碩士 / 國立成功大學 / 水利及海洋工程學系碩博士班 / 93 / The climate in Taiwan is influenced by air mass from the mainland and surrounding ocean due to the geographic environments. Strong wind comes from northern-east direction during the monsoon season every Oct. to the next Apr. and severe typhoons attack Taiwan usually during Jun. to Sep. each year. Draft sand phenomenon of the coastal flat beach is therefore quite obvious. Draft sand made the beach feature changed and increased/decreased the beach sand volume. Hence, it is important that how to utilize and protect/conserve the coast/beach in the crowded Taiwan with the help of draft sand research to predict/evaluate the beach topographical variation.
The coastal beach of Fu-Long to Ao-Di is chosen as the study site and three experimental procedures for the research are proposed in this paper. It included the beach physical properties test, draft sand test, and the field topography surveying. Draft sand source could be recognized by the beach physical properties test to analyze the sand size distribution and the sand physical properties. Draft sand test was using the DIY sand traps to catch the sand in site to estimate the draft sand transport rate and mass. The coastal beach topography could be obtained by GPS RTK surveying to evaluate the beach topographical variation of different time period and to correlate the relation between the amount of draft sand transport and the beach topographical variation.
The experimental results showed that the diameter range of draft sand size of Fu-Long to Ao-Di beach is from 2mm to 0.075mm, the coefficient of uniformity is 2.1, and the coefficient of curvature is 0.933. So this beach can be classified as a uniform graded beach. The density of the sand is 2.51g/ by pycrometer test and the major minerals are quartz and hematite. According to draft sand test, 80% draft sand size is less than 0.297mm. Draft sand density by pycrometer test is 2.61 g/ (same order with the beach sand density 2.51g/ ), and the vertical distribution of draft sand in site could be concluded by data analysis as the exponentiation function. The primary wind direction of each study site is northern east to north with 5 to 20 in between. The estimated draft sand transport rate of A site is 0.00057 , of B site is 0.00104 , and of C site is 0.00024 . The draft sand transport rate formula of Fu-Long to Ao-Di beach can be expressed as follow： , in which, is air density, is gravity acceleration, is wind friction velocity, and C is the local constant of experimental area with the value of 0.0298~0.1293(average 0.0774).
Finally, the DTM of study site by RTK GPS surveying of different period were used to measure the topography variation and then compared with draft sand transport result in the same time scale. The analyzing results showed that the amount of draft transport and the topographical variation volume were approximately in coincidence with the error of about 17.08%. So, the conclusion can be made that the coastal beach topographical volume net change of erosion/deposition could be estimate roughly by pick up the vertical draft sand data in site and cooperate with the primary wind direction and the draft transport rate formula then integrate the data through the quantification calculating procedure proposed in this paper. This method has been proved to be able to evaluate the whole draft sand amount and reflect the net variation of topography in situ.
| Identifer | oai:union.ndltd.org:TW/093NCKU5083049 |
| Creators | Yahoo Lin, 林雅谷 |
| Contributors | Pei-hwa Yen, 顏沛華 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 90 |
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