From the Editor’s Desk: A wave of waves, and the stories they tell
Lesley C. Ewing
The value of beach nourishment on a complex shoreline
James R. Houston
Lee County has the most complex shoreline among Florida’s 25 counties where beach nourishment has been placed. It has eight shoreline breaks such as passes (inlets) that have produced a very complex pattern of both significant shoreline recession and accretion since 1858. Beach nourishment would seem problematic on those shorelines that have experienced significant long-term recession. However, nourishment has been very successful, widening beaches an average of 132 ft from their first nourishments to 2018 along shorelines that had historically receded hundreds of feet. Tourism is the backbone of Lee County’s economy, supporting one of every five jobs. Beaches are the key to the county’s tourism, with more day visits annually than to the 12 most visited National Parks in America. Over 80% of Lee County tourists are beach tourists, and they had a 2019 economic impact in Lee County of $4.3 billion. Beach tourists generated $843 million in total taxes to federal, state, and local governments with these governments receiving $580, $160, and $40, respectively, in taxes for each $1 that they spent on beach nourishment. Moreover, Lee County received an economic impact of $690 for every $1 spent on beach nourishment. International beach tourists spent $462 million in Lee County in 2019, providing a gain in the U.S. international balance of payments. An investment in beach nourishment produces such compelling returns in taxes generated by beach tourists that the state and federal governments should reassess their priorities for this investment versus investments in inland flood control and navigation.
Adaptation pathways for climate change resilience on barrier islands
Dylan Anderson, J. Casey Dietrich, Sarah Spiegler, and Cayla Cothron
Coastal communities throughout the world will be faced with policy decisions that affect their resilience to climate change, sea level rise, and associated impacts. Adaptation pathways, a holistic approach to policy development, may be an ideal framework for municipalities to consider in low-lying, dynamic environments such as barrier islands. Adaptation pathways identify hypothetical future timelines whereby communities adopt a different policy in response to new environmental conditions. This takes into account changing conditions and resulting hazards that exceed a threshold agreed upon by the community. In this paper, we focus on barrier island communities and give an overview of adaptation pathway methodologies, highlight several common policies considered to increase resilience, review how coastal scientists have thus far contributed to such methods, and discuss specific research agendas that could aid in future implementations. Although the use of adaptation pathways is still in its early stages in many coastal communities, the success of the process is dependent on contributions from both quantitative hazard research and consistent engagement with stakeholders in an iterative co-development of prioritized policy trajectories. Scientific needs include: better understanding of future hazards due to climate change and sea level rise, better predictions of time-dependent processes such as barrier island response to human alterations to natural coastal defense systems, and improved communication between physical scientists, social scientists, managers, and stakeholders.
The Oktober Flut: An anomalous extreme high-water event in Annapolis, MD, USA, October 2021
Liliana Velásquez-Montoya, Alexander R. Davies, Peter Guth, Tori Tomiczek, Alexander Laun, Anna Wargula, Gina Henderson, Cecily Steppe, and Louise Wallendorf
Between 28 and 30 October 2021, Annapolis, Maryland, USA, experienced the third highest flood event on record, referred to as the “Oktober Flut.” Unlike many of the extreme coastal flood events that have impacted Annapolis in the past, the Oktober Flut was not associated with a tropical or post-tropical cyclone. Instead, sustained wind forcing from a series of passing extratropical storms drove anomalously high water levels. The maximum observed hourly water level during the event was 4.88 ft above mean lower low water (MLLW). This exceeded the Moderate Flood Stage, defined by the National Weather Service (NWS) as 3.3 ft (MLLW), and had an annual exceedance probability of 5.2%. In total, flood waters exceeded the NWS Minor Flood Stage (2.6 ft MLLW) for 78 non-consecutive hours over multiple tidal periods. Relative sea level rise and increasing instances of coastal nuisance flooding events, like the Oktober Flut, have the potential to impact the local economy in Annapolis, MD, and operations at the geographically adjacent U.S. Naval Academy. Coastal nuisance flooding events also challenge existing community resilience efforts and initiatives, particularly those related to preparing for natural hazards. This paper provides an overview of the meteorological factors that drove the anomalously high-water levels and coastal flooding at the U.S. Naval Academy. In addition to data analysis from fixed, long-term sensors maintained by federal partners, observations from spotdeployments in advance of the storm are also presented. The results are discussed with respect to the storm impacts on infrastructure and facility preparedness. Lessons learned are documented with the aim of informing other coastal communities on how to better assess local flood-specific action plans, based on the accuracy and timing of forecast data.
Strategic approaches to sediment management for restoration of a deltaic plain
Syed M. Khalil, Beth M. Forrest, Richard C. Raynie, and Edward L. Haywood
Sediment resources are essential to fulfill the State of Louisiana’s commitment to implement a Coastal Master Plan (CMP) to mitigate its chronic land loss, protect more than 2 million people who live in the coastal zone, and to save Louisiana’s rapidly disappearing complex and fragile ecosystem. With increasing rates of sea level rise and increased storm intensities along with continuing subsidence, the future quantity of sediment needed for ecosystem restoration will significantly increase, and at the same time, the accessibility to the sediment resources will become much more technologically challenging and cost prohibitive. These devastating environmental circumstances will compound the complexities of a sustainable ecosystem restoration in coastal Louisiana. Restoration projects must be robust enough (using adequate compatible sediment) to survive future environmental scenarios while the quantity of actively captured sediment resources available for critical restoration projects is likely to decrease, rendering the dredging and transporting of these sediment resources increasingly difficult and costly. These challenges will be an opportunity for Louisiana to utilize more sustainable, passively captured sediment (i.e. using large sediment diversions from the Mississippi River) to help offset limitations concerning actively harvesting sediment and to build and sustain wetlands in coastal Louisiana. Although any large-scale and meaningful restoration of the Louisiana coastal plain must involve sediments from the Mississippi River, the scope of this paper is restricted to offshore sediment resources. A strategic approach to optimize utilization of sediment resources includes minimizing handling and transport costs by first locating potential sediment sources and then identifying the most cost-effective way of using that sediment resource for restoration. The project cost and its success are defined by the sediment selection process. Thus, it is suggested that improvements in planning and management of multiple-use conflicts be based on regional understandings of sediment resources for an approach that maximizes benefits. The Louisiana Sediment Management Plan (LASMP) was conceptualized and formulated to improve planning and coordination of sediment utilization in Louisiana. This plan has evolved and has been adaptively managed in the absence of any prototype. Restoration activities are further complicated by competing interests and multiple uses of limited sediment resources. To maximize the availability of offshore sediment, the state is collaborating with the Bureau of Ocean Energy Management (BOEM) and engaging with other stakeholders in deciding the fate of decommissioned pipelines and to strategically plan the installation of new pipelines in offshore areas identified as significant sediment resources with the intent of protecting identified sediment resources for future use. Future offshore wind-farms may pose new challenges but simultaneously offer opportunities for conflict resolution via stakeholder engagement. For the past two decades the State of Louisiana/Coastal Protection and Restoration Authority (CPRA) of Louisiana has developed a considerable institutional knowledge base and expertise and improved the art and science of sediment management. A robust process has been adaptively developed with interagency collaboration and coordination to resolve conflicts/issues concerning obstacles to resource access. LASMP is not only a template for sediment management for coastal restoration, but also provides guidance for stakeholder engagement and conflict resolution for competing needs of seafloor resources especially in Northern Gulf of Mexico (NGOM).
Rip current and channel detection using surfcams and optical flow
Sean P. McGill and Jean T. Ellis
Rip currents are a common, naturally occurring surf-zone hazard that pose a risk to beach patrons. This study presents a remote-sensing-based algorithm to detect rip currents and rip channels. Optical flow-based computer vision methods are implemented to analyze large data sets and the automatic detection of these features. Surfcam video was collected from dissipative (La Jolla, CA), intermediate (Long Beach, NY), and reflective beaches (Pensacola Beach, FL) to demonstrate the efficacy of the methods. A clustering technique using the dominant wave period was implemented to transition from detected offshore movements to rip currents. The methods presented in this paper were used to detect 20,327 rip currents and 1,100 rip channels. The average accuracy for rip current and rip channel detection was 67.3% and 96.2%, respectively. The remote-sensing-based detection methods can be adapted for use on other video-based equipment and, with additional modifications, can be implemented in an operational capacity.
Research Letter: Improved wave predictions with ST6 Physics and ADCIRC+SWAN
Carter Day and J.C. Dietrich
The Simulating WAves Nearshore (SWAN, Booij et al. 1999) model is used widely for predictions of waves in coastal regions. Like other spectral wave models, SWAN uses parameterizations to represent wave evolution due to sources (e.g. wind), sinks (e.g. whitecapping, bottom friction, depth-limited breaking), and resonance (e.g. quadruplet and triad wave-wave interactions). Each parameterization is based typically on observational data to represent the transfer of energy to, from, and between waves. It is necessary for each term to represent its physical process, but it is also necessary for the terms to be calibrated collectively to represent their combined effects on wave evolution. The calibrated wave predictions can then be coupled with models for circulation and coastal flooding, e.g. ADvanced CIRCulation (ADCIRC, Luettich et al. 1992).
SWAN release version 41.20 included a new “package” of wave physics (referred to as ST6 physics). This package has new parameterizations of wind input, whitecapping, swell dissipation, wind speed scaling, and other processes (Rogers et al. 2012). The ST6 physics have been adopted by other wave models (e.g. NOAA’s WaveWatch III, Liu et al. 2019), and it may become the preferred physics package for SWAN. However, because the ST6 physics package has changes to so many parameterizations, it is necessary to quantify its effects on wave predictions. Recent studies (e.g. Aydogan and Ayat 2021) have demonstrated the benefits of using the ST6 physics in the standalone version of SWAN, but its effects have not been quantified for the coupled ADCIRC+SWAN (Dietrich et al. 2011a), which is used for real-time forecasts during impending storms. Do the ST6 physics improve the ADCIRC+SWAN wave predictions?
Coastal Forum: New 2021 sea level rise projections by the IPCC
James R. Houston
The Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC) should New 2021 sea level rise projections by the IPCC have been completed in 2019 based on IPCC’s normal six-year publication cycle of climate assessments following its Fifth Assessment Report (AR5) that was published in 2013 (IPCC 2013). A heavy review load caused by an explosion of research on climate change that needed to be evaluated in addition to the Covid- 19 pandemic caused a delay in AR6 until 2022. However, the portion of AR6 that deals with the physical basis for climate change including sea level rise was published in August 2021 (IPCC 2021a). IPCC (2021a) was supported by updated projections of the contributions of Antarctica (IPCC 2019) and Greenland (The IMBIE Team 2020) to sea level rise. IPCC (2021a) was peer reviewed extensively with the first draft receiving comments from 750 reviewers and the second draft from 1279 (IPCC 2021b).
An ASBPA White Paper: Human and ecosystem health in coastal systems
Nicole Elko, Diane Foster, Gregory Kleinheinz, Britt Raubenheimer, Susanne Brander, Julie Kinzelman, Jacob P. Kritzer, Daphne Munroe, Curt Storlazzi, Martha Sutula, Annie Mercer, Scott Coffin, Carolyn Fraioli, Luke Ginger, Elise Morrison, Gabrielle Parent-Doliner, Cigdem Akan, Alberto Canestrelli, Michelle DiBenedetto, Jackelyn Lang, and Jonathan Simm
U.S. coastal economies and communities are facing an unprecedented and growing number of impacts to coastal ecosystems including beach and fishery closures, harmful algal blooms, loss of critical habitat, as well as shoreline damage. This paper synthesizes our present understanding of the dynamics of human and ecosystem health in coastal systems with a focus on the need to better understand nearshore physical process interactions with coastal pollutants and ecosystems (e.g. fate and transport, circulation, depositional environment, climate change). It is organized around two major topical areas and six subtopic areas: 1) Identifying and mitigating coastal pollutants, including fecal pollution, nutrients and harmful algal blooms, and microplastics; and 2) Resilient coastal ecosystems, which focuses on coastal fisheries, shellfish and natural and nature-based features (NNBF). Societal needs and the tools and technologies needed to address them are discussed for each subtopic. Recommendations for scientific research, observations, community engagement, and policies aim to help prioritize future research and investments. A better understanding of coastal physical processes and interactions with coastal pollutants and resilient ecosystems (e.g. fate and transport, circulation, depositional environment, climate change) is a critical need. Other research recommendations include the need to quantify potential threats to human and ecosystem health through accurate risk assessments and to quantify the resulting hazard risk reduction of natural and nature-based features; improve pollutant and ecosystem impacts forecasting by integrating frequent and new data points into existing and novel models; collect environmental data to calibrate and validate models to predict future impacts on coastal ecosystems and their evolution due to anthropogenic stressors (land-based pollution, overfishing, coastal development), climate change, and sea level rise; and develop lower cost and rapid response tools to help coastal managers better respond to pollutant and ecosystem threats.
O’Brien Award Winners: An interview with Scott Douglass
The 2021 Photo Contest Winners