Technical Studies


Water Depth Information and Analysis of Elevation Datum Project in 2013

This project continues the “Bathymetric data and Height Datum Analysis” work conducted in 2012. There are four subjects within the scope of this project. First, the stability analysis of Dongsha satellite tracking station is continued and expanded to include a Taiwan tracking station located in Yangmingshan for comparison. Secondly, tidal observation and analysis are maintained for Dongsha. Thirdly, the operation procedure of coral reef patch mapping is studied and three 1/5000 map sheets are produced. In addition, on the coast near the Cheng-Bin fishing port, a temporary continuous tide stations is built on bare rock. This is a part of Taiwan Height Datum tidal station maintenance program.

Regarding the satellite tracking stations in Dongsha and Yangmingshan, the analysis indicated that the coordinate change is in accordance with ITRF2008 velocity field. The position relation among the main station and the three supplementary stations is also found stable. The scheme of object-based segmentation is found to be better than the trend removal approach for the coral reef patch mapping, based on the experiments with three map sheets of 1/5000 scale.In 2013, the tidal observation in Dongsha is mainly conducted with self-recording tide gauges. From harmonic analysis, both phase, amplitude, and the average sea surface are stable. Dongsha continuous tide station maintenance is completed on November 30. The installation of Cheng-Bin tidal station was completed on September 4. A pressure sensor tide gauge is used. The observation frequency is one Hz. Tidal data is transmitted to Central Weather Bureau, National Chiao-Tung University, and the maintenance vendor. The tidal characteristics of the new station are similar to the Keelung station based on the observation of two months.