Research On Urban Spatial Structure Evolution Of The Valley City

Valley city is defined as the cities whose main part(that is the built-up area or the core of the city) formed and developed in the valley. The development of valley city is limited by its natural environment, and its urban space has a typical characteristic to adapt the restriction of natural environment. This paper selected a typical valley city Yan`an, which located in loess plateau hills gully district as subject. By using the method of document analysis, induction and deduction, qualitative and quantitative of analyzing urban space and multidisciplinary analysis, research on the feature of its urban spatial structure evolution since 1935, impact elements, development status, dilemma and develop patterns, in term of the sustainable development strategy of urban space of the valley city.This paper contains the following three parts:First of all, by learning from domestic and foreign theories on urban spatial structure, and systematically review the development of valley cities in our country, in accordance with the feature of urban spatial structure evolution, dividing the development of urban space into four stages. Stage one(1935~1948), Yan`an developed its center from the Prefectural city to Shichanggou as commercial center and Xibeichuan as administrative centre, multi-node growing in the “Y” shape main axis; the second stage(1949~1978), the period of restoration construction development, Yan`an rebuilt the old city, make the intersection of rivers and mountains as complex, the Xibeichuan as cultural center, and developed multi-node along the main axis; the third stage(1979~1992), with the expediting of reform and open policy, the economy developed accelerated, and the city construction increased, and developed multi-code and vast stretched along the main axis; the last stage(since 1993), the period of fast construction development, with the support of public policy and improvement of regional transportation, the economic development and city construction rocket, there comes out the peripheral groups to relieve the contradiction of the central urban area, the city developed multi-node along the main axis to peripheral groups.And then, this paper taking time as main thread and changes of urban space as entry point, giving a thorough study combined with the evolution stages of urban space, and conclude the features of each stage of urban space evolution. Futhermore this paper explores mode of action of the city`s natural environment, traffic impact, economy, public policy, and social culture on its evolution of urban spatial structure.Finally, basing on the conditon of valley city analyzing the present situation and dilemma of the urban spatial development of Yan`an, concluding the restrictive factors and develop modes of urban spatial development, and put forward the sustainable development direction and strategies of urban space.The results shows that the development of Yan`an is affected by its valley terrain, regional advantage and traffic structure, economic and technology, social and culture, policy guidance, the urban spatial structure shows different characteristics in different periods. Yan`an city should insist on a sustainable development road which based on the ecological adaptability, construcing developement path of which adapt to the valley city, so as to ensure the urban spatial development of valley city ordered developed.