圖書典藏及影音數位平台

近年來苗栗海岸受海埔地開發、海岸結構物及河川輸沙量減少等影響，海岸多處呈現侵蝕後退之情形。經往年沿岸水深地形測量之結果顯示，部份海岸如苗栗青天泉等海岸呈現明顯侵蝕現象，為因應苗栗海岸防災減災整體性功能之發揮及檢討現有海岸防護設施的成效，擬進行相關調查研究及工程規劃，確定未來該段海岸環境復育具體方向，並事先研擬部份局部重點海岸地區的防護措施與具體改善對策，作為未來改善工程實施的依據。 海岸防護規劃需先進行海岸基本資料觀測調查作業，含括地形水深測量、波潮流觀測調查及漂沙觀測調查等，藉以分析本海岸地形侵淤變化特性，繼而據以研擬相關之對策作為日後實施防護工作之依據。 本計畫測量範圍為苗栗縣海岸北起後龍鎮南至苑裡鎮鄉縣界止之海岸線，本段海岸線共計長約40公里。

Many coasts in Miaoli have been eroded by the sea because of tidal land development, coastal structures and sediment load decreased. In order to strengthen the overall function of disaster prevention at Miaoli coast as well as review the efficiency of protective measure, the Second River Management Office of Water Resource Agency, MOEA plan to carry out the research of the coasts and the engineering projects. The government can use the research achievements as the reference for future improvement engineering projects. The project area is from Houlong Township, Miaoli County coast to Yuanli Township, Miaoli County coast. Planning to carry out two times of surveying, one is after summer wave effect; the other is after winter wave effect. The project area’s property of erosion and deposition can be analyzed once topographic data were acquired and were compared to prior data. Finally, series of protective measures can be proposed and the space of coast recovery area can be designed. Bathymetric data were acquired by Single Beam Echo Sounder System. The bathymetric surveying area is from tidal zone to the contour which depth is -20m. Terrestrial topography data were acquired by Airborne LiDAR (Light Detection And Ranging). The terrestrial surveying area is from tidal zone to costal structures, and extends 100m toward inland. Qingtianquan coast, Tong Xiao Coast and Yuanli coast were suggested as the prior recovery coasts by analyzing 0m contour overlap, erosion and deposition process, historical disaster events and SMC model analysis. 1.Qingtianquan coast (coastal erosion) protective measures: (1) Reconsider the weight of base rocks. (2) Build undersea jetties at the depth around 3m to reduce wave energy or catch sands. (3) Build a group of jetties: A. Direction of jetties: the angle between jetty and coast line is about 110°. B. Depth at the bottom of jetties: -1m. C. Length of jetties: 70m. D. Permeability: 0.3. E. Length between jetties: 140m. F. Location of jetties: build 4 jetties（CG0、CG0-2、CG0-4、CG0-6） 2. Tong Xiao Coast (coastal erosion) protective measures: (1) Reconsider the width of armor blocks jetties. (2) Build offshore jetties to reduce wave energy and catch sands. (3) Build a group of jetties: A. Direction of jetties: the angle between jetty and coast line is about 110°. B. Depth at the bottom of jetties: -0.5m. C. Length of jetties: 50m（TS-1、TS-2、TS-3、TS-5、TS-6、TS-7）、30m（TS-S）. D. Permeability: 0.3. E. Length between jetties: 100m. F. Location of jetties: build 7 jetties（TS-1、TS-2、TS-3、TS-5、TS-6、TS-7、TS-S）. 3. Yuanli coast (blowing sands) protective measures: (1) Keep sands and maintain plant on the coasts. (2) Build a group of jetties: A. Direction of jetties: the angle between jetty and coast line is about 110°. B. Depth at the bottom of jetties: -0.5m. C. Length of jetties: 70m（YG-1）、40m（YS-S）. D. Permeability: 0.3. E. Length between jetties: 210m between YG-1 and YS-S. F. Location of jetties: build 2 jetties（YG-1、YS-S）. Keywords: Single Beam Echo Sounder, Airborne LiDAR, Topography Change, Coast Recovery