Study On Urban Spatial Expansion Monitoring And Thermal Environment Change In The Center Of Chengdu City

With the rapid development of economy,the scale of the city is expanding and the process of urbanization is speeding up,which will lead to the change of the land use structure and the change of the regional environment.Therefore,make full use of the remote sensing technology to extract the information of land use,combined with the spatial analysis technology of geographic information system.Make an analysis of dynamic monitoring of city spatial expansion and driving force mechanism and monitor the city temperature distribution.The influence of urban expansion on regional temperature field is studied.Which has important significance to guide the the city future planning,to beautify the city environment and to realize the sustainable development of the city.This paper takes Chengdu city in 1992,TM images of 2002 and 2013 Landsat 8 phase three image as the main data source for the study.Based on the ENVI5.0 software,the three phase of remote sensing image geometric correction,image enhancement and cutting processing and then use the decision tree algorithm.To extract the construction land,cultivated land,woodland,water and other land information in the study area.Obtain the three phase of the land use classification of Chengdu city and compare the classification results with high spatial resolution images are proved by using decision tree classification has good accuracy and can be used to study the overall planning of the city.Secondly,make use of classification map of 1992,2002 and 2013 to extract Chengdu city boundary,through the introduction of growth rate,expansion intensity,barycentric coordinate transfer,compactness index.Make an analysis of the use of Arcgis spatial analysis and the transfer matrix of land use.The directional feature,quantitative features,Spatial morphological characteristics,temporal and spatial evolution rule and law of land use structure change in Chengdu urban expansion are studied.To explore the relationship between the city space expansion and nature,economy,policy and society driving factors.Finally,according to the feature of thermal information of the remote sensing image,in 1992,2002 and 2013 three period remote sensing inversion formulas in Chengdu city light temperature,through the inversion algorithm based on image(IB algorithm)to Chengdu city into the actual temperature of surface brightness temperature inversion,into the actual surface temperature and the actual temperature of the surface the distribution and change of Chengdu city shows that the distribution of the thermal environment in 1992-2002 showed increased gradually to the City suburb of temperature,formation characteristics of isolated island like high temperature area in the city.The urban land surface temperature decreased gradually and the suburban temperature increased in 2002-2013.The comparison of the thermal environment distribution map and urban spatial expansion map in Chengdu,draw a conclusion that the distribution of built-up area distribution and city heat environment in Chengdu city of the basic agreement,the two are closely linked to the space,during the 21 years,the distribution of the thermal environment in Chengdu has become larger with the expansion of urban space.