Urban pluvial flood scenario modeling and emergency response assessment using high resolution Lidar-DSM
YINJie收稿日期:2017-01-21
修回日期:2017-04-11
网络出版日期:2017-06-30
版权声明:2017《地理研究》编辑部《地理研究》编辑部
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1 引言
随着全球气候变化和快速城市化影响,城市暴雨洪涝事件频发,且呈现不断加剧的趋势。根据国际政府间气候变化组织（IPCC）评估报告显示,由于全球变暖和大气水汽增加,1900年以来观测降水具有明显增强趋势,强降水事件数量增多,未来降水发生频率和强度很可能还会持续上升,降水更趋于集中,尤其在中纬度地区洪涝风险将显著增大[1-3]。城市作为气候变化的敏感响应区域,持续高强度的人类活动导致河道不断减少、不透水面积增大,加之相对滞后的排水系统建设,大大削弱了城市自身调节和应对突发暴雨洪涝的能力[4]。北京、上海、广州、深圳、南京、杭州等中国主要城市每遇暴雨,即开启“看海模式”,造成了极为严重的灾害直接损失（人员伤亡与财产损失）和间接影响（基础设施破坏与公共服务中断）[5,6]。例如,2005年8月6日,台风“麦莎”带来的大暴雨造成上海市区200余条道路积水,直接经济损失13.6亿元;2012年7月21日北京暴雨洪涝灾害造成79人死亡,直接经济损失116.4亿元,城市交通大范围瘫痪。2015年,国务院办公厅出台的“关于推进海绵城市建设的指导意见”中明确要求综合采取“渗、滞、蓄、净、用、排”等措施,最大限度地减少城市开发建设对生态环境的影响,将70%的降雨就地消纳和利用,以增强城市防涝能力。因此,城市暴雨洪涝灾害防治已成为当前面临的重大科学问题与国家需求。近几十年来,城市暴雨洪涝灾害研究的热点主要集中在机理分析、数值模拟、预报预警、应急响应、损失评估以及风险管理等方面[7-10]。城市雨洪灾害的发生往往具有显著的突发性和短历时性,高效地应急响应可以显著降低洪涝灾害的损失和影响。因此,相对于其他研究方向,城市雨洪灾害的应急响应研究就显得尤为重要。目前,洪涝应急响应的研究多侧重于理论探讨和预案（规划）编制[11,12],少量的工作关注于受洪涝影响的路网节点或路段所引发的道路交通服务能力中断、可达性损失及应急疏散（路径优化）等方面[13-16],但是直接将洪涝淹没模拟（或预报）结果应用于城市关键基础设施（如交通、电力、通讯、给排水系统等）并评估（医疗、公安、消防、救援和抢险等）应急服务能力的研究案例还不多见,缺乏代表性研究范式和实证研究案例,难以满足城市暴雨洪涝灾害应急管理与可持续发展的需求。近十余年来,随着对城市下垫面及水文气象的观测、模拟、预报技术方法的不断发展,城市暴雨洪涝模拟与预报精度不断提升,也使得城市雨洪应急响应能力的精细化评价成为可能。本文拟通过聚焦暴雨洪涝灾害频发的典型城市中心区（上海市南京东路中央商务区）,开展暴雨洪涝灾害情景模拟与公共服务应急响应研究,以丰富、充实和发展城市尺度的暴雨洪涝应急响应评估理论和方法体系,其研究成果可为地方城市政府开展暴雨洪涝灾害的应急管理和决策提供重要的科学依据。
2 研究方法与数据来源
2.1 研究区概况
南京东路中央商务区（CBD）地处上海市黄浦区北部,北起苏州河,东临黄浦江,西至南北高架,东到延安高架,总面积约3.25 km2,是上海的政治、经济和文化中心区（图1）。该区域属于北亚热带季风气候,年均降水量超过1100 mm,每年汛期（6-9月）各种灾害性（强对流和台风）降水事件时有发生[17]。由于长期过度抽取地下水和大量高层建筑的压实作用,上海中心城区地面严重沉降（最大超过3 m）[18],导致研究区内地势低洼,平均高程仅3 m左右（吴淞高程）。
显示原图|下载原图ZIP|生成PPT图1研究区示意图
-->Fig. 1Location of the study area
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历史上,上海市中心城区暴雨洪涝灾害频发,据不完全统计,自251年至2000年,共发生雨洪事件272次,占全部洪涝灾害的54%[19]。为应对城市内涝顽疾,建国以来上海市不断改造和扩建城市排水系统,在中心城区形成了由排水管网和泵站组成的强排水系统。目前,南京东路周边大部分商务区排水能力为三年一遇（49.6 mm/h）水平,其他区域为一年一遇（36 mm/h）水平（图1）。长期的高强度人类活动使得该区域具有典型的城市景观格局与下垫面特征：自然河道几近消失,人口、建筑与路网密集,以及大面积的不透水地表[20,21]。
2.2 数据来源
数据主要包括降水数据、地形数据、路网数据和应急公共服务部门数据等。降水情景采用上海市暴雨强度公式计算得到的一年一遇（36 mm/h）、十年一遇（67 mm/h）和百年一遇（101 mm/h）小时降水量[22],不考虑降水空间变化,降水时间分布设置采用芝加哥雨型公式,雨峰系数r设置为0.4,时间间隔为1 min[23]。地形数据采用上海市测绘院提供的2006年中心城区航测激光雷达高程点云数据（约0.6 m水平分辨率,0.1~0.2 m垂直分辨率）,利用TerraSolid软件对原始数据进行质量控制和分层处理,去除行道树等地形干扰物,生成2 m分辨率的研究区高精度地形表面模型（DSM）[24]。路网数据采用华东师范大学地理信息科学教育部重点实验室提供的道路中心线GIS图层,并进行人工纠正以准确匹配研究区Lidar-DSM,包括主干道、次干道和支路共60余条,共计43.2 km。城市主要公共服务部门位置信息提取自交通导航数据库,本文选择医疗卫生（120急救）和公共安全（110出警）两类城市最为关键的公共服务应急响应类型,研究区内共有5所二级以上公立医疗机构和6个派出所以上级别的公安机关,不包括社区卫生站和社区警务室等不具备应急响应能力的基层单位（图1）。2.3 研究方法
2.3.1 城市洪涝模拟 城市暴雨洪涝模拟采用最新开发的基于栅格的高精度水文—水动力数值模型（FloodMap-HydroInundation2D）,该模型是在二维水动力模型（FloodMap）的基础上[25-28],耦合了城市水文过程（蒸发、下渗和排水等）模块,可被用于城市雨洪过程模拟研究。其中,下渗过程通过被广泛应用的Green-Ampt方程计算,蒸发量的估算基于前人研究的经验性正弦曲线公式（约3 mm/天）[29]。城市排水过程的模拟基于实际管网设计排水能力,将小时排水量线性分解到每个时间步长来计算。地表洪涝过程模拟基于圣维南方程描述浅水波非恒定流,采用与LISFLOOD-FP相似的模型结构[30],但使用不同的方法计算时间步长,虽然简化了水流的动能条件,但是其建模更为简单、运算效率更高且结果精度也较高。具体模型结构及其推导过程已在前期研究中列出[27],该模型在规则网格上的主要控制方程表达如下：式中：qt+△t为在时间t+△t的流量;qt为在时间t的流量;g为重力加速度;ht为在时间t的水深;z为栅格底部高程;n为曼宁系数（本文采用前期研究中率定的经验值0.06）。整个模拟时间设置为4个小时,以使洪涝过程达到稳定状态。基于上海市中心城区2011年8月12日发生的暴雨洪涝事件,对所构建的城市雨洪模型进行了验证和率定,所获取的经验参数用于本文的模拟研究工作[24]。
2.3.2 应急响应分析 在暴雨洪涝情景下,突发的公共安全和人员急救等事件需要城市应急响应部门在最短时间内（城市中心区一般要求5~10 min以内）到达事发地点处理和救助。因此,评估城市公共服务（110出警和120急救）应急响应能力的关键指标主要是基于路网的空间可达性及其服务范围。采用基于GIS的最快路径方法（两点之间的最短时间）,相对于传统的最短路径方法（两点之间的最短距离）,最快路径方法的优势在于可同时考虑出行的时间和距离成本[31]。分别以前述两类公共服务机构的位置作为起始点,参考《中华人民共和国公路工程技术标准（JTGB01-2003）》,结合城市中心区实际情况及暴雨洪涝影响,行车速度设置为：主干道30 km/h,次干道20 km/h,支路10 km/h,其他区域1 km/h（极缓慢步行）。
暴雨洪涝导致的路面积水是影响城市交通和应急响应能力的主要因素,也是本研究中需要界定的关键约束指标。通常车辆在道路积水超过15 cm时,应避免通行以防出现车辆损坏。而当积水达到25~35 cm（车辆排气口高度）时,大部分车辆可能出现熄火并导致人身安全事故,因此很多城市政府交通管理部门也将该积水阈值作为城市道路封闭的标准。考虑到部分应急车辆具有较好的涉水性能,且在紧急状况下应急响应车辆可不受城市道路交通规则（如单行、转向、红绿灯等）及封路的约束,因此本文将可通行的积水深度上限分别设置为30 cm（一般车辆）和50 cm（大中型或越野车辆）。将积水深度超过阈值标准的洪涝模拟结果和研究区路网进行叠置,得到各暴雨洪涝情景下可通行路段以评估城市的应急响应能力。
3 结果分析
3.1 道路积水分析
研究区暴雨洪涝情景模拟结果（最大淹没深度和范围）如图2所示,由于排水标准普遍超过一年一遇水平,因此仅有十年一遇和百年一遇降水出现内涝影响。城市道路路面高程普遍低于两侧地面,降水主要通过道路汇流,积水也大多集中在城市路网中。十年一遇降水情景下,研究区（尤其是CBD）大部分道路积水低于30 cm,主要公共服务部门周边道路也大多处于可缓慢通行状态,仅地势低洼的江西中路、广东路和四川中路交叉路口等部分路段出现50 cm以上积水,可能会严重影响附近的黄浦区中心医院的应急响应服务能力。百年一遇降水情景下,由于降水强度远超排水能力,大部分路网受淹严重,可通行路段急剧减少,主要公共服务部门周边道路几乎全部不能通行,整个路网面临瘫痪,而黄浦区中心医院附近路段大部分积水深度甚至超过80 cm,属于区域内重点易涝地段。
显示原图|下载原图ZIP|生成PPT图2研究区暴雨洪涝情景最大淹没模拟结果图
-->Fig. 2Maximum pluvial flood inundation maps under different rainfall scenarios
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3.2 应急响应能力评价
在正常条件（或一年一遇降水情景）下,假设城市路网完全畅通（没有积水）,研究区具有良好的应急响应能力。公安和医疗服务（10 min以内）的应急响应几乎可以覆盖整个研究区（99%以上）范围,其中120急救车辆可以在5 min以内到达82%的区域,公安110出警可以到达87%的区域。CBD区域由于路网密集且公共服务机构分布较多,可达性较高,可以获得更为快捷的公共应急响应服务。相对而言,研究区西南部由于公共开放空间（人民广场、公园绿地等）面积较大、路网稀疏,城市应急响应能力较弱,个别区域需要12~13 min才能到达（图3）。
显示原图|下载原图ZIP|生成PPT图3一年一遇降水情景（正常条件）下城市应急响应可达性与服务范围
-->Fig. 3Urban emergency service areas under 1 year rainfall scenario or normal conditions
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当暴雨内涝积水深度阈值为30 cm以上时,普通的公共服务车辆应急响应能力显著减弱,相对于公安机关,大部分医院的应急响应能力下降更为明显（图4）。十年一遇降水情景,10%左右的区域无法在10 min之内获得应急公共服务,公安和医院5 min以内的快速响应能力所覆盖的区域面积比例分别减少到59%和42%,个别医院（如东南部的黄浦区中心医院）的应急响应能力几乎丧失。百年一遇降水情景下,整个路网（除局部路段外）几近失去通行条件,应急响应车辆无法在10 min之内到达一半以上区域,仅不到20%的区域（大多位于医院和公安机关周边）可以得到5 min以内的快速应急响应公共服务。
显示原图|下载原图ZIP|生成PPT图4研究区暴雨洪涝情景（30 cm积水阈值）应急响应可达性与服务范围
-->Fig. 4Urban emergency service areas under pluvial flood scenarios with water depth higher than 30 cm
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当暴雨内涝积水深度阈值为50 cm以上时,涉水性能较好的大中型应急响应车辆仍可以维持较好的通行能力,其应急响应范围也较30 cm积水阈值情景明显增大（图5）。十年一遇降水情景下,公安和医院大型车辆的应急响应能力接近正常状态（无降水或一年一遇降水）水平,可在5 min之内快速到达近80%的区域,仅2%的区域无法在10 min之内获得应急响应公共服务。百年一遇降水情景下,公安和医院大中型应急车辆5 min以内的快速响应能力所覆盖的范围分别占63%和44%,约7%的区域无法在10 min之内获得应急公共服务。由于研究区内医院数量相对较少,且临近医院的路段大多积水较深,通行能力受阻,因此医疗急救的应急服务水平总体较公共安全的应急响应能力弱。
显示原图|下载原图ZIP|生成PPT图5研究区暴雨洪涝情景（50 cm积水阈值）应急响应可达性与服务范围
-->Fig. 5Urban emergency service areas under pluvial flood scenarios with water depth higher than 50 cm
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4 结论与讨论
利用城市水文—水动力模型和GIS空间分析方法评估了不同暴雨洪涝情景下上海中心城区关键公共服务（医疗和公安）的应急响应能力,为城市暴雨洪涝灾害的应急响应能力评估提供了可供参考的研究范式与典型案例。结果表明：① 正常状态（无降水或一年一遇降水情景）下,公安和医疗服务（10 min以内）的应急响应可以覆盖99%以上研究区范围,其中120急救车辆可以在5 min以内到达82%的区域,公安110出警可以到达87%的区域;② 十年一遇降水情景下,大部分路网仍可以维持可通行状态,城市应急响应可以覆盖90%以上的区域,涉水性能较好的大中型应急响应车辆的服务能力接近正常（无降水）水平;③ 百年一遇降水情景下,由于降水强度远远超出排水能力,绝大部分道路受淹严重,30 cm积水阈值可使超过一半以上区域无法在10 min内获得应急公共服务,50 cm积水条件下城市应急响应区域显著增大（约93%）。鉴于短历时极端降水对城市应急响应能力的显著影响,城市公共应急管理措施需重点应对远超城市排水能力的高重现期（如百年一遇）暴雨事件及重点低洼易涝区域,以保证主要路网的可通行性及区域应急服务的可达性。首先,对城市重点（低洼）易涝区域（如江西中路、广东路和四川中路交叉路口）应改造和扩建现有排水管网,使其实际排水能力达到5年一遇甚至更高标准。其次,利用并改造低洼区域周边部分地下空间作为临时蓄水设施,可有效缓解重点易涝区域的路面积水问题,维持道路处于可通行状态。最后,医疗和公安等城市应急公共服务部门应改装或配备进排气口高、涉（防）水性能好的特种车辆,可以保证在积水较深的路段通行并完成应急响应任务。此外,城市应急响应还可结合雷达降水短临预报和高精度雨洪数值预报,在可能发生严重积水的路段提前1~2小时设置临时抽排水设施等应对措施,以保障城市交通和应急公共服务。
城市暴雨洪涝过程受自然和人文等多重变异因素制约,具有较高的复杂性与不确定性。为不断提高城市洪灾的应急响应能力和管理水平,未来的研究工作可在以下方面进一步深化与扩展：① 暴雨洪涝情景下城市应急公共服务设施的空间布局优化;② 时间序列上城市应急响应（可达性）随积水深度变化的动态演变;③ 排水管网模型与地表水文—水动力模型的耦合模拟;④ 不同类型暴雨洪涝过程（台风降雨、强对流降水等）对城市应急公共服务的影响分析;⑤ 将道路网络交通流的多时段（早晚高峰、平时周末等）模拟纳入应急响应分析;⑥ 开展更大范围（整个市域）和不同类型城市案例研究以形成系统的应急响应评价理论与方法体系。
The authors have declared that no competing interests exist.
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| [5] | . 随着全球气候变暖，洪涝灾害愈加频繁，灾害风险监测预警评估作为防灾减灾的重要基础成为当前灾害学研究的核心内容之一。本文在总结国内外灾害研究和应用的基础上，阐述了洪涝灾害风险监测预警评估的概念、 内容、评估的基本思路和监测预警的技术方法。本文提出：①应结合中国实际，加强洪涝灾害的基础研究，深入机理层面探索洪涝灾害的孕育、发生机制，以及减少洪涝危险性和承灾体脆弱性分析的不确定性。②以研究技术手段的进步促进洪涝灾害风险监测预警评估的发展，改进传感器性能，提高监测精度；综合多源遥感和各种基础数据；进一步发展“3S”集成技术。 . 随着全球气候变暖，洪涝灾害愈加频繁，灾害风险监测预警评估作为防灾减灾的重要基础成为当前灾害学研究的核心内容之一。本文在总结国内外灾害研究和应用的基础上，阐述了洪涝灾害风险监测预警评估的概念、 内容、评估的基本思路和监测预警的技术方法。本文提出：①应结合中国实际，加强洪涝灾害的基础研究，深入机理层面探索洪涝灾害的孕育、发生机制，以及减少洪涝危险性和承灾体脆弱性分析的不确定性。②以研究技术手段的进步促进洪涝灾害风险监测预警评估的发展，改进传感器性能，提高监测精度；综合多源遥感和各种基础数据；进一步发展“3S”集成技术。 |
| [6] | . 暴雨内涝是城市自然灾害的主要形式之一,并长期困扰我国的许多城市。依据城市化进程及排水系统的发展趋势,揭示了我国城市暴雨内涝防治的误区,全面剖析了暴雨内涝的成因。结果表明：排水系统设计标准低下是我国城市暴雨内涝的一个重要的、但非唯一的成因;仅通过提高设计标准防治暴雨内涝投资巨大、实施困难,且成效不大。我国城市暴雨内涝的成因还包括城市下垫面不透水比例增加、暴雨洪峰流量增大、排水系统雨污混接现象普遍存在、地面沉降日趋严重、相关部门与专业缺乏沟通与合作等。基于发达国家城市暴雨管理的研究成果和实践经验,结合我国城市排水系统的实际情况,提出了暴雨内涝防治的应对策略,以促进城市暴雨管理体系的建立和完善。 . 暴雨内涝是城市自然灾害的主要形式之一,并长期困扰我国的许多城市。依据城市化进程及排水系统的发展趋势,揭示了我国城市暴雨内涝防治的误区,全面剖析了暴雨内涝的成因。结果表明：排水系统设计标准低下是我国城市暴雨内涝的一个重要的、但非唯一的成因;仅通过提高设计标准防治暴雨内涝投资巨大、实施困难,且成效不大。我国城市暴雨内涝的成因还包括城市下垫面不透水比例增加、暴雨洪峰流量增大、排水系统雨污混接现象普遍存在、地面沉降日趋严重、相关部门与专业缺乏沟通与合作等。基于发达国家城市暴雨管理的研究成果和实践经验,结合我国城市排水系统的实际情况,提出了暴雨内涝防治的应对策略,以促进城市暴雨管理体系的建立和完善。 |
| [7] | . 为了寻求新常态下城市防洪减灾的有效对策，通过实地调研、资料分 析与国内外的比较研究，探讨了我国城市洪涝损失激增的成因，分析了风险的演变倾向与重要特征。结果表明，2006年以来，我国每年受淹城市都在百座以上， 年洪涝直接经济总损失与受淹城市数量呈明显正相关，洪涝损失构成已发生显著变化；1998年我国人口城镇化率突破30%以来，城镇化进程规模空前，目前虽 已过了最为迅猛的状态，但仍处于中高速发展阶段，城镇化加剧洪涝风险的压力仍将持续增大；现代城市洪涝损失的连锁性与突变性日趋凸显，亟待基于风险评估建 立更为完善的应急响应机制；随着城市人口增长、规模扩张，安全保障要求显著提高，但防洪治涝基础设施建设欠账太多，达标城市数不增反降。为此必须因地制 宜，基于风险评估从流域、城市、社区等不同尺度上选择与发展阶段相适宜的减灾策略。 . 为了寻求新常态下城市防洪减灾的有效对策，通过实地调研、资料分 析与国内外的比较研究，探讨了我国城市洪涝损失激增的成因，分析了风险的演变倾向与重要特征。结果表明，2006年以来，我国每年受淹城市都在百座以上， 年洪涝直接经济总损失与受淹城市数量呈明显正相关，洪涝损失构成已发生显著变化；1998年我国人口城镇化率突破30%以来，城镇化进程规模空前，目前虽 已过了最为迅猛的状态，但仍处于中高速发展阶段，城镇化加剧洪涝风险的压力仍将持续增大；现代城市洪涝损失的连锁性与突变性日趋凸显，亟待基于风险评估建 立更为完善的应急响应机制；随着城市人口增长、规模扩张，安全保障要求显著提高，但防洪治涝基础设施建设欠账太多，达标城市数不增反降。为此必须因地制 宜，基于风险评估从流域、城市、社区等不同尺度上选择与发展阶段相适宜的减灾策略。 |
| [8] | . 智慧城市是城市发展的新兴模式。然而,近年来频发的城市洪涝给智慧城市的管理和发展带来了严峻的挑战。暴雨洪涝模拟是城市防洪减灾的关键技术之一,也是智慧城市风险应急管理中重要的决策支持依据。本文首先分析了智慧城市以及智慧水务的内涵,探讨了智慧城市发展和管理对于城市洪涝模拟新的需求;在此基础上梳理了智慧城市发展给城市洪涝模型带来的新的数据支撑;面向智慧城市应急管理决策,对比分析了3种现有的水文模型方法,认为在智慧城市大数据和技术的支持下,基于物理基础的分布式模型是未来城市洪涝模拟的主流发展方向。最后,探讨了建立城市洪涝模型的建模机制、尺度、基础数据库的建立、更新和管理、地表与地下管网模拟并重等关键问题,分析认为精细化、与RS和GIS技术融合、注重时空过程和智慧服务是智慧城市背景下城市洪涝模拟发展的必然趋势。 . 智慧城市是城市发展的新兴模式。然而,近年来频发的城市洪涝给智慧城市的管理和发展带来了严峻的挑战。暴雨洪涝模拟是城市防洪减灾的关键技术之一,也是智慧城市风险应急管理中重要的决策支持依据。本文首先分析了智慧城市以及智慧水务的内涵,探讨了智慧城市发展和管理对于城市洪涝模拟新的需求;在此基础上梳理了智慧城市发展给城市洪涝模型带来的新的数据支撑;面向智慧城市应急管理决策,对比分析了3种现有的水文模型方法,认为在智慧城市大数据和技术的支持下,基于物理基础的分布式模型是未来城市洪涝模拟的主流发展方向。最后,探讨了建立城市洪涝模型的建模机制、尺度、基础数据库的建立、更新和管理、地表与地下管网模拟并重等关键问题,分析认为精细化、与RS和GIS技术融合、注重时空过程和智慧服务是智慧城市背景下城市洪涝模拟发展的必然趋势。 |
| [9] | . China urban environments are particularly vulnerable to flooding due to climate change and rapid urbanization. Study of the urban flood risk analysis has significantly increased over the past decade, and this paper therefore reviews the main results (i.e. theoretical basis, methods, techniques, case studies) obtained in the literature from China. We focus on the following topics: (1) urban flood hazard analysis, (2) exposure and vulnerability analysis, and (3) urban flood risk assessment. Recent advances made in the research area are presented with suggestions for further research to improve the availability and reliability of urban flood risk analysis. |
| [10] | . 自然灾害是当代国际社会、学术界普遍关注的热点问题。随着自然灾害突发强度、频度和广度的不断增长,自然灾害预防工作显得格外重要。沿海城市作为人口集聚、国民经济、社会发展重要区域和战略中心,自然灾害带来的损失是剧烈、致命的,亟待开展沿海城市自然灾害风险研究。该领域目前主要探讨的问题:自然灾害类型与风险辨识;脆弱性评价指标体系与评价模型;自然灾害风险评估与风险管理;自然灾害数据管理范式研究等。沿海城市作为自然灾害频发和受损严重的地区,在全球变暖和快速城市化背景下,目前应集中开展自然灾害风险实证研究:沿海城市脆弱性评价指标体系和综合脆弱性评价方法;自然灾害风险评估程序规范和动态评估模型;自然灾害数据管理范式与模板;自然灾害风险评估GIS工具集等。 . 自然灾害是当代国际社会、学术界普遍关注的热点问题。随着自然灾害突发强度、频度和广度的不断增长,自然灾害预防工作显得格外重要。沿海城市作为人口集聚、国民经济、社会发展重要区域和战略中心,自然灾害带来的损失是剧烈、致命的,亟待开展沿海城市自然灾害风险研究。该领域目前主要探讨的问题:自然灾害类型与风险辨识;脆弱性评价指标体系与评价模型;自然灾害风险评估与风险管理;自然灾害数据管理范式研究等。沿海城市作为自然灾害频发和受损严重的地区,在全球变暖和快速城市化背景下,目前应集中开展自然灾害风险实证研究:沿海城市脆弱性评价指标体系和综合脆弱性评价方法;自然灾害风险评估程序规范和动态评估模型;自然灾害数据管理范式与模板;自然灾害风险评估GIS工具集等。 |
| [11] | . 通过采集2002年以来洪涝灾害风险应急响应的案例，梳理和分析了应急响应发展进程中存在的 问题。研究指出：（1）21世纪以来，洪涝灾害成为自然灾害中应急响应启动最频繁的灾种，逐渐进入了政府和主管部门公共管理的范畴，成为公众关注的重要行 为；（2）洪涝灾害应急管理存在上下级之间和部门之间，启动与响应两个层面管理机制不清、缺乏对应急响应全过程有效管理的问题；（3）应当从理论层面理清 应急启动与响应的功能，在管理层面逐渐形成启动与响应不同阶段，中央与地方政府、主管部门与民问统一指挥下的应急管理机制。在对问题探讨的基础上提出了应 急响应评价指标及等级划分框架的设计。 . 通过采集2002年以来洪涝灾害风险应急响应的案例，梳理和分析了应急响应发展进程中存在的 问题。研究指出：（1）21世纪以来，洪涝灾害成为自然灾害中应急响应启动最频繁的灾种，逐渐进入了政府和主管部门公共管理的范畴，成为公众关注的重要行 为；（2）洪涝灾害应急管理存在上下级之间和部门之间，启动与响应两个层面管理机制不清、缺乏对应急响应全过程有效管理的问题；（3）应当从理论层面理清 应急启动与响应的功能，在管理层面逐渐形成启动与响应不同阶段，中央与地方政府、主管部门与民问统一指挥下的应急管理机制。在对问题探讨的基础上提出了应 急响应评价指标及等级划分框架的设计。 |
| [12] | . |
| [13] | |
| [14] | . This paper aims to develop a decision-making tool that can be used by government agencies in planning for flood emergency logistics. In this article, the flood emergency logistics problem with uncertainty is formulated as two stochastic programming models that allow for the determination of a rescue resource distribution system for urban flood disasters. The decision variables include the structure of rescue organizations, locations of rescue resource storehouses, allocations of rescue resources under capacity restrictions, and distributions of rescue resources. By applying the data processing and network analysis functions of the geographic information system, flooding potential maps can estimate the possible locations of rescue demand points and the required amount of rescue equipment. The proposed models are solved using a sample average approximation scheme. Finally, a real example of planning for flood emergency logistics is presented to highlight the significance of the proposed model as well as the efficacy of the proposed solution strategy. |
| [15] | . This paper conducts an analysis to assess the significance of highway network links in Maryland under flood damage. An accessibility index is derived to incorporate the distance-decay effect and the volume of traffic influence on the transportation network. The accessibility level of individual counties and the state as a whole is checked before and after the hypothetical disruption of individual links within the floodplain. The results indicate that critical links identified based on the distance-only and the distance-traffic volume criteria appear to be different, implying that the priority of retrofit might also vary depending on what criterion to choose. The percentage loss of accessibility due to the disruption of a link is generally greater in the latter. However, distance-only consideration results in a more prominent spatial distribution pattern of links in percentage loss induced. Some links remain significant in both cases. Especially if the disruption of a certain link does not have an alternative solution (for example, if the link is the only way in and out of a certain county) and if counties connected by the link are low accessibility counties, the two criteria may produce a similar outcome. |
| [16] | . 为有助于有关部门更准确预测洪 涝灾害受灾民众的疏散量,结合非集计数据和集计数据的优点,提出分区集计数据的概念,设计了受灾区域分区方法,并通过意向偏好(SP)调查法对我国居民在 洪涝条件下疏散交通需求数据进行调查。在此基础上,引入BP神经网络建立基于分区集计数据的疏散交通生成预测模型。利用调查数据进行实证分析发现,所设计 方法取得了较好的预测效果,鲁棒性较好,平均相对预测误差仅为1.8%,其预测效果明显优于现有的非集计和整集计模型。 . 为有助于有关部门更准确预测洪 涝灾害受灾民众的疏散量,结合非集计数据和集计数据的优点,提出分区集计数据的概念,设计了受灾区域分区方法,并通过意向偏好(SP)调查法对我国居民在 洪涝条件下疏散交通需求数据进行调查。在此基础上,引入BP神经网络建立基于分区集计数据的疏散交通生成预测模型。利用调查数据进行实证分析发现,所设计 方法取得了较好的预测效果,鲁棒性较好,平均相对预测误差仅为1.8%,其预测效果明显优于现有的非集计和整集计模型。 |
| [17] | . The Shanghai metropolitan area is physically and socio-economically vulnerable to extreme precipitation events and associated flooding due to its location on the Yangtze estuary, low topography and high density of human activity. This paper presents a statistical analysis for the threshold of daily precipitation extremes at the city scale using percentile indices, probability distribution and detrended fluctuation analysis (DFA). A comparison of the statistical results with consideration of local impact factors suggests that the threshold of daily precipitation extremes over Shanghai increases from 7002mm in the western region to 8002mm in the city centre and then decreases to 7502mm in coastal areas. Finally, further suggestions are presented for decision makers, researchers and other concerned stakeholders to give a more complete picture of urban climatic extremes. |
| [18] | . 地面沉降导致上海地面高程损失,并降低防汛工程设防能 力.1921～2007年地面平均沉降1.973 m,最大沉降3.035 m,市区普遍低于江河高潮位.地面沉降在中心城区外滩黄浦江防汛墙四次加高改建中分别占增高幅度的98.O%,62.6%,30.1%,7.8%,目前防 汛墙仍受到地面沉降的持续影响,1994～2006年区域地面沉降占防汛墙总体沉降量的71.9%.地面沉降的长期危害是影响上海城市防汛安全的重要因 素,加强地面沉降监测与防治是上海城市灾害防御的重要内容. . 地面沉降导致上海地面高程损失,并降低防汛工程设防能 力.1921～2007年地面平均沉降1.973 m,最大沉降3.035 m,市区普遍低于江河高潮位.地面沉降在中心城区外滩黄浦江防汛墙四次加高改建中分别占增高幅度的98.O%,62.6%,30.1%,7.8%,目前防 汛墙仍受到地面沉降的持续影响,1994～2006年区域地面沉降占防汛墙总体沉降量的71.9%.地面沉降的长期危害是影响上海城市防汛安全的重要因 素,加强地面沉降监测与防治是上海城市灾害防御的重要内容. |
| [19] | . As one of the top 20 cities exposed to flood disasters, Shanghai is particularly vulnerable because it is exposed to powerful floods and poorly prepared. However, it is unclear to understand the evolution process of floods and the variation of flood risk in Shanghai during the past 1,000 years. This paper analyzed the spatial-temporal characteristics of flood disaster and evaluated the integrated risk of flood disaster in Shanghai based on the historical flood data from 251 to 2000. The results show that flood disaster in Shanghai was divided into storm surge-induced flood, rainstorm-induced flood and overbank flood. Flood disaster in Shanghai presents rising trend with time and mainly occurs in summer and autumn. Moreover, the flood disaster is dominated by rainstorm-induced flood, especially after the establishment of the People's Republic of China in 1949. Additionally, flood risk in different areas of Shanghai between the years 251-1949 and 1950-2000 changed significantly. Shanghai urban area, Jinshan District and Chongming County belong to increased flood risk area; Baoshan, Jiading, Qingpu, Songjiang, Fengxian, Pudong and Minhang District belong to decreased flood risk area. The integrated risk of flood disaster in Shanghai has presented spatial disparities evidently at present. Shanghai urban area is most likely to suffer flood disaster; Baoshan, Jiading and Minhang District have medium flood risk rank; and Jinshan, Songjiang, Fengxian, Pudong, Qingpu and Chongming County show low flood risk at present. The combined effect of urbanization, sea-level rise, land subsidence and the poor capacity of flood prevention facilities will give rise to the risk of flood in the next several decades. These results provide very important information for the local government to improve flood risk management. |
| [20] | . The waterlogging is one of the most serious hazards in Shanghai Municipality.Residences,especially the old-style residences in downtown of Shanghai are prone to be affected and even collapse during waterlogging disasters.The purpose of this paper is to carry out risk assessment of residences in the region based on scenario simulation and indicator system.The rainstorm scenario was simulated by the rainstorm simulation model developed by Shanghai Flood Risk Information Center.The inundation depth of each residence obtained by GIS is a degree of exposure of it.Then an exposure assessment model was built to integrate different ranks of exposure.According to the fact that old-style residences are main hazard-bearing bodies during waterlogging hazards,we established a vulnerability indicator.Finally the total risk feature of a region and the comparison of disaster situation among different districts are realized.Finally,using the storm scenario of 50-year return period,taking the streets as the assessment units,we made an assessment on the risk of residences in Shanghai downtown.It is obvious from the research result that the spatial distribution of hazard,exposure,vulnerability and risk are in accord with the fact.The method of risk assessment is applicable,which can provide necessary information for Shanghai Municipal Government to improve waterlogging management. |
| [21] | . Despite continuing efforts to upgrade the urban storm sewer system since the late 1950s, the City of Shanghai is still vulnerable to persistent rainstorm waterlogging due to excess surface runoff and sewer surcharge, which frequently cause significant damage to buildings and disruption to traffic. Rapid urbanization and associated land cover changes are the major factors contributing to waterlogging. However, it is unclear to what extent changes in rainfall variability over the past few decades are also involved. This paper investigates the combined impacts of land use and land cover change, storm sewer development, and long-term variations in precipitation. Evidence of persistent waterlogging is presented first. We then give an account of land surface modifications during the process of urbanization and the development of the city's urban storm sewer system. Statistical analysis suggests that the increase in runoff coefficient due to conversion of lands from agricultural to industrial, commercial, and residential uses is a major factor driving greater waterlogging risk. In particular, historical analysis of aerial photographs reveals the rate and extent of modification to river networks in the past few decades. The natural drainage network has shrunk by 270 km, significantly reducing the city's capacity to transport excess surface flow. In line with other studies, we find no significant overall trends in annual rainfall totals (at Baoshan and Xujiahui). However, seasonal and monthly rainfall intensities have increased. At the daily scale, we find that compared to pre-1980s: (i) there has been an increase in the number of wet days with precipitation exceeding 25 mm (Heavy Rainfall) and decrease in those below 25 mm and (ii) the number of consecutive wet days with precipitation maximum and average exceeding the threshold known to cause waterlogging shows an increasing trend. Since rainfall intensity is expected to increase under climate change, this could further compound the impacts of land use changes and place even greater pressure on the existing storm sewer system. |
| [22] | |
| [23] | . Urban pluvial flood are attracting growing public concern due to rising intense precipitation and increasing consequences. Accurate risk assessment is critical to an efficient urban pluvial flood management, particularly in transportation sector. This paper describes an integrated methodology, which initially makes use of high resolution 2D inundation modeling and flood depth-dependent measure to evaluate the potential impact and risk of pluvial flash flood on road network in the city center of Shanghai, China. Intensity uration requency relationships of Shanghai rainstorm and Chicago Design Storm are combined to generate ensemble rainfall scenarios. A hydrodynamic model (FloodMap-HydroInundation2D) is used to simulate overland flow and flood inundation for each scenario. Furthermore, road impact and risk assessment are respectively conducted by a new proposed algorithm and proxy. Results suggest that the flood response is a function of spatio-temporal distribution of precipitation and local characteristics (i.e. drainage and topography), and pluvial flash flood is found to lead to proportionate but nonlinear impact on intra-urban road inundation risk. The approach tested here would provide more detailed flood information for smart management of urban street network and may be applied to other big cities where road flood risk is evolving in the context of climate change and urbanization. |
| [24] | . This paper presents a numerical analysis of pluvial flooding to evaluate the impact of land subsidence on flood risks in urban contexts using a hydraulic model (FloodMap-HydroInundation2D). The pluvial flood event of August 2011 in Shanghai, China is used for model calibration and simulation. Evolving patterns of inundation (area and depth) are assessed over four time periods (1991, 1996, 2001 and 2011) for the downtown area, given local changes in topography and rates of land subsidence of up to 27 mm/yr. The results show that land subsidence can lead to non-linear response of flood characteristics. However, the impact on flood depths is generally minor (< 5 cm) and limited to areas with lowest-lying topographies because of relatively uniform patterns of subsidence and micro-topographic variations at the local scale. Nonetheless, the modelling approach tested here may be applied to other cities where there are more marked rates of subsidence and/or greater heterogeneity in the depressed urban surface. In these cases, any identified hot-spots of subsidence and focusing of pluvial flooding may be targeted for adaptation interventions. |
| [25] | . Abstract High-resolution data obtained from airborne remote sensing is increasing opportunities for representation of small-scale structural elements (e.g. walls, buildings) in complex floodplain systems using two-dimensional (2D) models of flood inundation. At the same time, 2D inundation models have been developed and shown to provide good predictions of flood inundation extent, with respect to both full solution of the depth-averaged Navier tokes equations and simplified diffusion-wave models. However, these models have yet to be applied extensively to urban areas. This paper applies a 2D raster-based diffusion-wave model to determine patterns of fluvial flood inundation in urban areas using high-resolution topographic data and explores the effects of spatial resolution upon estimated inundation extent and flow routing process. Model response shows that even relatively small changes in model resolution have considerable effects on the predicted inundation extent and the timing of flood inundation. Timing sensitivity would be expected, given the relatively poor representation of inertial processes in a diffusion-wave model. Sensitivity to inundation extent is more surprising, but is associated with: (1) the smoothing effect of mesh coarsening upon input topographical data; (2) poorer representation of both cell blockage and surface routing processes as the mesh is coarsened, where the flow routing is especially complex; and (3) the effects of (1) and (2) upon water levels and velocities, which in turn determine which parts of the floodplain the flow can actually travel to. It is shown that the combined effects of wetting and roughness parameters can compensate in part for a coarser mesh resolution. However, the coarser the resolution, the poorer the ability to control the inundation process, as these parameters not only affect the speed, but also the direction of wetting. Thus, high-resolution data will need to be coupled to a more sophisticated representation of the inundation process in order to obtain effective predictions of flood inundation extent. This is explored in a companion paper. Copyright 2005 John Wiley & Sons, Ltd. |
| [26] | . This paper develops and tests a sub-grid-scale wetting and drying correction for use with two-dimensional diffusion-wave models of urban flood inundation. The method recognizes explicitly that representations of sub-grid-scale topography using roughness parameters will provide an inadequate representation of the effects of structural elements on the floodplain (e.g. buildings, walls), as such elements not only act as momentum sinks, but also have mass blockage effects. The latter may dominate, especially in structurally complex urban areas. The approach developed uses high-resolution topographic data to develop explicit parameterization of sub-grid-scale topographic variability to represent both the volume of a grid cell that can be occupied by the flow and the effect of that variability upon the timing and direction of the lateral fluxes. This approach is found to give significantly better prediction of fluvial flood inundation in urban areas than traditional calibration of sub-grid-scale effects using Manning's n . In particular, it simultaneously reduces the need to use exceptionally high values of n to represent the effects of using a coarser mesh process representation and increases the sensitivity of model predictions to variation in n . Copyright 2005 John Wiley & Sons, Ltd. |
| [27] | . The influence of catchment hydrological processes on urban flooding is often considered through river discharges at a source catchment outlet, negating the role of other upstream areas that may add to the flooding. Therefore, where multiple entry points exist at the urban upstream boundary, e.g. during extreme rainfall events when surface runoff dominates in the catchment, a hydro-inundation model becomes advantageous as it can integrate the hydrological processes with surface flow routing on the urban floodplain. This paper uses a hydro-inundation model (FloodMap-HydroInundation2D) to investigate the role of catchment hydrological parameters in urban surface water flooding. A scenario-based approach was undertaken and the June 2007 event occurred in Kingston upon Hull, UK was used as a baseline simulation, for which a good range of data is available. After model sensitivity analysis and calibration, simulations were designed, considering the improvement of both the urban and rural land drainage and storage capacities. Results suggest the model is sensitive to the key hydrological parameter soil hydraulic conductivity. Sensitivity to mesh resolution and roughness parameterisation also agrees with previous studies on fluvial flood modelling. Furthermore, the improvement of drainage and storage capacity in the upstream rural area is able to alleviate the extent and magnitude of flooding in the downstream urban area. Similarly urban drainage and storage upgrade may also reduce the risks of flooding on site, albeit to a less extent compared to rural improvements. However, none of the improvement scenarios could remove the flow propagation completely. This study highlights that in some settings, urban surface water flood modelling is just as strongly controlled by rural factors (e.g. infiltration rate and water storage) as internal model parameters such as roughness and mesh resolution. It serves as an important reminder to researchers simulating urban flooding that it is not just the internal parameterisation that is important, but also the use of correct inputs from outside the area of study, especially for catchments with a mixture of urban and rural areas. |
| [28] | . 黄浦江流域是典型的风暴洪水脆弱区。随着气候变化和海平面上升，未来该区域可能遭受更为严重的灾害影响。从海平面绝对上升、构造沉降和压实沉降三个方面预测了2030 年和2050 年该区域海平面相对上升值为170 mm和390 mm。在此基础上，结合最大天文潮位值和最大风暴增水值，估算了2030 年和2050 年极端风暴洪水位将分别达到7.17 m和7.39 m。基于高精度洪水数值模型开展了2030 和2050 年两种极端风暴洪水情景模拟，结果显示黄浦江两岸地区均可能被淹没，上游地区较中下游地区受淹将更为严重。进而提出未来研究中需重点关注不确定性分析、防汛墙溃堤淹没情景分析和风暴频率—强度变化等领域。 . 黄浦江流域是典型的风暴洪水脆弱区。随着气候变化和海平面上升，未来该区域可能遭受更为严重的灾害影响。从海平面绝对上升、构造沉降和压实沉降三个方面预测了2030 年和2050 年该区域海平面相对上升值为170 mm和390 mm。在此基础上，结合最大天文潮位值和最大风暴增水值，估算了2030 年和2050 年极端风暴洪水位将分别达到7.17 m和7.39 m。基于高精度洪水数值模型开展了2030 和2050 年两种极端风暴洪水情景模拟，结果显示黄浦江两岸地区均可能被淹没，上游地区较中下游地区受淹将更为严重。进而提出未来研究中需重点关注不确定性分析、防汛墙溃堤淹没情景分析和风暴频率—强度变化等领域。 |
| [29] | . |
| [30] | . This paper describes the development of a new set of equations derived from 1D shallow water theory for use in 2D storage cell inundation models where flows in the x and y Cartesian directions are decoupled. The new equation set is designed to be solved explicitly at very low computational cost, and is here tested against a suite of four test cases of increasing complexity. In each case the predicted water depths compare favourably to analytical solutions or to simulation results from the diffusive storage cell code of Hunter et al. (2005) . For the most complex test involving the fine spatial resolution simulation of flow in a topographically complex urban area the Root Mean Squared Difference between the new formulation and the model of Hunter et al. is 65102cm. However, unlike diffusive storage cell codes where the stable time step scales with (1/Δ x ) 2 , the new equation set developed here represents shallow water wave propagation and so the stability is controlled by the Courant–Freidrichs–Lewy condition such that the stable time step instead scales with 1/Δ x . This allows use of a stable time step that is 1–3 orders of magnitude greater for typical cell sizes than that possible with diffusive storage cell models and results in commensurate reductions in model run times. For the tests reported in this paper the maximum speed up achieved over a diffusive storage cell model was 1120×, although the actual value seen will depend on model resolution and water surface gradient. Solutions using the new equation set are shown to be grid-independent for the conditions considered and to have an intuitively correct sensitivity to friction, however small instabilities and increased errors on predicted depth were noted when Manning’s n 02=020.01. The new equations are likely to find widespread application in many types of flood inundation modelling and should provide a useful additional tool, alongside more established model formulations, for a variety of flood risk management studies. |
| [31] | . <p>分层诊疗制度有利于充分利用已有的医疗资源,是医疗卫生体制改革的重要内容。但是目前关于医疗设施可达性的研究普遍存在两个问题：没有考虑医疗机构的层级性;没有考察城市的多模态道路设施对医疗机构空间可达性的影响。通过构建两阶段的两步移动搜寻法,同时利用多模态网络数据集的网络分析法,研究在不同转诊率条件下北京城六区医疗设施的空间可达性。研究发现：① 医疗设施的总体空间可达性随转诊率的提高呈现倒U型走势;60%左右的转诊率情况下医疗设施总体空间可达性最高。② 在60%的转诊率条件下,考虑地下交通时的医疗设施总体空间可达性比不考虑地下交通时提高约9.81%,街道医疗设施空间可达性方差下降8.58%。这说明地铁建设不仅可以提升医疗设施总体的空间可达性,还可以降低街道之间空间可达性的不均衡性。③ 医疗资源“倒金字塔”型分布是制约分层就诊体系建立的关键,建立分层就诊体系需要同时调整医疗资源在不同等级医院之间的分布。</p> . <p>分层诊疗制度有利于充分利用已有的医疗资源,是医疗卫生体制改革的重要内容。但是目前关于医疗设施可达性的研究普遍存在两个问题：没有考虑医疗机构的层级性;没有考察城市的多模态道路设施对医疗机构空间可达性的影响。通过构建两阶段的两步移动搜寻法,同时利用多模态网络数据集的网络分析法,研究在不同转诊率条件下北京城六区医疗设施的空间可达性。研究发现：① 医疗设施的总体空间可达性随转诊率的提高呈现倒U型走势;60%左右的转诊率情况下医疗设施总体空间可达性最高。② 在60%的转诊率条件下,考虑地下交通时的医疗设施总体空间可达性比不考虑地下交通时提高约9.81%,街道医疗设施空间可达性方差下降8.58%。这说明地铁建设不仅可以提升医疗设施总体的空间可达性,还可以降低街道之间空间可达性的不均衡性。③ 医疗资源“倒金字塔”型分布是制约分层就诊体系建立的关键,建立分层就诊体系需要同时调整医疗资源在不同等级医院之间的分布。</p> |
