The abstracts of this issue are below. Note that ASBPA members only 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!
From the Guest Editors Desk: Navigating the turbulent seas: The impact of extreme events on our coasts
Tiffany Roberts Briggs, Lindino Benedet, and Tim Kana
From the Editor’s Desk: Together, we’ve made shores and beaches better
Lesley C. Ewing
Integrating Hurricane Ian-induced morphology change and GIS-based channelization modeling for barrier island vulnerability
Leanne Hauptman, Tiffany Roberts Briggs, and Diana Mitsova
https://doi.org/10.34237/1009241
Beaches are vital for storm protection to coastal communities. The nearshore environment, subaerial beach, and dune system provide a first line of defense against hurricane impacts. Hurricane Ian made landfall in Lee County in 2022 and caused devastating damage to coastal communities, estimated at more than $112 billion U.S.. This study aims to create an integrated approach to analyze Hurricane Ian’s impacts on Estero Island, in Lee County, Florida, by examining changes in elevation, shore- line morphology, beach volume, and modeled channelization linked with estimated property damage to the households’ demographic and socio-economic characteristics. The modeled channelization resulting from receding flood waters and ebb surge is compared to impacts on the barrier island’s morphology and estimated damages. The study found that Estero Island sustained volume loss to the subaerial beach after Hurricane Ian with models indicating channelization of water across the barrier island and a greater number of buildings with increased damages were associated within 30 m of the modeled channels. Census data indicated that over 50% of the population on the island is 65 years of age and older, with the majority of households in income brackets below $100K, and approximately 17% living in poverty. The findings from this study present the importance of an integrated approach for extreme events for vulnerable populations, such as those on Estero Island, with a particular emphasis on addressing the needs of elderly residents, lower-income households, and structures built near modeled channels for future management efforts.
Hurricane Idalia (2023)-induced dune erosion along west-central Florida barrier-island coast and post-storm restoration
Ping Wang, Elizabeth L. Royer, and Sophia M. Gutierrez
https://doi.org/10.34237/1009242
Hurricane Idalia made landfall on 30 August 2023 along the relatively sparsely populated Big Bend coast of Florida as a strong Category 3 hurricane. Although the heavily developed west-central Florida barrier islands were not in the direct path of Hurricane Idalia, the distal passage of the storm generated a combined storm surge and high wave conditions that were favorable for inducing severe dune erosion. Since a significant portion of the studied beaches were regularly nourished, the fact that the storm impact occurred near the end of a beach-nourishment cycle exacerbated the dune erosion due to the generally narrow pre-storm beach. An emergency artificial dune restoration was started within 1.5 months after the storm impact and completed in four months. The artificial dunes were approximately 0.5 to 1.0 m higher than the natural dunes, 2.0 m-2.5 m above the beach versus 1.5 m-1.8 m above. A significant portion of the coastal dunes that were developed from the roughly 40 years of repeated beach nourishment were eroded. Degree of dune erosion can be reduced by a wider pre-storm beach and intertidal zone, in addition to the presence of a nearshore bar. Wide beach-intertidal zone and nearshore bar also improve the performance of the post-storm artificial dune restoration. A minimum of 10-m beach width at the dune base was necessary for the post-Idalia constructed dunes along the west-central Florida coast to last through the first winter. A combined beach and dune restoration would be ideal to mitigate storm impact. Management obstacles should be overcome to enable synchronized beach-dune nourishment. Emergency dune restoration alone may not be a sustainable longer-term solution.
Evaluating the response of a pilot dune restoration project on an urban beach to an extreme wave surge event
Kyle A. Emery, Timothy I. Baxter, Maxmilian C. Callahan, Kyle C. Cavanaugh, Jenifer E. Dugan, Laura E. Engeman, David M. Hubbard, Karina K. Johnston, Ian J. Walker, and Jenna Wisniewski
https://doi.org/10.34237/1009243
Coastal dunes are globally recognized as natural features that can enhance coastal resilience and protection from wave events, storm surges, coastal flooding, and longer- term sea level rise. As a result, dune restoration is being increasingly used along urban and natural coasts as an adaptation option for climate change. However, information on the performance of restored dunes in response to extreme events is limited. On urban beaches where management includes grooming, dunes are often degraded or absent, leaving coastal communities more vulnerable to flooding and erosion during storms and wave events. Following an extreme wave surge event in December 2023, we compared the performance of a small (1.2 hectare) pilot dune restoration on an intensively groomed urban beach in southern California to an adjacent mechanically groomed control site. We used total water level (wave setup, tide, wave runup) as a proxy for flooding potential. The average wave runup incursion distance was extended 13.6 m farther inland on the groomed control site compared to the dune restoration site. This result demonstrates the potential for restored dunes to enhance flood protection and the potential for increasing coastal resilience using nature-based solutions on urban beaches.
The Shade Curtain Barrier, a new storm surge barrier concept for the San Luis Pass (Texas)
M.M.J. van Schaijk, S.N. Jonkman, E.C. van Berchum, and J. Figlus
https://doi.org/10.34237/1009244
Many low-lying, densely populated coastal areas across the world are under threat of hurricane-induced floods. In response to this threat for the upper Texas coast, the U.S. army Corps of Engineers (USACE) has proposed a plan to reduce the risk of flooding for the Greater Houston-Galveston Metropolitan Area (GHMA) and Galveston Bay. This plan includes a storm surge barrier at the entrance channel to Galveston Bay (Bolivar Roads), while the other inlet at San Luis Pass (SLP) remains open. However, leaving SLP open could still result in a significant rise in the water level of Galveston Bay during storm impact, potentially weakening the overall flood risk reduction strategy. This paper introduces and conceptualizes an innovative barrier for the San Luis Pass. It would protect against storm surge, while also taking the local natural habitat and landscape into account. Conventional storm surge barriers do not fulfill all these requirements for the San Luis Pass. The “Shade Curtain Barrier” concept is proposed as a new barrier type. It functions by being deployed (i.e., rolled down) from the highway bridge across SLP ahead of forecast extreme conditions and stored rolled-up underneath the bridge during normal conditions. The main advantage of this barrier is that it has very limited impacts on flows, sedimentation, and the environment in daily conditions. Preliminary structural calculations have been made to test the resistance of the barrier and simple experiments have been conducted to test its performance on both glass and sandy bottoms. Although the concept is in a very early stage of development, it is a promising solution for a storm surge barrier at SLP to contribute to a resilient Texas coast and it may also be of interest for other bays and estuaries. However, further research is required to verify the functionality and safety of this type of barrier.
Effects of soil properties on erosion and breaching of natural coastal barriers under extreme storm surges
Saber M. Elsayed, Hocine Oumeraci, and Nils Goseberg
https://doi.org/10.34237/1009245
Natural coastal barriers (NCB), e.g., barrier islands and dunes, represent important defense features against storm surges and coastal flooding. Due to climate change, the probability of extreme storms has been increased. Consequently, NCB may suffer significant erosion, which increases their breaching probability. However, available numerical models for NCB breaching still predict locations and sizes of possible breaches with moderate accuracy. This observation highlights the need for a deeper understanding of the factors triggering the alongshore variable response of NCB to storm surges so that weak locations can be determined. This exploratory study offers a synthesis of evidence that alongshore varying soil permeability of unvegetated NCB may control the alongshore varying abiotic soil resistance to erosion and determine possible breaching locations. Following research, therefore, presents an extension to the XBeach model, now accounting for spatial variability of soil resistance through soil permeability. To numerically quantify soil permeability effects on wave-induced breaching, the extended XBeach has been applied to a synthetic case study of spatially varying soil resistance. Results revealed that longshore variability of soil resistance along the barrier is mainly triggered by spatially varying permeability. The results also guide toward enhancing the resilience of NCB against breaching through improving their soil properties.