1987—2017年粤港澳大湾区城市群的不透水地表扩张与梯度演化

不透水地表是衡量城市化过程与空间扩张的重要特征。本文以我国最具经济活力的城市群-粤港澳大湾区城市（以下简称大湾区）为研究区,采用重心-标准差椭圆与梯度分析等方法,探讨其1987—2017年不透水地表的时空扩张分布特征与演化趋势。结果表明：① 30年来大湾区的不透水地表面积从1839.34 km²持续增长至12 385.93 km²。城市化进程进入21世纪后明显加快,整体形成了广、深、港、澳等中心城市带动,各次级城市组团,网络结构发展的空间扩张格局。② 大湾区不透水地表重心位于广州番禺与佛山顺德交界处附近,城市建设扩张靠近大陆海岸带区域,范围不断扩大。广、莞、佛等地的城市建设极大带动了不透水地表重心与方向的变化;③ 城市建设以珠江支流与大陆海岸线为轴心扩张的特征明显,各地核心城区与海湾区域的建设扩张共同构成了大湾区的发展核心,整体形成了中心城区为主、大陆海岸线为辅的协同发展趋势。粤港澳大湾区建设已上升为国家战略,未来需进一步强化内部各城市间的要素交互,在发挥核心城区辐射引领作用的同时,充分利用沿海产业优势,带动实现大湾区的城乡融合发展。

The Expansion and Gradient Evolution of Impervious Surface within the Guangdong-Hong Kong-Macao Greater Bay Area from 1987 to 2017

The impervious surface is considered an important feature to measure the urbanization and its spatial expansion. In the current study, the spatial-temporal expansion characteristics and evolution trends of the impervious surface are explored using gravity center, standard deviation ellipse, and gradient analysis in Guangdong-Hong Kong-Macao(GHM) Greater Bay Area during 1987-2017. The results show that:(1) The impervious surface areas of GHM Greater Bay Area has increased from 1839.34 km2 to 12 385.93 km2 in the past30 years, with an annual growth area of 351.55 km2. In the 21 stcentury, the urbanization process accelerated, and and each city exhibited different expansion characteristics. Moreover, it formed a spatial expansion pattern driven by core cities such as Guangzhou, Shenzhen, Hong Kong, and Macao, resulting in the formation of various secondary cities, and the development of network structures;(2) Urban construction and expansion are close to the coastal area. The gravity center of the impervious surface of the GHM Greater Bay Area is located near the junction of Panyu, Guangzhou, and Shunde, Foshan. However, the gravity center and urban development trends are from west to the east bank of the Pearl River, and toward Guangzhou, Dongguan, and Foshan. The urban development of Guangzhou, Dongguan, and Foshan promoted the change of gravity center of impervious surface;(3) The urban development of the GHM Greater Bay Area has apparent features of the expansion along the Pearl River and the coastline. Urban construction along both sides of the Pearl River tributary has always occupied a central position. Early urban construction was concentrated in the 70 km area on both sides, and the intensity of urban expansion increased sharply in the 21 stcentury. The area within 50 km of the coastline is an urban high-intensity construction area. The expansion of the core urban and bay area in various places constitutes the development core of the GHM Greater Bay Area. Moreover, the urban construction has formed a coordinated development trend that is dominated by the main urban area and supplemented by the coastline. Furthermore, Although the construction of the GHM Greater Bay Area has become China’s national strategy, but there exist problems due to the weak connections between cities. It is necessary to strengthen the interaction of elements in various cities, and make full use of the leading advantages of the core urban area to develop coastal industries, so as to realize the integration of urban and rural areas and economic development in the GHM Greater Bay Area.