SECT. 3] 



BEACH AND NEARSHORE PROCESSES 



551 



Symbols — continued 



Symbol 



Dimensions 



Description 



Jb^ Js 

 K 



l,h 



m 



r 

 S 



s 



T 



T 



ML -2 



L2T-1 



L 

 L3T-1 



L 



ML -IT -2 



T 



Energy loss by bed friction i^er unit area, AE\ — 



AE2 = 8E 



Fluid foi'ce on a grain, per unit of effective grain area 



Acceleration of gravity 



Whole height of a surface wave 



Energy head of a stream 



Water depth or flow depth 



Dynamic transport rates of sediment past a whole 



section of flow, i etc. times width of section 



Total longshore dynamic transport rate of sediment, 



[(ps-p)/ps]9J 



Dynamic transjaort rate of sediment past unit width 

 of flow, total load = if, + ig 



Bed load and suspended load contributions to 

 ''> [{ps - p)lps'\9 cos ^jb or js 



Dry mass of sediment passing in unit time across a 

 whole section of flow, j etc. times width of section. 

 J is also longshore mass transport rate of sediment ; 

 total dry mass passing beach section in unit time 

 Sediment transport rate, dry mass of sediment 

 passing unit width in unit time — mU =ji}+js = 

 mbtJb + nisUs 



Bed load and suspended load contributions to j 

 Ratio i/co 



Distance along the shore ; average separation 

 between rip currents 



Mass of total sediment load over unit bed area, 

 m = nif) + nig 



Mass of bed, suspended load over unit bed area 

 Grain concentration by volume = grain-occupied 

 space/whole space 



Proportion of energy travelling forward with wave 

 phase velocity C 



Dispersive grain stress normal to shear planes (trans- 

 mitted from grain to grain) 



Longshore component of wave power, per unit 

 length of shore 

 Fluid pressure 



Longshore discharge of water ; mean velocity times 

 cross-sectional area 



Volume discharge of water in unit time per unit 

 width of flow 



Semi-amplitude of wave displacement close to bed 

 Longshore bulk -volume transport rate of sand, 

 volume is measured at rest and includes voids 

 S = Jlps' 



Distance between wave orthogonals or rays (Fig. 1 lb) 

 Grain shear stress, transmitted from grain to grain 

 Wave period 



