基于“源-汇”景观格局的城市热岛效应及影响因素分析--以合肥市为例

Analysis of urban heat island effect and influencing factors based on the"source-sink"landscape pattern:a case study of Hefei

选择城镇化增速居长三角三省一市第一位的合肥市作为研究区,通过提取植被指数、湿度指数、不透水面指数等地表特征敏感的遥感指数和地表温度来识别城市热岛的“源-汇”景观,结合土地利用类型对“源”景观贡献度及城市热岛效应进行研究.结果表明:合肥市热岛“源”景观的升温影响范围为150m,“源-汇”景观格局能有效缓解城市热岛效应,缓解程度由东南至西北呈强至弱的趋势,庐江县、巢湖市的缓解效果最好,蜀山区、瑶海区的缓解效果最差;“源-汇”景观面积的比值、“源”景观的有效粒径尺度越小,“源”景观的标准形状指数在0~0.35且景观斑块越离散,热岛效应的缓解程度越好;对任何地物斑块而言,热岛效应导致的温度上升都会削弱“源-汇”景观格局对热岛效应的抑制效率,增加林地的覆盖是减轻区域升温、缓解区域热岛的有效手段之一.

Hefei,which has the highest urbanization growth rate among the three provinces and one city in the Yangtze River Delta,was selected as the research area.The"source sink"landscape of urban heat islands was identified by extracting surface temperature and sensitive remote sensing indices to surface features such as vegetation index,moisture index and impermeable surface index,and then the study was conducted combined with the urban heat island effect and the contribution of land use types to the"source"landscape.The results showed that the heating impact range of the"source"landscape in Hefei was 150m,and the"source-sink"landscape pattern could effectively alleviate the urban heat island effect.The degree of relief showed a strong to weak trend from southeast to northwest,with Lujiang county and Chaohu city having the best relief effect,while Shushan district and Yaohai district having the worst relief effect.The smaller the ratio of the"source sink"landscape area and the effective particle size scale of the"source"landscape,the standard shape index of the"source"landscape was between 0 and 0.35,and the more dispersed the landscape patches,the better the degree of relief of the heat island effect.For any land feature patch,the temperature rise caused by the heat island effect will weaken the inhibitory efficiency of the"source-sink"landscape pattern on the heat island effect.Increasing forest cover is one of the effective means to reduce regional warming and alleviate regional heat island.