AgentR11 wrote:Sea level rise gets all the play, only because it makes a great visual on the GIS mapping models. In reality, it happens slowly. So slowly that it is slower than building depreciation.
In addition, just looking at my topo map, the Pentagon for instance is kinda on a hill, at a good 35+ft above sea level. The White House is 55+ft above sea level as well. Not to mention that "Capital Hill" really is on a hill, at a good 70 ft above sea level.
I kind of doubt that given that the Tidal Basin of the Potomac behind the Jefferson Memorial is tidal, the Washington Mall used to have a canal, and ocean going ships used to dock on the Virginia and Maryland shores. The Potomac is tidal under all those bridges up to Little Falls below Georgetown. Regardless of the actual sea level elevation +/- inches, slight sea level will cause the storm drains to back up in normal rains. Also, areas along the Potomac like Foggy Bottom have always been prone to flooding when the watershed gets a good hurricane or snow melt. What happens when the Chesapeake is a couple feet higher and the Potomac has nowhere to go? Believe me, the Potomac can get massive in hurry.
The Washington Harbor commercial complex already has floodgates, here they weren't raised. Oops! This is the sort of thing they might already deal with a couple times a year. Imagine a really good river flood with a high tide that is already a couple feet higher.
3:15 p.m. update: The National Weather Service has extended the coastal flood warning for the District, Arlington, and Alexandria until noon tomorrow. Tides are expected to be 3 to 5 feet above normal, increasing water levels to 10-10.5 feet. At 10 feet, water approaches K St. at Washington Harbor and at 10.5 feet water approaches Independence Avenue at 17th St. along the Tidal Basin and the GW Parkway at the railroad bridge north of National Airport. High tides are between 9 and 9:30 p.m. tonight, and 9:30 and 9:45 a.m. Tuesday morning.