Boulder Transport Dynamics in Coastal Environments

Coastal boulder transport comprises the detachment, movement and deposition of large clasts by extreme wave activity, encompassing both high‐energy storm waves and tsunamis. These boulders, often weighing tonnes and perched well above normal sea level, serve as tangible archives of past marine incursions and inform our understanding of coastal hazard regimes. Detachment mechanisms include quarrying and notch undercutting of rocky platforms and cliff faces, driven by sustained hydrodynamic pressures and, in particular, impulsive forces generated by breaking waves or bore fronts. Once mobilised, boulder trajectories and resting positions depend on a complex interplay between wave height and period, local bathymetry, platform morphometry, boulder shape and mass, and the presence of geomorphological controls such as fractures and platform roughness. Advances in field measurement—ranging from high‐resolution unmanned aerial surveys and LiDAR scanning to laboratory wave‐flume experiments and phase‐resolving numerical models—have refined estimates of wave power required for movement, revealed the limitations of classical force‐balance equations, and emphasised the importance of three‐dimensional boulder geometries. Globally, studies from temperate rocky shores to tropical island settings illustrate that both storm and tsunami events can produce overlapping boulder signatures, underscoring the need for multidisciplinary approaches to discriminate emplacement mechanisms. Improved quantification of wave forcing and boulder transport enhances coastal risk assessments, guides resilience planning and informs the interpretation of palaeoenvironmental records.

Research from Nature Portfolio

A new methodology for extracting coastal boulder shapes concealed beneath dense vegetation harnesses combined UAV‐mounted and mobile LiDAR surveys to generate high‐fidelity point clouds. A novel filtering algorithm isolates boulder surfaces from surrounding foliage, enabling accurate 3D reconstructions. Incorporation of these detailed geometries into forward‐type transport models substantially improves estimations of wave heights associated with past extreme events. The approach promises broader applicability in unveiling hidden geological and archaeological features and represents a significant advance in field data acquisition for boulder transport studies.

Boulder Transport Dynamics in Coastal Environments publication trend

The graph below shows the total number of articles in boulder transport dynamics in coastal environments across all publications each year (not limited to Nature Index journals).

Technical terms

Boulder transport model: A mathematical or numerical framework that relates wave forcing and boulder characteristics to predict detachment, movement and deposition of coastal boulders.

Impulsive wave force: A short‐duration, high‐magnitude pressure exerted by breaking waves or bore fronts on coastal structures or boulders.

Structure from Motion–MultiView Stereo (SfM‐MVS): A photogrammetric technique using overlapping images to reconstruct three‐dimensional models of objects or terrain.

Point cloud: A set of data points in space obtained by LiDAR or photogrammetry representing the surface geometry of objects.

References

1. Elucidation of wave pressure acting on a wave-cut notch beneath a coastal cliff based on laboratory experiments and numerical modeling. Ocean Engineering (2023).
2. The application of UAV-derived SfM-MVS photogrammetry for the investigation of storm wave boulder deposits on a small rocky island in the semi-enclosed Northern Adriatic Sea. Geomatics Natural Hazards and Risk (2023).
3. A new point cloud processing method unveiled hidden coastal boulders from deep vegetation. Scientific Reports (2023).
4. Systematic Review Shows That Work Done by Storm Waves Can Be Misinterpreted as Tsunami-Related Because Commonly Used Hydrodynamic Equations Are Flawed. Frontiers in Marine Science (2020).