| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 100 === This study is aimed at analyzing the impact of the coast based on the characteristics of 20 historical maps from 1896 to 2011. Each map has been processed through positioning, geo-reference, digitalization and characteristic extraction. The extracted characteristics by cluster analysis method of multivariate statistics were used for coastline segmentation.Then, the natural and hazard factors were considered to explore the extent of coastline change and hazard. The data quality of these historical maps were first analyzed, and then the variation of extracted characteristics were discussed.
The results show that the quality of depend mainly on the resolution, scale, the boundary complexity of the original map, zooming magnification by digitalization. For the extraction characteristics of the maps, the coordinate value is the most significant variable (factor) in cluster analysis. The different combinations could affect the segment length and segment order. The location of segment to the largest change is located on the north side and the least change is located on the northwest side. By taking into account the natural factors, the most vulnerable change was found to be on the northwest side with rapid and extreme change. By taking further account of disaster factors, it is found that the more factor conditions change, the higher the response of hazard. The long-term change of the north side is typically slow and it belongs to be coastal terrain of slow recovery. To further explore the coastal change and hazard, we can not just consider the single factor, but also the multiple factors. Once the factors are revised, they should be re-evaluated to the impact of changes.
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