Floods in megacities: impacts of urban growth, sustainable infrastructure and climate change

在全球范围内，洪水是最具破坏性的自然灾害之一，影响许多地区，每年造成数千人伤亡和数十亿美元的损失。由于城市化、基础设施老化以及极端天气事件的频率和强度不断增加，所有城市都变得越来越容易受到洪水的影响。特别是特大城市（人口超过1000万的城市）面临更大的风险，这些地区的城市增长速度快于其他地区，大中心受影响的人口和经济资产数量也远高于其他地区。因此，必须制定更好的城市防洪方法，包括改进洪水预报方法和有效的防洪基础设施。***本研究计划旨在通过关注三个相互关联的短期目标来解决这些问题。首先，研究了全球特大城市的历史洪水，以提高我们对这些地区雨洪控制过程的理解。概念性的全球尺度和城市尺度的数值模型将用于确定上个世纪特大城市的洪水是如何变化的，以及经济增长、气候变化和区域特征将如何影响未来的洪水事件。在此之后，可持续的“绿色”基础设施技术，以减轻未来特大城市洪水事件的能力将使用耦合模型和实验方法进行调查。实验部分将优化这些技术的设计，以满足在建模方法中建立的降低洪水风险的标准。本研究计划的最后一个组成部分侧重于风险和经济分析，以确定实施可持续基础设施的净财务效益。这项研究将提高我们对城市水系统的复杂性和不确定性的理解。通过该项目开发的新型技术和经济评估工具将帮助水资源管理者在基础设施资金有限的情况下做出更明智的战略决策。结果将是更有弹性的城市环境。

Globally floods are one of the most devastating natural disasters, impacting numerous regions, responsible for thousands of casualties and billions of dollars in losses annually. All cities are becoming more vulnerable to flooding due to urbanisation, ageing infrastructure, and the increasing frequency and intensity of extreme weather events. In particular, megacities (cities with a population greater than 10 million) face even greater risks the urban growth in these areas is faster than other regions and the number of people and economic assets affected in large centres is also far higher than anywhere else. It is therefore essential to develop better urban flood protection methods, including improved flood forecasting methods and effective flood mitigation infrastructure.***This research program aims to address these issues by focusing on three inter-related short term objectives. First, historical floods in global megacities are investigated to improve our understanding of pluvial flood governing processes in these regions. Conceptual global-scale and city-scale numerical models will be used to determine how floods have changed in megacities over the last century, and how growth, climate change, and region-specific characteristics will impact future flood events. Following this, the ability of sustainable “green” infrastructure technologies to mitigate future flood events in megacities will be investigated using a coupled modelling and experimental approach. The experimental component will optimise the design of these technologies to meet the flood risk reduction criteria established in the modelling approach. The last component of this research program focuses on a risk and economic analysis to determine the net financial benefits of implementing sustainable infrastructure. ***This research will improve our understanding of the complexity and uncertainty in urban water systems. The novel technical and economic assessment tools developed through this program will assist water resource managers in making more informed, strategic decisions in the face of limited infrastructure funding. The outcome will be more resilient urban environments.