| Summary: | 碩士 === 國立成功大學 === 水利及海洋工程學系碩博士班 === 94 === Taiwan is surrounded by the sea and adjacent to Taiwan Strait in the west and Pacific in the east. So, the climate is influenced by the air mass of mainland and marine nearby. Monsoon season begins from October to next April and serious Typhoon attack in the period of June to September every year. Hence, the coast appears different features by actions of wave, tide, and current constantly. Coastal zone variation is a dynamic equilibrium process and the longshore sand drifting dominates the influencing mechanism. Sand drifting phenomena caused the coastline retreat or advance. Because of the limit territory and large populations in Taiwan, the coastal process research should be paid much attention.
Numerical simulation of coastal process comes into vogue in recent years with the aids of excellent computational and treatment abilities of computer. However the coastal process is extremely complicated and could not get the ideal simulation result because of its insufficient input or boundary conditions. So, a fluorescence tracer test base on the Spatial sampling method (SIM) is provided in substitute for calculating the drift sand moving average speed then estimating the yearly sand drifting amount in the case study site by cooperate with the geological, topography conditions and wave, tide, current parameters. The site pictures taken by ROCSAT-2 satellite was being used to estimate the shoreline changes and compared with the drift sand amount in same period. The SOP of fluorescence tracer test and error analysis of these procedures were proposed in this paper as well. So, this research is beneficial to the coastal process research, numerical simulation’s data-input, coast disaster preventing policy’s drawing up and advance the sand drift field testing techniques.
The case study has been carried out on Yilan County offshore between Wushih and Su-ao fishing harbor. The average moving speed of drift sand were measured as Va=0.0218m/sec in Jhu-an River outward with the direction of southwest and Va=0.0012m/sec in Lanyang River outward with the direction of northeast. Yearly drift sand amount was estimated for 1.35x106m3/year by the fluorescence tracer test mentioned above and quite closed to the assessed value of 1.38x106m3/year by ROCSAT-2’s images comparison results. The most erroneous of drift sand average moving speed calculations lies on the precision of sampling time and should not exceed 13% while in field sampling operation on every single section.
Keywords: coastal process, sand drift, fluorescence tracer test, SOP.
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