When preparing an editorial, members of the Editorial Board sometimes discuss cases of floods that are topical at the time of writing. In this editorial, I have chosen to reflect briefly on three catastrophic cases of flooding and consequential impacts following the failure of dams, which illustrate why the scope of the Journal of Flood Risk Management includes flood risks associated with dams. Although the impacts are mainly quantified as numbers of deaths, building damaged, etc., it is important for all involved in flood risk management to recognise the emotional distress that flooding causes to the survivors. These human impacts can persist for years and permanently change behaviour.

When I started to consider composing this editorial, there had been international news reports of flash flooding in Southern Europe in Bulgaria, Greece and parts of Turkey from storm Daniel where in some areas over 750 mm of rain had fallen on 5 September, see NASA (2023). In the subsequent days, this weather system passed over the warm waters of the Mediterranean Sea to the south and developed in intensity into a ‘Medicane’, a storm of hurricane force winds that struck the coast of Libya. Although not in the location of the most intense rainfall over Libya, European Commission (2023), extreme flooding occurred without warning in Derna on the Mediterranean coast at the outfall of the Wadi Derna in the early hours of September 10. The immediate cause of the disaster was the cascade failure of the Derna and Mansour dams, which had been constructed on the wadi for flood control. The impacts for the town of Derna were catastrophic, with the dam-break flood causing around 4000 fatalities, internally displacing over 16,000 people, destroying 876 buildings and damaging 3100; further consequences of the flooding include the disruption of health services and the lack of safe and affordable water, see United Nations Office for the Coordination of Humanitarian Affairs (2023). Governance in this part of Libya has been contested since the Spring uprising in 2011, most likely leading to poor maintenance of the dams; moreover, the dams were designed using climatic conditions prevailing in the 1970s. An initial assessment of the influence of climate change has indicated that an event as extreme as the one observed over Libya has become up to 50 times more likely and up to 50% more intense compared with a 1.2°C cooler climate, see World Weather Attribution (2023).

Early on the morning of 6 June 2023, the failure of the Kakhovka Dam in the Russian occupied area of Ukraine led to widespread flooding downriver on the Dnipro River. Being in an active war zone, the cause and responsibility for the failure of the dam are contested. However, the impacts are clear: extensive inundation, loss-of-life, destruction of buildings, internal displacement of those affected, loss of hydro-electric power generation at the site and loss of water resources in a large area. The UN Country Team in Ukraine (2023) has published an early assessment of the long-term consequences of the destruction of the dam including impacts on the internal displacement of people; health, water and sanitation; chemical hazards; agriculture, fishery and forestry; community infrastructure; energy; housing; and culture.

In January 2019, the Dam ‘B1’ of the Córrego do Feijão mine in Brazil, 9 km from the town of Brumadinho, collapsed without warning. Prior to collapse, the dam was about 80 m high and its crest length was 700 m; the failure released about 9.7 million m³ of mining waste, causing between 270 and 320 deaths and significant environmental pollution; see Robertson et al. (2019). Tailings dams are generally not constructed in the same way as permanent earth embankment dams used for flood control, water resources, hydropower, etc., instead they are raised progressively as the mining waste consolidates during the life-time of the operations. At this site, construction started in 1976 and tailings disposal in the dam ceased in July 2016, 30 months before the failure. The post-event expert report into the disaster, see Robertson et al. (2019), concluded that the design and construction of the dam contributed to its failure, in particular, the design resulted in a dam that was steep with a lack of sufficient drainage. The expert report also concluded that none of the monitoring devices at the site detected precursors to failure; rather, the dam's failure was sudden and abrupt. However, Lumbroso et al. (2020) show through modelling that if a warning had been issued even as the dam failed the number of fatalities could have been reduced significantly.

These three dams differed in design and primary function, but their failures led to immediate catastrophic human and environmental impacts, which will continue in the long term. Although these incidents had differing and complex causes—design, construction, inspection and maintenance, hydrometeorology, and governance—the consequences and risks have many similarities. This is why the Journal of Flood Risk Management seeks to publish advances in knowledge on all such aspects of flood risks and their management.

Another category of infrastructure that can pose some similarity in the risk of dam failure, albeit less extreme, includes raised flood defences—embankments and walls that impound water level temporarily above the surrounding ground level during river floods or coastal surges. Four papers in this issue of the journal relate to the management of flood risks in areas protected by embankments; the first covers the ‘source’, the second and third the ‘pathway’ and the fourth the ‘receptor’ in the well-known ‘source-pathway-receptor’ framework for analysis of flood risk.

In the first paper, Sarwar and Borthwick (2023) consider the uncertainty in the future hydrodynamic loading on coastal embankments in Bangladesh. Extensive embankment construction has been undertaken along the Bangladeshi coastline to protect people and properties in nearby cities and villages from flood inundation and land erosion. Sarwar and Borthwick (2023) develop a derived distribution approach to assess uncertainty in extreme water levels. The analytic version of the derived distribution approach, where the dependence of the output parameter on the input parameter is known, has been used for 50 years in flood frequency and water resources estimations. However, the innovation in the paper is that it is the first to report on the application of the numerical analogue of the derived distribution approach to maximum tidal elevations in the context of an actual large-scale bay subject to sea level rise.

The second paper is from Pennisi et al. (2023), who discuss the use of ground penetrating radar as a non-invasive survey technique to assess the presence and extent of animal burrows in flood embankments (levees). Animal burrows can provide preferential seepage routes within and below raised flood defences. The authors present a case study of the Dirillo River in Sicily where several failures of the levees occurred during a flood in 2012. The site investigation reported in the paper illustrates the depths and paths of dens inside the levee. Moreover, they reveal that the tunnels start as a single straight tunnel and, inside the levee, they split into more than one tunnel connecting the riverside slope to the landside slope. This new evidence highlights the potentially destructive impact of animal dens inside the levees. In the worst case, such tunnels may trigger intense erosion in floods that could trigger the failure of the overall structure.

For several years, fragility curves have been used to assess the failure probability of flood defences when undertaking probabilistic flood risk assessments. In the third paper, Mainguenaud et al. (2023) propose a probabilistic method to assess levee failure probability by integrating three failure mechanisms relevant to fluvial levees: sliding, internal erosion and overflowing. This aggregation of failure probabilities from the three mechanisms provides a single fragility curve to represent the failure probability and avoids making a biased interpretation of the results due to distinct fragility curves for the same levee segment. The authors illustrate the method on a reach of the Bow River in Canada and recommend the use of Monte-Carlo aggregated fragility curves in practice.

Drawing on the national conditions in Aotearoa, New Zealand (A-NZ), the fourth paper by Fu et al. (2023) discusses the management of residual flood risks for the population behind raised defences. The so-called ‘levee-effect’ leads to a false sense of security and underestimation of flood risk. Fu et al. (2023) discuss empirical findings from a survey carried out with flood risk practitioners from the public and private sector. They argue that, without a change in approach—through a national directive for A-NZ and the provision of resources—residual flood risk is likely to continue to rise in flood-prone communities, which will cause all stakeholders to underestimate their flood risk as well as the necessary insurance coverage.

Finally, I wish to thank colleagues on the journal's panel of editors, the associate editors and especially all the anonymous peer reviewers for their contribution to the success of the Journal of Flood Risk Management over the past year.

在准备社论时，编辑委员会成员有时会讨论撰写本文时热门的洪水案例。在这篇社论中，我选择简要回顾三起灾难性洪水案例以及大坝溃决后的后果性影响，这说明了为什么《洪水风险管理杂志》的范围包括与大坝相关的洪水风险。尽管影响主要量化为死亡人数、建筑物受损等，但对于所有参与洪水风险管理的人来说，重要的是要认识到洪水给幸存者带来的情感困扰。这些人类影响可能持续数年并永久改变行为。

当我开始考虑撰写这篇社论时，国际新闻报道称，9 月 5 日，丹尼尔风暴在南欧保加利亚、希腊和土耳其部分地区引发山洪，部分地区降雨量超过 750 毫米，参见 NASA（2023）。在接下来的几天里，这一天气系统越过地中海的温暖水域向南延伸，并在强度上发展为“Medicane”，这是一场袭击利比亚海岸的飓风风暴。欧盟委员会（ 2023年）虽然不是利比亚降雨量最强的地点，但9月10日凌晨，地中海沿岸的德尔纳干河谷的排污口毫无预警地发生了极端洪水。灾难是为防洪而建在干河上的德尔纳和曼苏尔大坝的梯级溃决。溃坝洪水对德尔纳镇造成了灾难性影响，造成约 4000 人死亡、16,000 多人在境内流离失所、摧毁 876 栋建筑物、3100 人受损；洪水的进一步后果包括卫生服务中断以及缺乏安全和负担得起的水，请参阅联合国人道主义事务协调厅（2023）。自2011年春季起义以来，利比亚这一地区的治理一直存在争议，很可能导致水坝维护不善；此外，水坝的设计考虑了20世纪70年代的气候条件。对气候变化影响的初步评估表明，与气温下降 1.2°C 相比，在利比亚观察到的极端事件发生的可能性高出 50 倍，强度高出 50%，请参阅世界天气归因（2023）。

2023年6月6日凌晨，俄罗斯占领的乌克兰地区卡霍夫卡大坝溃决，导致第聂伯河下游大面积洪水泛滥。由于处于活跃的战区，大坝溃坝的原因和责任存在争议。然而，其影响是显而易见的：大面积洪水泛滥、人员伤亡、建筑物被毁、受影响者在境内流离失所、现场水力发电丧失以及大面积水资源流失。联合国驻乌克兰国家工作队（2023）发布了对大坝破坏的长期后果的早期评估，包括对国内流离失所者的影响；健康、水和卫生设施；化学危险；农业、渔业和林业；社区基础设施；活力; 住房; 和文化。

2019 年 1 月，距离布鲁马迪尼奥镇 9 公里的巴西 Córrego do Feijão 矿的“B1”大坝在没有任何预警的情况下倒塌。溃坝前坝高约80m，坝顶长700m；此次事故释放了约970万立方米^的采矿废物，造成270至320人死亡，并造成严重的环境污染；参见罗伯逊等人。（2019）。尾矿坝的建造方式通常与用于防洪、水资源、水电等的永久性土堤坝不同，而是随着采矿废物在运营周期内的固结而逐渐升高。该工地于 1976 年开始施工，大坝尾矿处置于 2016 年 7 月停止，即溃坝前 30 个月。事后专家对灾难的报告，参见 Robertson 等人。（2019）得出的结论是，大坝的设计和施工导致了大坝的失败，特别是设计导致大坝陡峭且缺乏足够的排水。专家报告还得出结论，现场的监控设备均未检测到故障先兆；相反，大坝的溃坝是突然而突然的。然而，Lumbroso 等人。（2020）通过模型表明，如果即使在大坝溃决时也发出警告，死亡人数可能会大大减少。

这三座大坝的设计和主要功能各不相同，但它们的失败直接导致了灾难性的人类和环境影响，而且这种影响将长期持续。尽管这些事件有不同且复杂的原因——设计、施工、检查和维护、水文气象和治理——但后果和风险有许多相似之处。这就是为什么《洪水风险管理杂志》寻求发表有关洪水风险及其管理的所有这些方面的知识进展。

另一类基础设施可能会造成大坝溃决风险的一些相似之处（尽管不那么极端），包括升高的防洪堤——在河流洪水或海岸潮汐期间将水位暂时蓄积在周围地面以上的堤坝和围墙。本期杂志中的四篇论文涉及堤坝保护地区的洪水风险管理；第一个部分涵盖“源头”，第二个和第三个部分涵盖“路径”，第四个部分涵盖著名的“源头-路径-受体”框架中的“受体”，用于洪水风险分析。

在第一篇论文中，Sarwar 和 Borthwick ( 2023 ) 考虑了孟加拉国沿海堤坝未来水动力荷载的不确定性。孟加拉国沿海岸线进行了大规模的堤坝建设，以保护附近城市和村庄的人民和财产免受洪水淹没和土地侵蚀。Sarwar 和 Borthwick ( 2023 ) 开发了一种派生分布方法来评估极端水位的不确定性。派生分布方法的分析版本（其中输出参数对输入参数的依赖性已知）已在洪水频率和水资源估计中使用了 50 年。然而，该论文的创新之处在于，它首次报道了在受海平面上升影响的实际大型海湾背景下，将导出的分布方法的数值模拟应用于最大潮汐高程。

第二篇论文来自 Pennisi 等人。（2023），他们讨论了使用探地雷达作为一种非侵入性测量技术来评估防洪堤（堤坝）中动物洞穴的存在和范围。动物洞穴可以在防洪堤内和下方提供优先的渗流路线。作者介绍了西西里岛 Dirillo 河的案例研究，该河段的堤坝在 2012 年的洪水期间发生了多次溃决。论文中报告的现场调查说明了堤坝内洞穴的深度和路径。此外，他们还透露，隧道一开始是一条直隧道，在堤坝内部，它们分成多个隧道，连接河边斜坡和陆侧斜坡。这一新证据凸显了堤坝内动物巢穴的潜在破坏性影响。在最坏的情况下，此类隧道可能会引发洪水的强烈侵蚀，从而引发整体结构的失效。

多年来，在进行概率洪水风险评估时，脆弱性曲线一直被用来评估防洪失败的概率。在第三篇论文中，Mainguenaud 等人。( 2023 )提出了一种概率方法，通过整合与河流堤坝相关的三种失效机制：滑动、内侵蚀和溢流来评估堤坝失效概率。三种机制的失效概率的聚合提供了一条单一的脆弱性曲线来表示失效概率，并避免了由于同一堤坝段的不同脆弱性曲线而对结果做出有偏见的解释。作者以加拿大弓河河段为例阐述了该方法，并建议在实践中使用蒙特卡罗聚合脆弱性曲线。

Fu等人的第四篇论文借鉴了新西兰Aotearoa（A-NZ）的国情。（2023）讨论了对防御工事后面的居民的剩余洪水风险的管理。所谓的“堤坝效应”会导致错误的安全感和对洪水风险的低估。傅等人。（2023）讨论了与公共和私营部门的洪水风险从业者进行的一项调查的实证结果。他们认为，如果不改变方法——通过澳大利亚-新西兰国家指令和提供资源——易受洪水影响的社区的剩余洪水风险可能会继续上升，这将导致所有利益相关者低估他们的洪水风险，因为以及必要的保险范围。

最后，我要感谢该杂志编辑小组的同事、副主编，特别是所有匿名同行评审员，感谢他们在过去一年中为《洪水风险管理杂志》的成功做出的贡献。