Potential Impacts of Sea Level Rise on the Beach at Ocean City, Maryland
Potential Impacts of Sea Level Rise on the Beach at Ocean City, Maryland (PDF, 61 pp., 1.0 MB) , was edited by James G. Titus with papers by James G. Titus, Stephen P. Leatherman, Robert G Dean, Craig Everts, and David Kriebel (EPA 230-10-85-013). The report's Summary and Conclusions are available below. Please note: currently, of the report's four chapters, only Chapters 1 and 2 are available in an electronic form.
For additional reports focused on the implications of rising sea level, go to More Sea Level Rise Reports.
Summary
Recent reports by the National Academy of Sciences and others have concluded that increasing atmospheric concentrations of carbon dioxide and other gases can be expected to cause a global warming that could raise sea level a few feet in the next century. Unfortunately, it is not yet possible to accurately predict future sea level. Estimates for the year 2025 range from five to twenty-one inches above current sea level, while estimates of the rise by 2100 range from two to eleven feet.
Several issues must be resolved for society to rationally address the possibility of a significant rise in sea level. Officials in coastal areas making decisions about near-term projects with long lifetimes must determine whether the risk of sea level rise justifies a shift to strategies that can more successfully accommodate a rise in sea level. The research community needs to decide whether to accelerate studies to more accurately project future sea level. These decisions require assessments of the adequacy of existing forecasts, prospects for improving the estimates, and the level of resources that can be saved if more definitive estimates become available.
These decisions also require an understanding of the consequences of sea level rise. To further this understanding, EPA has initiated studies of the impacts of sea level rise on Charleston, South Carolina; Galveston, Texas; coastal wetlands; municipal drainage facilities; and salinity of surface and ground water.
This study examines the potential implications of sea level rise for efforts to control erosion of the beach at Ocean City, Maryland, a typical Atlantic Coast resort. Because current trends in sea level and other factors are already causing significant erosion at Ocean City and other ocean beach resorts, strategies for addressing coastal erosion constitute a class of near-term decisions that may depend on sea level rise. Because land and improvements are often worth well over one million dollars per acre in these areas, and erosion increases the likelihood of storm damage and federal disaster payments, the success of erosion control measures has great economic importance to the nation. We hope that this report will promote a reasoned consideration of the long-term consequences of sea level rise, and thereby enhance the eventual success of erosion control strategies at Ocean City and other coastal communities.
In this report, three independent teams of coastal process scientists estimate the erosion that will take place at Ocean City for three scenarios of future sea level rise: (1) current trends of I foot per century along the Atlantic coast; (2) the National Academy of Sciences estimate of a 2-1/3 foot global rise in the next century with an 11 inch rise by 2025; and (3) the EPA mid-high scenario of a global rise of 4-1/2 feet in the next century and 15 inches by 2025. The quantity of sand necessary to maintain the current shoreline is also estimated for each of the scenarios. Using these estimates and previous studies by the Corps of Engineers and others, the potential costs of erosion control are also examined.
Conclusions
- Sea level rise could double the rate of erosion at Ocean City in the next forty years. If no additional erosion control measures are taken, the shore will erode 85-153 feet by 2025 assuming current sea level trends. An 11-inch global rise in sea level would increase expected erosion to between 180 and 238 feet, if no additional measures are taken; a 15-inch rise would increase expected erosion to between 216 and 273 feet.
- The projected rise in sea level would increase the quantity of sand necessary to maintain the current shoreline for the next forty years from 5-10 million cubic yards if current trends continue, to 11-15 million cubic yards for the two scenarios of accelerated sea level rise.
- Projected sea level rise would increase the priority of erosion control-measures under current policies of the Corps of Engineers. Current policies place a greater emphasis an flood protection than recreational benefits provided by proposed projects. Because of the substantial erosion that could occur from a rise in sea level, the need for flood protection will be greater if sea level rises.
- A significant rise in sea level would require a change in the technology used to control erosion at Ocean City. The current plan to construct groins was designed to curtail erosion caused by sand moving along the shore. However, groins do not prevent erosion caused by sea level rise. Placement of additional sand onto the beach would offset erosion caused by both sea level rise and alongshore transport.
- The cost of controlling erosion caused by sea level rise does not threaten the economic viability of Ocean City in the next forty years. Even the most pessimistic estimate of future erosion control implies a cost of less than fifty cents for every visitor that comes to Ocean City each year. Protecting the shore at Ocean City will continue to be economically justified.
- Understanding the likely impact of sea level rise on Ocean City in the next century will require identification of the most cost-effective and environmentally acceptable sources for up to fifty million cubic yards of sand to be placed on the beach.
- Better estimates of future sea level rise would enable decision makers to more adequately determine the most prudent strategy for controlling erosion at Ocean City.
- Although improved procedures for estimating erosion are desirable, current methods are sufficient to yield first-order estimates for use in long-term planning.
This document has been reviewed in accordance with the U.S. Environmental Protection Agency peer and administrative review policies and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Please send comments to James G. Titus, U.S. Environmental Protection Agency, Washington, D.C. 20460.