| 摘要: |
| 我国多次海岛数量普查因界定标准不一而结果相差巨大, 为了满足海洋主管部门对海岛的管理要求, 亟需研究合理的方法界定海岛数量。利用高分辨率遥感影像解译嵊泗县海岛2 875个, 以分形理论讨论海岛数量与海岛面积、海岛间距的关联。结果表明, 嵊泗县50%的海岛面积小于50 m2或岛间距不足6 m, 海岛数量与界定标准间呈分维数先增大后稳定的变维分形特征, 分维数在220 m2和28.5 m之后稳定在1.80和2.25。以200～500 m2为界区分大小岛, 小岛数量和海岛间距也存在变维分形特征, 且分维数在间距大于50 m后趋于稳定。故嵊泗海岛最佳界定方法为以220 m2筛选出计数海岛后再补充间距大于50 m的较小海岛, 该方法下界定嵊泗海岛681个。 |
| 关键词: 海岛数量 海岛面积 海岛间距 变维分形 |
| DOI：10.11759/hykx20161223001 |
| 分类号: |
| 基金项目:国家自然科学基金(41576095); 我国近海海洋综合调查与评价专项(908-ZC- I-09, ZJ908-01-02) |
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| The variable fractal dimensions characterizing of the statistical number of islands — a case study of Shengsi County |
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WANG Xin-kai,XIA Xiao-ming,CHENG Lin
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| Abstract: |
| It is imperative that the oceanic authority who manages the islands count them. However, because of the inconsistencies in statistical standards, different numbers of the islands in China can be attained. This paper examines the islands of Shengsi County as a case study and uses the fractal theory to determine the most suitable standard by which to count islands. From high resolution remote-sensing images, 2 875 islands were detected visually in Shengsi County; more than half of these are smaller than 50 m2 in area or with a separation distance shorter than 6 m. In both aspects of island area and separation distance, the relevant statistics for island numbers display the characteristics of variable fractal dimensions. At first the fractal dimensions increase then stabilize at 1.80 and 2.25 for areas larger than 220 m2 and distances greater than 28.5 m, respectively. For islands separated by 200, 300, 400 and 500 m2, the number of smaller islands and their separation distances from the larger islands also display the characteristics of variable fractal dimensions. And for separation distances greater than 50 m, the fractal dimensions are stable for each of the four cases previously discussed. Therefore, the rational standard for counting islands in Shengsi is by screening out those islands larger than 220 m2 and then by supplementing them with those islands whose separation distance is larger than 50 m. Using this method, the number of islands in Shengsi is 681. |
| Key words: number of islands area of islands distance of islands variable fractal dimension |
