南沙岛礁及周边港口可达性评价模型研究

中国的南沙群岛位于南海南部,岛礁星罗棋布,但受到岛礁自身面积及其他自然条件的限制,自持力和承载能力都较差,需要外界的持续补给才能维持大量人口的活动。南沙岛礁远离大陆,分布于被称为“危险地带”的珊瑚礁丛中,补给受到很大影响。目前,南沙群岛的岛礁部分被菲律宾、越南和马来西亚等国非法侵占,这些被其他国家非法控制的岛屿和沙洲的控制态势对其周边的海域产生一定的控制,并且将对通过的船舶产生较大的影响。针对南沙岛礁补给困难和控制态势复杂的现状,本文从南沙岛礁的自然条件和控制态势入手,提出了一种基于最小累积成本距离和加权Voronoi图的综合可达性指数,通过建立水深与航行成本的分级对应关系,构建了南沙岛礁及周边港口可达性评价模型,计算了南沙23个岛礁和周边国家9个重要港口之间的综合可达性指数,通过分析南沙主要岛礁和周边国家重要港口之间的综合可达性的优劣,可以为中国在南沙建设补给和中转基地选址提供决策参考。可以为中国开发和管理南沙群岛、制定海洋发展战略提供依据。

Research on accessibility model of Nansha Islands and surrounding seaports

Nansha Islands are located in the south of South China Sea. The islands and coral reefs are scattered in the sea area. Area and other natural conditions of these islands are not the factors limiting intensive human activities, only if there are continued supplies from the mainland. But the supplies shipping to Nansha islands dotted in "Dangerous Area" are not easy jobs. At present, many islands, cays and reefs of Nansha Islands have been invaded and occupied by Vietnam, Philippines and Malaysia. The control states generated by these islands and reefs will affect the ships passing by. Considering the complex situation of Nansha, an accessibility index based on the least accumulative cost distance is proposed. The accessibility model of Nansha Islands and surrounding seaports is established based on the index. Two scenes of natural situation and control states are simulated to calculate the average access times between 23 islands or cays of Nansha and 9 surrounding seaports belong to the 4 countries. The result shows that the control states of islands have a great impact on the accessibility; as the main island of Nansha, Taiping Island gets the optimal accessibility to other islands or cays, which is very suitable to be built as the supply base; Seaports of Vietnam, Malaysia and Philippines get the optimal accessibility to the islands or cays in Nansha, therefore their control abilities to Nansha Islands are very strong and cannot be ignored. However, our seaports get the worst accessibility, so it is our top priority to set frontier supply bases on suitable islands, cays or reefs in Nansha so as to loosen the stress from surrounding countries. In current situation, Zhubi Jiao and Yongshu Jiao are the suitable options to be built as supply and transit bases for China. This research can be a reference for the development and management of Nansha Islands or decision-making of marine development.