城市热环境灾害的规划应对途径研究——以重庆市主城区为例

In recent years, high temperature and heat waves in large cities are threatening human health and excessively consuming energy, which seriously affect the quality of human settlements. This project focus on the urban thermal environment problem result from the combined effect of climate warming and urban heat island and studies the response of urban planning to hazard risk from the perspective of natural hazard science. Taking the main city of Chongqing as an example, 3S (GIS, RS and GPS) technologies and numerical simulation method are used to analyze hazard factors, hazard-inducing environments, hazard-affected bodies and resilience using on multi-source data. Based on the urban planning scenarios, we predict possible thermal intensity and spatial distribution, then assess the hazard risk. Then we will develop a visualization system for risk assessment of urban thermal environment hazard: urban thermal environment mapping, to achieve the two-way feedback between thermal environment hazard and urban planning. The vulnerability of hazard-affected bodies is assessed and two planning methods are put forward for transferring hazard risk and reducing hazard risk. Finally, we try to integrate hazard mitigation measures into the urban planning, and to explore feasible integration methods and ways in index of the master plan and regulatory plan. The study aims to move the urban hazard prevention and mitigation to the urban planning stage, to explore the viable solution to response to thermal environment hazard in urban planning, to improve the climate adaptability of urban planning, to increase urban resilient, to reduce urban carbon emissions and to lead the development of climate-adaptive cities.

近年来大城市高温热浪频发，威胁人体健康，导致能源消耗过渡，严重影响了人居环境质量。本项目以气候变暖与城市热岛的叠加效应——城市热环境为研究对象，利用灾害学分析方法，以降低灾害风险为目标导向，探索规划应对途径。以重庆市主城区为例，基于多源数据，应用3S技术和数值模拟，剖析热环境灾害的致灾因子、孕灾环境、承灾体和抗灾能力；基于城市规划情景预测热环境的强度与分布；开发城市热环境灾害风险评估可视化系统——城市热环境制图，实现城市规划编制与灾害风险之间的反馈；评价承灾体的脆弱性，提出转移灾害风险和降低灾害风险的规划编制方法；在总体规划和控制性详细规划两个法定规划层面上，尝试将热环境减灾措施融入规划指标体系中，形成可实施的融入方式和途径。该研究旨在探寻应对热环境灾害风险的规划编制方法和分析技术，弥补传统规划方法的不足，提升城市规划的气候适应性，降低城市碳排放，引领气候适应型城市发展。

气候变暖和城市热岛效应的叠加，导致夏季城市温度异常升高，威胁人体健康，增加能源消耗和碳排放，对建筑和设施产生了重大影响，已演变为城市热环境灾害。从城市空间形态入手，尝试可视化热环境灾害风险底图，融合到城市规划编制过程中，并使用数值模拟方法检验规划情景下的热环境效应。（1）多尺度多维度的城市空间形态与地表温度LST的相关分析发现，天空开阔度（SVF）、表面粗糙度（USR）、建筑密度（BD）等形态因子对城市热环境影响较显著；紧凑型的空间形态和高层建筑有利于降低热环境水平。（2）以致灾因子、孕灾环境、承载体和抗灾能力为视角，耦合城市物理和社会的暴露、敏感和适应特征，构建了热环境灾害脆弱性评估模型，并基于ArcGIS可视化，与城市规划方案进行叠加，实现交互反馈。（3）多个分散的绿色空间比单个大型绿色空间更有利于城市降温，乔木林相比低矮灌丛和草地有更好的降温增湿作用；绿色空间的良好热舒适性对游人的停留、健身和社会交往有明显的吸引作用。（4）大型水体在白天有较好的降温增湿作用，降温作用最远可达1km，小型水体的降温作用与其周边的植物和建筑布局形式有密切关系。（5）基于WRF模拟背景风，结合城市通风潜力和城市下垫面特征以及城市结构、道路系统、开敞空间构建了重庆市主城区三级城市通风廊道共32条。（6）以降低致灾因子危险性、孕灾环境敏感性和承灾体脆弱性，增加热适应力，提升抗灾能力为导向，在城市总体规划、详细规划、专项规划和城市设计层面上提出了减缓热环境灾害的措施。（7）利用ENVI-met模拟多种规划情景下的热环境水平，并结合调控成本和可操作性，比选最优的规划调控方案。本项目将热环境现状分析和规划情景结合，重点识别绿色空间、蓝色空间和风场空间减缓热环境的关键要素，融入多层级的城市规划提出可操作性的措施，期望通过规划的实施达到 “源头”治理的目的，从而增强城市热环境的适应能力，改善人居环境质量，提升城市生活品质，促进城市绿色低碳发展。