南沙岛礁及周边港口可达性评价模型研究

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石伟, 苏奋振, 周成虎, 吴文周. 南沙岛礁及周边港口可达性评价模型研究. 69(10): 1510-1520
SHI Wei, SU Fenzhen, ZHOU Chenghu, WU Wenzhou. Research on accessibility model of Nansha Islands and surrounding seaports. Acte Geographica Sinica, 69(10): 1510-1520 复制到剪切板

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南沙岛礁及周边港口可达性评价模型研究

石伟^1,^2,³, 苏奋振^1,³, 周成虎^1,³, 吴文周^1,^2,³

1. 中国科学院地理科学与资源研究所, 北京100101

2. 中国科学院大学, 北京 100049

3. 中国南海研究协同创新中心, 南京 210093

苏奋振, 男, 研究员, 博士生导师, 从事海岸带海洋空间信息系统及时空数据挖掘研究。E-mail: sufz@lreis.ac.cn

作者简介：石伟 (1983-), 男, 博士研究生。研究方向为海洋地理信息系统。E-mail: shiw.11b@igsnrr.ac.cn

基金:国家自然科学基金项目 (41271409); 国家“863”计划项目 (2012AA12A406)

摘要

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。

关键词: 南沙群岛; 综合可达性; 控制态势; 最小累积成本距离; 乘法加权Voronoi图

Research on accessibility model of Nansha Islands and surrounding seaports

SHI Wei^1,^2,³, SU Fenzhen^1,³, ZHOU Chenghu^1,³, WU Wenzhou^1,³

1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China

2. University of Chinese Academy of Sciences, Beijing 100049, China

3. Collaborative Innovation Center of South China Sea Studies, Nanjing 210093, China

Fund:The National Natural Science Foundation of China, No.41271409; National High Technology Research and Development Program of China, No.2012AA12A406

Abstract

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.

Keyword: Nansha Islands; accessibility; control state; the least accumulative cost distance (LACD); multiplicatively weighted Voronoi diagrams (MWVD)

Show Figures

1 前言

南沙群岛位于南海的南部, 是中国南海诸岛中位置最南的群岛。20世纪60年代以来, 随着南沙群岛海域油气资源的勘探和开发, 周边国家纷纷以各种手段非法窃取和强占了许多岛礁, 特别是岛屿和沙洲。目前, 中国 (包括台湾省) 驻守的有8个岛礁, 菲律宾、越南和马来西亚非法侵占了40多个岛礁; 其中, 越南非法侵占29个岛礁, 菲律宾非法侵占8个岛礁, 马来西亚非法侵占5个岛礁^[1]。

这些岛礁面积小、自然条件差, 导致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。它们远离大陆, 且分布于被称为“ 危险地带” 的珊瑚礁丛中, 船舶的运输补给受到很大影响。此外, 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, 并且也将对通过的船舶产生较大的影响, 尤其是过往的货轮及在岛礁附近作业的渔船。面对南沙岛礁的复杂情况, 需要一种描述周边国家港口对南沙岛礁的补给能力以及南沙岛礁的接受补给的能力的有效模型或方法。

可达性指从一个地方达到另一个地方的容易程度, 可以用于表述一个地方的地理区位, 特别是交通区位, 在很大程度上代表该地方的开发潜力^[2]。有关可达性的研究最早出现于20世纪50年代末^[3], 经过近60年的发展, 可达性研究的理论和方法都有了很大的扩展。主要集中于区域经济和城市发展及交通网络等方面。Gutierrez和Gonzalez对跨欧洲高速铁路网可能引起的欧洲各城市可达性值的变化进行了研究^[4], 结果表明, 2010年可达性较低的区域面积相比1993年将会大幅度减少, 可达性最高的前两个等级的区域面积有巨大提升。Bowen通过对东南亚航空中心1979-1997年国际航空可达性的研究^[5], 评价了不同的国家航空政策对航空节点城市可达性的影响。曹小曙等基于多种模型对339个中国国家干线公路网络联结的城市通达性进行了分析^[6]。金凤君等研究了中国铁路网的扩展与可达性的变化^[7]。在港口可达性方面, 曹有挥和吴威等从运输成本的视角, 对以港口为中心的区域综合交通可达性及空间格局进行了一系列研究^{[8, 9, 10, 11]}, 并提出了综合运输成本时空演化的基本模式; Francesco和Albert针对全球化航运提出了一种基于全球港口网络的船舶配置与通达的定量评价模型; Pierre和Martijn从交易成本资源配置的角度借助可达性分析^[12], 认为港口的竞争的关键是整合海运和腹地运输链^[13]; Jean-Claude和Hyunwoo借助引力模型, 研究了美国货物联运到达东西海岸及墨西哥湾的各大港口的可达性^[14]。

与以往针对港口可达性的研究不同, 本文将港口与岛礁间的可达性作为研究对象, 以水深对船舶航行安全的影响的作为成本权重, 对不同势力控制下岛礁的控制范围及强度进行了分级量化, 从南沙岛礁的自然条件和控制态势入手, 以后勤补给和物资中转的视角, 提出了基于最小累积成本距离 (LACD) 和乘法加权Voronoi图 (MWVD) 的综合可达性指数, 通过构建南沙岛礁及周边港口可达性评价模型, 分析了南沙群岛主要岛礁的综合可达性, 对港口的补给能力和岛礁的受补给能力进行评价, 并对南沙补给和中转基地的选址提出了建议。该研究可为中国进一步开发和管理南沙群岛、制定海洋发展战略提供参考依据。

2 研究区概况

南沙群岛位于南海南部, 地处12° 10′ ~3° 25′ N, 108° 15′ ~119° 00′ E, 南北宽约970 km, 东西长约1200 km, 海域面积82万km²。南沙群岛海区海底地形复杂, 主要分布在巽他大陆架至南海中央海盆的大陆坡, 其间交错分布着南沙台阶, 其上隆起的海山顶部发育了星罗棋布的礁滩, 形成了南沙群岛的主体。其中干出礁55座, 常年出露水面的单体35座^[15]。干出礁上发育的23个灰沙岛 (包括岛屿和沙洲) 面积都很小, 最大的太平岛也仅有0.4 km²。南沙大部分海域水深都在1000 m以上, 适宜船舶航行, 但在岛礁分布区, 水深变化剧烈, 可在礁体边缘的数海里内从数千米深的海盆上升为几米深的礁坪^[16]。南沙群岛除西南海区为全日潮外, 其余部分为不正规日潮。整个海区平均潮差较小为0.5~1 m, 但岛礁区受浅水地形影响, 其潮差远大于深水区, 通常大其1倍以上^[17]。

南沙群岛有人常驻的岛屿、沙洲中 (弹丸礁通过人工改造面积扩展较大, 将其列为人工岛) (图1), 除面积最大的太平岛由我国控制外, 其他18个, 均被菲律宾、越南和马来西亚非法侵占瓜分 (表1)。

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	图1 南沙群岛珊瑚礁及主要岛屿、沙洲分布图Fig. 1 Location of islands and cays in Nansha

表1 南沙主要岛礁基本信息 Tab. 1 Islands and reefs in Nansha

本文选取了南沙周边国家和地区对南沙群岛有补给能力和控制能力的主要民用和军用港口, 分别属于中国、菲律宾、越南和马来西亚 (图2和表2)。

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	图2 南沙周边主要港口分布图Fig. 2 Distribution of seaports around Nansha

表2 南沙周边国家和地区主要港口 Tab. 2 Seaports around Nansha

3 南沙岛礁— 港口可达性评价模型

3.1 基于最小累积成本距离的综合可达性指数

将港口和岛屿抽象为点目标, 假定航行的单位成本为w, 定义任两点之间的成本距离如下：

(1)

式中：D为点A(x_a, y_a) 到点B (x_b, y_b) 的成本距离, w为两点间的航行成本权重。

若任意一点至目标点间由不同权重的n段路程组成, 则其最小累积成本距离D_sum可表达为：

$\begin{matrix} D_{sum} = \overset{n}{\sum_{i = 1}} \min (D_{i}) \end{matrix}$ (2)

假定航行速度为船舶航行的速度v, 基于公式 (3) 则可以得到两点间的最小累积成本时间T, 用于描述两点间的可达性; 然后计算一点至其他各点的最小累积成本时间的平均值, 作为该点的综合可达性指数Acc, 得公式 (4)。

$\begin{matrix} T = \frac{D_{sum}}{v} \end{matrix}$ (3)

$\begin{matrix} Acc = \overset{n}{\sum_{i = 1}} \frac{T_{i}}{n} \end{matrix}$ (4)

3.2 自然条件下的南沙岛礁-港口可达性评价模型

在海上自然航行时, 航行安全是通达的第一保障, 本文排除了台风、巨浪等特殊情况的影响, 仅考虑一般情况下的航行问题。海上船舶航行安全主要受水深影响, 因此, 在自然条件下, 岛礁— 港口可达性评价模型以水深为成本权重。

当海区的水深较深时, 船舶可以安全的高速通行, 但当通过岛礁分布区或靠岸航行时, 由于水深逐渐变浅, 船舶需要降低航行速度, 或者绕开浅水区域航行。船舶在浅水区域航行, 需要预留出足够的富裕水深, 防止触礁或搁浅。因此, 需要考虑船舶自身的吨位、吃水、潮汐、波浪等因素的影响。为最大程度保证航行安全, 参考船舶吨位、吃水以及富裕水深的相关资料^[18], 将船舶的安全水深H_safe定义为：

$\begin{matrix} H_{safe} = α \times H_{draft} + H_{tide} + H_{wave} \end{matrix}$ (5)

式中：α 为安全系数, H_drft为船舶标准吃水, H_tide为潮差, H_wave为一般海况下波浪平均起伏高度。

由于外海的潮汐、波浪等都有较大变化, 海底地形及底质复杂, 且海图不如近岸海域详细, 在此将安全系数α 定为1.2, 在南沙海域, 潮差一般在1 m左右, 珊瑚礁区受地形影响潮差略大约为2 m, 南海多为2~3级海况, 即波浪起伏在3 m左右。因此, 排水量5万t船舶的吃水约为10 m, 在南沙海域的安全水深为15 m以上; 排水量10万t船舶的吃水约为15 m, 在南沙海域的安全水深为25 m以上; 排水量20万t船舶的吃水约为25 m, 在南沙海域的安全水深为50 m以上。如20万t船只在50 m以上水深海域可安全的自由航行; 而当其在25~50 m水深海域航行时, 处于安全考虑, 需降低航行速度, 但10万t的船舶在此水深则不受影响, 因此若不降低航速, 1条20万t的船舶分为2条10万t船舶, 航行成本变为前者的2倍; 以此类推, 在10~25 m水深海域航行的成本为4倍; 在0~10 m水深航行时的成本为8倍。综合考虑以上因素, 将水深按0~15 m, 15~25 m, 25~50 m和50 m以上划分为4个级别, 分别赋予成本权重分别为8, 4, 2, 1, 代表通过该水深级别区域耗费成本的倍率。

3.3 考虑控制态势影响的南沙港口— 岛礁评价模型

岛屿对周边海域的控制态势受到两个因素的制约：一为距离, 二为周边岛屿。参照《联合国海洋法公约》中关于岛屿制度及领海的相关规定, 12 n mile表示领海能力、24 n mile表示毗邻区能力、36 n mile表示内预警区、48 n mile表示外预警区。岛屿对周边海域的影响强度会随距离的增加而衰减。

Voronoi图是描述空间配置关系的常用方法之一^[19], 多用于空间剖分, 势力范围划分等^{[20, 21, 22]}。本文采用乘法加权Voronoi图, 用于划分岛屿之间的控制范围。

综合岛屿距离和权重两个因素, 首先生成控制态势下的岛屿控制范围, 然后计算得到航行的成本权重, 计算综合可达性指数, 进行港口和岛礁的可达性评价。

(1) 岛屿控制范围的生成

岛屿控制范围的生成主要包括多级影响区域的生成和控制范围分割两个步骤。

第一, 在模型中, 以各个岛屿为中心, 分别以12 n mile、24 n mile、36 n mile、48 n mile作为影响半径, 生成的影响缓冲区分别代表各个岛屿的1、2、3、4级区域（图3）。

第二, 岛屿与其周边的岛屿对海域的控制为竞争关系, 在模型中, 岛屿受自身能力的限制, 其影响海域的能力与其自身能力成正比。因此, 岛屿对周边海域的分割可表示为：

$\begin{matrix} D_{i} / D_{j} = W r_{i} / W r_{j} \end{matrix}$ (6)

式中：D_i和D_j为海域中任一点到岛屿i和岛屿j的距离, Wr_i和Wr_j为岛屿i和岛屿j的权重。本文中采用岛屿的等面积圆的半径表示该岛屿权重, 见公式 (7)。

(7)

根据上述定义, 本文利用岛屿自身的位置和权重, 生成乘法加权Voronoi图 (Multiplicatively Weighted Voronoi Diagrams, MWVD), 表示各个岛屿对海域的影响区域划分（图3）。

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	图3 岛屿对周边海域的影响区域的划分和各级影响范围Fig. 3 Control areas and classes of islands

(2) 成本权重的计算

当己方船舶通过岛屿的有效控制区域时, 船舶通行不受岛屿控制的影响。但当非己方船舶通过岛屿的有效控制区域时, 在1~4级控制区域内受到的影响分别为5, 4, 3, 2倍迟缓效应, 即船舶的航行速度降低的倍率。

当考虑控制态势时, 可达性模型中关于通行成本权重的部分进行了相关的调整,

$\begin{matrix} w = w_{n} \times w_{c} \end{matrix}$ (8)

式中：w为综合权重; w_n为受水深等级影响权重; w_c为控制态势影响权重。

4 实验及分析

4.1 自然条件下的南沙港口— 岛礁可达性评价

4.1.1 岛礁可达性评价在自然条件, 仅考虑水深影响, 基于综合可达性指数的公式, 分别计算23个南沙岛屿的最小累积成本距离分布及综合可达性, 结果如表3所示; 并对我国进驻的岛礁之间的可达性进行了统计, 结果如表4所示。实验中, 以正常海况下货轮平均航速为例, 取值为20节。

在表3中, 第一列表示岛礁的综合可达性排名, 第二列和第三列为各岛礁的名称及控制方, 第四列为岛礁到其他岛礁的平均最小累积成本距离, 第五列为岛礁到其他岛礁的综合可达性指数。由表可以看出：太平岛的综合可达性排名为第一, 这是因为太平岛位于南沙群岛的中心, 至其他各个岛礁的平均可达时间最短, 综合可达性最强。因此太平岛最为适合作为补给中转基地。但可达性最好的岛礁, 基本被越南和菲律宾侵占。相比较而言, 南威岛和弹丸礁, 由于地处南沙群岛西南部和东南部的边缘, 其到达其他各个岛礁的平均可达时间最长, 综合可达性最差, 排名倒数后两位。

表3 南沙主要岛礁间平均最小累积成本距离及综合可达性指数 Tab. 3 Average LACD and accessibility of main islands in Nansha

中国进驻的岛礁, 由于地处水深较深且开阔的南沙各大水道附近, 岛礁的综合可达性较好, 除太平岛外, 综合可达性最优的渚碧礁到其他岛礁的综合可达时间在5小时以内, 适合作为潜在的补给或中转基地进行建设。

在表4中, 第一列表示岛礁的综合可达性排名, 第二列为各岛礁的名称, 第三列和第四列分别为岛礁到其他岛礁的平均最小累积成本距离和岛礁到其他岛礁的综合可达性指数。可以看出：在我国进驻的岛礁中, 太平岛的综合可达性最强, 至其他各个岛礁的平均可达时间最短。虽然太平岛是中转补给基地最优选择, 但由于历史诸多原因, 暂时无法直接进行开发利用。渚碧礁和永暑礁的综合可达性略逊于太平岛, 可作为南沙补给基地的首选。

表4 中国进驻的南沙主要岛礁间平均最小累积成本距离及综合可达性指数 Tab. 4 Average LACD and accessibility of main islands under control by China in Nansha

4.1.2 港口可达性评价在表5中, 第一行为起点港口的名字, 第一列为终点岛礁的名字, 表中值分别表示各港口至各岛屿相互之间的最小累积成本距离, 表的最后两行分别表示各港口至各岛礁的综合可达性指数及其排名。由表可以看出：作为距离南沙群岛最近的港口, 马来西亚的哥打基纳巴卢港的优势突出, 综合可达性最好, 其至南沙各主要岛礁的综合可达时间最短, 平均约15.7小时, 其次是越南的金兰湾港约17.3小时, 位于菲律宾巴拉望岛的普林塞萨港需不到21小时, 越南的胡志明港和菲律宾的马尼拉港需不到30小时, 而我国距离南沙群岛最近的三亚港则需超过31小时, 高雄港需47小时, 而从广州港出发则需要约47小时, 是排名前三港口的三倍。可见, 马来西亚、越南和菲律宾等国的港口到达南沙诸岛礁有着非常便利的条件, 而我国的港口则距离较远, 基本没有优势。

表5 南沙主要岛礁与周边重要港口的最小累积成本距离及综合可达性指数 Tab. 5 LACD and accessibility of seaports around Nansha

对于中国而言, 从港口出发向南沙岛礁运送补给或集中渔获产品时间很长且成本很高, 因此, 在南沙选择适合的岛礁建设补给基地和中转基地是十分必要的。结合岛礁间的综合可达性分析, 除太平岛外, 渚碧礁是个不错的选择。

4.2 考虑控制态势影响的南沙港口— 岛礁可达性评价

在计算受控制态势影响的岛礁可达性时, 首先要计算各个岛屿控制范围, 利用3.3节中的模型生成基于乘法加权Voronoi图的南沙23个岛屿控制范围（图4）。然后, 与以12 n mile、24 n mile、36 n mile、48 n mile作为半径, 生成的缓冲区分别代表岛屿的1、2、3、4级影响区域进行叠加, 生成23个岛礁的1~4等级控制区域, 在图5中1, 2, 3, 4级的控制区域分别用红色、橙色、黄色和蓝色标示。

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	图4 基于乘法加权Voronoi图的南沙23个岛屿控制范围Fig. 4 Control areas of 23 islands of Nansha based on MWVD

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	图5 南沙23个岛屿对周边海域的4级控制区域Fig. 5 Control areas and classes of 23 islands in Nansha

在考虑控制态势的情景下, 平均航速按20节计算, 计算岛屿之间、岛屿与港口之间的综合可达性指数（表6-8）。

表6 南沙主要岛礁起点平均最小累积成本距离及综合可达性指数 Tab. 6 Average LACD and accessibility of main islands as origin in Nansha

表7 南沙主要岛礁终点平均最小累积成本距离及综合可达性指数 Tab. 7 Average LACD and accessibility of main islands as destinations in Nansha

表8 南沙主要岛礁与周边重要港口的最小累积成本距离及综合可达性指数 Tab. 8 LACD and accessibility of seaports around Nansha

4.2.1 岛礁可达性评价表6和表7分别表示南沙主要岛礁作为起点和终点时与其他岛礁的综合可达性, 其中, 第一列表示岛礁的综合可达性排名, 第二列和第三列为各岛屿的名称及控制方, 第四列为岛礁到其他岛礁的平均最小累积成本距离, 第五列为岛礁到其他岛礁的综合可达性指数。从结果可以看出, 受岛礁控制态势的影响, 岛礁作为起点和终点, 其综合可达性有较大差别。

当岛礁作为起点时, 太平岛综合可达性最好, 从此出发到达其他岛礁平均仅需7.3小时, 比较适宜作为补给基地进行开发。双黄沙洲、南钥岛、中业岛、西月岛等菲律宾非法侵占的岛礁综合可达性均较好, 越南非法侵占的岛礁综合可达性相对较差, 中国进驻的永暑礁至其他岛礁的综合可达时间约8.8小时, 可作为建设补给基地的重要参考。

当岛礁作为终点时, 太平岛虽然略逊于染青沙洲和敦谦沙洲, 但仍然有较好的综合可达性, 也比较适宜作为物资中转基地, 方便从各个岛礁集中渔业等产品进行加工或中转运出。越南非法侵占的岛礁的综合可达性较好, 菲律宾非法侵占的岛礁则相对较差, 中国进驻的渚碧礁和美济礁也较为适合作为物资中转的备选基地进行建设。

对比自然条件下的可达性指数 (表3), 分析可得：在南沙岛礁复杂的控制态势的影响下, 岛礁至岛礁间的综合可达时间大为增长, 平均增长3.4小时。并且位于稀疏分布区域的岛礁较分布密集区域的岛礁的综合可达性受岛礁控制态势的影响较更大, 如位于南沙西北部北子岛、南子岛, 位于西南部的南威岛以及位于东南部的弹丸礁等岛礁的综合可达时间增长非常显著。

4.2.2 港口可达性评价在表8中, 第一行表示港口的名字, 第一列表示岛屿的名字, 表中值分别表示各港口至各岛屿相互之间的最小累积成本距离, 表的最后两行分别表示各港口的综合可达性指数及其排名。对比自然条件下的可达性指数 (表5), 分析可得：在南沙周边的各个港口至各个岛礁的平均可达时间均有所增长, 平均约3小时; 越南的金兰湾港综合可达时间最短, 平均约20小时, 其次是马来西亚的哥打基纳巴卢港20.2小时, 菲律宾的普林塞萨港约23小时, 菲律宾的马尼拉港和越南的胡志明港需约30小时, 我国的三亚港需约35小时和37小时, 马来西亚的古晋港需约36小时, 高雄港增至50.6小时, 从广州港出发则需要约50.8小时, 仍是金兰湾的约2.5倍, 对岛礁的补给效率不及后者的一半。可见, 岛礁控制态势对港口到岛礁的可达性的影响比较有限, 不能对其格局产生颠覆性的改变。

对于中国而言, 三亚港对南沙岛礁的综合可达性最好, 可作为南沙方向的重点补给港口。结合岛礁间的综合可达性, 除太平岛外, 永暑礁可作为南沙的补给基地, 渚碧礁可作为南沙的中转基地。

5 结论

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, 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, 为中国在南沙建设补给和中转基地选址提供了决策支持。模型在自然条件和控制态势影响两个情景下, 计算了南沙23个主要岛礁的平均可达时间, 获得了这些岛礁的综合可达性; 以及计算了南沙周边4个国家和地区的9个主要港口至南沙23个岛礁的平均可达时间, 获得了这些港口的综合可达性。通过分析发现, 南沙岛礁对周边海域的控制态势对其可达性有较大影响; 太平岛与其他南沙岛礁间的综合可达性较优, 适宜作为补给基地进行建设; 越南、马来西亚及菲律宾等的港口至南沙主要岛礁的可达性较优, 其对南沙各个岛礁的潜在控制能力不容小觑, 而我国的港口则相对不足。因此急需在南沙选择合适岛礁, 建设前沿补给基地, 以应对周边其他国家的压力。对于现状而言, 渚碧礁和永暑礁应优先作为补给基地和中转基地进行开发, 为我国在南沙群岛进行后勤补给、中转渔获、维护渔权、宣示主权等活动服务。但模型中成本权重的确定仅是理想状态下的情况, 未将复杂海况如潮汐变化、海流、风场、恶劣天气以及岛礁建设等因素考虑在内, 随着研究的深入, 我们将对模型进行进一步修正, 以期获得更优的结果。

The authors have declared that no competing interests exist.

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2002

0.0

0.2551

Jinming.

The present situation of sovereignty dispute over the South China Sea.

Southeast Asian Affairs, 2002, (1): 53-65.

[李金明. 南海主权争端的现状. 南洋问题研究, 2002, (1): 53-65. ]

本文叙述了我国南沙群岛岛礁被周边国家占据的现状,以及南沙群岛的战略地位与自然资源,并分析了对南沙主权争端的影响,论述了当前南沙主权争端复杂化主要表现的几个方面.

... 其中,越南非法侵占29个岛礁,菲律宾非法侵占8个岛礁,马来西亚非法侵占5个岛礁^[1] ...

1973

0.0

... 可达性指从一个地方达到另一个地方的容易程度,可以用于表述一个地方的地理区位,特别是交通区位,在很大程度上代表该地方的开发潜力^[2] ...

1959

0.0

... 有关可达性的研究最早出现于20世纪50年代末^[3],经过近60年的发展,可达性研究的理论和方法都有了很大的扩展 ...

1996

0.0

... Gutierrez和Gonzalez对跨欧洲高速铁路网可能引起的欧洲各城市可达性值的变化进行了研究^[4],结果表明,2010年可达性较低的区域面积相比1993年将会大幅度减少,可达性最高的前两个等级的区域面积有巨大提升 ...

2000

0.0

... Bowen通过对东南亚航空中心1979-1997年国际航空可达性的研究^[5],评价了不同的国家航空政策对航空节点城市可达性的影响 ...

2005

0.0

2.937

Cao

Xiaoshu

, Xue

Desheng

, Yan

Xiaopei.

A study on the urban accessibility of national trunk highway system in China.

Acta Geographica Sinica, 2005, 60(6): 903-910.

[曹小曙, 薛德升, 阎小培. 中国干线公路网络联结的城市通达性. 地理学报, 2005, 60(6): 903-910. ]

Based on the "shortest path matrix", the selected characteristic indices-distance, time and speed, this paper analyses the current spatial structure of accessibility in the cities which the national trunk highway system connects, and impacts the speed index made. The cities connected by the national trunk highway system turn out the obvious "core-periphery" model with speed index. The top 50 most accessible cities are concentrated in the middle of eastern China, and the bottom 50 ones are located at the periphery such as northwestern, southwestern and northeastern China. The spatial structure of accessibility measured by time index shows a concentric layer structure with attribute falling gradually from interior to periphery. Moreover, the spatial structure of accessibility in cities connected by the national trunk highway system has obvious boundary effect, which shows wave transformation under different speed conditions. The evidence shows that the change in speed acceleration of the national trunk highway system with an urban accessibility of 60-80 km/h is significantly greater than that of 80-100 km/h. For a given city, averaged 33 cities can be reached within eight hours--a normal working day. Most of the cities with the maximum urban access in eighty hours are concentrated in eastern China, averaged 70 cities. The cities with the minimum urban access in eighty hours are located in the northwestern, southwestern, northeastern and southeastern parts of China. Besides further construction, accelerating the speed of the future national trunk highway system will bring about more impacts on the spatial structure of the cities in China.

School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China

以"最短路径模型"为基础,选取距离与时间两个特征指标以及联结两者的速度指标,分析了目前中国国家干线公路网络联结的城市通达性空间格局。结果显示,国家干线公路网络联结的城市呈现明显的"核心—外围"模式,通达性最高的50个城市集中分布在东部的中部地区,通达性最低的50个城市散布在西北、西南、东北等外围地区;通达性空间格局呈现同心圈层结构,由最优区域向外逐渐降低;国家干线公路网络联结的城市通达性空间格局具有显著的边界效应,在不同的速度状态下呈现波状形态变化;国家干线公路网络中行车速度从60~80 km/h的城市通达性变化显著大于80~100 km/h的城市通达性变化;120 km/h时速下,8小时以内每个城市连接的城市数量平均为33个,联结数量最多的城市集中分布在东部,平均每个城市可联结数量为70个,联结数量最少的城市分布在西北、西南、东北、东南,平均每个城市可联结数量为6个。未来国家干线公路网络除继续建设外,行车速度的提高将大大影响城市通达性的变化。

... 曹小曙等基于多种模型对339个中国国家干线公路网络联结的城市通达性进行了分析^[6] ...

2004

0.0

2.937

Jin

Fengjun

, Wang

Jiao'e

. Railway network expansion and spatial accessibility analysis in China: 1906-2000. Acta Geographica Sinica, 2004, 59(2): 293-302.

[金凤君, 王娇娥. 20世纪中国铁路网扩展及其空间通达性. 地理学报, 2004, 59(2): 293-302. ]

In this paper, the indexes and models are used to measure the accessibility of transport network, such as total transport distance Di and accessibility coefficient. On the basis of "The Shortest Route Model", the evolution of railway network, changes of the spatial structure in accessibility, the relationship between railway network distribution and spatial economic growth in the past several hundred years in China are analyzed. The results show that the evolution of railway network in China experienced 4 stages, i.e., initial stage, constructing stage, extending stage and optimizing stage, but the speed of spatial expanding is relatively slow. One hundred years' construction of railway leads to "time-space convergence". The spatial structure of accessibility displays "different circles with one core", and radiates from North China to the surroundings. The area, higher than the national average level in accessibility, expands from North China to East China and Central China, and the center of accessibility moved from Tianjin to Zhengzhou gradually.

Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China

作者设计了运输距离Di和通达性系数等度量交通网络通达性的指标，并以“最短路模型”为基础，分析了100年来中国铁路交通网络的发展以及由此引起的通达性空间格局的变化。结果显示，中国铁路网络结构的演化经历了起步、筑网、延伸、优化4个阶段，但空间扩展的速度相对缓慢。路网扩展和原有路网优化是通达性提高的主要方式；100年铁路建设导致“空间收敛”效果显著。通达性空间格局呈现同心圈层结构，由华北区向四周辐射；且通达性高于全国平均水平的范围也由华北向华东区、中南区扩展，交通中心由天津向郑州逐渐转移。铁路的建设推动了社会经济空间结构的演化，运输走廊的现代化将推动空间经济轴线进一步强化。

... 金凤君等研究了中国铁路网的扩展与可达性的变化^[7] ...

2004

0.0

2.937

Cao

Youhui

, Li

Haijian

, Chen

Wen.

The spatial structure and the competition pattern of the container port system of China.

Acta Geographica Sinica, 2004, 59(6): 1020-1027.

[曹有挥, 李海建, 陈雯. 中国集装箱港口体系的空间结构与竞争格局. 地理学报, 2004, 59(6): 1020-1027. ]

In this paper, two mathematic models are used to measure the spatial structure and the competition pattern of the coastal container port system of China from 1992 to 2001. Shift-share analyses reveal some characteristics for the competition pattern of the coastal container port system of China: (1) Both between (inter) and within (intra) the different port ranges, the net volumes of the shift effects are very notable. (2) In competition, the Pearl River Delta container port ranges are all along superiorior; the around the Bohai Sea container port range is throughout inferior; the Changjiang River Delta container port range is relatively complicated. (3) From 1995 to 1998, Shanghai was one of the major winners interms of total shift, but in the other two periods, it lost some TEU. (4) Shenzhen and Ningbo ports have been the major winners interms of total shift since 1992.

1. Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, China; 2. Department of Geography, Anhui Normal University, Wuhu 241000, China

集装箱港口体系的空间结构演化与竞争格局变动是一个问题的两个侧面，互为因果。作者对近10年中国沿海集装箱港口体系的空间结构演化与竞争格局变动进行定量测度。赫希曼－赫芬达尔指数 (Hirshmann-Herfindahl index) 计算表明：集中化在整个港口体系空间结构演化中已经显现；但集中化过程在珠三角、长三角和环渤海三大港群内差异明显，且在不同时段上呈现出一定的波动。偏移－分享分析 (shift-share analysis) 显示：整个港口体系内的箱源偏移增长量一直很大，这既反映在3大港群之间，更反映在各港群内各港口之间；珠三角港群始终正偏移增长，环渤海港群一直负偏移增长，长三角港群先正偏移增长后负偏移增长；上海港在1995~1998年曾出现了一定程度的正偏移增长，但在其他两个时段则为负偏移增长；深圳、宁波2港始终正偏移增长，且偏移增长量相当可观。

... 在港口可达性方面,曹有挥和吴威等从运输成本的视角,对以港口为中心的区域综合交通可达性及空间格局进行了一系列研究^[8,9,10,11],并提出了综合运输成本时空演化的基本模式 ...

2007

0.0

Wei

, Cao

Youhui

, Cao

Weidong.

et al.

On the patterns of integrated transportation accessibility in the Yangtze River Delta under opening conditions.

Geographical Research, 2007, 26(2): 391-402.

[吴威, 曹有挥, 曹卫东等. 开放条件下长江三角洲区域的综合交通可达性空间格局. 地理研究, 2007, 26(2): 391-402. ]

Choosing weighted average travel times as indicator, county as research unit, this paper analyses the accessibility patterns of highway, railway, waterway and civil aviation respectively in the Yangtze River Delta under opening conditions, with these results, the accessibility patterns of integrated transportation are elaborated. The accessibility of highway takes on a layered pattern with Shanghai, Suzhou and Jiaxing as the center, which implicates the transport convenience of nodes within the region. Most nodes are better but those located in the south of Taizhou and Zhoushan (Zhejiang province) are worse in railway accessibility. In waterway transport, the accessibility shows an arc belt pattern, with better accessibility, in the center composed of Shanghai, Ningbo and Zhoushan, the belt along the Yangtze River in the north and along the East China Sea in the south but it decreases southwestwards and northwards (northeastwards).The accessibility of civil aviation takes on a south-north symmetry pattern approximately, having nodes with better accessibility concentrated in the middle part. Shanghai is the best node in civil aviation accessibility, Hangzhou, Nanjing and Ningbo are better than those nodes around them, which form the "islands-shaped" pattern. As to integrated transportation, Shanghai and nodes around it are best in accessibility, centered around this area, the accessibility decreases to the periphery, and the area with better accessibility forms "Z-shaped" pattern, which is consistent with the regional transport and megalopolis pattern, and the accessibility of the nodes in the south and north edge are worse, as a whole, the north is better than the south and the east is better than the west in accessibility. According to the analysis of accessibility coefficient, the highway is the best one in equilibrium of accessibility distribution, integrated and civil aviation transportation takes the second place, waterway is worse, and railway is the worst. For the sake of integration of this region, the consummation of integrated transportation system should be focused on improving the accessibility of the edge nodes in the future.

1. Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, China; 2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China

本文基于区域经济系统的开放性,以县域为研究单元,采用加权平均旅行时间指标,分析了长江三角洲区域公路、铁路、水运、航空等单方式交通可达性空间格局,并以此为基础剖析了区域综合交通可达性格局:公路交通可达性大致呈环状格局,铁路交通大部分节点可达性较好,台州市域南部节点和舟山可达性差,水运形成了弧状条带分布格局,航空可达性大致呈南北对称分布;综合交通可达性以上海及周边节点为中心向外围呈不规则环状逐渐降低,可达性较好区域大致构成"Z"字形。通过可达性系数分析,公路交通可达性分布较为均衡,综合交通和航空次之,水运较差,铁路最不均衡。文章的最后提出了区域交通可达性及其均衡性提高的针对性措施。

2009

0.0

2.779

Wei

, Cao

Youhui

, Cao

Weidong.

et al.

Spatial pattern of regional comprehensive transportation cost: The case of Jiangsu Province.

Scientia Geographica Sinica, 2009, 29(4): 485-492.

[吴威, 曹有挥, 曹卫东等. 区域综合运输成本的空间格局研究: 以江苏省为例. 地理科学, 2009, 29(4): 485-492. ]

In macroscopic, regional comprehensive transportation cost is relative to regional integrated transportation accessibility and the scale of passenger and freight. With the formation of some relative conception, choosing the counties as the basic research units and GIS as the support technology, from the macroscopic view, the comprehensive transportation cost in Jiangsu Province is calculated and its pattern is analyzed in this paper. The result shows that the southern Jiangsu Province is superior to the northern one in all three indices—the integrated transportation accessibility, passenger and freight scale, and the comprehensive transportation cost. But there are some differences among three indices about the spatial structure. It takes on "dual-nuclei" pattern in integrated transportation accessibility, and "islands-shaped" pattern in passenger and freight scale, and both the two patterns are showed in the comprehensive transportation cost, i.e., "dual-nuclei" pattern in south and "islands-shaped" pattern in north. In the economic statistics, Jiangsu Province involves three areas, the southern, the central and the northern of Jiangsu. The southern Jiangsu is the best one in all the three indices, and the central Jiangsu is better than the northern Jiangsu. As to the equilibrium among three areas, the northern Jiangsu is better than the central Jiangsu, and the southern Jiangsu is the worst areas in the integrated transportation accessibility and comprehensive transport cost. In the passenger and freight scale, the central Jiangsu is the most balanced one; the northern Jiangsu takes the second place. With those results, some measures are proposed to decrease the comprehensive transportation cost in central and northern Jiangsu Province, and its imbalance within southern Jiangsu Province. Also, some relative focus needing more attention is put forward.

1. Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing Jiangsu 210008; 2. College of territorial Resources and Tourism, Anhui Normal University, Wuhu Anyui 241000

在宏观尺度上,区域综合运输成本是区域综合交通可达性和客货运规模的函数。以县域为基本研究单元,地理信息系统技术为主要支撑,通过对综合交通可达性和客货运规模的综合集成,在宏观层面上对江苏省综合运输成本的空间格局进行计算和分析。结果表明:江苏省综合交通可达性、客货运输量及综合运输成本均呈南优北劣态势,其中可达性双核格局特征明显,客货运输量岛状分布特征突出,而综合运输成本在区域南部呈双核结构,在区域北部呈岛状结构;从分区域角度看,三指标皆以苏南为优、苏中次之,苏北较差,但各指标的分区域均衡性特征略有差别,可达性及综合运输成本均衡性皆以苏北为优,苏中居中,苏南较差,但客货运输量均衡性苏北较差,苏南次之,苏中稍好。

2011

0.0

2.937

Wei

, Cao

Youhui

, Liang

Shuangbo.

On the theory of regional integrated transportation costs.

Acta Geographica Sinica, 2011, 66(12): 1607-1617.

[吴威, 曹有挥, 梁双波. 区域综合运输成本研究的理论探讨. 地理学报, 2011, 66(12): 1607-1617. ]

At present, important advances in transportation costs studies have been achieved at sector and enterprise levels. However, at the regional level, relevant studies focused primarily on the impacts of transportation costs. Based on the regional perspectives and macro-scales, this paper attempts to build a theoretical framework on the regional integrated transportation costs, which consists of its concept, the main influencing factors, the measurement model, the mechanism of pattern formation and changes, and the spatial-temporal evolution rules. For a particular geographic unit, the regional integrated transportation cost is a general measurement of the resistance of passenger and cargo flows, which is greatly influenced by the integrated transportation accessibility, the passenger and freight traffic scale, and the external costs of transportation, with the integrated transportation accessibility serving as a fundamental role. On this basis, the integrated transportation costs index is built to reflect the difference among node costs. The formation and evolution of the pattern of regional integrated transportation costs is the comprehensive result of the distribution pattern of transportation infrastructure, the stage of economic and social development, and the relevant policies. In general, spatial pattern evolution of integrated transportation costs follows a four-stage evolution model: Primary Divergence - Convergence - High Convergence - Divergence. The integrated transportation costs decrease gradually over the time, and its spatial distribution evolves from the initial equilibrium to non-equilibrium, and eventually to the high-level equilibrium.

Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, China

当前从部门和企业层面对运输成本的研究已较为深入,而在区域层面,相关研究主要集中于运输成本效应的分析,本文尝试立足于区域视角和宏观尺度,从概念内涵、主要影响因素、计量模型、空间格局的形成演化机制及时空演化规律等方面构建区域综合运输成本研究的理论框架.区域综合运输成本是对特定地域单元为进行客货流动所必须克服的阻力的一个宏观的、一般的衡量,深受一地综合交通可达性、客货运输规模及运输外部成本的影响;以此为基础,构建了区域综合运输成本指数以反映不同节点成本的相对高低.综合运输成本空间格局的形成与演化是交通基础设施格局、经济社会发展阶段及政府政策取向等共同作用的结果,一般条件下,其时空演化遵循"初级发散—收敛—高度收敛—发散"的基本模式,随时间推移,综合运输成本逐渐下降,而在空间分布上则由最初的低级均衡演化为非均衡,最终又趋于高级均衡.

2008

0.0

Francesco

Parola

, Albert W

Veenstra.

The spatial coverage of shipping lines and container terminal operators.

Journal of Transport Geography, 2008, 16(4): 292-299.

Abstract The aim of this paper is to provide a quantitative basis for the discussions about globalization of carriers and container terminal operators. A measuring framework is developed that allows for the comparison of the distribution of ship carrying capacity across various regions, and the comparison of the distribution of terminal throughput worldwide. This approach also allows the investigation of the degree to which liner shipping networks match related terminal portfolios. The main outcomes highlight significant differences between the geographical scope of liner networks, and between the coverage of corresponding terminal portfolios. Interesting results emerge from the matching of networks of integrated operators: early-movers such as Maersk and latecomers such as MSC have very different levels of vertical integration.

... Pierre和Martijn从交易成本资源配置的角度借助可达性分析^[12],认为港口的竞争的关键是整合海运和腹地运输链^[13] ...

2010

0.0

... Pierre和Martijn从交易成本资源配置的角度借助可达性分析^[12],认为港口的竞争的关键是整合海运和腹地运输链^[13] ...

2010

0.0

Jean-Claude Thill, Hyunwoo Lim.

Intermodal containerized shipping in foreign trade and regional accessibility advantages.

Journal of Transport Geography, 2010, 18(4): 530-547.

Abstract Intermodalism has become one of the most significant transformations of freight transportation in the United States over the past two decades. The coupling of shipping modes has enabled shippers to more fully realize the respective time and costs advantages of respective modes. The opportunity to take advantage of intermodalism when shipping manufactured goods overseas may provide an essential competitive edge to a company or to an entire region engaged in world commerce. The change in the freight accessibility map of the United States to foreign markets that can be ascribed to intermodal infrastructures and operations has so far not been studied. With the help of a geographic information system, this paper analyzes this transformation in the United States by mapping integral place accessibility measures of five-digit zip code areas with respect to gateways for export of manufactured goods, especially containerized freight. The performance of the intermodal freight network is evaluated by comparing accessibility measures based on the highway network and on the intermodal network, respectively, for all North American container ports, as well as for subgroups of container ports on the Eastern Seaboard, the Western Seaboard, and the Gulf Coast of North America. The paper discusses regional winners and losers in the new national freight transportation system.

... Jean-Claude和Hyunwoo借助引力模型,研究了美国货物联运到达东西海岸及墨西哥湾的各大港口的可达性^[14] ...

1996

0.0

... 其中干出礁55座,常年出露水面的单体35座^[15] ...

1996

0.0

... 南沙大部分海域水深都在1000 m以上,适宜船舶航行,但在岛礁分布区,水深变化剧烈,可在礁体边缘的数海里内从数千米深的海盆上升为几米深的礁坪^[16] ...

1996

0.0

... 5~1 m,但岛礁区受浅水地形影响,其潮差远大于深水区,通常大其1倍以上^[17] ...

1986

0.0

... 为最大程度保证航行安全,参考船舶吨位、吃水以及富裕水深的相关资料^[18],将船舶的安全水深H_safe定义为： ...

1997

0.0

Okabe

, Suzuki

Locational optimization problems solving through Voronoi diagrams.

Europe Journal Operation Research, 1997, 98: 445-456.

This paper reviews a class of continuous locational optimization problems (where an optimal location or an optimal configuration of facilities is found in a continuum on a plane or a network) that can be solved through the Voronoi diagram. Eight types of continuous locational optimization problems are formulated, and these problems are solved through the ordinary Voronoi diagram, the farthest-point Voronoi diagram, the weighted Voronoi diagram, the network Voronoi diagram, the Voronoi diagram with a convex distance function, the line Voronoi diagram, and the area Voronoi diagram.

a Department of Urban Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan b Department of Information Systems and Quantitative Sciences, Nanzan University, 18 Yamazato-cho, Showa-ku, Nagoya 466, Japan

... Voronoi图是描述空间配置关系的常用方法之一^[19],多用于空间剖分,势力范围划分等^[20,21,22] ...

2000

0.0

... Voronoi图是描述空间配置关系的常用方法之一^[19],多用于空间剖分,势力范围划分等^[20,21,22] ...

2004

0.0

0.462

Shengquan

, Hu

Peng

, Yan

Weiyang.

Delimitation of central cities influenced regions based on weighted-Voronoi diagram.

Engineering Journal of Wuhan University, 2004, 37(1): 94-97.

[李圣权, 胡鹏, 闫卫阳. 基于加权Voronoi图的城市影响范围划分. 武汉大学学报: 工学版, 2004, 37(1): 94-97. ]

确定中心城市的吸引范围是城市体系规划、城市经济区划的一项基础工作.总结并分析以往方法的问题和不足,以河南省为例,通过选取指标体系,运用统计分析和数据变换的方法,确定中心城市的中心性强度,在此基础上提出城市断裂点理论与加权Voronoi图相结合的方法,实现对各中心城市空间影响范围的界定与生成.

... Voronoi图是描述空间配置关系的常用方法之一^[19],多用于空间剖分,势力范围划分等^[20,21,22] ...

2009

0.0

Xie

Shunping

, Feng

Xuezhi

, Wang

Jiechen.

et al.

Radiation domain of commercial centers in Nanjing based on analysis of road network weighted Voronoi diagram.

Acta Geographica Sinica, 2009, 64(12): 1467-1476.

[谢顺平, 冯学智, 王结臣等. 基于网络加权Voronoi图分析的南京市商业中心辐射域研究. 地理学报, 2009, 64(12): 1467-1476. ]

Road network system plays an important role in social and economic activities in cities. It is the bridge linking up commercial centers with demands, thus the update and change of road network will certainly affect the relevancy of commercial centers and demands. Voronoi diagram is an effective tool to partition spatial domain of influence, and the weighted Voronoi diagram based on road network analysis can simulate the actual situation of function radiation of commercial centers. This paper proposed an approach to constructing weighted Voronoi diagram based on network analysis. By contrast of different Voronoi diagrams, the weighted Voronoi area diagram based on network path time analysis is affirmed to be most effective to simulate the radiation domain of commercial centers. We integrated spatial interaction theory and breakpoint theory with network weighted Voronoi area diagram, and simulated spatial pattern change of radiation domain and demand coverage change of commercial centers in Nanjing under different traffic conditions. The covering information of radiation domain including area, population, the furthest path distance and average path distance of commercial centers were picked up so as to analyze radiation domain changes, the relativity of expanding area and subway adjacency of commercial centers. In addition, radiation domain adjacent matrix was proposed to express the balance and unbalance status of spatial partition, which can reveal the trend of spatial competition. The results of simulation experiments and analysis show that there is correlation between expanding area and subway adjacency of commercial centers, and that road network system with fast rail transit plays a key role in spatial competition among the commercial centers.

School of Geographic and Oceangraphic Scienses, Nanjing University, Nanjing 210093, China

道路网络在城市社会和经济活动中发挥重要作用，它是联系商业中心与需求间的桥梁，道路系统的更新与变化必然会对它们的关联产生影响。Voronoi图是划分势力空间的有效工具，基于道路网络分析构建的加权Voronoi图可以模拟城市商业中心功能辐射的实际情形。本文给出了基于道路网络分析的Voronoi图和加权Voronoi图构建方法，通过对各种Voronoi图的比较分析，认为基于网络路径时间分析构建的加权Voronoi面域图在商业中心辐射域模拟中最为有效。将空间相互作用和断裂点理论与网络加权Voronoi面域图相结合，模拟不同交通条件下南京市商业中心辐射域空间格局及其需求覆盖变化，并提取了辐射域的覆盖面积、覆盖人口、最远辐射路径距离和平均辐射路径距离等信息。对商业中心的地铁邻近度与其辐射域的扩张面积进行相关分析，采用域邻接矩阵描述空间划分平衡与不平衡之间的相互转变过程，可分析道路系统变更后商业中心之间空间竞争的变化趋势。分析结果表明商业中心的地铁邻近度与辐射域的扩张具有较大的相关性，快速轨道交通在商业中心空间竞争中发挥关键作用。

... Voronoi图是描述空间配置关系的常用方法之一^[19],多用于空间剖分,势力范围划分等^[20,21,22] ...