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!
Editorial: From moments to millennia and meters to miles: Coastal variability over time and space
Tiffany Roberts Briggs, and Bret Webb
https://doi.org/10.34237/1009410
Observation of the surfing climate at Ditch Plains, New York
Mackie Myers-Aldous and Henry Bokuniewicz
https://doi.org/10.34237/1009411
The beach at Ditch Plains, New York, is a popular surfing destination on Long Island, and consequently important to the economy of this coastal community. Evidence is presented to show that the conditions favorable for surfers can result from a convergence of its particular glacial geology and the climatic expressions of waves and winds. The study site is in a gap of the glacial moraine at this location flanked by a rocky seabed east and west. Glacial erratics and clay layers likely mark the former southern edge of the moraine offshore. Into this setting, consistent waves and winds produce conditions favored by the surfing community. The study of those coastal processes particular to surfing need to be considered in shore protection project.
Evaluation of temporal steric adjustment methodologies in hydrodynamic storm surge modeling: A case study of Kwajalein Atoll
Sydney Crisanti, Fatima Bukhari, Leigh Provost, and Amanda Tritinger
https://doi.org/10.34237/1009412
Precise initialization of background water levels is fundamental to the accuracy of hydrodynamic storm surge models. However, steric variations driven by thermosteric and halosteric dynamics are frequently simplified in numerical simulations using static offsets or broad climatological means, potentially obscuring critical subseasonal variability. This study evaluates the sensitivity of the Advanced Circulation (ADCIRC) model to two temporal steric adjustment methodologies: A 24-hour pre-storm average (event-specific) and a monthly mean water level (climatological). Utilizing Kwajalein Atoll as a marine case study, quantify the impact of initialization protocols on model fidelity during historical extratropical storms. Results indicate that the temporal resolution of the steric adjustment is a governing factor in model performance, particularly during periods of oceanographic anomaly. For Storm 121, the monthly mean methodology (Method 2) failed to capture the antecedent steric setup, resulting in a systematic negative bias of -0.135 m and a Root Mean Square Error (RMSE) of 0.150 m. In contrast, the 24-hour pre-storm baseline (Method 1) successfully resolved the initial anomaly, reducing the bias to -0.032 m and the RMSE to 0.073 m, a 51% reduction in total model error. Conversely, during Storm 92, which occurred under near-climatological conditions, the divergence between methodologies was negligible (<1.1 cm difference in bias). In conclusion, relying on monthly mean steric values introduces a significant risk of underestimation during anomalous events.
Observations of infragravity wave energy on a microtidal barrier island during an extreme event
Sean McQuagge, Bret M. Webb, Stephanie M. Patch, and Jack A. Puleo
https://doi.org/10.34237/1009413
Infragravity (IG) waves are responsible for large volumes of nearshore sediment transport and therefore have a large influence on barrier island morphodynamics, especially during extreme event scenarios. While IG waves have been studied at length in the nearshore, less research has been dedicated to their behavior and contributions to morphological change of barrier islands during extreme event overwash and inundation. Continuous measurements of water pressures were collected along two cross-shore transects on Dauphin Island, AL, during Hurricane Nate (2017). Using small-amplitude wave theory, instantaneous water surface elevations were estimated from these pressures. These elevations were filtered to separate waves into IG and surface gravity wave components, and changes across the transects were characterized. IG wave energy was found to comprise a majority of the total wave energy, and its relationship to water depth and morphological change was explored. As a general observation, IG wave energy increased with water depth until a certain point where the energy began to decrease, likely due to a breakdown of IG wave generation mechanisms, while inundation continued to its peak depth. It was found that locations experiencing high IG wave energy exhibited high cross-shore sediment transport during the storm.
Research Letter: Coastal nature-based solutions and remote sensing data: Selecting performance metrics and evaluating data availability
Scott L. Spurgeon, Justin L. Shawler, Kathryn J. Smith, Loderay I.M. Bracero Marrero, and Samuel S. Jackson
https://doi.org/10.34237/1009414
While traditional field-based methods are typically used to assess project performance of nature-based solutions (NBS), the U.S. Army Corps of Engineers’ National Coastal Mapping Program (NCMP) has regularly collected coastal imagery and Lidar datasets, resulting in a wealth of information proven successful for assessing coastal storm risk, storm impacts, and dune vegetation benefits. This Research Letter identifies and describes performance metrics that are suitable for analysis using remote sensing data, using three coastal NBS project sites in Mississippi and Florida as demonstrations of the data types and analytical tools available. The intended audience for this Research Letter is coastal practitioners interested in using readily available remote sensing data to track the performance of coastal NBS. We conclude with how our examples from beach-dune and barrier-island systems are transferable to other NBS such as cobble berm revetments, mangroves, and salt marshes, among others. Development of selected performance metrics from these readily available nationwide datasets can provide decision-support value and support the creation of design guidelines, adaptive management strategies and risk-informed planning frameworks.
Hydrodynamic performance of marsh islands as Natural and Nature-Based Features: Design analysis and case studies across coastal systems
Amanda Tritinger, Sydney Crisanti, and Sally C. Dillon
https://doi.org/10.34237/1009415
This study examines the hydrodynamic functions of marsh island systems and marsh mounds in mitigating storm-induced wave action within semi-enclosed and fully enclosed coastal basins along U.S. shorelines. Employing case studies informed by numerical simulations, we quantify the impacts of storms on wave dynamics and sediment transport under scenarios with and without these features. The findings underscore the essential contribution of these features in dissipating wave energy, stabilizing shorelines, and enhancing system resilience during extreme storm events. Case studies include the New Jersey Back Bay marsh islands, Chesapeake Bay’s Swan Island, Mississippi’s Deer Island, and marsh mounds at Hamilton wetland in San Francisco Bay. Insights from these examples advance the understanding of marsh-island systems and marsh mounds as integrated components of coastal protection strategies. This work complements ongoing efforts in nature-based restoration and informs sustainable and adaptive management solutions for coastal environments.
Assessing and mapping public access along California’s coastline: A spatial analysis for the California Ocean Health Report Card
Laura M. Bliss, Linda Locklin, and Stephen B. Weisberg
https://doi.org/10.34237/1009416
Beach and shoreline access is a vital component of California culture, and one that is legally protected under the Coastal Act of 1976. However, estimates for extent of coastal access in the state are lacking. Here, we integrate multiple datasets to answer two questions: 1) How much shoreline is physically accessible to the public by walking one-quarter mile or less from an access site; and 2) What basic facilities (parking, restrooms, and accessibility improvements, such as wheelchair-friendly restroom stalls) are available at these coastal access areas? Approximately 39% of California’s coastal miles are publicly accessible. Southern California has the highest (61%), and Northern California has the lowest (25%) percentage of miles with access. However, the vast majority of the coastal population has high access to coastal areas. About 15% of the California shoreline without public access is attributable to geomorphological constraints (e.g., steep cliffs), and another 9% due to military-use restrictions. Eighty-nine percent of California beach access points had at least one basic facility, and 41% of access points had all three of the facilities assessed. The assessment developed here is part of a report card that quantifies California’s success in ocean and coastal management and can help prioritize investments in beach and shoreline access maintenance, considering anticipated climate change impacts on shoreline availability.
Public coastal access at risk: Integrating social and environmental data to assess vulnerability to sea level rise
Nathaniel Merrill, Nathan Vinhateiro, Emi Uchida, Jesse Reiblich, Elin Torell, Sarah Schechter, Leah Feldman, Claudia Weitman, and Drew Powell
https://doi.org/10.34237/1009417
Sea level rise poses significant risks to coastal infrastructure and recreational activities, limiting public coastal access. In this study, we evaluate the current use and measure the recreational value of coastal access areas in Bristol County, Rhode Island, while assessing the vulnerability of those areas to rising sea levels. By combining measurements of non-market economic value derived from cellular device location data with modeled future sea level projections, we quantify the economic value at risk under different inundation scenarios. We produce site-level results, which provide context and quantifiable measurements of social value that can guide prioritization of mitigation strategies to address future impacts. We discuss the benefits and challenges of integrating social and environmental data and methods.