Climate change impacts on Virginia water resources

Carl Hershner

Currently anticipated changesby 2100

• Temperature +2oC to +5oC– more hot days

• Storm frequency?– intensity may increase

• Precipitation – more intense events– more draughts ?

• Sea level +3 to +7 +9 ft

‐1.5

‐1

‐0.5

0

0.5

1

water level relative to NAV

D88

 in fe

etSewells Point water level 1970 through 2015

relative to NAVD88

observed water level linear trend mean sea level 1983 ‐ 2001

Relative sea level rise in Virginia

• Global sea level rise (NASA)– Melting ice caps (1.26mm/yr) 

– Warming (expanding) ocean water (1.58mm/yr) 

– Land water storage (0.32mm/yr)

• Land sinking  (USGS)– Isostatic glacial rebound (1mm/yr)

– Local subsidence • Ground water withdraw (0.1 – 3+mm/yr)• Meteor crater sediment compaction (0mm/yr)

• Ocean circulation 

Cumulative change in the total mass (in Gigatonnes, Gt) of the Greenland Ice Sheet between April 2002 and April 2015 estimated from GRACE measurements. Each symbol is an individual month and the orange asterisks denote April values for reference. Tedesco et al, 2015. Greenland Ice Sheet, Arctic Report Card: Update for 2015 available at: http://www.arctic.noaa.gov/reportcard/greenland_ice_sheet.html

Greenland Ice Sheet massmelting ice caps

http://www.ncdc.noaa.gov/indicators/

World ocean heat content ‐ top 700 meters

warming ocean water

glacier

100,000 yrs ago

20,000 yrs ago

today

isostatic glacial rebound

land subsidencedue to 

groundwater withdrawals 

after Pope and Burbey, 2004

Atlantic MeridionalOverturning Circulation

Sverdrup = 1 million

0

1

2

3

4

5

6

7

8

9

1992 2002 2012 2022 2032 2042 2052 2062 2072 2082 2092

feet abo

ve 1992 level

year

Relative Sea Level Rise for SE Virginiain feet above 1992 level

highest

high

low

historic

2066+2.2ft

2046+1.2ft

2016

Pamunkey River

Hill Marsh

high marsh communityin tidal freshwater

low marsh communityin tidal freshwater

low marsh communityin tidal freshwater

1 ft 2 ft  3 ft 4 ft 5 ft 6 ft 7 ft 8 ft 9 ft 10 ftAccomack County 100 100 100 100 100 100 100Virginia Beach city 20 20 20 20 20Norfolk city 8 8 31 39 54Portsmouth city 25 75 75 75Hampton city 17 17 17 33 33Newport News city 14 29 29 29

Percent of hospitals flooded at these water levels

Climate Central (2014). Sea level rise and coastal flood exposure of Hopitals by County in VA, in Surging Seas Risk Finder. Retrieved from http://ssrf.climatecentral.org/#state=Virginia&level=10&category=Hospitals&geo=County&pt=p&target=&p=S&protection=tidelthresh&folder=Critical

1 ft 2 ft  3 ft 4 ft 5 ft 6 ft 7 ft 8 ft 9 ft 10 ftAccomack County 7.7 7.7 7.7 7.7 15.4 23.1 23.1 23.1 23.1 23.1Virginia Beach city 1.1 1.1 1.1 3.4 5.6 7.9 11.2 18Norfolk city 1.6 3.3 4.9 6.6 9.8 14.8 26.2 42.6Chesapeake city 1.9 1.9 7.5 7.5 7.5 28.3Portsmouth city 3.6 3.6 14.3 17.9 39.3 50Hampton city 5.7 17.1 28.6 34.3 40Newport News city 2 3.9 3.9 3.9York County 5Poquoson city 50 50 100 100 100 100 100Gloucester County 10 10 10 10

Percent of schools flooded at these water levels

Climate Central (2014). Sea level rise and coastal flood exposure of Public Schools by County in VA, in Surging Seas Risk Finder. Retrieved from ssrf.climatecentral.org/#state=Virginia&category=Schools_public&geo=County

Langley Air Force Base

Fort Eustis Army Base

Norfolk Naval Base

Portsmouth Naval Shipyard Oceana Naval Air Station

Fort Monroe

Currently anticipated changesby 2100

• Temperature +2oC to +5oC– more hot days

• Storm frequency?– intensity may increase

• Precipitation – more intense events– more draughts ?

• Sea level +3 to +7 +9 ft

Southeast Temperature: Observed and Projected

Figure source: adapted from Kunkel et al. 2013

Variation in storm frequency and intensity during the cold season (Nov to Mar)

frequency intensity

The intensity, frequency, and duration of North Atlantic hurricanes, as well as the frequency of the strongest (Category 4 and 5) hurricanes, have all increased since the early 1980s.

http://www.chesapeakedata.com/changingchesapeake/

Watershed Implementation Plans

Projected Changes in Water Withdrawals

Figure source: Brown et al. 2013

http://www.chesapeakedata.com/changingchesapeake/

http://www.intechopen.com/books/evapotranspiration

• 77oF to 80.6oF

• +16% ET

evapotranspiration

Trends in Water Availability

Figure source: adapted from Sun et al. 2013

Water Stress in the U.S.

Watersheds are considered stressed when water demand (from power plants, agriculture, and municipalities) exceeds 40% (water supply stress index of 0.4) of available supply. (Figure source: Averyt et al. 20111

September 2002

September 2003

Rappahannock River at Fredericksburg

Walkers Dam on the Chickahominy River

10

9 8

76

5

4

3

2

1

VA Coastal Plain Aquifer Cross‐Section

McFarland & Bruce, 2006

1. sea level is rising2. it’s getting warmer3. a bit more precipitation4. more intense storms5. BMPs underperform6. beneficial uses may 

suffer

Things you should have heard

Carl Hershner

Virginia Institute of Marine ScienceCollege of William and Mary

carl@vims.edu