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Article | WTW Research Network Newsletter

Flood and Water Management

WTW Research Network Annual Review 2023

By Neil Gunn | May 19, 2023

Whether from the perspective of the scale of human suffering, or insurance and capital markets, it’s important to understand flood & drought in the face of climate change to respond appropriately.
Willis Research Network

Casting back through 2022 we might remember Hurricane Ian, the calamitous flooding in Pakistan, South Africa and Australia to name a few. If not the floods, one might recall the droughts of the last year. In the American Southwest, the Horn of Africa or China where low flows limited hydro power causing the lights in Shanghai to dim and making rivers in Europe and the United States unnavigable.

From a flood and drought perspective was 2022 an exceptional year with an unusually large number of rare events? Or in the face of the obvious evidence of climate change, have we become sensitised to natural disasters? Whether from the perspective of the scale of human suffering, or in insurance and capital markets, it is important to understand this to respond in an appropriate manner.

Either way a growing proportion of the world’s population are at risk of flooding1 and other severe weather events like wildfire or drought. Therefore, the need to develop tools that help improve the understanding of risk is obvious. We will continue to work with our partners at Newcastle University to improve and develop novel uses for the CityCAT model. This type of tool is useful to deal with simple cause and effect, for instance where heavy rainfall causes flooding.

However, global systems are becoming more complex and interrelated, this makes it hard to understand overlapping vulnerabilities. There were several notable occasions in 2022 where one event could be linked to the another, or where the harm of subsequent events was amplified. An example of this occurred east of Los Angeles. In 2020 a fire scorched the hillsides leaving them bare and weakening the soil2. This was followed in 2022 by rainfall on the burn scar which caused severe landslides putting lives at risk and damaging property.

The field of “compound” events, covering hazards as well as interacting risk, is receiving a lot of attention in academic and practitioner communities. This is not a new topic; it is covered in a 2005 Department for Environment Food and Rural Affairs report ‘Dependence Mapping and Best Practice3’. It has gained prominence due to high impact events involving multiple drivers such as those described above. We will work toward a better understanding of the nature and dependences of these sequences to develop improved tools for analysis, simulation and estimation for risk management and insurance purposes.

While we will retain a global focus with Newcastle University, we will also zoom into Southeast Asia with our partners at the National University of Singapore. In this case we will also look at a range of CMIP6 (Coupled Model Intercomparison Project Phase 6) scenarios using regional climate models to show how the risk landscape is evolving. These will be used to unpack climate impacts on various sectors in the region

This brings us back to water management in a changing climate. Traditional methods of reducing risk are effective but, owing to the carbon footprint arising from construction and operation of assets, the potential to use them may be limited. There are two ways around this which we intend to explore in more detail. When our systems fail, we should either ensure they do so gracefully and recover quickly; or we should find novel ways to reduce the risk of drought or flooding. Natural and Nature-Based Solutions have the potential to fill a part of this gap and may also offer enticing co-benefits. However, quantification of these benefits needs further development.

Click on the links or download the pdf to read more :-


1 Tellman, B., Sullivan, J.A., Kuhn, C. et al. Satellite imaging reveals increased proportion of population exposed to floods. Nature 596, 80–86 (2021). Satellite imaging reveals increased proportion of population exposed to floods

2 After the Fires: Hydrophobic Soils. Dr Randy Brooks. University of Idaho Extension Forestry Information Series

3 Joint Probability: Dependence Mapping and Best Practice: Technical report on dependence mapping R&D Technical Report FD2308/TR1 March 2005

Title File Type File Size
Flood and Water Management PDF 1.2 MB

Head of Flood & Water Management
WTW Research Network
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