城市内涝的空间分布规律及其与绿地格局的关系

Spatial Distribution Characteristics of Urban Flooding and its Relationship with Green Space Pattern

气候变化和快速城镇化的影响下,城市内涝频发,由于各大城市中心城区开发强度高,不透水面积比重大,地下管网复杂,正在面临严峻的雨洪问题,需要充分挖掘内涝分布特征和规律,以新的视角和思路寻找有利于缓解内涝的途径。绿地作为透水面,可下渗和存蓄雨水,并协助分担管网的排水压力,而中心城区绿地面积有限,需通过优化其分布格局来提高缓解内涝的能力。本文选取内涝问题相对严重的八个城市为研究对象,用积水点数据分析内涝分布特征,通过聚合度(AI)、连接度(CONNECT)等9个景观格局指数来反映绿地分布格局,运用ArcGIS的空间分析方法,Fragstats移动窗口法,统计学分析方法,探究更有利于缓解内涝的绿地格局。结果表明:城市积水点呈聚集分布,且集中分布在主城区内;积水多发生在道路沿线,并且未能排入两侧绿地内;绿地斑块密度和连接度指数的增加有助于其更好地发挥调蓄雨洪的作用。

Under the influence of climate change and rapid urbanization,urban flooding occurs frequently,which has attracted widespread attention from various countries.Two-thirds of China’s land ares are influenced by different types and degrees of urban flooding disasters,and it is one of the countries with the most serious urban flooding issues in the world.Due to the high development intensity of the central urban areas of major cities,the large proportion of impervious area,and the intricate underground pipe network,cities are facing severe stormwater problems.And it is necessary to fully explore the formation process,distribution characteristics and laws of urban flooding,and find ways to alleviate urban flooding from new perspectives and ideas.As a permeable surface,green space plays the role of rainwater infiltration and can help share the drainage pressure of the pipe network.While the green space in the central urban area is limited,its distribution pattern needs to be optimized to improve the ability to alleviate urban flooding.The spatial distribution of urban flooding is closely linked to the pattern of green space,and due to the particularity of scale and region.The current research objects are mostly solitary city,and there is a lack of comprehensive comparison of multiple cities,and the study cases have certain limitations.In order to enrich the research on the relationship between the overall urban flooding characteristics of the city and the overall green space pattern,big data technology was applied to obtain multiple urban flooding points and green space data,the spatial distribution characteristics of urban flooding was analyzed,and the impact of green space pattern on urban flooding mitigation was illustrated,and the green space pattern model that can alleviate urban flooding better according to local conditions was explored in this paper.In this research,eight cities(Beijing,Shanghai,Guangzhou,Shenzhen,Tianjin,Nanjing,Wuhan and Xi’an)with relatively serious urban f looding problems in China are selected as the study cases,and the distribution characteristics of urban flooding are analyzed by the distribution characteristics of urban flooding points,and the distribution pattern of green space is reflected by nine landscape pattern indexes such as aggregation index(AI)and connectivity(CONNECT),and the spatial analysis method of ArcGIS is used to study the characteristics of urban flooding,including the quantity,location and severity of urban flooding points,so as to reflect the urban flooding situation.Fragstats software and mobile window tool were used to calculate the green landscape pattern index of each city’s study area,so as to reflect the spatial characteristics of green space distribution.SPSS was utilized to analyze relevant data to study the relationship between urban flooding and green space pattern,and explore the green space pattern that is more conducive to alleviating urban flooding.The results show that the urban flooding points in the city are distributed in clusters,and most of the urban flooding points appear in main city areas other than natural depressions,and the data show that the urban flooding points along roads,overpasses,tunnels and road intersections account for more than 90%,and it is difficult to discharge urban flooding water into the green space on both sides.Combined with the green space pattern index,from the two forms of moving window and to overall index,it can be seen that the increase of green patch density and connectivity index can help reduce the possibility of urban flooding events,and the change of green patch density has a greater impact on stormwater regulation and storage.Therefore,in the case of the same area,the number and density of green space patches should be increased as much as possible,and the connection of green space can be improved by reorganizing and connecting the existing green space,so as to improve the role of green space in stormwater control and storage.In addition,based on the comparison results of the above macro data,the environmental characteristics such as urban green space pattern,urban location and geographical conditions,and road network are analyzed,and similar environmental optimization ideas are summarized for urban flooding problems under similar“urban scenarios”based on literature support.In future research,more urban stormwater data can be obtained,and appropriate landscape pattern indexes can be selected according to separate research scales and environmental characteristics,so as to improve the research on the relationship between urban flooding characteristics and urban green space.At the same time,efforts should be made to consider green infrastructure and gray infrastructure in an integrated manner and cooperate with each other to better achieve the goal of alleviating urban flooding.