The abstracts of this issue are below. Note that ASBPA members now have access to a full digital edition of Shore & Beach (click here). Become a member now to get immediate access to the latest issue!
Guest Editorial: Cobbles — a versatile coastal component
Lesley Ewing
https://doi.org/10.34237/1009340
Research Letter: Shoreline typology of the United States
Nick Brown
https://doi.org/10.34237/1009341
The United States shoreline is vast, spanning over 184,000 miles and consisting of diverse geomorphic settings that range from beaches and marshes to rocky cliffs and coastal tundra. Historically, shoreline assessments nationally have focused solely on length, and geomorphic typology reviews have been concentrated within states or regions. This paper presents a synthesized national shoreline typology analysis and updated estimated shoreline length for the United States, including the Atlantic, Gulf of Mexico, Pacific, and Great Lakes shorelines. Results show that the overall dominant shoreline typology is vegetated shorelines (62.8%), followed by beaches (15.2%), rocky/ steep-sloped (13.0%), armored (8.1%), and tidal flats (0.9%). The paper also summarizes the lengths for each shoreline type by state and region, providing a modern estimated shoreline length of 184,828 miles.
Multi-year morphological changes at two adjacent high-energy composite beaches: La Palue and Lostmarc’h in northwest France
Stéphane Bertin, Jérôme Ammann, Galien Duault, Marion Jaud, and Clara Saint-Jean
https://doi.org/10.34237/1009342
Composite beaches, defined by a steep gravel berm fronting a low-angle sandy foreshore, remain understudied despite their increasing relevance as models for nature-based coastal defenses called dynamic cobble berm revetments. To support development of effective designs in diverse coastal settings and improve understanding of coastal change and resilience across beach types, detailed field observations of composite beaches are required. Since September 2020, a regular monitoring program has been conducted on two adjacent high-energy composite beaches — La Palue and Lostmarc’h on the Crozon peninsula (northwest France). Using drone photogrammetry, this program investigates the morphodynamic response of gravel berms to varying wave energy and changes in sand level on the beach face. The results reveal consistent temporal patterns, including a pronounced seasonal signal: The gravel berm tends to widen over winter, when sand levels are lower, whereas gravel exposure decreases during calmer, low-energy periods. Berm and foreshore morphologies also exhibit large interannual variability driven by fluctuations in winter wave energy and storm characteristics. Integration of high-frequency satellite imagery further demonstrates that gravel exposure adjusts rapidly to shifts in wave forcing and sand levels. These findings highlight the dynamic and coupled nature of gravel-sand interactions on composite beaches and underscore the need for comparative investigations across sites with differing hydrodynamic and sedimentological settings.
Coastal Observation: Cobbles: Coastal storytellers, adaptation engineers, and unlikely heroes
David Revell
https://doi.org/10.34237/1009343
Cobbles play a critical yet underrepresented role in coastal geomorphology and shoreline resilience. This paper synthesizes field observations and monitoring results from dynamic cobble revetments and living shoreline projects along the U.S. West Coast, including Cape Lookout, OR, and Goleta Beach and Surfer’s Point, CA. Cobble berms dissipate wave energy through mobilization, interlocking, and permeability, providing adaptive, low-impact protection while maintaining sediment exchange and habitat value. Integrating cobble processes into sediment management frameworks enhances system-scale resilience and supports nature-based adaptation to sea level rise. Improved understanding of cobble transport, sourcing, and regulatory recognition is essential for advancing coastal sediment management and design practices.
Surfers Point managed shoreline retreat project: Lessons from a cobble beach pilot on a dynamic delta
Bob Battalio, Marc Beyeler, David M. Hubbard, A. Paul Jenkin, Kiki Patsch, and Louis A. White
https://doi.org/10.34237/1009344
The Surfers Point Managed Shoreline Retreat Project in Ventura, California, USA, demonstrates an alternative to conventional shoreline armoring by using natural materials and geomorphic design to avoid the negative consequences associated with riprap and seawalls. This paper evaluates the physical performance of Phase 1 of the project, which constructed a dynamic cobble berm/sandy beach and dune system within the active delta of the Ventura River. The design replicated shore form and function while relocating infrastructure inland to restore space for coastal processes. The project met multiple objectives including erosion and flood mitigation, access and recreation benefits, and restoration of natural morphology and ecology. Implementation required extensive coordination among public landowners, managers, regulators, funders, stakeholders, and the public. The engineering design consists of a base layer of cobble, topped with sand and vegetated dunes, intended to respond dynamically to elevated waves and river flows, and variable sediment input from upcoast and the Ventura River. Monitoring from 2011 through 2024 shows a dynamically stable and resilient system. The project provides a valuable case study for cobble-based living shorelines in high-energy coastal environments. An applied geomorphology approach informed by reference sites is a valid basis for establishing the geometry and materials for cobble-boulder berms and vegetated dunes. Landward realignment of built infrastructure was required to provide sufficient space for natural processes. Setback distances were informed by wave run-up calculations. Parametric equations for wave run-up combined with engineering judgement can inform development setbacks. Native dune vegetation and low-relief foredune geometry have proven resilient within this coastal flood plain, with the cobble berm providing protection. The natural infrastructure has accommodated erosion events, dissipated wave run-up and recovered repeatedly with sand deposition since construction in 2012.
Physical model studies and design guidelines for a new type of composite dynamic revetment
Mauricio A. Wesson, Mark Wagstaff, Mitchel Provan, and Timothy Wagner
https://doi.org/10.34237/1009345
A pebble or cobble beach, also known as a dynamic revetment, can provide a softer shore edge while also providing the resiliency necessary to prevent shoreline erosion. Research on dynamic revetments is very limited, especially when looking at design-ing for different sizes of cobble, and thus reliance on numerical solutions can lead to gaps in the expected performance of the design. For a proposed cobble beach on Lake Michigan’s Chicago shoreline, large-scale physical model tests were conducted to evaluate how the physical model would perform compared to the numerical models. These tests utilized a wave flume to run six alternative cross-section configurations. Two cross-sections evaluated small cobbles of uniform size, two configurations added a partially submerged detached breakwater in front of a uniform cobble beach, and the last two configurations looked at how a combination of small and large cobble behaved. Tests on the uniform configurations showed there was a feedback mecha-nism between the surging wave-breaker type and beach profile-shape deformation, resulting in the formation of a scour step at the toe and a large crest. Adding a de-tached breakwater provided no changes in the wave breaker causing scour step and crest formation. The composite dynamic revetment profile resisted formation of the scour step by reinforcing the toe and changing the wave breaker type to a plunging wave that breaks further offshore. This change disrupts the feedback mechanism that leads to the typical dynamic revetment profile. Simple mathematical relationships were derived to aid design of a new type of composite dynamic revetment offering improved coastal performance.