Construction land expansion and influencing factors of typical river valley cities in Northeast China: Taking Jilin City as an example

Jilin City is a typical river valley city in Northeast China.In this paper,the authors studied the spatial and temporal expansion characteristics of the built-up areas in Jilin City from 1990 to 2020 using the analysis of expansion speed and strength,fractal dimension,barycenter coordinate transfer index and sector analysis.The ultimate-goal is to analyze the driving and restrictive factors that affect the spatial expansion of river valley cities.The results indicate that(1)the expansion speed of urban land in Jilin City has been re-latively slow in the past 30 years,while only slightly faster in 2010–2020;(2)in the spatial dimension,Jilin City mainly expanded to the south,then to the west,and extensive expansion has resulted in complex mor-phology with little stability and compactness;(3)the expansion is affected by multiple factors,of which the positive factor is industrial development,while the restrictive factors include natural factors,population loss,etc.This study provides a case for the formulation of land use policies and land space planning in river valley cities.

RESEARCH ON IMAGO SPACE OF VALLEY CITY——A Case Study of Lanzhou City

Currently domestic researches on urban imago space concentrate in a few cities that lie in the advanced region, such as Beijing, Guangzhou, Wuhan, etc., but in so far as those cities that lie in the northwest inland region, the research of this aspect is still few. In order to supplement a special example to the urban imago space theory and to validate former theory, this article studied the Lanzhou urban imago space. During the course of researching, authors adopted some investigating methods, such as visiting on the spot, photograph identification method and sketch map identification method etc. Using investigated data, this paper made an elementary research on urban imago space of Lanzhou, which is a typical valley city in the western China. The result of study indicated that the urban imago space of Lanzhou takes Xiguan Cross as its center (Lanzhou involves four districts of Chengguan, Qilihe, Anning and Xigu). In the process of recognition of urban imago space, the Huanghe (Yellow) River and mountains beside the city are the dominant factors and the main nodes of cognition. So the urban imago space of Lanzhou is quite different from that of plain cities. Interviewee did well in the spatial structure map, which was made up of mountainous land, river and main trunk roads,the group structure took profound impression on people.

Strategies for Constructing“Green Heart” in Valley Cities of the Loess Plateau

Green heart is an important part of urban ecosystem and urban public space. Due to the limitation of geography, hydrology, soil, climate, transportation and other factors, valley cities in the Loess Plateau have certain particularities in the construction of their green hearts. Based on the connotation and characteristics of green heart, a typical valley city of Shenmu in Shaanxi Province was selected for research, and explored the adaptive design strategy of green heart in the city combining with the planning and design of the Central Park in Shenmu, so as to provide a reference point for the construction of green heart in the same type of city.

WINTER BOUNDARY LAYER CHARACTERISTICS OVER A VALLEY CITY

I. INTRODUCTION A synthetic field observation was made in Lanzhou from January 10 to 19, 1989. Lanzhou city (36°N, 104. 3°E )is in an elliptical basin, of which the length from east to west is about 13 km, and the width from south to north is about 6 km. This area is