A Risk-based Framework for Predicting Long-term Beach Evolution

EPSRC Grant EP/C005392/1
 
Prof Dominic Reeve; Prof Andrew Chadwick; Dr Mark Spivack (Cambridge); Dr Ping Dong (Dundee); Dr David Simmonds; Dr Mark Davidson

Effective management of the coastline is crucial to the protection and preservation of all coastal communities. In the UK, authorities responsible for engineering coastal defences against erosion and providing protection against coastal flooding are now required by government to produce plans that will look 70 years into the future. The aim of this project is to protect existing and future coastal development and land use against coastal erosion, the effects of rising sea levels and increased storminess aggravated by geological subsidence and global warming. Currently, there are no reliable methods for predicting either how the natural coastline will evolve over this timeframe or the likelihood of a piece of coastline being damaged beyond recovery such that it fails to protect from flooding. The evolution of the coastline over time is determined by its exposure to processes that add to or erode from it.

Figure 1. Field site: Christchurch Bay

Beaches are the most dynamic of coastal features and evolve in relation to the supply of sediment from adjacent cliffs, sandbanks or other beaches and the wind, waves and currents that move the sediment around. The research developed here aims to develop a means of making predictions of long term beach evolution and to assess the probability that a given piece of coast will fail to protect from flooding. The predictions will be made using computer models that will be calibrated against a field experiment and tested against historical surveys of the coastline. The methodology we develop will enable UK coastal authorities and others responsible for coastal management to achieve predictions of shoreline change over the time scales now required by Government.  It is thus important not only to develop the framework, but also to demonstrate its practicability using a standard of data quality and coverage that can be reasonably achieved by UK coastal authorities.   The methodology will also be capable of worldwide application.

To achieve the stated aims of this project, we will integrate the three following activities:

A Uncertainty and Process Modelling.

The objective of this activity is to formulate new morphodynamic models for predicting the stochastic behaviour of defined lengths of beach, (the elements of the system from the perspective of reliability theory), at both operational and strategic scales.

B System Reliability Framework Development. 

The objective in this activity is to apply system reliability techniques to calculate the probabilities of shoreline failure (defined as occurrence of an erosion event that exceeds a prescribed level) along a coastline within a strategic life cycle, usually 50-100 years.

C Field Monitoring, Data Assimilation and Analysis.

This activity involves the collection of the essential data and establishing the ground truth for both activities A & B.  The analysis will also focus on techniques for identifying the definitive processes that control morphodynamic behaviour at different spatial and temporal scales.

More details will be posted as the project progresses.