Study On Thermal Environment Changes And Spatial Pattern Optimization Of Chang-Zhu-Tan City Cluster In The Context Of Spatial Expansion

Rapid urbanization has resulted in worsening urban biological environments and an increasingly severe urban heat island effect.The Chang Zhu Tan city cluster is the second biggest in central China.The Chang Zhu Tan urban agglomeration’s thermal environment issue is getting worse due to the ongoing spatial growth in recent years.The present study on the urban thermal environment has made many advances,yet there are also certain gaps.To begin,the present research focuses on the microscopic and urban scales,with little emphasis dedicated to regional and urban cluster scales.Second,previous macro-scale studies are constrained by the precision of remote sensing data,therefore most of them disregard the influence of more specific urban indicator changes on the thermal environment of urban clusters.Third,the present research is mostly concerned with analyzing the current features of the urban thermal environment,with few forecasts of urban future thermal environment scenarios.Existing research has limits in developing effective regulatory policies and planning suggestions for cities to deal with future climate change.The urban agglomeration of Chang Zhu Tan is used as an example in this study.Based on the multi-temporal land use data and building road data,the WRF/UCM model is used to quantitatively analyze the relationship between anthropogenic heat emission,urban form(building density and building height),changes in the land type of urban agglomeration green center and the thermal environment of urban agglomeration.Second,simulations based on"double evaluation"of land spatial planning coupled with cellular automation estimate the scale of building land in 2035 in Chang Zhu Tan urban agglomeration,and the distribution features of the thermal environment in 2035 in Chang Zhu Tan urban agglomeration.To begin,the study’s findings reveal that the overall anthropogenic heat emission in the Chang Zhu Tan urban agglomeration was 3.49×1017J/a in 2017,and the average anthropogenic heat intensity was 14.22 W/m~2,with significant disparities across cities in the urban agglomeration,with Changsha having a greater anthropogenic heat intensity than the other two cities.Second,it is discovered that an acceptable increase in building density or height may somewhat lessen the thermal environment of urban clusters,with building density having a more noticeable cooling impact.Meanwhile,the thermal environment of urban clusters was discovered to be greatly worsened by human heat emission.Third,the study’s findings indicate that between 1990 and 2017,Changsha,Zhuzhou,and Xiangtan cities’built-up areas rose by 88%to 324%,the average temperature climbed by around 0.4 to 1.1°C,and the spread of high-temperature zones inside cities increased by 68%to 173%.The research also revealed that in the"green heart"region,the cooling impact of water bodies and woods is far greater than that of cultivated land.Finally,it is discovered that the temperature within the urban cluster grows in 2035,with a maximum increase of 1.73°C,and the high-temperature zones are concentrated and continuous.In addition,it is discovered that the temperature within the green heart area increases greatly,and the cold island effect of the green heart diminishes significantly.Based on the aforementioned findings,this research suggests a method for optimizing the territorial spatial pattern of the Chang Zhu Tan urban agglomeration in terms of climate adaptability.To begin with,the research advises a decentralized spatial layout pattern of"polyester+cluster,"and each city in the urban agglomeration should keep a specific amount of open space as a barrier to avoid continual development.Simultaneously,a larger value of building density or building height is permitted in a specific part of the city,but the value of another indication should be decreased properly,and the circulation of the main air ducts in summer should be as unobstructed as feasible.Second,the research stated that urban cold sources like parks,squares,and rivers should be tightly preserved in terms of the country’s spatial structure.The research also proposes that urban development operations in urban green areas and locations near green centers of urban clusters be rigorously limited to prevent natural winds from infiltrating the urban core.Third,the research advises exploiting the green core of the Chang Zhu Tan urban agglomeration and the Xiangjiang River in the building of ventilation corridors to connect wind systems across different cities in the urban agglomeration and direct natural gas flow to urban regions.Four ventilation corridors—the Liuyang River Ecological Corridor,the Changsha Bypass Ecological Corridor,the Shanghai-Kunming High-speed Railway Ecological Corridor,and the Xiangjiang River Ecological Corridor are suggested to be built,according to the report.Finally,the study proposes that,in terms of land use pattern,the industrial structure may be adjusted to further limit the influence of human heat emissions on the thermal environment of urban agglomerations.The proportion of development land in the green center of urban clusters should be rigorously limited to 28%,and a decentralized pattern should be used.Meanwhile,green vegetation should be primarily planted with trees to improve the cooling impact of the regional thermal environment.