Spatial Interaction Research Of Urban Agglomerations Along The Silk Road Economic Belt

China is in an important stage with comprehensive transformation of society and economy at present. With basis of high temporal-spatial accessibility and high density of population and economy, a new regional complex formed by means of product elements concentrating, regional economic integration and industrial specialization is becoming more and more mature and strong. Among them, urban agglomeration which constituted with cities in the particular area has increased and become the main form to drive regional economic development. Guanzhong-Tianshui, Lan-Bai-Xi, Jiu-Jia-Yu and the northern slope of the Tianshan Mountains urban agglomeration which along the Silk Road Economic Belt have gradually entered a period of rapid development in recent years. The explorative empirical research through the quantitative analysis method is made on the above four urban agglomerations in this study. Firstly, the boundary scopes have been defined. Secondly, economic influence field intensity of cities and counties of four urban agglomerations in the northwest has been quantitatively measured. Thirdly, urban agglomeration internal and external spatial interaction strength has been researched empirically. Finally, dynamic variation tracks of the economic and population gravity centre of the four urban agglomerations from 2003 to 2012 have been depicted and analyzed. The results show that:(1)To determine the spatial scope of each urban agglomeration through the regional economic integration is more reasonable. Economic influence field intensity of cities and counties along China section of the Silk Road Economic Belt shows that both ends are low, and the middle is high.(2)The total economic linkage of Xi’an is the strongest of one hundred and nine cities and counties of four urban agglomerations, followed by the center cities and secondary center cities of Guanzhong-Tianshui, Lan-Bai-Xi and the northern slope of the Tianshan Mountains. These cities and counties with stronger total economic linkage are concentrated in the Guanzhong-Tianshui.(3)At the level of cities and counties, it is absolute advantage of economic linkage strength of Guanzhong-Tianshui to the inside; Economic linkage strength of Lan-Bai-Xi to the inside is bigger than that to the other urban agglomerations overall; Economic linkage strength of Jiu-Jia-Yu to the inside is smaller than that to Guanzhong-Tianshui; It is obvious advantage of economic linkage strength of the northern slope of the Tianshan Mountains to the inside.(4) Every center cities are significantly different on their central position in their urban agglomeration. Spatial interaction strengths between center city and other city(county) of urban agglomeration show a large difference. Center cities’ radiation and leading ability for the whole urban agglomeration from strong to weak is: Xi’an, Urumqi, Lanzhou and Jiuquan.(5) Internal gravity of Guanzhong-Tianshui performances a spatial pattern of multicenter and network of high strength, and its internal spatial structure is very reasonable. Lan-Bai-Xi shows two centers and spatial pattern of low intensity divergence and its internal spatial structure is reasonable. While internal gravity of Jiu-Jia-Yu is weak and its internal spatial structure is extremely unreasonable. The northern slope of the Tianshan Mountains shows single center and low intensity spatial pattern of divergence to the periphery and its spatial structure is not reasonable.(6) Spatial interaction strength between urban agglomerations has enhanced persistently and rapidly in the ten years. At the same year, spatial interaction from Guanzhong-Tianshui to Lan-Bai-Xi was most powerful, then from big to small is as follows: the northern slope of the Tianshan Mountains to Guanzhong-Tianshui, to Lan-Bai-Xi, Jiu-Jia-Yu to Guanzhong-Tianshui, to Lan-Bai-Xi, to the northern slope of the Tianshan Mountains.(7) Spatial interaction direction between urban agglomerations at the level of cities and counties: it is strong between Guanzhong-Tianshui and Lan-Bai-Xi, it is weak from Jiu-Jia-Yu to Guanzhong-Tianshui and Lan-Bai-Xi, both the northern slope of the Tianshan Mountains to Guanzhong-Tianshui and Lan-Bai-Xi show that gravity is mainly between two core cities and it is very weak between the northern slope of the Tianshan Mountains and Jiu-Jia-Yu.(8) Gravity of Guanzhong-Tianshui presents "centrifugal" displacement, Lan-Bai-Xi shows "centripetal" displacement, Jiu-Jia-Yu shows deviation to the provincial regional center, displacement of economic and population gravity center of the northern slope of the Tianshan Mountains are backward and their tracks are volatile.