| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 103 === Taiwan is hit by typhoon almost every summer. There is narrow conshelf and steep slope eastern Taiwan. Deep water wave energy without dissipating that is up to coastal and cause shoreline erosion. In addition, the sediment transport resulted from the river flow so that it can supply sediment to coastal. Both of the results, coastal zone’s accretion and erosion of sediment become balance.
The study area is focus on Beinan River and near sea area. This project combined with topographic survey data and numerical model to figure out the effect of Beinan River. According to the survey results are found out that Beinan River is the main source of coastal sediment during typhoon attacks, its mechanisms of influence that the change of estuarine coastal morphology in typhoon is important.
In order to clear understand the ocean and river force's influence of changes in coastal topography. This study explored the forces uses DHI MIKE21 as research tools. All the simulation process consist of five modules: Spectral Waves Module (SW), Parabolic Mild-Slope Wave Module (PMS), Hydrodynamic Module (HD), Sand Transport Module (ST), and Particle Analysis Module(PA). There are three cases in this study: Haitang typhoon, Talim typhoon and Longwang typhoon in summer 2005. There are different characteristics.
Haitang typhoon is the mainly event that topography changed depositing in north estuary. Talim typhoon is short-term rainfall causing accretion in north estuary. Longwang typhoon is almost no rainfall and no sediment transport causing erosion in estuary. Overall, topographic change is deposit in north estuary and erosion in south estuary in summer 2005. That is persuasive to prove the main affect of the short-term coastal topography change is by Beinan River sediment transport in rainfall typhoon season. The result found that the general direction of the net longshore sediment transport by wave and current is from north to south. In the estuary zone main sediment supplied is from river transport, after into the sea is attacked by wave and current interaction then cause topographic change.
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