Study On Urban Expansion And Heat Island Effect Of Three Provinces In Northeast China

In recent years, with sustained development of economy, China’s urbanizationprocess is accelerating. Traditional monitoring methods are difficult to get theinformation of the urban expansion fast and efficiently. Since the1970s, RemoteSensing technology has been developing and improving continuously. RemoteSensing and Geographic Information Systems technology have many advantages instudying the urban expansion, for example, a short cycle, low labor intensity, andsaving money and so on, and gradually become the main methods of monitoringurban expansion.In this paper, MSS data in the1975s, TM data in the1990s, ETM data in the2000s and CBERS data in the2007s of covering the three provinces in northeast chinawere used as the primary data source. Based on previous experience and the spectralfeatures of urban built-up areas, interpretation signs were established. The fourvector data of cities was processed by the Human-computer Interaction Interpretation.This article studied the situation of the city’s current distribution, calculated its areachanges, the dynamic degree and extended intensity information and so on, and usedgray correlation degree analysis method to analyze the driving force of the urbanexpansion on the base of data of statistics. Based on fractal theory, scale distributionand spatial correlation of the urban system of three provinces in northeast china werestudied. At the same time, MODIS LST and Landsat TM/ETM data were used in theinversion of the surface temperature and impermeable surface so that the urban heatisland effect was studied from both macro and micro scale. This paper gets thefollowing conclusions based on the above studies:1. Area and distribution characteristics of cities in three provinces in northeastchina in the four periods.The terrain of northeast region which has superior natural conditions is flat.Urban built-up areas are mainly distributed below500m, undulating below75m; theirslope is below8°. The cities mainly distribute along the major trunk roads and drainage. According to statistics, most of the region distributes in the distance of10km from transportation routes and rivers, so the distribution of the city has theobvious characteristics of the axial. In1975,1990,2000and2007, areas of thebuilt-up areas within the Administrative Region above the county level arerespectively2039.35km2,3829.70km2,4641.24km2and6693.91km2in threeprovinces in northeast china. Areas of the built-up areas in Liaoning Province whichhave always been the largest are respectively875.69km2,1615.43km2,2040.57km2and3020.81km2; followed by the Heilongjiang Province, areas of the built-up areasare respectively700.87km2,1322.34km2,1556.81km2and2128.24km2; areas of thebuilt-up areas in Jilin Province which have always been the smallest are respectively462.79km2,891.93km2,1043.86km2and1544.86km2.2. The expansion situation and features of cities in three provinces in northeastchina.The newly expanded urban built-up areas are mainly located below the elevationof500m and the slope of5°. The average annual rates of expansion of Heilongjiang,Jilin, Liaoning and overall urban built-up areas in1975-1990are respectively5.91%,6.18%,5.63%and5.85%; the average annual rates of expansion of Heilongjiang, Jilin,Liaoning and overall urban built-up areas in1990-2000have decreased, respectively,1.77%,1.70%,2.63%and2.12%; in2000-2007, the average annual rates ofexpansion of Heilongjiang, Jilin, Liaoning and overall urban built-up areas arerespectively5.24%,6.86%,6.86%and6.32%.Cities in three provinces in northeast china have the similar characteristics in theprocess of expansion. Based on the pace of expansion of1975-1990, they have gonethrough the process of the slow expansion in the first and the rapid expansion later.From5.85%in the first stage, they fall to2.12%in the second stage and then rise to6.32%in the third stage. In the process of urban expansion, the sub-provincial citieshave been at the heart; the prefecture-level cities are the main body of urbanexpansion; the county-level cities and counties have been in a stage of rapidexpansion; in addition to the1990-2000, expansion dynamic of the county-level citiesand counties degrees are higher than the sub-provincial cities and prefecture-levelcities. The larger expansion intensity area is mainly concentrated in Harbin-Daliantraffic economic belt. These regions which distribute in the form of the point and thedough are relatively independent of each other. Harbin, Changchun, Shenyang andDalian which are treated as the core in the expansion mode develop towards thesurrounding in the form of radiation. In the three-stage expansion process, urban expansion intensity of the second phase on the whole is less than the first stage; theextension strength of the third stage over the previous two phases improves clearly,especially in the coastal cities; these regions develop from the shape of point to theshape of large areas of the face in the figure.Cities in three provinces in northeast china are mainly distributed in the broadplains. Urban expansion is less affected by the terrain and shows the form of spreadmostly; some cities along the river are restricted with river, so they show contiguousexpansion; energy cities which are influenced with distribution of resources showenclave expansion.This article analyzed the driving force of urban expansion in the gray correlationdegree theory. The results show that the GDP and the area of urban built-up areashave the highest correlation degree, followed by the non-farm population, real estateinvestment, rail and road transport routes length.3. The scale’s distribution of urban agglomeration and the fractal characteristicsof urban system’s spatial structure in three provinces in northeast china.The scale’s distribution and urban system’s spatial structure of Liaozhongnanurban agglomeration, Hadaqi urban agglomeration and Jizhong urban agglomerationwere studied in fractal theory in three provinces in northeast china. The results showthat scale’s distribution of Hadaqi urban agglomeration has gradually been optimizedin30years; urban development in the urban agglomeration tends towards equilibrium;the spatial structure of the urban agglomeration tends to be compact. Jizhong urbanagglomeration has experienced optimized at first and then tends to disperse, but ingeneral, spatial structure tending to be compact. In addition, urban architecture of theHadaqi urban agglomeration and Jizhong urban agglomeration is still not perfect; thescale of cities is not continuous. Sub-provincial cities, prefecture-level cities,county-level city and county third-tier cities of Liaozhongnan urban agglomerationare very different in scale and appear significantly out of line between levels; thespatial structure of the urban agglomeration which has the obvious axis characteristicstends towards homogenization at first and then is attracted by transportation routes.4. Characteristics of urban heat island effect in three provinces in northeastchina.In winter, the distribution of the temperature in three provinces in northeastchina is mainly affected by the dimensions, namely the temperature decreasesgradually with the increasing dimension; in the spring, summer and autumn, thedistribution of the temperature is more affected by the geographical impact, the temperature of the western and southwestern is higher than that in eastern andnorthern regions on the whole. The region where the heat island effect appears ismainly distributed in the city and its surrounding areas, as well as mining nearby. Theintensity of heat island effect in summer is generally higher than that in spring andautumn. Urban cold island effect will appear in winter because of soot and other airpollutants.The surface temperature of the Changchun City was calculated in theArtis&Carnahan single-channel method. Study shows that the high temperature zonein Changchun City is located in the industrial park; the low temperature region ismainly located in the tourist scenic spot. Contrast to the two temperature data from1993and2001, study shows: after eight years of urban development, area of urbanheat island effect increases, but area of the high temperature zone and very hightemperature zone, however, reduces.Opaque surface information was extracted by spectral mixture analysis (SMA)in Changchun City. The study finds that the rate of impervious surface, surfacetemperature and NDVI are relevant. When NDVI>0, NDVI and surface temperatureshow a linear relationship; surface temperature gradually decreases with the increaseof NDVI. The rate of impervious surface and surface temperature show a linearrelationship, surface temperature gradually increases with the rate of impervioussurface increasing. With the continuous expansion of the city, the area of impervioussurface increases every year, and the area of the urban heat island region will continueto increase. NDVI and the rate of impervious surface have a linear relationship, NDVIdeclines with the rate of impervious surface increasing.