes== | ||
| − | The longshore current is generated by the shore-parallel component of the stresses associated with the breaking process of obliquely incoming waves, the so-called [[radiation stress]]es. It is generally a fluctuating and meandering current that dominates in the [[surf zone]]. | + | The longshore current is mainly generated by the shore-parallel component of the stresses associated with the breaking process of obliquely incoming waves, the so-called [[radiation stress]]es. It is generally a fluctuating and meandering current that dominates in the [[surf zone]]. Other, generally smaller components of the longshore current are: currents driven by alongshore gradients in [[wave set-up]] and currents driven by tide and wind. |
| − | For further explanations, see [[Shallow-water wave theory#Longshore Currents]]. | + | For further explanations, see [[Shallow-water wave theory#Longshore Currents]] and [[Littoral drift and shoreline modelling]]. |
An empirical formula for the longshore current <math>V</math> halfway the surf zone is<ref>Komar, P.D. 1979. Beach-slope dependence of longshore currents. Journal of the Waterway, Port, Coastal and Ocean Division 105(4): 460–464</ref> | An empirical formula for the longshore current <math>V</math> halfway the surf zone is<ref>Komar, P.D. 1979. Beach-slope dependence of longshore currents. Journal of the Waterway, Port, Coastal and Ocean Division 105(4): 460–464</ref> | ||
Latest revision as of 11:25, 3 July 2022
Definition of Longshore current:
Current running parallel to the shore generated by obliquely incident waves.
This is the common definition for Longshore current, other definitions can be discussed in the article
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Notes
The longshore current is mainly generated by the shore-parallel component of the stresses associated with the breaking process of obliquely incoming waves, the so-called radiation stresses. It is generally a fluctuating and meandering current that dominates in the surf zone. Other, generally smaller components of the longshore current are: currents driven by alongshore gradients in wave set-up and currents driven by tide and wind.
For further explanations, see Shallow-water wave theory#Longshore Currents and Littoral drift and shoreline modelling.
An empirical formula for the longshore current [math]V[/math] halfway the surf zone is[1]
[math]V = 1.17 \sqrt{g H_b} \sin \theta_b \cos \theta_b ,[/math]
where [math]g[/math] is the gravitational acceleration ([math]\approx 9.8 m^2/s[/math]), [math]H[/math] the root-mean-square wave height and [math]\theta[/math] the wave incidence angle. These quantities are evaluated at the depth of incipient wave breaking indicated by the subscript [math]_b[/math].
Recommended review article:
- Hanes, D.M. 2022. Longshore Currents. Treatise on Geomorphology, 2nd edition, Chapter 8.04. Elsevier.
Recommended book:
- Komar, P.D. 1998. Beach Processes and Sedimentation. Second edition. Prentice-Hall, 544pp.
References
- ↑ Komar, P.D. 1979. Beach-slope dependence of longshore currents. Journal of the Waterway, Port, Coastal and Ocean Division 105(4): 460–464
