海绵城市建设视角下长沙市城市热岛效应时空机制研究

Study on the Spatiotemporal Mechanisms of the Urban Heat Island Effect in Changsha from the Perspective of Sponge City Construction

摘要: 快速城市化引发的下垫面硬化问题，导致城市热岛效应持续加剧，严重制约城市生态宜居性。海绵城市可通过优化城市下垫面调控热环境，但现有研究缺乏对其净政策效应与非线性驱动机制的系统量化解析。以长沙市为研究对象，基于2022年、2025年两期遥感影像与海绵城市建设数据，构建DID-SHAP + LightGBM联合分析框架，系统探究海绵城市建设对城市热岛效应的时空调控机制。结果表明：长沙市热岛效应呈现极强空间集聚特征，2022~2025年长沙市中心城区热岛显著缓解、高值区由连片集聚转为碎片化分布，远郊快速城镇化片区因建成区扩张出现局部增温，热岛重心向东北方向迁移；海绵城市建设具备显著降温净效应，高强度建设区域热岛强度较对照组平均下降0.55℃，且存在显著空间异质性，主城区降温效果优于郊区；不透水面、建成区占比为核心增温因子，绿地、水域等蓝绿基础设施为关键降温因子，连片化绿地降温边际效应最优。研究可为长沙市海绵城市优化建设、热岛效应精准治理提供科学支撑，也为同类城市生态热环境调控提供参考。

Abstract: The surface hardening issue induced by rapid urbanization has exacerbated the urban heat island (UHI) effect, severely undermining urban ecological livability. Sponge city initiatives can regulate thermal environments by optimizing urban underlying surfaces; however, existing studies lack systematic quantitative dissection of their net policy effects and nonlinear driving mechanisms. Taking Changsha as the research object, this study constructs an integrated analytical framework of DID-SHAP + LightGBM, leveraging remote sensing images from 2022 and 2025 as well as sponge city construction data, to systematically explore the spatiotemporal regulation mechanisms of sponge city construction on the UHI effect. The results indicate that: (1) The UHI effect in Changsha exhibits a strong spatial agglomeration characteristic. From 2022 to 2025, the UHI intensity was significantly alleviated in the main urban area, while localized warming emerged in rapidly urbanizing suburban areas, with high-value zones transforming from contiguous clusters to fragmented distributions, and the UHI centroid migrating northeastward. (2) Sponge city construction demonstrates a significant net cooling effect: the UHI intensity in high-intensity construction areas decreased by an average of 0.55˚C compared to the control group, with notable spatial heterogeneity—cooling effects in the main urban area outperformed those in suburban regions. (3) Impervious surfaces and the proportion of built-up areas are core warming factors, while blue-green infrastructure such as green spaces and water bodies are key cooling factors; contiguous green spaces exhibit the optimal marginal cooling effect. This study provides scientific support for the optimized construction of sponge cities and precise governance of the UHI effect in Changsha, and also offers a reference for ecological thermal environment regulation in similar cities.