| With the economic development,the acceleration of the urbanization process,the transformation of towns and cities into cities,it will inevitably bring frequent conversion of the nature of the land,the expansion of the urban built-up area and the increase in the population density of the urban center have all caused the urban thermal environment to become more serious.The urban heat island is the most direct manifestation of the urban thermal environment in terms of temperature.At this stage,the heat island not only simply affects the local climate environment,but also affects the planning and layout of the various functional areas within the city and the physical and mental health of the residents.This article takes Ganzhou as the research area and takes 2000 as the initial period of the study.The Landsat satellite series of remote sensing images at intervals of 4-5 years are used as the basic data support.They are 2000,2005,2009 and 2014 respectively.The analysis of the spatial and temporal changes of land use and surface temperature in Ganzhou City in 2018,and through the use of superposition analysis and linear analysis methods to analyze the correlation between the land use types and the spatial and temporal distribution of heat islands show:(1)In the past 20 years,the conversion of various land types in Ganzhou has been relatively frequent.Among them,the construction land area has always maintained a growing trend.The construction land area increased by 1238.15 km2 from 2000 to 2018,and the increase area was 1.71 in the early 2000 s.Unused land has the largest area fluctuation among all land types;water area changes less;forest land and cultivated land account for the largest proportion,and it is also the main contributor to area transfer.On the whole,the dynamic change degree of land use in various areas was the largest in 2000-2005,and decreased in 2014-2018,that is,the speed of land use change in the later period gradually slowed down.(2)At the same time,there is a significant temperature difference in Ganzhou City.Among them,there is a difference of 14.86°C between the highest temperature and the lowest temperature in the study area in 2014.In addition,the average surface temperature of Ganzhou City has been maintained for the past 20 years.rise.According to the mean-standard deviation,the surface temperature of each year in the study area is graded,and the comparison shows that the distribution of heat island effect in Ganzhou has obvious changes: the time distribution shows the high temperature area and sub-high temperature affected by the heat island in 2000-2009 The increase in the area of the area changed into a decrease in the area of the secondary high temperature area in the later period,and the area of the high temperature area increased rapidly;the spatial distribution showed a pattern of "strong north to south" and "strong east to west".(3)The research on the relationship between the land use and the heat island spatial intensity shows that the average temperature of the construction land and unused land is always higher than that of the forest land and water distribution area.The average temperature of the unused land in 2009 was 8.91? higher than the average temperature of the forest land;At the same time,the construction land and unused land are mainly manifested as high temperature and sub-high temperature on the heat island level.The proportion of construction land in the high-temperature area and the sub-high temperature area is maintained at about 80% in each year,unused in 2005 and 2014 The area of the middle-high temperature area accounts for more than 90%;the land types of forest land,cultivated land and water area are mainly manifested as middle temperature and sub-medium temperature in the heat island grade distribution.In the quantitative analysis,the normalized building index showed a strong positive linear correlation with the surface temperature,and the vegetation coverage,the normalized water body index and the surface temperature showed a negative correlation.The results showed that the normalized water body index increased by 0.1,corresponding to The surface temperature of is reduced by 1.15?,indicating that the water body has a good cooling effect.This article analyzes the land use status and the spatial and temporal distribution of the heat island effect in Ganzhou City respectively,and uses ArcGIS to superimpose the two.Based on the results of the superimposed analysis,the paper proposes feasible suggestions for mitigating the heat island effect in Ganzhou City.In the process of urban development,it is necessary to rationally arrange the spatial distribution of various land use types,and try to avoid the urban heat problems caused by the increase of the impervious surface of the built-up area and the reduction of the green area.The characteristics of this article are mainly reflected in: the selection of research areas,compared with the first-tier megacities in Beijing,Shanghai,Guangzhou,etc.in the early days of the heat island research,began to pay attention to some well-developed provincial cities by the middle of the year.This paper selected economic development In the national ranking,the backward Ganzhou city is the research area.The area of the jurisdiction is large.The districts and counties are relatively scattered and the number of districts and counties in the jurisdiction is large.On the other hand,the research time of this paper is continuous and the time span is long.As the starting time of the study after the retreat into the city,it can well show the spatiotemporal changes of the heat island effect in the whole development process of Ganzhou City. |
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