Climate extremes, floods and modelling approaches

Professor Rob Lamb (JBA), Dr Fredi Otto (Oxford University)
Event date
Event time
17:00 - 18:30
Christ Church
St Aldate's
Venue details

Blue Boar Lecture Theatre

Event type
Lectures and seminars
Event cost
Disabled access?
Booking required

Global warming is expected to increase the likelihood of extreme precipitation events and flooding. This seminar brings together two leading experts – Oxford University’s Dr Fredi Otto, and Professor Rob Lamb, Chief Scientist of JBA Consulting – to discuss modelling advances and the implications for flood risk management and climate adaptation.

The seminar will feature presentations from both speakers followed by a Q&A. Abstracts for each talk are found below:

Dr Fredi Otto: What is driving the rain? An event attribution approach to flooding
Some consequences of a warming world are predictable, such as an increased likelihood of more heat and high precipitation extremes. However, these so-called thermodynamic consequences only hold on average globally. Regionally, impacts can be influenced by a number of factors including dynamic effects of anthropogenically induced changes in atmospheric circulation, and local forcings.

To understand how the risks relating to extreme flood events are changing requires holistic perspectives, which combine an understanding of both thermodynamic and dynamic effects, and can translate precipitation estimates into flood forecasts.

Recent advances in the emerging science of event attribution provides the necessary basis on which to build the tools needed to assess such risks at the spatial scales that matter to people.

Professor Rob Lamb: Statistical models for floods of all shapes and sizes
Planning for the risk posed by flooding involves learning from what has happened in the past, but also being prepared for events that could be worse in the future. This means that a risk analysis should take account of plausible extreme events that encompass historical observations, and also of events that could be more extreme than anything previously seen. Applications of extreme value theory have a long history in the analysis of river flows and are widely used in engineering practice and in flood risk planning to estimate the probabilities of extreme flood events.

Up until recently, statistical methods employed both in research and in practice have been suitable for analysing extreme events at specific locations, but not able to assess the joint probability of extreme conditions being experienced at multiple locations. Yet real flood events come in many shapes and sizes. A risk assessment for extreme flood events should therefore consider the joint probability of extreme conditions over many locations and multiple scales.

This talk will discusses a statistical modelling approach for multivariate extremes that has been applied to model the joint probability of extreme river flows over the entire network of around 1,000 river flow gauges in England and Wales. The model accounts for both the statistical distribution of extreme river flows at each gauge and the spatial and temporal dependence between gauges. This model has been used within insurance industry catastrophe risk models, new emergency planning scenarios for the National Risk Assessment, national scale assessment of the risk of bridge failures on the British rail network and to inform the government’s 2016 National Flood Resilience Review.

About the speakers

Dr Fredi Otto
Fredi is a senior researcher in the Environmental Change Institute at the University of Oxford and leads and coordinates the distributed computing climate modelling project

Her main research interest is on extreme weather events, improving and developing methodologies to answer the question ‘whether and to what extent external climate drivers alter the likelihood of extreme weather’. She also investigates policy implications relating to this emerging scientific field.

Fredi joined the ECI in 2011 to work on ensemble-based quantification of uncertainty in climate impact projections and continues to work on the quantification of uncertainty and validation of climate models. She is the ECI lead scientist on the international project World Weather Attribution which aims at providing an assessment of the human-influence on extreme weather in real-time and co-investigator of several other projects.

Fredi is a physicist by training but gained a PhD in philosophy of science from the Free University Berlin.

Professor Rob Lamb
Rob has been working for over 20 years in academic and commercial research and development, first at the Centre for Ecology and Hydrology in Wallingford, and since 2002 at JBA Consulting. A hydrologist and numerical modeller by training, he specialises in flood risk science. Rob has published work in numerous journals and is co-author of two text books. He directs the JBA Trust’s programme of research, maintaining an active interest in research on risk analysis, climate change and links between engineering and environmental science.

Since 2013 Rob has been an Honorary Professor at Lancaster University’s Lancaster Environment Centre. In 2016 he joined the government’s scientific advisory group on flooding.

This is the first in a series of four Oxford Water Network seminars exploring the theme of flooding. It is also part of the Environmental Change Institute’s “Welcome to the Anthropocene” week, which provides an overview of the driving forces and implications of global environmental change. After the seminar, there will be the opportunity for informal networking over a glass of wine. The event is free to attend but online booking is required as spaces are limited.