| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系 === 85 === The effect of protrude vegetation on the propagation and peak
attenuation ofa flood event are examined experimentally in a
compound channel. The compoundchannel has a protrude vegetation
on the left flood-plain (F/P) and has a muchsmoother bed on the
right flood-plain. Several steady flow experiments arealso
conducted to understand how the flow distributed laterally in
the com-pound channel.
The flood event considered in this study has been divided
into three cate-gories,long(LDF),mid(MID) and short(SDF)
duration floods.During onetest run, atotal of 18 water stage and
3 velocity measurements are takenalong the channel. The
Manning''s roughness n for the three vegetation layouts,that are
uesd inthe test, are calibrated beforehand in a rectangular
channel. All the data arecollected by a automatic acquisition
system and the errorare maintained within5.0% of a measurement.
All data are achieved and may be used as the data basefor the
verification of numerical models.
The experiments show that the protrude vegetation has the
following effect onthe flow in compound channel:
Both on the channel alignment and vegetation type can effect the
lateral dis-tribution of the steady flow. The main channel
has the highest unit widthdischarge and the protrude vegetated
flood-plain has the lowest one. The attenuation of the
flood peak is related to both the layout and densityof the
vegetation. Dense vegetation retards the flood and has a higher
atten-uationto the flood peak.
The front of a flood wave propagate faster in the smoother F/P
than that inthe vegetated F/P for the three flood
categories. The moving speed of thefrontfor the MDF can be
predicited by the moving surge equation.
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