| Summary: | 碩士 === 國立中興大學 === 水土保持學系 === 91 === Abstract
Lots of landslides were occurred and yielded sediments in mountain areas of Taiwan. The movement of these sediments will produce scouring or settling along the stream bed, depending on the hydraulic conditions. The unequilibrium of channel bed due to scouring or settling will influence the design for the torrent control works. Therefore, this study is going to investigate the sediment delivery and deposition in Gan-hsi watershed and conduct a simulated experiment in laboratory. A relation between sediment delivery and deposition will be trying to derive for the application.
According to field investigation, the maximum scouring of each pile during flooding is greater than the deposition depth after flooding, and the deposition quantities have a tendency to increase to downstream. There are weak relations between total rainfall and channel variations, however the channel variations significant relates to rainfall intensity basing on hydrologic data.
According to different peak discharges of simulated experiment result, there are scouring often occurred in the upstream, and there are deposition phenomenon displayed in the downstream. And each cross section of canal has stronger scouring capability between 0.75 with 1.00 for Q/Qp, it reach surely to 2.0(cm/min) for scouring velocity. In the same hydrograph circumstances the sediment concentration during flood raising period is higher than during flood recession period, because movable bed tends gradually to become mild during flood and brings on shear stress to become small. In the other head, there are power function’s relations increasing between qs/q and slope of movable bed, because steeper slope of movable bed increases larger horizontal quantity of gravity for sediment and stronger tractive force.
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