| Summary: | 碩士 === 國立成功大學 === 自然災害減災及管理國際碩士學位學程 === 107 === In recent years, the frequency of extreme weather under global warming has become higher and higher. Long-duration and high-intensity rainfall events occur more frequently.Environmental factors, such as steep terrain, high speed of river flow, fragile geology and extreme rainfall, have made sediment related disasters commonly and caused a lot of losses and casualties in Taiwan. Therefor, how to effectively and accurately monitor the movement of sediment will be a very important part in the management and prevention of sediment-related disasters.
At present, the Taiwan government mainly used two methods to estimate the sediment transport rate. One is that the sediment transport rate is estimated by using an empirical formula; the other is that the sediment transport rate is estimated by samples from the river-bed. But these methods are inadequate. The results of the empirical formula are easy to overestimate the rate of sediment transport, and the sampling work is high risk for staff due to severe weather. Therefore, a new monitoring method to indirectly obtain the data of sediment becomes a worth study.
In order to estimate the bed-load transport rate, the study used a Japanese pipe hydrophone to measure. The relationship between sound pressure and momentum and the relationship between average water flow velocity and particle velocity are determined experimentally and statistically. And using this relationship, a method for estimating the quality of sediment has been established in this study.
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