Research On The Impact Of Land Use Change On The Surface Thermal Environment In Urumqi City

With the rapid development of social economy and the increasing urbanization process,the types of land resources within the city have undergone tremendous changes.The original land types and spatial structure have been destroyed.At the same time,the rapid expansion of construction land has caused the original grassland underneath,Woodlands and waters have been replaced by a series of artificial buildings,and the environmental problems caused by this have become increasingly prominent.Changes in land use types will affect the surface's albedo and absorption of solar radiation,as well as the absorption and emission of carbon,which will increase the amount of greenhouse gases in the atmosphere and affect the land surface temperature.The continuous rise of surface temperature will also increase the spread of infectious diseases,reduce the production of food crops,and may even trigger a series of natural disasters.Therefore,climate change caused by land use changes has become the top priority of research.This article uses Urumqi as the research area to explore the changes in land use and the distribution of surface thermal environment from 2000 to 2019 in the past 20 years,and provide a scientific and reasonable basis for land planning and urban construction in Urumqi.Using the maximum likelihood method in the supervised classification method,extracting land use change information based on Landsat images,using MOD SI data to obtain surface temperature data products,and analyzing land use changes and surface temperature distribution conditions,using the overlay analysis tool in ArcGIS The superposition analysis of land use types and the spatial distribution of the surface thermal environment resulted in the following research results:(1)Grassland and unused land are the main types used in Urumqi.The area of cultivated land,woodland and construction land is in the middle,and the water area is the least.Among them,only construction land has maintained a growth trend during the study period.The growth range of construction land mainly extends along the northwest-southeast longitudinal axis,and its expansion presents a "T-shaped"distribution with a narrow northwest and a wide southeast.(2)The value of the comprehensive land use index of Urumqi in the study interval is 182.83,183.85,185.96,188.52,and 189.71.The index value is increasing,but the growth rate is small,and it does not reach the upper limit of utilization,indicating that the land resources Development and utilization are continuing,but there is still a certain amount of land resources that have not been developed and used.This is because Urumqi has many mountains and deserts,and its development and utilization cycle is long,and it cannot be changed in the short term.Secondly,there are a large number of deserts and wastelands near the edge of Midong District and Chaiwopu Lake,which are not suitable for development and utilization.(3)According to the distribution of surface temperature in Urumqi City,it is divided into five intervals at equal intervals.The high temperature areas are mainly distributed in Jiancheng District,and the area is expanding;the sub-high temperature is mainly distributed in Toutunhe District and Daban District.And Urumqi County;the distribution range of the medium temperature zone is relatively fixed,mainly distributed at the foot of the mountain range in Daban City and Urumqi County.There are more grassland and woodland at the foot of the mountain,and less bare land,which can effectively suppress the rise of surface temperature;second The low temperature areas are mainly distributed in Dabancheng District and Urumqi County,and they are concentrated in the snow-capped mountains on the top of the mountain.(4)The growth of construction land area and the expansion of high-temperature areas show a trend of mutual response and mutual restraint.High-temperature areas and construction land are concentratedly distributed,and then spread to the surrounding area.The area to which construction land belongs has always been in the high-temperature range,and the expansion trend of construction land has always been consistent with the expansion trend of high-temperature areas.(5)There is a high negative correlation between the surface temperature and the normalized vegetation index and the improved water body index,with R2 of 0.7157 and 0.8384 respectively,which shows that vegetation and water areas can both play a certain role in the increase of surface temperature.Inhibition.