Processes and landforms

Examining the natural dynamics of the coastline.

Processes and landforms

Processes and landforms

Examining the natural dynamics of the coastline.

We examine the natural dynamics of the coastline at instantaneous to decadal time. Offshore, nearshore, estuarine and beach/dune environments are investigated to examine how physical processes modify contemporary coastlines

In our research we utilise wave refraction models of sea/ocean waves over various seafloor bathymetric configurations (natural or artificial) to gain insights into sediment dynamics and transport. These are augmented by field investigations and studies of map, photographic and documentary evidence of coastal change and associated driving forces.

Key research foci are on aeolian sediment transport, beach nearshore and estuarine morphodynamics:

Aeolian Sediment Transport

Aeolian research

Wind-blown sediment from beaches to coastal dunes is an important formational process for many dune coastlines around the world. We undertake field studies into wind-blown (aeolian) sand dynamics on a number of spatial and temporal scales. High resolution sediment trapping methods are used to unravel the relationship between forcing factors and sediment bed response in natural beach-dune settings.

Investigations are focussed on effective fetch distance and its control on aeolian flux patterns, lee-side airflow dynamics at coastal foredunes and turbulence effects on sediment transport. A number of techniques are employed in this including use of electronic sediment traps, grain impact sensors, 3D acoustic anemometry and remote sensing. Our suite of instruments include 24 three-dimensional anemometers (50Hz, 3D Gill), 20 electronic sand traps (25 Hz), 18 Safire impact sensors (up to 200Hz), 17m instrument masts and an associated mobile data acquisition system, Terrestrial Laser Scanner (Faro 360), making it the largest field measurement set-up in Europe for aeolian field studies.

Recent findings have isolated the importance of offshore wind regimes and corresponding lee-side eddying in building up foredune morphology.  As part of this we also use 3-D Computational Fluid Dynamics (CFD) to model airflow over measured beach and dune terrain, validated by airflow and transport flux field data as a method to extend the spatial measurement range in natural settings.

Our group also uses CFD combined with detailed HiRISE imagery to understand formative dune processes at various locations across the surface of Mars.

Recent research collaboration has involved Dr Andreas Baas (Kings College London); Dr Kevin Lynch (National University of Ireland, Galway); Dr Keiko Udo (Japan); Dr Mary Bourke (Trinity College Dublin).

Recent aeolian grants

  • Secondary airflow patterns under offshore winds over coastal foredunes: implications for aeolian sediment transport, £470K Standard NERC grant.
  • Post-storm beach recovery through aeolian and wave processes. Travel award. Daiwa Anglo-Japanese Foundation.
  • Swash zone and aeolian sediment supply to beaches, Japan. Collaboration award. The Great Britain Sasakawa Foundation.
  • Vice Chancellor Research Scholarship 'Dune dynamics on Mars' Carin Cornwall PhD Student.

Beach Morphodynamics

Sandy beach behaviour is driven by numerous environmental variables from wave forcing to sediment type. We investigate beach morphodynamics on a number of spatial and temporal scales using empirical and modelling techniques. Nearshore bar movements, depth of disturbance and swash zone processes are examined along with other phenomena which contribute to beach morphodynamics.

At present we are studying beach morphodynamics at a variety of sites in Europe, Australia, USA and the Caribbean.

Shoreface studies

The shoreface can be defined as the zone in which waves are shoaling but not breaking in high-energy conditions. Forcing parameters such as tidal, wave-driven, wind-driven and density-driven currents may exert strong influence over seabed flows during most of the year, whereas sea waves and sea wave-driven currents largely act on the bed in higher-energy conditions.

Using marine geophysical techniques and wave modelling we examine the contemporary processes on the shoreface in fair weather and storm conditions and in particular investigates the antecedent sediment supply and its geological setting and their influence on the modern dynamics of the shoreface profile itself.

Coastal evolution

Increasing attention is being focussed on the coastal zone due to the rapid development of this region and the sometimes hazardous impacts of short- and long-term natural processes. Episodic and cyclical events from hurricanes and severe storms have had dramatic effects in many coastal regions.

Analysis of mesoscale trends in storm occurrence, sea-level changes and longer term (decadal) coastal response has never been more important. We focus on all these themes.