Accounting for Climate Change Uncertainty in Flood Hazard Prediction

Lead Research Organisation: Heriot-Watt University
Department Name: Sch of Energy, Geosci, Infrast & Society


Floods are the most common and widely distributed natural risk to life and property worldwide, causing over £4.5B worth of damage to the UK since 2000. Managing flood risk therefore presents a substantial challenge to this and future governments. Arising from the requirements of the EU Floods Directive (2007/60/EC), flood hazard maps for the UK must be delivered by December 2013. Due to limitations in current methodologies these maps take a deterministic approach to mapping catchment scale flood hazard, and do not incorporate climate change projections. Climate projections are predicted to result in the increase of UK properties at risk from flooding and coastal erosion: understanding the uncertainty these bring to flood hazard is therefore of vital economic significance to the UK.
Different methods to assess or determine flood hazards have evolved through research and practice. However, these do not allow for uncertainty estimates to be explicitly included within the process. While uncertainty analysis has been an area of research over a number of years, it has not yet achieved widespread implementation in flood modelling studies and decision making for a number of reasons. With developments in the field, such as improved computational power and newly available standardised climate datasets, incorporating uncertainty into assessments is becoming increasingly possible and indeed essential.
It is clear that a gap currently exists in uncertainty estimation in flood hazard prediction, particularly in relation to climate change projections, and that this area of research is critical to current policy and operational drivers. This proposal has been developed to comprehensively address this gap. The project will develop a novel probabilistic modelling framework to assess the impact of uncertainty arising from climate change on flood hazard predictions, generate exemplar probabilistic flood hazard maps for selected case study catchments and attempt to quantify the change to flood hazard as a result of climate projections.

Planned Impact

The potential beneficiaries from the outcomes of the proposed research include regulators and statutory consultees (including the Environment Agency (EA), the Scottish Environmental Protection Agency (SEPA), policy makers (specifically the EA, SEPA, the UK and Scottish Governments), engineering and environmental consultants, academic researchers (universities and research institutes) and in the longer term members of the public living in flood prone areas. These beneficiaries will be interested in both the scientific outcomes of the project as well as the technique development.
As set out in the Case for Support, flood hazard poses a significant on-going economic burden to the U.K. with potential impacts from the uncertainty arising from climate predictions adding extra pressure. Regulatory and policy requirements arising from the EU Floods Directive and national legislation (such as the Flood Risk Management (Scotland) Act 2009) necessitate the development of flood hazard maps for the UK. At present these maps do not account for the potential impact posed by climate uncertainty to flood hazard. Hence the output of this research will be of direct interest to regulators and statutory consultees (EA and SEPA) as it will provide quantitative projections of the change to flood hazard (velocity, floodplain extent and depth) resulting from climate projections (UKCIP 09). This information will be of direct benefit when developing strategies to manage flood risk in particular areas allowing prioritisation of economic resources, as well as policy development. It is this point regarding policy development which will be of interest to the UK and Scottish governments, as being able to quantify the potential change to flood hazard in vulnerable areas will allow policy makers to assess, and adjust policy accordingly.
The recent UK Flood and Coastal Erosion Risk Management (FCERM) research strategy highlights that 'uncertainty propagation associated with all forms of flooding', as well as the need to understand the response of hazard to climate change, is critical to current policy and operational drivers. Consequently, regulators (EA and SEPA) and engineering and environmental consultancies are likely to be interested in the development of the method as well as the end products (maps, software and quantitative understanding of change to hazard). Through the different engagement activities described in the Pathways to Impact document the project will seek to maximise the utility and clarity of developed techniques and outputs. These will provide a methodology which will be applicable for any catchment in the UK. While developed for the UK the method will also be applicable more widely and therefore of interest to consultants who work internationally.
Once developed across the UK, this information will be of direct benefit to members of the public residing within flood prone areas. From the outputs potential quantitative changes to flood hazard over the 50-80 year time period will be available. This will allow greater understanding of the threat posed by flooding which can feed into flood policy development, flood defence/alleviation strategies and management plans.
Description So far we have uncovered the regional difference across the UK for future extreme flows. In subsequent grants we are finding that these results are corroborated even when analysing more recent (ie CMIP5) climate projections
Our key findings are as follows:
1. Across Great Britain spatially contrasted 1:100yr return period flood estimates (yrF) are predicted by the 2080s. The highest 1:100yrF are computed on the west coast, with the lowest climate model and probabilistic distribution uncertainties. Similarly, the lowest 1:100yrFs are found in south and southeast of England, with the highest uncertainties across Great Britain.
2. We have regionalised these changes to explore what may control these. Additionally this regionalisation may mean that they are accessible across ungauged catchments, and we have investigated how these changes translate into flood extents and flood hazard.
3. We have created a database which is freely available to practitioners, have developed a probabilistic flood mapping method, and investigated different sources of uncertainty and how they propagated through the modelling process.
Exploitation Route For our case study location (the River Don), SEPA are interested in our hazard estimates incorporating uncertainty.
Sectors Environment

Description The findings of our research have been shared across countries in order to discuss potential ways to understand the impact of climate change uncertainty at a regional/national scale. Currently this is shared between practitioners discussing best practice and ways forward. We have also shared this with practitioners across Scotland, some of which have directly used the database, and others used this to investigate the change to flood hazard in the future assuming climate change (capturing uncertainty)
Sector Environment
Impact Types Policy & public services

Description EPSRC Impact Acceleration Award (Institutional)
Amount £11,713 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2016 
End 07/2016
Title Statistical analysis of future extreme events across the UK 
Description Extreme event prediction for high flows across Great Britain (281 catchments) for a range of return periods (baseline and future) 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact Consultants keen to use the data - eg KayaConsulting using the data for an Uncertainty analysis of flows for the River Cree 
Description Climate Change Uncertainty in Future Flood Frequency (Scotland) using R to analyse the database 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact 2 stakeholders from the Scottish Environment Protection Agency, 2 Flood hazard consultants from Kaya Consulting and 6 PhD students from Heriot-Watt University attended this dissemination workshop.
The aim of this workshop was to disseminate and discuss the main methods / results and present the statistical database of extreme peak flows that was created during the research project for use by practitioners.
A practical tutorial with the software R was given to show how to open and anaylse the statistical database.
The audience was particularly interested in the possible impacts of climate change on extreme peak flows and the quantification of uncertainty.
They are really keen on further collaborations to implement this approach and results in flood risk assessment to better understand and anticipate climate change impacts in their practice.
Year(s) Of Engagement Activity 2016
Description Climate Uncertainty and Impact on Flood Risk - Applied Research using Future Flows 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Invited Oral Presentation at Scottish Hydrological Group & Institution of Civil Engineers meeting (15/02/2017)
Year(s) Of Engagement Activity 2017
Description SEPA presentation: Norwegian Delegation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact SEPA invited presentation - Norwegian delegation (transfer of knowledge and recent research developments)
Year(s) Of Engagement Activity 2015
Description SEPA/Environment Agency Meetings 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Discussion of research as it progresses, and outcomes
Year(s) Of Engagement Activity 2015,2016