Flash flood mitigation: recommendations for research and applications

Abstract

New technologies promise reduced flash flood losses. However, real-time observations with vast multi-sensor networks, more precise mapping capabilities using remote sensing and GIS, quicker hydrological and meteorological models, and increasing forecast lead times have not reduced losses. In November, 1999, 35 researchers from nine countries met in Ravello, Italy at a NATO sponsored Advanced Study Institute, to discuss these issues and to develop a research agenda that incorporates the various components required to cope with flash floods. The key recommendations from the Institute were: (1) greater emphasis on increasing understanding of the social processes involved in flash flood warning, particularly in the response phases, and (2) the need to reduce vulnerability in sustainable ways compatible with long-term economic and social goals. The relationship between hydrometeorology and social science is seen as critical to advancing our abilities to cope with flash floods.     

Contextual influences on national level flood risk communication

With high profile flooding events and increasing risk and probable damages of flooding in the future flood risk management (FRM) in England and Wales has undergone substantial changes over the last decade. The contextual influences on flood risk communication in the areas of flood forecasting, warning and response, spatial planning and development control and flood insurance at a national level are investigated in this paper. Research is based on qualitative interviews with 21 representatives of key organisations and activities at a national level of FRM. Drawing on communication theory the research highlights the key contextual features at play: the characteristics of communication flow through organisations, the importance of policy as a communication tool informed and constrained by flood events, organisational agendas, communication approaches and the development of knowledge and technology. The paper describes the influence of clear policy guidance on activities in certain government FRM communication initiatives and the commercial imperative driving the insurance industry activities.     

Contextual influences on national level flood risk communication

With high profile flooding events and increasing risk and probable damages of flooding in the future flood risk management (FRM) in England and Wales has undergone substantial changes over the last decade. The contextual influences on flood risk communication in the areas of flood forecasting, warning and response, spatial planning and development control and flood insurance at a national level are investigated in this paper. Research is based on qualitative interviews with 21 representatives of key organisations and activities at a national level of FRM. Drawing on communication theory the research highlights the key contextual features at play: the characteristics of communication flow through organisations, the importance of policy as a communication tool informed and constrained by flood events, organisational agendas, communication approaches and the development of knowledge and technology. The paper describes the influence of clear policy guidance on activities in certain government FRM communication initiatives and the commercial imperative driving the insurance industry activities.     

'It'll never happen to me': understanding public awareness of local flood risk

Following the severe flood events of 1998 and 2000, the United Kingdom's Environment Agency prioritised the need to increase public flood risk awareness. Drawing on data collected during research undertaken for the Environment Agency, this paper contributes to understanding of one aspect of flood awareness: people's recognition that their property is in an area that is potentially at risk of flooding. Quantitative analyses indicate that class is the most influential factor in predicting flood risk awareness, followed by flood experience and length of time in residence. There are also significant area differences. Our qualitative work explores how those defined as 'at risk' account for their lack of awareness or concern about their risk status. We conclude that the problem is often not simply a lack of awareness, but rather, assessments of local risk based on experience that underestimate the impact of rare or extreme events. We underline the importance of engaging with local perspectives on risk and making local people part of 'awareness-raising' processes.     

New insights into the benefits of flood warnings: Results from a household survey in England and Wales

The flood defence agency in England and Wales has been pursuing a programme of flood warning system enhancement, engaging householders at risk in improving their warning responses. The immediate aim of this paper is to test and revise a model of economic benefits of warnings, but the survey data also generate insights into the constraints acting upon flood warning responses. Damage saving is less than previously anticipated: warning reliability and householder availability problems limit savings. Warnings are less likely to be received by those in lower social grades, and flood warning lead time is a factor in avoiding damage. The survey data indicate the complexities involved in improving flood warning response, and provide policy pointers.     

New insights into the benefits of flood warnings: Results from a household survey in England and Wales

The flood defence agency in England and Wales has been pursuing a programme of flood warning system enhancement, engaging householders at risk in improving their warning responses. The immediate aim of this paper is to test and revise a model of economic benefits of warnings, but the survey data also generate insights into the constraints acting upon flood warning responses. Damage saving is less than previously anticipated: warning reliability and householder availability problems limit savings. Warnings are less likely to be received by those in lower social grades, and flood warning lead time is a factor in avoiding damage. The survey data indicate the complexities involved in improving flood warning response, and provide policy pointers.     

区域洪水灾害风险评估体系(Ⅱ)——模型与应用

准确了解区域洪水灾害风险分布状况及规律,对于洪水灾害预警与管理具有重要意义。首先分析了模糊综合评估法的原理,以GIS空间技术为手段,建立了基于GIS的洪水灾害风险评估模型。然后以马来西亚洪水灾害风险评估应用为例,剖析了洪水灾害风险模糊评估的方法及过程,利用该模型计算出洪水灾害风险并制作了洪水灾害风险等级图和风险指数图。结果表明,该模型对于评价洪水灾害风险是行之有效的。     

The performance of the sydney flood warning system, august 1986

During August 1986 Sydney experienced its worst flooding for decades. Some 2,500 properties were flooded and transport was severely disrupted in much of the metropolitan area. The flood provided an opportunity to examine the operation of a warning system in a major Australian city. Pre-existing research into flood warnings was expanded to take advantage of the opportunity.
The warning system is examined in terms of: its impact on flood losses; consumer satisfaction; and inefficiences or breakdowns within the system. Much of the flooded area was not covered by a formal warning system. For the area that was covered, performance could be improved. Problems were experienced with the data collection and transmission network. Warning dissemination was inadequate, and the majority of those surveyed claimed that they did not receive warnings. The actions of householders reduced the flood damage substantially, but this does not appear to be the result of official warnings. Key recommendations concern improving the reliability of the flood detection network and information management.     

基于河网水系变化的水灾危险性评价——以永定河流域京津段为例

城市化过程中不合理的土地利用导致河道填塞、河网缩减现象普遍，城市水灾增加。基于灾害系统思想，构建了基于河网水系变化的水灾危险性评价体系，并以永定河京津段为例进行了实证分析。结果表明：（1）近40年来研究区水系结构简单化趋势明显，河道长度减少了20．5％，条数减少了36．4％，水系调蓄能力下降，在同样的致灾强度下水灾危险性加大；（2）在假设暴雨重现期为50年的条件下，经济密度差异决定了水灾潜在危险区的空间格局，居民用地将成为水灾重度危险区；平原段水灾重度危险区占5．7％，中度危险区占33．1％，滨海段重度危险区占13．9％，中度危险区占26．8％。研究结果可为区域综合减灾、水灾预报提供依据。     

Ensemble predictions and perceptions of risk, uncertainty, and error in flood forecasting

Under the auspices of the World Meteorological Organization, there are a number of international initiatives to promote the development and use of so-called ensemble prediction systems (EPS) for flood forecasting. The campaign to apply these meteorological techniques to flood forecasting raises important questions about how the probabilistic information these systems provide can be used for what in operational terms is typically a binary decision of whether or not to issue a flood warning. To explore these issues, we report on the results of a series of focus group discussions conducted with operational flood forecasters from across Europe on behalf of the European Flood Alert System. Working in small groups to simulate operational conditions, forecasters engaged in a series of carefully designed forecasting exercises using various different combinations of actual data from real events. Focus group data was supplemented by a follow-up questionnaire survey exploring how flood forecasters understand risk, uncertainty, and error. Results suggest that flood forecasters may not instinctively use ensemble predictions in the way that promoters of EPS perhaps think they should. The paper concludes by exploring the implications of these divergent ‘epistemic cultures’ for efforts to apply ensemble prediction techniques developed in the context of weather forecasting to the rather different one of flood forecasting.     

基于GIS的地质灾害风险预警系统设计

利用GIS软件的二次开发技术,应用基于风险评价的预警方法建立地质灾害预警模型,设计地质灾害风险预警系统,在Visual Studio 2012.NET的开发环境下,以C#作为开发语言,并结合ArcGIS Engine研发.最后以通化县作为研究区域,验证此系统的可行性,结果表明该系统实现了地质灾害风险预警预报,具有较高的...     

Ensemble predictions and perceptions of risk,uncertainty, and error in flood forecasting

Under the auspices of the World Meteorological Organization, there are a number of international initiatives to promote the development and use of so-called ensemble prediction systems (EPS) for flood forecasting. The campaign to apply these meteorological techniques to flood forecasting raises important questions about how the probabilistic information these systems provide can be used for what in operational terms is typically a binary decision of whether or not to issue a flood warning. To explore these issues, we report on the results of a series of focus group discussions conducted with operational flood forecasters from across Europe on behalf of the European Flood Alert System. Working in small groups to simulate operational conditions, forecasters engaged in a series of carefully designed forecasting exercises using various different combinations of actual data from real events. Focus group data was supplemented by a follow-up questionnaire survey exploring how flood forecasters understand risk, uncertainty, and error. Results suggest that flood forecasters may not instinctively use ensemble predictions in the way that promoters of EPS perhaps think they should. The paper concludes by exploring the implications of these divergent ‘epistemic cultures’ for efforts to apply ensemble prediction techniques developed in the context of weather forecasting to the rather different one of flood forecasting.     

基于GIS的上海浦东暴雨内涝灾害脆弱性研究

随着全球气候变化和城市化进程的加速发展,城市暴雨洪涝灾害的频度和强度不断加强。灾害脆弱性研究是当前灾害研究的热点,基于灾损率的脆弱性分析方法是当前灾害脆弱性研究的重要课题点与前沿。采用G IS和遥感技术,依据20年、50年、100年、200年、500年、1000年一遇的6个重现期情景,对上海浦东新区开展了基于灾损曲线的脆弱性研究。研究中修正了上海地区的径流模型,基于G IS栅格编制了不同重现期的淹没深度图,实地调查了研究区暴雨内涝灾害的灾损率数据,确定了研究区的脆弱性等级划分,并利用G IS编制了基于不同重现期情景的上海浦东脆弱性图。研究中提出的方法对于沿海城市开展暴雨内涝等自然灾害脆弱性研究具有借鉴意义,研究结果可供区域灾害风险评估和防灾减灾规划参考。     

城市化与现代社会中的水害演变：从日本经历看今日深圳

我国沿海经济开发区正进入城市化的活跃发展时期。发达国家的经历表明,城市化必将导致水灾害模式的变化,引出城市水灾损失持续上升的严重问题。日本从60年代中期开始研究城市型水灾害问题,随后其治水事业从方针、政策到对策均作了重大的调整,为社会经济的持续稳定发展创造了良好的条件。深圳市1993年两次暴雨洪涝成灾,损失惨重,其水情灾情均受到了该区域城市化的显著影响,说明我国城市型水灾害的研究亟待加强。本文从治水的角度将日本的城市化现象及其引起的水灾害特征变化与深圳市的实际情况进行了比较并得出若干有益的结论。     

Flood risk and inequalities between ethnic groups in the floodplains of England and Wales

Previous research has shown that many vulnerable communities experience disproportional exposure to flood risk. This paper, though, is the first to look at broad ethnic/racial group differences in the United Kingdom. It contends that differences in culture and language, especially those of new immigrants, bestow vulnerabilities on such communities, resulting in a lack of knowledge that enables people to be aware, to be prepared, or to recover expediently after a flood emergency. Using UK 2011 Census data and Environment Agency flood maps, the paper demonstrates that it is the non‐white communities in Wales that confront the most disproportionate level of flood risk: 23 per cent as compared to 11.4 per cent of their white neighbours. In contrast, the difference in flood risk between white and non‐white ethnic/racial groups in regions of England is within a range of plus or minus two per cent, except for in Yorkshire and The Humber where white populations face a much greater risk of flooding.     

气候变化和人类活动对天津海岸带影响综述

21世纪全球海平面上升和区域地面沉降叠加所致的相对海平面上升速率存在加快趋势,将加剧天津沿海地区风暴潮、洪涝灾害和土地淹没的危害,影响沿海地区的城市抗灾功能、建筑物安全及生态资源。为此,本文综合讨论了气候变化导致的海平面上升和地面沉降对天津沿海风暴潮、海岸侵蚀以及港口码头的影响。建议滨海新区建设要高度重视海洋灾害的监测预警,提高沿海地区防潮和防汛工程的设计标准和城市抗灾能力,以有效实现滨海新区经济和社会可持续发展。     

Heading for higher ground: factors affecting real and hypothetical hurricane evacuation behavior

Abstract

The purpose of this paper is to assess the determinants of hurricane evacuation behavior of North Carolina coastal households during Hurricane Bonnie and a future hypothetical hurricane. We use the data from a telephone survey of North Carolina coastal residents. Hypothetical questions are used to assess whether respondents will evacuate and where in the case of a future hurricane with varying intensities. We examine the social, economic, and risk factors that affect the decisions to evacuate and whether to go to a shelter or motel/hotel relative to other destinations. The most important predictor of evacuation is storm intensity. Households are more likely to evacuate when given evacuation orders, when they perceive a flood risk, and when they live in mobile homes. Households who own pets are less likely to evacuate. Non-white households, pet owners and those with more education are less likely to go to either a motel/hotel or shelter, preferring instead to stay with friends or family.     

Risk communication and risk perception: lessons from the 2011 floods in Brisbane,Australia

Risk communication and risk perception are critical factors in disaster management. Governments at all levels play a part in communicating risk, whereas the perception of risk entails active roles by community participants, including potential and actual victims of disasters. This paper discusses these matters in relation to the floods in Brisbane, Australia, in 2011. The findings are based on interviews with representatives of households whose dwellings or business premises were fully or partially inundated by the waters. The research shows how important it is to recognise the problems of institutional fragmentation in terms of communication and the active engagement of recipients in understanding and interpreting flood risk information (especially for slow‐onset riverine flooding, such as that suffered by Brisbane). Locally targeted information on risk is of vital importance in avoiding the misinterpretation of warning information in relation to environmental cues and in promoting adequate responses. The paper concludes with some recommendations.     

Flood management in Canada at the crossroads

Abstract

Although Canadian flood management efforts have gained worldwide recognition, flood damages continue to increase. The current practice for preventing, responding to and recovering from floods in Canada is described by focusing attention on the 1997 Red River and 1996 Saguenay River floods. A set of cultures is identified that contribute to the trend of increasing flood damages. These include a culture of conflict, a culture of land development, a culture that impeded native people from easily implementing flood management programs, a culture of institutional fragmentation and a culture of dependency. These foster an inevitable cycle of increasing flood damages. The potential of recent proposals made by Emergency Preparedness Canada and the Insurance Bureau of Canada to address these cultures is assessed. While these documents represent significant progress, they continue to adopt an intermittent project rather an ongoing program perspective, fail to identify the need to adopt specific initiatives tailored for aboriginal communities, and ignore the need to enhance the operational capacity of relevant public and private participants. Addressing these requirements will further reduce future losses and vulnerability.     

The Protection of China's Ancient Cities from Flood Damage

Over many centuries, the repeated and serious flooding of many of China's ancient cities has led to the development of various measures to mitigate the impact of floods. These have included structural measures, such as the construction of walls, dams and dykes, with tree planting for soil consolidation; installation of drainage systems and water storage capacity; the raising of settlement levels and the strengthening of building materials. Non-structural measures include warning systems and planning for emergency evacuation. Urban planning and architectural design have evolved to reduce flood damage, and government officials have been appointed with specific responsibilities for managing the flood control systems. In view of the serious consequences of modern neglect of these well-tried methods, this paper examines China's historical experience of flooding and demonstrates its continuing relevance for today. A brief historical survey is followed by a detailed discussion of various flood prevention measures. The paper is illustrated by city plans from ancient local chronicles.