应对暴雨洪涝灾害的平原城市生态水文调节服务供需评估——以天津市为例

Assessment of the supply-demand relationship of plain urban eco-hydrological regulation service in response to rainstorm-flood disaster:a case study of Tianjin City

生态水文调节服务是生态系统服务的重要组成,能够有效调节地表径流,缓解暴雨洪涝灾害。但由于城市建设扩张、生态环境退化、极端降雨频发等因素,导致生态水文调节服务出现供需失衡。平原城市中地形水动力较弱及城市发展需求高的特征更是加剧了这种现象。基于生态系统供需视角,以生态水文调节率表征城市生态水文调节服务的生态供给,以暴雨洪涝风险表征城市生态水文调节服务的社会需求,构建应对暴雨洪涝灾害的平原城市生态水文调节服务供需研究框架。以典型平原城市天津市为例,应用SWAT模型、随机森林模型和ArcGIS定量测度城市生态水文调节服务供需水平,划分四种供需空间匹配类型,识别供需失衡关键区域,并进行五级规划干预等级分区。结果表明:(1)供给能力呈现“东南沿海高,西北近山低”的空间分布;需求水平表现出“多中心聚集,圈层向外递减”的分布规律。(2)供需空间分布呈现正相关关系,低供-低需在四种供需匹配类型中占据主导,同时空间聚集性最明显。(3)规划干预分区存在明显的空间差异,优先干预区占比5.41%,整体与建成区分布一致,大部分集中在市内六区,其次分布在滨海新区核心区,是未来规划治理的重点。研究结果为城市规划管理从生态水文调节服务供需视角防控平原城市暴雨洪涝灾害提供科学依据。

Eco-hydrological regulation service is an important component of ecosystem services,which can effectively regulate surface runoff and alleviate rainstorm-flood disasters.However,due to the expansion of urban construction,the degradation of the ecological environment,and the frequent occurrence of extreme precipitation,the spatial imbalance between the supply and demand of eco-hydrological regulation services has emerged.This phenomenon was exacerbated by the weak terrain hydrodynamic force and high demand for urban development in plain cities.In this study,from the perspective of the supply and demand of ecosystem services,we used the runoff regulation capacity to characterize the supply level of eco-hydrological regulation services and expressed the demand level of eco-hydrological regulation services by the risk of rainstorm-flood disasters,to construct a research framework on the supply and demand of eco-hydrological regulation services in plain cities.Therefore,we took Tianjin as an example to evaluate the supply and demand level and their spatial distribution characteristics of eco-hydrological regulation services based on the SWAT model,random forest model,and ArcGIS platform,and then we used the matching degree of supply and demand to divide the research unit into four types.Finally,we used the priority index to divide these areas into five planning intervention priorities.The results showed that:(1)the supply capacity exhibited a feature that the distribution was high in the southeast coastal area and low in the northwest mountainous area.The distribution of demand levels presented a multicenter aggregation and gradually decreases from the center to the outside.(2)There was a positive correlation between supply and demand spatial distributions.Low supply-low demand dominated four types of supply and demand matching,which had the most obviously spatial aggregation.(3)There were obviously spatial variations in planning intervention zones.The priority intervention area was consistent with the urban built-up area distribution,accounting for 5.41%of all the planning intervention zones.Such areas were mainly concentrated in the central city,followed by the core area of Tianjin Binhai New Area,which was the focus of future planning and governance.The results provided a scientific basis for urban planning management to prevent and control rainstorm-flood disasters in plain cities according to the supply-demand relationship of the eco-hydrological regulation service theory.