Title: Understanding and communicating widespread flood risk
Authors: Jonathan Tawn - Lancaster University (United Kingdom)
Ross Towe - Lancaster University (United Kingdom) [presenting]
Rob Lamb - JBA Trust and Lancaster University (United Kingdom)
Abstract: During the winter of 2015/2016, the UK was hit by a sequence of storms that resulted in widespread flooding. As a result of these storms, the UK government formed the National Flood Resilience Review (NFRR) to better understand the drivers of flooding. Some of the questions raised by the NFRR included: what is the chance of an extreme river flow occurring at one or more gauges, somewhere within the national river gauge network in any one year? In order to address questions of this nature it is vital to understand the dependence of large values of river flow and determine which combinations of locations are likely to simultaneously observe high flows. We use a multivariate extreme value model to summarise the changing behaviour of floods across the UK. In order to account for the likelihood of missing data at a number of river flow gauges, an adaption to the current methodology is proposed. A constraint of the current methodology is that events are restricted to the locations where measurements of river flow are made. A number of algorithms can be used to interpolate river flow to ungauged parts of the river network, however we propose to also use information about rainfall.