w vertical (z) component of local fluid velocity or current 



velocity 



X (=x/^) 



X a x-direction coordinate perpendicular to the wave crest 



X a dimensionless x-direction coordinate using x^ as the 



length scale 



X coordinate direction system where the origin is taken at the 



maximum setup line and a positive x is facing seaward 



X a direction coordinate system where the origin is taken at 



the maximum setup line and a positive x is facing seaward 



|x| distance from shore 



X, breaker position in x coordinates 



Xi midsurf position 



X plunge point distance between the breakpoint and plunge point 



of a curling breaker 



Y a y-direction coordinate along the wave crest 



Y a dimensionless y-direction coordinate using y_ as the 

 length scale 



y coordinate direction alongshore, positive to right when 



facing seaward 



Z, the vertical distance of the bed above an arbitrary datum 



and always positive 



z the bed elevation above an arbitrary dattmi 



ot angle between wave crest and bottom contour 



a angle between wave crest and the shoreline 



ou angle between breaking wave crest and shoreline 



ot deepwater wave angle 



ex mean deepwater approach angle 



3 angle of beach slope with horizontal 



r horizontal (wave) mixing coefficient in surf zone, as 



introduced by Longuet-Higgins (1970, 1972a) 



18 



