西宁绿地生态对城市热岛效应的影响分析

Analysis of the Influence of Xining Green Space Ecology on Urban Heat Island Effect

文章分析了2009年~2018年绿地生态对西宁城区热岛的影响,分析表明:(1)西宁城市热岛呈现从城市中心向外辐射的分布格局,热岛主轴与人类活动聚集区对应。(2)与2009年相比,2018年西宁城区高温区向城郊扩展,城市热岛范围和强度更强,2018年西宁城区热岛面积增加32.02 km2。(3)表征人文因素的归一化差指裸地与建筑指数NDBBI、归一化差值不透水面指数NDISI与LST呈正相关,表征自然因素的归一化植被指数NDVI、植被覆盖度FVC和数字高程DEM与LST呈负相关,其中NDVI的负相关系数超过0.5,表明植被覆盖区可以抑制城市热岛。(4)2009年和2018年西宁的耕地、林地和水体的贡献度CI为负值,其中,有林地的CI 2018年最低,为-0.4;城镇用地和建设用地的贡献度CI为正值,说明这两种地类是西宁城区LST升高的主要贡献源。分析表明林地、耕地、草地等绿地对城市LST的升高有抑制作用,可以减缓城市热岛效应,而城市建设等人类活动会导致LST升高,加剧城市热岛。

The impact of green space ecology on Xining urban heat island from 2009 to 2018 was analyzed.The results showed that the urban heat island in Xining city presented a distribution pattern radiating outward from the urban center,and the main axis of the heat island corresponded to human activity accumulated area.Compared with 2009,the high-temperature area in Xining urban was expanded to the suburbs in 2018,and the spatial scope and degree of urban heat island increased.The area of Xining urban heat island increased by 32.02 km2 in 2018.NDBBI and NDISI representing human factors were positively correlated with LST.NDVI,FVC and DEM representing natural factors were negatively correlated with LST.The negative correlation coefficient of NDVI exceeded 0.5,indicating that green vegetation coverage area showed cooling effect and could inhibit urban heat island.The CI of cultivated land,forest land,grassland and water body in Xining were negative.The CI of urban land and construction land was positive,and the CI of urban land increased from 0.6 in 2009 to 0.7 in 2018,indicating that these two land types were the main contribution sources of urban elevated LST.The analysis demonstrated that forest land,cultivated land,grassland and other urban green space ecology could inhibit the rise of LST and slew down the urban heat island effect,while human activitiessuch as urban construction would increase LST and aggravate the urban heat island.