IV. Retreatin~ Shorelines
199
r (seBeach head
a wall, revetment, dune or cliff)
Groyffe. I'~~~~~
root ' i ~~z-"~-i~~'~!
"
eac
"
'
;;,'~ ~
=o-I~='tBeach wmthm~~;'.
I
• groyne bay .,...~
,~_- .....
_Gro ne -~ ....
,...~,--- ~
~ _EEl-----.
Y
: .::.........
.. ,..,, ..
- : .
head
..,.. .... .~-,~..~3| ~, uy ne spacm_ g
r3
(also consloered in terms
of spacing/length ratio)
Plan
Groyne Length
Beach--J~ K.~'~:~~
-
" !
-head
°'" "~" "-;':':~
Beach 4-J Groyne hei~(:l~h~
normal (average) beach pro}ile '
Elevation
Groyne length, L,
Distance from limit
of wave uprush
(which may be on
the natural beach
or the beach head)
to the groyne head
(a) Groyne dimensions
III
r-- Beach head
Straight
Inclined
Zi~z-za¢,
(b) Farms of ~oyne geometry
j,
Y-shaped
T-~a~
or fishtail
Fig. 15 : Definition sketch for groin terminology (Flemming)