Simulating spatially coherent widespread flood events across the UK (Webinar)

UK Climate Resilience Programme Webinar Series 2021

24 February 2021

Speakers: Paul Sayers (Sayers and Partners); stakeholder response from Mike Steel (Environment Agency)

Chair: Suraje Dessai

See links to a video of the webinar and slides below

Abstract

CAT modelling was developed in the late 1980s to capture the spatial correlation of extreme events, with event footprints being used to demonstrate how an extreme event impacts different locations at a similar time. Separately, current approaches to at-site flood risk estimation apply climate change allowances to flood frequency estimates based on observations from the current period. These modified flow frequency estimates are then used to calculate flood risk and associated losses using a variety of means.

The present work brings together these two strands to develop spatially resolved projections of changes in river flow and, together with new analysis of the spatial coherence, to generate a wider collection of plausible events to improve risk modelling of the rarest events. This was achieved by improving known methods to generate extreme, widespread flood events directly based on outputs from the Grid-to-Grid hydrological model (Bell et al., 2009), driven by UKCP18 datasets. These modelled events provided coherent and highly credible descriptions of changes in flow based on spatially coherent climate change information. These small number of widespread extreme events generated directly from Grid-to-Grid have been extended using copula-based methods to generate a collection of plausible “extreme” events based on the climate of 1980-2010 and on climate projections of 2050. The collection of events is then applied to an event based risk analysis using Future Flow Explorer (FFE).

Biographies

Paul Sayers is a recognised expert on climate, its impact on flood and coastal risks (at a community, city and regional scale) and the development of resilience and adaptation policies and strategies.   Paul has over 25 years of experience in all aspects of flood, water and  coastal management, including the leading the flood projections for the latest UK climate Change Risk Assessment.  Paul has worked in the UK and internationally, including collaborations on strategic responses to climate issues in Australia, China, Malaysia, Indonesia, Guyana, Denmark, Norway, Italy, Netherlands, Canada, Nigeria, Ethiopia, Kenya and the USA (and many others).   In addition to his applied research consultancy activities at Sayers and Partners, Paul continues to be part of leading international research groups at the University of East Anglian (the Tyndall Centre) and TU Delft/IHE in the Netherlands.  Paul is also an advisor to the Joint Defra/Environment Research Programme (on flood and coastal Asset Management) and is an Associate Fellow of the ODI (Global Risk and Resilience).   Paul is also a member of the Editorial Board for the Journal of Flood Risk Management and acts as a reviewer for many others international journals and is currently leading exploration of spatially coherence events within the UK climate Resilience programme and contributing to the development of UKRC funded project, OpenCLIM.

Sayers and Partners are principal investigators of UKCR project, AquaCAT.

Read Paul’s blog, Exploring spatially coherent flood risks – present and future 

Dr Mike Steel, Environment Agency: Mike is responsible for the Environment Agency’s long-term investment scenarios (LTIS) for flood and coastal risk management. LTIS is an economic assessment showing what future flood and coastal risk management could look like over the next 50 years in England. The latest LTIS study was published in 2019. Mike has previously worked on national flood risk assessment, and the plans to manage flood risk in the Thames Estuary until the year 2100 (TE2100). He has a PhD in hydrology and climate change, and is a Chartered Water and Environment Manager.