In recent year, tidal gauge has progressed in temporal resolution or measurement accuracy, so that the quality of observational data tends to stable and reliable. However, setting up tidal gauge in the offshore areas restricts may apply due to many factors such as seabed topography, weather, sea state and leveling survey from land to gauge. Good tidal correction is one of key factors to the accuracy of bathymetric survey and to the area where tidal range is large.
This study tried to use tide prediction data derived from the Yu(1993)¡¦s tide numerical model and verified with actual observed tide data, and further establishing a tidal zone of Taiwan Strait by tidal characteristic. Using Taichung and Mailiao tide stations as a reference tidal station, the direct tide station correction, tidal zone correction, nearest model grid correction, and virtual station correction methods were applied to evaluate the accuracy of tide calculating value by amplitude ratio and tidal phase difference. The tidal zone correction is not totally depending on the spatial distance from reference tidal station, and it is found that correction result of this approach is one of the best. However, further improvement in tide correction may need to explore due to different spatial resolution applied in different numerical models.
In addition, the boundary condition of a harbor for tidal model is very complicated. This is why it is hard to make a numerical model for a harbor. In this study, two additional high accuracy radar tidal gauge were installed in Kaohsiung harbor and first-class leveling survey was performed in order to maintain tidal measurement accuracy, also to avoid the effect of errors propagation. According to the results from experiment, average tidal phase of second entrance of the Kaohsiung harbor is earlier than that of first entrance about 6 minutes, and average difference of tidal height is approximately 2-3cm. For this reason, we should pay attention to decide a proper reference tide station for tidal correction for dredging hydrographic surveying. And any possible tidal observation errors, such as meteorological tide. If two additional tidal gauges of this study are removed in the future, we still can predict tide height from fixed tidal gauge.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0210109-181808 |
| Date | 10 February 2009 |
| Creators | Wang, Wei-hua |
| Contributors | Chih-chung Kao, Shiahn-wern Shyue, Jason C.S. Yu, Tian-yuan Shih, Ming-jer Huang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0210109-181808 |
| Rights | unrestricted, Copyright information available at source archive |
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