城市扩张对热环境时空演变的影响——以哈尔滨为例

Urban Expansion and Its Influence on Spatio-temporal Variation of Thermal Environment: A Case Study of Harbin City

城市发展过程中土地利用类型及其景观格局的变化是影响城市地表温度的主要原因,为定量揭示城市扩张过程中土地利用景观格局的变化对夏季地表温度的影响及作用机制,以哈尔滨为例,基于1984—2015年Landsat数据,通过分析城市建筑用地和地表温度的时空演变特征,以及地表温度与建筑用地、植被和水体之间的关系,揭示哈尔滨城市扩张过程中夏季城市热岛格局的演变特征及影响因素,为政府部门制定城市热岛效应的缓解措施提供参考。结果表明,1984—2015年哈尔滨市建筑用地面积由187 km^2扩大到571 km^2,平均扩张速度为13 km^2·a^(-1),建筑用地重心向东南方向移动了1.01 km。与1984年相比,2015年哈尔滨市有44.84%区域地表相对温度升高,有10.63%区域地表相对温度下降;从空间分布看,2015年中心城区出现热岛效应减弱、热岛斑块面积减小的趋势,周边区域出现热岛效应加强、热岛斑块面积增大的趋势。城市建筑用地与地表温度之间存在正相关关系,水体和植被与地表温度之间存在负相关关系,建筑用地的增温效应远远大于水体和植被的降温效应。在城市热岛效应分析中,应用Shannon熵的研究结果与景观指数的研究结果具有很好的一致性。在城市建设中,减小集中连片的建筑用地,增加城市绿地面积,是缓解城市热岛效应的有效手段。

The change of land use types and their landscape patterns is the main factors to affect surface temperature during urban development.In order to quantitatively reveal the impact and mechanisms of the change on surface temperature in summer,Landsat Thematic Mapper remote sensing data from 1984 to 2015 of Harbin city were used to analyze the spatiotemporal variation of surface temperature and building lots and then to identify the relationship between surface temperature and building lots as well as vegetation and water.This study results could be helpful to provide some reference for urban planning and Urban Heat Island(UHI)controlling.The results showed that building lots area increased from 187 km2 to 571 km2 with average rate of 13 km2·a-1.And its gravity centre moved towards southeast by 1.01 km.Compared with 1984,the surface relative temperature tended to rise in 44.84%of the whole regions and it tended to descend in 10.63%of the regions in 2015.In the aspect of spatial distribution,the UHI effect was abated and the UHI patches decreased in central city,but they were opposite in surrounding regions.Surface temperature had a positive correlation with building lots and a negative one with vegetation and water.The warming effect of building lots was much bigger than the cooling effect of vegetation and water.Information entropy was an index of indicating the concentration or diffusion of geographical units.The results of applying it had a good consistency with those of landscape indexes in analyzing UHI effect.In the process of urban construction,it is an effective means to mitigate UHI effect by reducing the area of centralized building and increasing the area of urban green lands.