Forum Bulletin

Rising Sea Levels Threaten Historic Coastal Cities 

04-20-2012 00:00

The National Alliance of Preservation Commissions’ biennial meeting, Forum 2012, will be held in Norfolk, Va., July 18 – 22. The city provides a laboratory for preservation commission staff to explore a variety of preservation issues – two of particular interest are the effect of rising sea levels on historic resources and the perennial problem of appropriate infill in historic districts. In anticipation of the upcoming conference, NAPC members are contributing background articles on a few of the issues that will be explored in Norfolk.

The City of Norfolk, Va., created by a 1636 land grant from England, has faced a range of challenges over its three centuries of continuous settlement including fire, invasion, and epidemics.

Now a far more modern challenge threatens the heritage of Norfolk and the surrounding Hampton Roads region in southeastern Virginia. A 2007 European study ranked Hampton Roads as number ten in the world for value of assets at risk from sea-level rise. The past century saw a measured rate of sea-level rise of around 1.5 feet. In the coming century, this rate is expected to double. Norfolk is not alone; all coastal communities will eventually face this dilemma. How the city addresses this issue could be a model for future programs. Attendees at the National Alliance of Preservation Commissions’ conference will have a chance to see first-hand the challenges of sea-level rise adaptation on one of Norfolk’s older neighborhoods during a kayak tour on the Lafayette River.

Hampton Roads is flat and interlaced by tidal creeks and rivers, features that made this region attractive to early settlers for whom ships were the principle means of commerce and transportation. The region’s present water-dependent economy is a legacy of those times. Hampton Roads is home to the only remaining US shipyard capable of building aircraft carriers, numerous ship repair facilities, nationally-ranked port facilities, and the largest naval base in the world. In addition, much of its extensive tourist economy is water-dependent, with wide oceanfront beaches attracting hundreds of millions of dollars a year to the region. All of this economic activity takes place along the shoreline, and all of it is increasingly at risk from sea-level rise and storms that ride higher atop those seas.

The current rate of sea-level rise is a fairly recent phenomenon. After rapid sea-level rise following the end of the last glacial period, some 15,000 years ago, sea-level rise rates stabilized around 5,000 years ago. From those early days of human civilization, sea levels have remained abnormally stable. People settled along shorelines assuming they would always stay in place. When sea levels began to rise again over a century ago, this began to change.

Today the impacts are being felt in Hampton Roads as streets in older neighborhoods flood with the spring tides of the new and full moon. Visible reminders of the region’s long history, such as the fort at Jamestown, are being inundated. Low-lying communities on islands in the Chesapeake Bay are starting to be abandoned and are disappearing.

Virginia is suffering in particular, since most of its land is sinking faster than in other parts of the country. While, all regions experience nearly the same rate of sea-level rise, Norfolk’s relative low sea level rivals even New Orleans and Galveston, making it especially vulnerable. And, when you build on top of filled-in wetlands, which many older cities did, the land sinks even faster, causing anything built atop the old marshes to experience additional flooding.

All communities along the tidal waters of the United States are facing, or will soon face, similar challenges. Many regions have begun planning for sea level rise and are figuring out how to deal with higher tides and storm surges. Cities such as Portland, Maine; Groton, N.Y.; and Lewes and New Castle, Del.; as well as entire regions such as Maryland and Virginia’s Eastern Shore, Coastal North Carolina, Southeastern Florida--from one end of the Atlantic Coast to the other--are planning for sea-level rise. And on the Gulf and West Coasts even more is happening. 

The trials, successes, and failures of the Hampton Roads area could serve as models as these other tidal communities plan for their future. Hampton Roads has a number of sea-level rise studies underway. The Navy is almost finished with a major review of the impact of rising sea levels on its Naval Station Norfolk, and the nearby National Aeronautics and Space Administration (NASA) facility held a workshop on climate threats to the installation. The regional governmental coordinating entity, the Hampton Roads Planning District Commission, is in year three of a regional look at sea-level rise. Norfolk is just finishing an inundation study and many surrounding cities have included sea-level rise in their long-range land-use plans, their emergency management plans, and even economic development strategies. 

As these studies bring sea-level rise into focus, the difficulty of dealing with the problem becomes ever more apparent. Protecting the tidal shoreline is expensive, involving a variety of approaches ranging from armoring (building sea walls and dykes) to adapting (elevating buildings and roads) to retreat (removing buildings and infrastructure).  Property values and the shoreline portion of the property tax base are adversely affected by increased flooding and higher insurance costs at a time when taxpayer outlays to preserve critical infrastructure increases. Dealing with shoreline historic and cultural features is difficult.

For Norfolk, the costs of dealing with sea-level rise are real and starting to pile up. Two neighborhoods identified in the inundation study just completed are slated for major public works projects to protect them. With costs of between $90 and $200 million (in a city with an annual storm water budget of $5 million) these projects, which involve storm surge gates across tidal openings, will require significant federal funding. These projects are just a start. Many other neighborhoods in Norfolk and other adjacent cities will need protection as well.

Developing a comprehensive regional plan is the next step in the city’s adaptation work. The Virginia state legislature authorized a study of adaptation options which will be delivered later this year. The study will look at everything from local government land-use tools to large regional approaches like efforts to protect the Thames estuary in England.

Forum 2012 presents an opportunity to explore this latest challenge to historic preservation. Sea-level rise and increased inundation will affect all coastal cities eventually; there is great opportunity to learn from Norfolk.

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Author(s):Skip Stiles