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The main purpose of this thesis is to analyze the effect of
submerged break-waters on beach protection via 2-D hydrodynamic
model experiment. The exper-iment is divided into two parts.
In the first part, the fixed-bedmodel, was used to measure the
waves reflection and transmission coefficients,through
twoimpermeable submerged rectangle breakwaters. The aim of the
experiment is to find the best reducing energy set-up of double
submerged breakwaters. In the second part of experiment,
movable-bed model, was used to find the influence of single and
double permeable submerged breakwaters on beach profile. The
experiments lead to find the change of shoreline, and size of
berm for differ-ent arrangement of submerged breakwaters.
The experiments show that : transmission coefficient has become
minimum whenincident wave length is equal to twice the
distance between adjacent break-waters and twofold crest width,
〔L=2(l+2B)]. The transmission coefficient was attenuated 20~40%
when ratio of submerged breakwater''s height to water depth, a/d
increased per sixth, or ratio of submerged breakwater''s distance
to break-water''s crest width, l/B increased one. The beach
will accrete when the Sunamura*s coefficient Cs lesser than
four. Shoreline will move seaward after the Dean*s parameter(HT/
wsT) greater than 1.76 , or the Sunamura''s parameter (HT2/gT2
d50) greater than 0.81. We also propose a formula to estimate
the var-iation of shoreline and size of berm.
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