Gravel barrier resilience in a changing climate (#gravelbeach)

Increasing our understanding of gravel barrier dynamics to develop practical management tools.

Beach and barrier systems with a substantial gravel fraction, including ‘pure’, ‘composite’ and ‘mixed sand-gravel’, are common globally at mid to high latitudes. These geomorphological features, collectively referred to herein as ‘gravel barriers’, represent up to 20% of the wave-exposed coastline of Great Britain. They provide natural protection against coastal flooding and erosion, and support unique ecosystems. However, much of our ability to predict their morphodynamics comes from research on sandy coasts, which is flawed in translation. Specifically, our understanding and capability to model the morphodynamics of barriers comprising sand-gravel mixtures is significantly lacking.

Gravel barriers have an important role in providing coastal protection. Traditionally they have been maintained through sediment recycling and beach nourishment. However, evidence indicates that some of these practices negatively impact barrier stability making it unsustainable, particularly under rising sea levels. Thus, this project (#gravelbeach) aims to develop, reliable, consistent and appropriate approaches for working with, and making space for, these natural features, to enable more sustainable and adaptive national-scale management practices.

#gravelbeach will deliver new scientific advances through an integrated and comprehensive morphosedimentary evaluation, intense field observations, targeted laboratory experiments, and numerical model development/simulation. Cross-shore stratigraphy and groundwater analysis will offer insights into the geomorphological controls on barrier dynamics and evolution, and the development and persistence of some of the ‘vegetated shingle’ ecosystems. Implementing this enhanced understanding into numerical tools capable of modelling barrier morphodynamics over timescales relevant to management decision making, ranging from storms through seasons and decades to centuries, will provide confidence to bring these natural changes and responses into sustainable coastal management methods. This will increase coastal resilience and reduce vulnerability to climate change.

To enable fundamental improvements in the management of gravel coastlines, #gravelbeach will:

1. provide a typology of gravel barrier systems
2. enable quantitative process understanding of barrier response over a range of temporal scales
3. develop new gravel-specific predictive tools
4. inform future management decisions related to barrier evolution and changes to the barrier ecology
5. provide case study sites, involving stakeholders at a local, regional and national level, to demonstrate transferability of the results and create a blueprint for managing gravel coastal systems.