Trends: socio-economic, climate change
The effects of climate change, sea-level rise, and more intense and frequent storm surges will increase riverine, tidal, and interior flooding risks in vulnerable areas of Washington, DC. The city is home to a wide range of beautiful historical buildings and important museums that need to be protected. Obviously, the threat of flooding also puts the population at considerable risk. In the future, Washington DC will need to introduce changes in the following three factors.
The consequences of climate change are projected to increase annual average as well as summer temperatures in future years in Washington, DC. Heat waves, defined as three or more consecutive days with daily maximum heat index values exceeding 95°F, will become more intense, more humid and of longer duration. Studies show that baseline or historic conditions (1981-2000) for summer daytime maximum temperatures currently average 87°F with night-time minimum temperatures averaging around 66°F. These values are projected to increase by 2.5-3°F by the 2020s, 5-7°F by the 2050s, and as much as 6-10°F by the 2080s.
Washington, DC currently has an average of 10 days per year with more than 1 inch of rain in 24 hours, and an average of 1 day per year with more than 2 inches of rain in 24 hours. By the 2020s, the number of days per year with more than 1 inch of rainfall in 24 hours is expected to reach 11. That number is projected to increase to 12 days by the 2050s and 13 days by the 2080s. The number of days per year with more than 2 inches of rainfall in 24 hours is expected to increase to 3 by the 2020s, an average of 3.5 days per year by the 2050s, and between 3.5 to 4.5 days per year by the 2080s.
Washington, DC has three major natural flowing bodies of water: the Potomac River and two tributaries, the Anacostia River and Rock Creek. The confluence of the Potomac and Anacostia Rivers is at sea level and influenced by tidal water from the Chesapeake Bay and the Atlantic Ocean. Over the past century, sea levels have been rising as a result of climate change. Locally, sea levels on the Washington, DC waterfront have risen by 11 inches since 1924, and are expected to continue to rise in the future. The United States Army Corps of Engineers (USACE) North Atlantic Coast Comprehensive Study, released in January 2015, estimated a relative sea-level rise (SLR) of 0.4 to 1.4 feet by 2050 and 0.7 to 3.4 feet by 2080, depending on the SLR scenario (USACE low, medium, or high sea-level rise scenario from 2014). Impacts from projected SLR on DC waterfronts include overwhelmed stormwater drainage outfall and capacity, frequent road and business closures, and general deteriation and corrosion of infrastructure not designed to withstand frequent inundation or salt-water exposure.