www.floodrisk.org.uk EPSRC Grant: EP/FP202511/1

From offshore wave to coastal erosion and overtopping

Nicolas Chini1, Lucy Bricheno2, Chris Wilson2, Maurice McCabe1, Judith Wolf2 & Peter Stansby1

1 The University of Manchester2 National Oceanography CentreNicolas.Chini@manchester.ac.uk

Context and Motivations

Operational Modelling Systems

Predicting offshore extreme conditions

But missing nearshore physical processes

Need to downscale the offshore predictions in order to assess water levels and wave conditions at the toe of the sea defence

Creation of an integrated modelling system and application to the November 2007 event that causes £170,000 worth damages at Walcott on the East Coast

GLOBAL CLIMATEMODELLING

climate scenario A1B

REGIONAL CLIMATEMODELLING

offshore waves

tides surges

COASTAL CLIMATEMODELLING

nearshore waves

tides surges

OVERTOPPINGMODELLING

CLIFFRECESSION

BEACH PROFILEMODELLING

Simulation of nearshore conditions

Comparison with field measurements

Estimation of the nearshore conditions off Walcott for the overtopping modelling

21 24 27 30 33 36 39 42 450

1

2

3

4

5

6

Day in year 1986

H m0 (m

)

measurementmodel

Long term coastal wave modelling

Scatter plot of water level and significant wave height over 140 years off Walcott without including SLR

Tyndall Coastal program GHG emission scenario :

A1B

From 1960 to 2100

Cliff recession (TOMAWAC - SCAPE)

Extreme value joint probability

Scatter plot of water level vs SWH including joint probability isolines in 2100 without slr and showing the location of the nov 2007 event (red point)

The same but with 1m SLR in 2100

Conclusions

- A model has been set up and validated to transfer wave parameters towards the shore including the effect of varying water depth, requiring small computational times.

- Regional modelling of water levels is sufficient for predicting nearshore conditions

- Assessment of climate change scenarios and SLR impacts on nearshore wave conditions

- Analyses of climate change and SLR impacts on cliff recession (SCAPE)

- Simulation of the nearshore conditions for 2007 event at Walcott inputs for overtopping modelling

www.floodrisk.org.uk EPSRC Grant: EP/FP202511/1

AcknowledgementThe research reported in this presentation was conducted as part of the Flood Risk Management Research Consortium with support from the:

• Engineering and Physical Sciences Research Council • Department of Environment, Food and Rural

Affairs/Environment Agency Joint Research Programme • United Kingdom Water Industry Research• Office of Public Works Dublin• Northern Ireland Rivers Agency

Data were provided by the EA and the Ordnance Survey.