Study On Spatial-temporal Distribution And Causes Of Heat Island Effect In Zhengzhou

With the acceleration of urbanization in China,accompanying environmental problems are becoming more and more serious,ecological security is threatened.These problems have seriously threatened the improvement of the natural environment and human living environment.Zhengzhou city is an important provincial capital city in the central region and the core city of the Central Plains Economic Zone,it is also a national central city determined by the national urban system planning(2016-2030).In recent years,like the level of economic development,the process of urbanization and industrialization in Zhengzhou has also developed rapidly.The ecological environment is becoming more and more serious due to the extensive mode of economic development and irrational human development.The heat pollution problem represented by urban heat island is especially serious.Quantitative analysis of variation characteristics of urban thermal environment,to explore the driving mechanism of natural environment and socio-economic conditions to heat island effect,so as to effectively control and mitigate the heat island effect in Zhengzhou City.This is the ecological environment problem that should be solved urgently in Zhengzhou.Take Zhengzhou City area as the research area,using Landsat image,thermal infrared band,using Image-based Method to build temperature model,inversion of surface temperature in Zhengzhou,1996,2000,2006,2010 and 2014.The inversion temperature is divided into different heat island grades by means of mean-standard deviation method.The spatial and temporal evolution pattern of heat island effect in Zhengzhou City in the past 20 years was analyzed from three perspectives of gravity center migration,spatial autocorrelation and heat landscape pattern.Analyzes the driving mechanism of heat island effect in Zhengzhou from two aspects of nature and human economy.The main conclusions are as follows:(1)From 1996 to 2014,the average temperature of Zhengzhou was 29.225 ?,29.728 ?,29.037 ?,31.964 ?,31.964 ?,and the standard deviation was 4.078,4.390,3.398,3.237,2.639,Which indicates that the surface temperature of Zhengzhou city increased from 1996 to 2014,and gradually changed to a relatively stable high temperature state,and the heat island degree became more and more serious.(2)Before 2006,the urban heat island effect was obvious in central Zhengzhou,after 2006,with the urbanization of the continuous advance,farther away from the center of the city,the suburbs are also beginning to heat up.The proportion of high temperature landscape is higher and higher,The spatial distribution is characterized by dispersion,agglomeration and dispersion.The high-temperature agglomeration pattern of Zhengzhou is gradually evolved from the initial single-center aggregation state to the multi-center diffusion state.The agglomeration core is transferred from the geometric center to the suburbs.Among them,to the Northeast Jinshui district and the Western Zhongyuan district shifted to the greatest extent;(3)In the past 20 years,the overall pattern of high temperature landscape in Zhengzhou is gradually complex and fragmented.The dispersion of the high temperature plaques and the irregular shape are favorable for the diffusion of heat.This will help ease urban heat island effect.But in Jinshui district and Zhongyuan district,the industrial parks are more intensive and the socio-economic activities are fierce.The proportion of high temperature landscape in these two areas increased rapidly,and the shape of high temperature patches gradually became regular and simplified,the degree of diversification and diversification of the high temperature plaques decreased continuously.It is indicated that the two districts have become more and more disturbed,and the new heat island core area is gradually forming;(4)Among the types of land use,the impervious layer and vegetation had the most significant effect on the urban thermal environment.There was a significant positive correlation between the impervious layer and LST,and the vegetation could significantly reduce the LST.Among the various factors of social and economic development,the level of economic development,population density,urban construction and industrial development have a strong driving effect on heat island effect,among which the driving force of industrial development is the strongest.In recent 20 years,the spatial distribution of the thermal landscape grade increase zone of Zhengzhou and the new industrial parks in Zhengzhou have a high degree of coincidence.Industrial transfer is bound to have a certain impact on the urban thermal environment,but these industrial parks are located around the city,the spatial distribution is more dispersed,relatively conducive to the loss of heat.