基于小尺度的城市暴雨内涝灾害情景模拟与风险评估

Small-scale Based Scenario Modeling and Disaster Risk Assessment of Urban Rainstorm Water-logging

自然灾害情景模拟与风险评估是灾害研究的核心内容和热点问题之一,但城市自然灾害风险评估至今却缺乏统一的程序与范式。本文选择了城市频发的暴雨内涝灾害为研究对象,结合上海市静安区实证研究,提出了一套基于小尺度的城市暴雨内涝灾害风险评估的思路与方法。基于灾害风险的基本理念,从致灾因子分析、脆弱性分析和暴露分析三方面入手,探讨不同情景下的小尺度城市暴雨内涝灾害情景模拟与风险表达方式;提出了小尺度城市暴雨内涝灾害风险评估宜采用情景模拟和综合分析方法,充分考虑城市的内部地形特征、降水、径流和排水等因素,创建一个基于GIS栅格的城市内涝模型,并基于多种重现期灾害情景,更客观地模拟内涝积水深度和淹没面积;采用多次实地调查获得的内涝损失数据,拟合出居民房屋和室内财产的灾损曲线;利用灾损曲线评估脆弱性、暴露要素和损失,建立超越概率-损失曲线,创建了基于GIS栅格城市暴雨内涝灾害的风险评估模型与范式,为制订城市暴雨内涝灾害风险管理和规划奠定了基础。这亦为进一步开展小尺度城市自然灾害情景模拟和风险评估研究提供了一种新探索。

Scenario modeling and risk assessment of natural disaster is one of the hotspots of disaster research. However, urban natural disaster risk assessment, so far, is lack of common procedures and program. This paper selects rainstorm water-logging as research disaster, which is one of the most frequent occurring hazards in most cities of China, and sets up a small-scale based integrated methodology for hazards risk assessment of rainstorm water-logging, taking Jing＇an District in Shanghai as an example. Based on the basic concept of disaster risk, this paper applies scenario modeling to express the risk of the small-scale urban rainstorm water-logging disasters in different return periods. Through the analysis of hazards, vulnerability and exposure, we simulate different disaster scenarios and propose a comprehensive analysis method and procedure for the small-scale urban storm water-logging disaster risk assessment. A grid-based GIS approach, including urban terrain model, urban rainfall model, urban rainfall model and urban drainage model, was applied to simulate inundation area and depth. And then, stage-damage curves for residential buildings and contents were generated by the loss data of water-logging from the field surveys and the insurance company, which were further applied to analyze the vulnerability, exposure and loss assessment. Finally, the exceedance probability curve for disaster damage was constructed by using the damages of each simulated event and its respective exceedance probabilities. A framework was also developed for coupling the water-logging risk with the risk planning and management through exceedance probability curve and annual average of water-logging loss. And this is a new exploration for small-scale urban natural disaster scenario simulation and risk assessment.