Implications, Planning, and Design Considerations for Rising Sea Levels at the Coast

The ASCE/Coasts, Oceans, Ports and Rivers Institute (COPRI) Coastal and Estuarine Hydroscience Committee has taken on a goal of educating and engendering discussion on the general topic of sea level rise as it relates to our professions. At the First Annual COPRI Congress, the committee held a technical session entitled “Water Resources Policies and Authorities Incorporating Sea Level Change Considerations in Civil Works Programs.” The committee also hosted a symposium and a special session at the 11th and 12th Estuarine and Coastal Modeling Conferences, held in Seattle (in 2009) and St. Augustine, Florida (in 2011), respectively. All of these events proved to be of keen interest to the attendees (in fact the sessions were among the best-attended) and generated much discussion.

A common recognition from the conference sessions is the lack of recent attention that the topic of sea-level rise (and its implications) has received from the ASCE/COPRI in particular and our shared professions in general. The authors have found this to be especially true with respect to the published literature in coastal engineering-related journals, particularly with respect to applications. The authors are hopeful that this Focus Issue on Implications, Planning, and Design Considerations for Rising Sea Levels at the Coast will facilitate engineers and scientists of related COPRI professions to further consider these problems and brainstorm solutions, and inspire future discussion and research.

This Focus Issue comprises five technical papers, one case study, and one technical note. Of these, three papers address the state of knowledge and methods for interpreting observed sea level trends and impacts, as well as published global projections. Two papers illuminate the potential future impacts of sea-level rise via computational modeling and analysis. Finally, two papers are included that address quantification of future extreme-value probabilities and uncertainty.

Opening the issue is Houston’s paper “Global Sea Level Projections to 2100 Using Methodology of the Intergovernmental Panel on Climate Change.” In this paper, Houston discusses observed sea-level rise trends and acceleration over the last 100 years, and he then introduces a probabilistic interpretation of recently published future projections for 2100. The second paper is an observational paper by Ruggiero, “Is the Intensifying Wave Climate of the U.S. Pacific Northwest Increasing Flooding and Erosion Risk Faster Than Sea-Level Rise?,” which interprets 30 years of observational data in the Pacific Northwest to elucidate the relative impacts of local sea-level rise and increasing wave heights. Ruggiero concludes that, for the Pacific Northwest, increasing wave heights may have a greater influence on coastal flooding and erosion with respect to sea-level rise.

In the third paper, “Sea-Level Rise Effects on Storm Surge and Nearshore Waves on the Texas Coast: Influence of Landscape and Storm Characteristics,” Atkinson et al. present and interpret computational simulation results when a suite of potential future sea-level rise, storm, and land cover scenarios are assumed. For the Texas case study location, although there is a general trend of increased flooding and wave heights with sea-level rise, the authors conclude that the exact impact of future sea-level rise on storm impacts is site specific. Hagen et al., in the fourth paper, entitled “Sea-Level Rise Impact on a Salt Marsh System of the Lower St. Johns River,” also use computational simulations to study future impacts of sea-level rise, but in this case the hydrodynamics are coupled with a marsh equilibrium model. Here, the authors investigate salt marsh sustainability at a case study location along the east coast of Florida. Hagen et al. conclude that tidal range response to sea-level rise is a highly spatially variable, and as a direct result, the marsh response is nonlinearly linked with sea-level rise magnitude.

In Irish and Resio’s paper “Method for Estimating Future Hurricane Flood Probabilities and Associated Uncertainty,” statistical methods are presented for evaluating future extreme-value flood elevations and uncertainty based on future projections of sea-level rise and tropical cyclone conditions. The authors conclude that climate-related uncertainty minimally contributes to the overall uncertainty inherent in hurricane flood statistics, whereas errors in mean climate trends are more impactful, leading to the need for adaptive management practices. The sixth paper is a case study by Obeysekera et al. entitled “Probabilistic Projection of Mean Sea Level and Coastal Extremes.” In this paper, the authors apply a method for incorporating uncertainties in sea-level rise acceleration projections to a case study location in Southern Florida. Their approach considers the range of sea-level accelerations reported in the recent literature. Concluding this Focus Issue is a technical note entitled “Matching Mean Sea Level Rise Projections to Local Elevation Datums.” In this paper, Flick et al. presents a method for linking future global sea-level rise projections with local observations for setting tidal datums. Flick et al. finish their paper with case study applications at La Jolla, California, and Hampton Roads, Virginia.

In closing, this Focus Issue is intended to bring attention to the future challenges presented to coastal engineers and planners resulting from sea-level rise. This compilation of papers is intended to initiate dialogue and research to further understanding of and preparedness for managing coastal impacts arising from sea-level rise.