HI. Sediment Transport
125
Dean (1973) found that the wave steepness separating a bar profile from a step
profile varied with the fall velocity of the sediment w divided by the deepwater
celerity co =Lo/T, thus Ho/Lo = C W/Co. This can be rewritten as Ho/(wT) = C,
where w is the fall velocity of the median grain size Ds0. Dean concluded that
C=0.85. According to the U.S. Army Corps of Engineers, Shore Protection
Manual (edition 1984), it can be assumed that erosion usually occurs for C>I and
accretion for C Manual dissociates itself from the opinion that the presence of a berm
characterizes an accreted profile and a bar characterizes an eroded profile. On an
accreted beach a berm may be absent, while nearshore bars do not directly
indicate an eroded beach. Battjes (1974) has shown that bars are connected in
complicated ways with breaker processes.
0 Sol&~a~s Club Beach
"7
,~" TaaR Finn Bea~a
/
S~]a Beach, M~ l.~di~
~e B~r.,~ SmdFa~ It
~o
~
,,~ Pt.R~ersBcach
.r~ ~
1950
• I!
1
I
i
1 I I
I
~z
S~a,aM,~I~-R.B~ l
I!
I
I
I I I I
I
~ cu~s~T~a~t,B,~,~ /
o.9~
~
t]
Op~a~oB M~ Beadles
~.1
l
.I
I
I 1 I I
I
I
~'~l
I i,t
I
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o .~. Various pad~ C.om Bea~¢~, Bast.am, 195 I
o.el--v-~'~.F ~"
.
~
+
N~ Ja~-r B~a~ ~
u s a.Em~n,
I.*L I N I I" I I
I
x ~o.-~c~,i.B~,a~ 'r Bi~ i9~
I,\~' ~(% I I\1 .?,,'~,'--L, I
z p~,~u,m.Bo~h ...J
'
O.
"~
SX*OP( Of" 6gASH FACE
Fig. 24 : Beach slope versus grain size and wave load
Further, Dalrymple and Thompson (1976) concluded that the above parameter
Ho/(wT) determines to some degree the slope of the wet beach above still water
level, as is shown in Fig. 24.