| Summary: | 碩士 === 國立中興大學 === 水土保持研究所 === 84 === The compound spillway flood detention dam is the traditional
check dam with a narrow rectangular opening down to the
downstream river bed in the center. Owing to the vertical
narrow opening the nappe also presents the same shape. An
elliptical scouring pool and a crescent dune form in the
downstream river bed. In this study, six different discharges
, five different slopes and three kinds of opening widths are
used to find the type of scouring under the situation of
cantilever flood-detention dam in flume experiment, and to
compare them with the gravitational flood-detention dam. From
the results of the experiments. The flow condition of the
cantilever flood-detention dam, according to weir
classification, is similar with narrow-crested weir. Instead
of narrow-crested weir, the flow condition of gravitational
flood-detention dam is similar with broad-crested weir. The
effectiveness of energy dissipation and the depth of scouring
pool will increase if discharge and slope of channel increase.
The wider the opening width is, the smaller energy dissipation
effect will occured. The scouring profile has two anti-curve
point, which expressed by fourth power equation, and the
profile before semi-section is curving downward. It is good
for dam body safety. The scouring depth of the cantilever flood-
detention dam is smaller than that of the gravitational flood-
detention dam . For cost saving, we suggest to use the
cantilever flood -detention dam.
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