澎湖桶盤嶼東側外海的海床形貌分類調查研究

The Study of Seabed Morphological Classification in the Eastern Offshore of Tungpanyu (Penghu)

李玉涵(Yu-Han Lee)

指導教授 ： 宋國士

國立臺灣大學/理學院/海洋研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.00006

摘要

目前對於海床地貌與底質辨識研究所使用的聲學儀器主要為側掃聲納，藉由人工判讀聲學影像的回散射能量強弱與紋理型態，來得到海床地貌、底質的資訊，這樣的方式雖然有效，卻欠缺客觀性。因此，本研究利用加拿大QTC公司研發的SwathView軟體來進行聲學影像分類的工作，其特點為利用影像分割法將側掃聲納影像數化，我們將其應用在桶盤嶼東側外海海域的側掃聲納地貌探測資料，並配合地形調查、地質探勘、底質沉積物採樣及水下攝影的結果，來探討SwathView軟體能否準確能否準確地將不同底質類型的海床進行分類，特別是區分有珊瑚生態的岩石海床與無珊瑚生態的岩石海床，並將分析結果與側掃聲納影像進行對照，來評估利用側掃聲納影像區分有珊瑚生態的岩石海床與無珊瑚生態的岩石海床是否可行。

研究結果顯示，研究區域的地形深度介於0~60公尺之間，根據地形特性可將研究區域分為風櫃近岸區、中央水道區及桶盤近岸區。而研究區域涵蓋的底質種類包括砂質海床、岩石海床及有珊瑚分佈的岩石海床，其中風櫃近岸區的底質以砂質海床為主，海床表面最平坦；中央水道區的底質以岩石海床為主，海床上有砂礫與貝類生物碎屑覆蓋，部份區域有少量珊瑚分佈，海床表面較崎嶇；桶盤近岸區的底質則以珊瑚分佈的岩石海床為主，海床上的沉積物相當少，並有較多珊瑚分佈，海床表面最崎嶇。

利用QTC SwathView軟體對研究區域的側掃聲納影像進行分析所得到的分類結果，與底質沉積物採樣結果及水下攝影影像進行對比後顯示，若軟體對聲學影像有足夠的解析力，則可有效地將具有不同聲學特性的底質類型進行分類。此外，軟體分類結果與側掃聲納影像對照後顯示，利用側掃聲納影像來區分有珊瑚生態的岩石海床與無珊瑚生態的岩石海床是可行的。

關鍵字

側掃聲納 ； 海床分類 ； 聲學影像 ； QTC SwathView

並列摘要

At present, the acoustic instrument mainly used for the researchs of seabed morphology and habitat classification is side-scan sonar, to get the informations of seabed morphology and habitat by using artificial identification for the acoustic images with back-scatter energy intensity and texture patterns.This method is effective but lack objectivity. Therefore,we use SwathView which produced by QTC in Canada to process acoustic classification.The main feature of SwathView is segmentation method.We apply SwathView to analyze the side-scan sonar data of Eastern Offshore of Tungpan Yu, Penghu,with the result of topography investigation、morphology survey ,sample of habitat sediments and underwater photography to discuss the accuracy of seabed classification by using SwathView, specifically distinguish the coral rocky seabed and the no-coral rocky seabed.We also compare the SwathView analysis results and the side-scan sonar images,to evaluate the feasibility for using the side-scan sonar images to distinguish the coral rocky seabed and the no-coral rocky seabed.

The results show that the study area depth ranges between 0 and 60m,and the study area can be divided into Fongguei Coastal Zone , Central Channel Zone and Tungpan Coastal Zone.And the habitat types of the study area consists of sand,rock and coral. The habitat type of Fongguei Coastal Zone is sand mainly,and the seabed is very flat. The habitat type of Central Channel Zone is rock mainly,there are many gravels and shell scraps on the seabed, part of the zone has some coral,and the seabed is rugged. The habitat type of Tungpan Coastal Zone is coral mainly,the seabed is very rugged ,and the seabed has many corals,less semidents.

Comparison of the analysis results by using QTC SwathView for the side-scan sonar data ,sample of habitat sediments and underwater photography images,we get the conclusion that QTC SwathView can classify the habitat types which have different acoustic characteristics effectively if the software have enough image resolution.In addition, comparing the SwathView analysis results and the side-scan sonar images,we get the conclusion that the way of using the side-scan sonar images to distinguish the coral rocky seabed and the no-coral rocky seabed is feasible.

並列關鍵字

side-scan sonar ； seabed classification ； acoustic image ； QTC SwathView

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