The Study Of Underwater Topography off Northern and Western Taiwan.

• Main Authors: I-Chen Su, 蘇儀真
• Other Authors: Gwo-Shyh Song
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/41866419039218968684

碩士 === 國立臺灣大學 === 海洋研究所 === 95 === There had been no sufficient bathymetrical data as abundant as those collected on land in nearshore area off Taiwan coast, such that systematical gathering of bathymetrical data was undone and there was merely a few studies related with the morphology or underwater topography research off the coast of Taiwan. In this study, single beam sounding data had been gathered and checked using the cross over check method. After that, sets of data had been edited by ruled out those inaccurate measurements. The data thus was used to make the plots according to density distribution and precision of data sets. Area off the coast was divided into the following regions: 1、Northern region, northern part of the coast extended north from DanShuei River, it passes Pitoujiao to Linsanpi, and surrounds the Datun volcanic mountain. The ocean bottom behaves same feature as shown on land, and the descending slope near the coast is at 1/110, which is steeper than the slope shown in coastal area south to DanShuei River, gradient at 1/192, in which is the area extended from Linkou Terrace.；2、Middle strait region, this portion of seabed has been covered by recent sediments, where the sediments have been transported under the influence of tidal flow. Except in the offshore region outside Taichung coast, where a structural coastal terrace extended offshore from coastal line for 10 kilometers, and along shore for 30 kilometers long. Seafloor in this region is covered by sand waves, and together with the pattern shown by underwater topography, it is indicated that sediments have been moved from south to north in this area..；3、South strait region, it is occupied by a vast area of tidal flat; there are two tidal flats in the region, northern one is called Waisandingjou,which is located offshore of Tonshi, southern one is located off Tseng-wen River estuary. Two tidal flats have formed in triangle shape, with their headlands being the place with greatest descending slope off the coast line. They all show with about 5 degree descending angle from 20 meters to 120 meters water depths. We can observe possible topographical lineation of Lungdung Fault、Kanchiao Fault and Chinshan Fault on land , extended into the ocean floor in the bathymetrical maps produced in this study. In addition, a triangular shape linear depression is shown in the northern offshore seafloor of Kaohsiung Harbor area. This depression is located just outside of Chishan Fault on land, and was formed by left lateral transcurrent motions.