多情景洪水灾害对城市道路拓扑特征影响研究——以武汉市中心城区为例

Urban road network topological characterization of multi-scenario flooding impacts:A case study of Wuhan Metropolitan Region

以武汉市中心城区为研究区构建道路拓扑网络,通过水文过程模拟获取积水地图、通勤出行模拟获取道路车流量,选取3种中心性指标表征多降雨重现期下道路网络拓扑特征,通过描述性统计、分布规律拟合及空间可视化等方法分析道路网络拓扑特征变化规律。结果发现:①洪水事件对城市道路网络拓扑特征影响显著,50年一遇情景下,道路网络节点与连边数量分别减少20.29%和37.04%,超过80%的节点或连边的中心性指标值发生变化。②洪水情景下道路网络中介中心性最大值及99%分位数有所提高、邻近中心性值有所下降,表明洪水事件使关键节点或连边在道路网络中的影响更加凸显,但节点或连边之间的联通程度受到破坏;中心性累积分布函数的尾部分布也证实了这一结论。③中心城区内关键道路及节点的分布随洪水强度增大呈现出向城市内部收缩的态势,具体表现为由城市二环线附近转移至一环线内沿江大道区域。在未来灾害管理和城市规划过程中,应当重视对核心区域道路疏通管控工作,防止拥堵现象发生;同时,加强外围区域道路建设、提高道路排水性能及路网连通性也是降低洪涝灾害对城市道路网络影响的关键。

The article bases on the method of network topology to explore the impact of multi-scenario flood events on the road network from the perspective of commuting with the central urban area of Wuhan as the study area.Firstly,we used flood hydrological simulation to obtain the flood map and reconstructed the road network under different scenarios initially.Then,we obtained road traffic volumes by commuter travel simulation based on Baidu traffic big data.The traffic volume was supplemented as a road attribute to complete the road network reconstruction.Finally,three centrality indicators were calculated under multi-scenario flood events to show the impact of flooding hazards on the topological characteristics of the urban road network by statistical and spatial analyses.The results showed:1)Flood events change the characteristics and patterns of urban road network.Under the 50-year-flood scenario,the number of network nodes and links decrease by 20.29%and 37.04%,respectively,and the centrality values of more than 80%of nodes or links have changed.2)When the flood occurs,the maximum and 99%quantile value of betweenness centrality increase while the closeness centrality decrease,indicating that the occurrence of flood makes the impact of key nodes or edges in the road network more prominent but the connectivity between nodes or edges worse.The conclusion is also confirmed by the tail distribution of the centrality cumulative distribution function.3)Key edges and nodes'locations shift with the occurrence of flood events and shrink towards the central city area with increasing flood intensity.Specifically,it is transferred from the Second Ring Road of Wuhan to the Yanjiang Avenue within the First Ring Road.The findings of the study are important references for identifying critical areas of urban traffic and for disaster emergency management.In flood disaster management,attention should be paid to the core areas to prevent congestion;And in urban planning,strengthening road construction in peripheral areas,improving road drainage performance and road network connectivity are the key to reduce the impact of flood disasters on urban road network.