缓减热岛和热浪效应的城市绿地景观构建

Urban heat islands and heat waves pose profound impacts on regional economies, ecosystems, and human health and well-being. Spatial patterns of urban heat island intensity are evidently affected by landscape configuration of green spaces. However, a comprehensive understanding on the relationships between the configuration of green spaces in cities and urban climate change are sorely lacking, which undermines the development of effective urban planning strategies to mitigate and adapt climate change in cities such as heat island, heat wave and other extreme weather events. In reality, the great heterogeneity of landscape configuration within city provides an ideal spatial planning model to learn and adopt for mitigating and adapting urban heat island and heat wave effects even global climate change. This proposed project will focus on relatively understudied urban ecosystems, which, however, represent the most important habitats of humans (our backyards) and receive increasingly attention from the global change study community in recent years. We will take full advantage of the great heterogeneity of landscape configuration within city, identify the existing best and worst modes for the spatial configuration of urban landscape along urban development intensity gradient, interpret the mechanisms behind using the structural equation modeling (SEM), and develop a set of optimal landscape configuration options, key technologies and scientific frameworks for cities across various geographical regions and multiple level of urban administrative hierarchy to mitigate and adapt urban heat island and heat wave effects. This project will ultimately provide applicable options for urban planning strategies to build the resilience and capacity of urban ecosystems to adapt to existing and future climate change impacts.

城市热岛和热浪效应已经对社会经济、生态环境及人类生活产生了深刻的影响。城市热岛效应的空间格局明显受城市绿地景观特征的影响。然而，目前对城市绿地景观构建模式与城市气候变化关系的认识十分匮乏，不能有效的指导城市发展规划以应对日益加剧的城市气候变化问题如城市热岛、热浪和其它极端气候事件。本项目将着眼于研究十分薄弱，但直接关系到人类福祉，并在全球变化中越来越受到关注的城市热岛、热浪与绿地构建关系问题。充分利用城市现有绿地景观构建的空间异质性，识别沿城市化发展程度梯度缓解热岛效应的绿地景观构建现成的最优和最差模式，解析其机理，挖掘制定一整套适合于我国不同自然地理区和不同行政等级城市应对热岛、热浪的城市绿地景观构建最优模式、关键技术和理论体系，有效指导城市发展规划以应对日益加剧的城市气候变化问题。

城市热压力可能是我们这个时代最大的挑战之一。城市中热环境的空间异质的可能为解决城市热问题提供了现成的解决方案。城市中同时存在最理想和最不理想的景观结构，可以采用或避免这些景观结构来缓解城市热问题。本项目以长江三角洲城市群、北京市和西安市作为典型城市群和城市，利用Landsat 8获取的地表温度、SPOT 6解译的景观特征在不同城市群、不同城市及城市内部三个尺度开展城乡梯度热环境和景观构建研究。发现热环境有很强的空间异质性，城市中冷点和热点共存。同一城市化梯度内存在着较大的地表温度差异，表明在城市环境中存在着现成的景观结构来维持舒适的地表温度。地表温度随水体和林地覆盖度的增加而降低，林地的降温强度约为水体降温强度的一半，草地和耕地覆盖度对地表温度的影响并不大。城市自身可以通过改变景观结构来改善城市热环境，在城市设计中应当更优先考虑纳入林地作为天然降温措施。景观结构对城市地表温度有非常重要的影响，最优和最差的景观结构模式随着景观覆盖度的不同而有很大差异。在城市内部和城市之间，应根据具体的城市环境来制定缓解城市热环境的城市景观规划和设计策略。