Long-term sea level rise in Washington, D.C. could have significant impact

Short-term predictions suggest that sea level will rise 0.1 meters by the year 2043 and flood about 103 properties and other infrastructure, costing the city about $2.1 billion. By 2150, 0.4 meters of SLR is likely to impact 142 properties. For long-term effects if sea level rise were to reach 5.0 meters, the authors warn of significant damages in excess of $24.6 billion to commercial buildings, military installations, museums and a number of government agencies, including the Federal Bureau of Investigation, the Justice Department, the Internal Revenue Service, the Federal Trade Commission and the Department of Education. While a rise of 5.0 meters is considered unlikely, recent weather events such as Tropical Storm Isabel in 2003 and high tides and rains in April of 2011 triggered waterfront flooding in the city and Northern Virginia. The authors warn that extreme weather may increase the chances of flooding as sea levels increase.

The study, by University of Maryland researchers, examines its results in comparison with a set of models generated by authoritative international bodies and experts. Researchers Bilal Ayyub, Haralamb G. Braileanu and Naeem Qureshi of the Center for Technology and Systems Management of the Department of Civil and Environmental Engineering at the College Park campus of the University of Maryland published the paper. The article, entitled "Prediction and Impact of Sea Level Rise on Properties and Infrastructure of Washington, DC," appears in the November 2012 issue of Risk Analysis, published by the Society for Risk Analysis.

The research relies on an unrealistically optimistic model in which SLR increases in a straight line consistent with recent trends. Other studies suggest the pattern shows increasing rates of SLR leading to, for example, a one meter SLR by the year 2100 compared with the 0.4 meter SLR rise employed in this analysis. Thus, the authors say their approach may underestimate the city's SLR in the future.

To fully assess the potential damage, the researchers used Geographic Information System (GIS) tools and data from government agencies as well as real-estate listings for property values. The results show that the current rate of SLR in Washington, D.C., is about 3.16 millimeters per year and that at the low levels of increase expected in the near future, SLR would lead to a minimal loss of city area. But if 0.1 meters of SLR occurs by 2043 as the authors expect, nearby Bolling Air Force Base would lose 23 buildings.

With dramatic SLR increases over the long term, predictions suggest that billions of dollars in damage would result. Above 2.5 meters of SLR, the authors write, the "numbers become staggering. . . 302 properties are affected, costing $6.1 billion, finally at 5.0 meters of SLR, the numbers increase to a dramatic 1,225 properties and at least $24.6 billion" in damage. They add that these monetary estimates focus on real-estate property values and exclude additional damage valuations to water and sewer systems and other infrastructure, as well as to federal and industrial facilities, which they say should be included.

The authors conclude, "Decisions must be made in the near future by lawmakers or city planners on how to reduce the impact of and adapt to SLR. A planned retreat is not an option when dealing with SLR in such an important area. . . A short-term solution, like creating a small flood barrier, may give the city time to examine this challenge and produce cost-effective solutions. Cost-effective methods to deal with SLR should be developed, and long-term solutions that extend well into this millennium are necessary."