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Study on sampling methods for estimating the sand flushing volume via Yuanshanzih Flood Channel
|Authors: ||Li-Cheng Yin|
|Contributors: ||NTOU:Department of Marine Environmental Informatics|
Yuanshanzih Flood Diversion;sedimentation;sampling;System design
|Issue Date: ||2013-10-07T02:53:55Z
|Abstract: ||為解決台北市汐止地區開發後逢大雨即淹的問題而架構了員山子分洪工程，截斷基隆河的洪水，直接輸向東北角海域。洪水挾帶漂砂的嚴重性是最重要的海域環境問題，因此，必須監測排洪中的漂砂量。由於颱風或豪大雨中進行海上取樣幾乎不可能，所以必須於洪水入海前進行取樣，後續進行數值模擬推估其影響程度與範圍才為可能。 海洋大學胡健驊教授實驗室於營運期間所設計之自動化洪水採樣系統已初步成功，惟遇強勁分洪，即因含砂分層而誤差明顯，必須改進。仍以隧道口消能廳或改以出海口消能池為取樣地點的優缺點被被仔細分析，並對應提出了「隧道口導流墩全高程採水」及「出海口消能池三層抽水」兩項新設計。最後考慮施工的簡易度、設計複雜度、後續的維修保養及成功率等各方面因素，結論傾向採取後者之設計概念。此外，另建議（1）現階段的自動化系統保留作為對照之用，（2）必須於消能廳內增建樣品收集室以安置擴大的採樣系統。|
To solve the frequent flooding which occurs after heavy rainfalls in the Hsichih area of Taipei, the Yuanshanzih Flood Diversion (YFD) construction was established to block up the floods from Keelung River for bypassing to the northeast coast of Taiwan. How serious the sedimentation transported by the flooding would be the most important environmental issue. Therefore, to monitor the volume of the sedimentation in the diverted flood is demanded. Since it is impossible to carry out the sampling in the sea during a typhoon or heavy rainfall, the sampling must be implemented before the flood goes into the sea. And then it will become possible to execute the numerical modeling for estimating the influence range and degree of the diverted flood. A system for automatic flood sampling was initially successful in operating the YFD. The device was designed by the laboratory of the National Taiwan Ocean University, hosted by Prof. Jian-Hwa Hu. However, it encountered a problem of obvious error when the diverted flood was severely strong. The error could be caused by the stratification of sand contained in the flood and hence requires considerable improvement. The advantages and disadvantages of sampling location being either still in the Energy Dissipation Hall or in the Energy Dissipation Pool was analyzed in details. And then two types of sampling methods were proposed respectively. One is to collect waters at levels to full elevation on the diversion post right outside the tunnel. The other one is to pump waters at three levels near the outlet of the Pool. Considering the simplicity for construction, the complexity for design, the following maintenance and the probability to succeed, the conclusion is to prefer the later. Besides, the additional suggestions are (1) the present automatic system can be reserved for comparison, (2) a room to collect samples in the Energy Dissipation Hall is required to settle the expand system.
|Appears in Collections:||[海洋環境資訊系] 博碩士論文|
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