Coastal Morphological Change of South Dansuie River Estuary, North Taiwan
Date Issued
2007
Date
2007
Author(s)
Yang, Lan-Ya
DOI
zh-TW
Abstract
The estuary is highly sensitive to environmental processes. It is simultaneously affected by natural factors and artificial factors. The change of coastal landform also influences land use, so coastal research is significant for human. In the Recent Decade, coast of southern Dansuie estuary was one of serious erosion part in Taiwan. Coastal landform change of southern Dansuie estuary is mainly influenced by river discharge, so the change of the discharge is important. The effects of Northern dike to landform change were worthy to research after port of Taipei built in 1993. The purpose of this research is to understand geomorphological changing and influence of artificiality at Dansui estuary.
From 1987 to 1998, coastal landform change approximately trended to erosion. After 1998, Coastal erosion had been turned into accretion and deposition position appeared in northern dike. The coastline has changed from straight to arc shape, and furthermore expands to the seaward.
The result of this study is to analyze coastal landform change from channel to northern dike. The main reason influencing the landform change should be discharge of Dansuie River before 1998. When the discharge increased, the coastal landform was eroded. Oppositely, when the discharge reduced, the coastal landform was accreted. Landform change is negative correlation with discharge in this period. When northern dike was completed in 1998, sediments were accreted in the study area as river discharge increasing. It's reveal that most sediments are blocked by northern dike, and deposited in north of dike.
Seasonal dynamic change shows that there was sand ridge and trough phenomenon in nearshore and maintained dynamic equilibrium. The sediment budget maintained dynamic equilibrium, but it show seasonal replace. From September to next April, the coastal landform was usually eroded because northern monsoon increasing. After Port of Taipei was built in 1998, jetty produced to sand ridge and trough phenomenon were dissolved.
The profile is composed of narrow foreshores which are steep and flat terrace in summer. There are two types of profile change processes, including cross shore and longshore sediment transport dominate. The process of cross shore dominant area is broader than longshore dominant area. Longshore dominant exists near Dansuie estuary, and cross shore dominant is very wide distributed in southern area.
Subjects
淡水河口
海岸地形
地形變遷
人工構造物
季節變化
Dansuie estuary
coastal landform
morphological change
artificial exploitation
seasonal change
SDGs
Type
thesis
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