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年度	103	專案性質	實驗性質
專案類別	研究專案	研究主題	底泥
申請機構	國立台灣大學	申請系所	海洋研究所
專案主持人	黃千芬	職等/職稱	教授
專案中文名稱	運用地層剖面儀進行河口底泥物理性質之空間變異研究
中文關鍵字	聲學遙測；反射係數；底泥平均粒徑
專案英文名稱	Applications of Subbottom Profiler on Probing Horizontal Variations of Sediment Physical Properties in River Mouth Area
英文關鍵字	Acoustic Remote Sensing；Reflection Coefficient ；Mean Grain Size
執行金額
執行期間	2014/4/25 至 2014/11/24
計畫中文摘要	傳統上海床/河床底質沉積物的量測均使用現場定點底泥採樣的調查方式，以獲得底泥的物理性質，然此方法因海/水上作業不易，難以進行大範圍的水域的探測。鑑此，近年來海洋地球物理領域已快速發展聲納儀器，利用聲波於海水傳播的特性與訊號處理的技術進行地層遙測以提升探勘效率。本研究專案之目的為引進地球物理聲學遙測技術 – 變頻聲納海底地層剖面儀 (Chirp sonar sub-bottom profiler) 進行河川底泥物理性質之大範圍調查。變頻聲納海底地層剖面儀主要可提供高解析度底床淺層沉積物垂直面資訊，該資訊不僅可以直接解讀底泥厚度，經過後續資料分析，透過底泥聲學性質與物理性質間的關係式，即可估算底泥物理性質（如平均粒徑、孔隙度、滲透率、密度等）。本研究擬於基隆河與淡水河口進行變頻聲納地層剖面儀調查，並輔以現場底泥採樣。將利用測線上的聲學資料估算底泥之平均粒徑、滲透率與底泥厚度（視該區域底泥分層厚度而定）以建構底泥空間分佈。比較聲學遙測與底泥採樣結果，並評估聲學遙測方法於該區域進行底泥辨識之可行性，期建立適用於台灣河床聲學遙測分析方法，以提供未來河川底泥整治位置的優先順序之參考。
計畫英文摘要	The project investigates the acoustic surveying tools, including the chirp subbottom profiling system (SBP) and the dual-frequency side-scan sonar (SSS), to map the distribution of river sedimentary environments. The experimental sits was in the river mouth of Keelung and Tamsui Rivers. The results show that, near the relatively flat area on both sides of Tamsui River, the values of reflection coefficient (RC) measured by the SBP are between −20 to −10 dB. The SBP information indicates that the sediment is dominated by sand and silt in various amounts, which is consistent with the analysis of the in-situ grab samples. In the deeper water area the lower RCs are observed, indicating a rocky riverbed. However, the SBP information is less correlated with the grab samples. The reason might be that the deeper areas are eroded by the river flow and the bedrock is exposed with few amount of sand/silt deposited. In addition, the study uses the multiple reflections to develop an algorithm for calculating the RCs. The values of RC are corrected for the case when the sediments are resuspended from the riverbed. We find that integrating the information provided by SBP along with higher-frequency SSS can make better interpretation of the acoustic data for inference of the sediment types.