关键词: 城镇体系, 形成与发展机制, “卅”字型城市空间推进模式, 水资源约束, 河西走廊

Abstract: The article sets Hexi Corridor of Gansu Province as a study case, probes into the mechanism, arrangement characteristics and space organizing form of urban system forming and development under the restriction of water resource in northwest arid area. Study results indicated that the rational city and urban position has relatively been selected on superior natural position, the opening of ancient “Silk Road” has brought up the primitive framework of the urban system, the space distribution of the mineral resources controls the rational location of the industrial or mining cities and towns, the improvement of the traffic condition has accelerated the development of urbanization and the administrative interference is a propeller for development of the cities and towns. The essential features of the urban system's development and overall arrangement are shown as following: the primate city is not obvious, the grade is small in scale, the urbanization level and process are higher than the average level in Gansu Province but lower than the national average level; the urban function relies mainly on resources processing and rural market fair, and it is dull, urban density is low and the space overall arrangement assembles near the second Asia-Europe Transcontinental Bridge. Because of the restriction of water resource, a space advance pattern with a shape of “卅”for urban system is suggested and it is composed of “one core and four poles”, “one axis and three strips” and “all the towns prosper together”. Make one core combined by Jiuquan, Jiayuguan and Yumen city and be the only megapolis in Hexi Corridor whose non-agricultural population exceeding 500 000 in its urbanizational area. Upgrade Dunhuang to the prefecture-level city and turn Zhangye, Wuwei, Jinchang and Dunhuang four medium-sized cities into the important strategic point cities and bright phearl cities of the Hexi Corridor. Make Hexi section of Longhai-Lanxin economy strip composed of Lanxin railway and No.312 national road be the main horizontal axis for urban development. Make eco-economy strip of Shiyanghe drainage area, eco-economy strip of Heihe drainage area and eco-economy strip of Shulehe drainage area be the main lengthways axis. The existing 85 towns are going to be expanded to 100 through township reform to adapt to the urbanization development model that “puts the ecological immigrant in superior place step by step”. A netted space pattern with a shape of “卅”of urban system will be formed, in which large, small and medium-sized cities coordinately develop.

Key words: urban system, mechanism of forming and development, urban space advance pattern with a shape of “卅”, restriction of water Resource, Hexi Corridor