Impact of Climate Change on Water Supplies of Coastal Communities

Impact of Climate Change on Water Supplies of Coastal Communities

Brian L. Ramaley, P.E.Director, Newport News Waterworks andPresident, Association of Metropolitan Water Agencies (AMWA)

World Water Week21 August 2008

Newport News Waterworks

Comprises the largest publicly owned U.S. Comprises the largest publicly owned U.S. metropolitan water systemsmetropolitan water systems

Members provide drinking water to over 127 Members provide drinking water to over 127 million people in the U.S.million people in the U.S.

Focus on the U.S. Congress, the Administration Focus on the U.S. Congress, the Administration and Management Issues facing metropolitan and Management Issues facing metropolitan water suppliers.water suppliers.

New focus: Climate Change and International New focus: Climate Change and International Outreach and Knowledge Exchange.Outreach and Knowledge Exchange.

AMWA – Leaders in WaterAMWA – Leaders in WaterAMWA – Leaders in WaterAMWA – Leaders in Water

Expand and enhance AMWA's value to US metropolitan Expand and enhance AMWA's value to US metropolitan

drinking water utilities through access and engagement drinking water utilities through access and engagement

with similar metropolitan utilities in other countries. with similar metropolitan utilities in other countries.

Exchange experience and knowledge with utility managers Exchange experience and knowledge with utility managers

abroad and to provide opportunities for peer-to-peer abroad and to provide opportunities for peer-to-peer

exchange of ideas and skills.exchange of ideas and skills.

International knowledge exchange on climate change International knowledge exchange on climate change

matters is of greatest importancematters is of greatest importance. .

AMWA’s International InvolvementAMWA’s International InvolvementAMWA’s International InvolvementAMWA’s International Involvement

Presentation OutlinePresentation Outline

Background on Newport News Waterworks

Specific Impacts of Climate Change

Conclusions for the Future

Newport News WaterworksNewport News Waterworks

Municipally owned system that serves drinking water to more than 400,000 people

3 cities, two counties, many military bases

Mid-Atlantic location at mouth of Chesapeake Bay

In coastal plain, average elevation < 10 meters

Newport News Climate InformationNewport News Climate Information

Month Avg. High Avg. Low Mean Avg. Precip

Jan 47°F 32°F 39°F 4.08 in.Feb 49°F 34°F 42°F 3.60 in.Mar 57°F 41°F 49°F 4.73 in. Apr 66°F 49°F 57°F 3.35 in.May 73°F 58°F 66°F 4.03 in. Jun 81°F 67°F 74°F 3.44 in. Jul 85°F 72°F 79°F 4.86 in. Aug 84°F 71°F 77°F 4.74 in. Sep 78°F 65°F 72°F 4.84 in. Oct 68°F 53°F 61°F 3.45 in. Nov 60°F 44°F 52°F 3.35 in. Dec 51°F 36°F 44°F 3.43 in.

Newport News - LocationNewport News - Location

Newport News

Atlantic Ocean

Virginia

North Carolina

Stockholm –>

Newport News, VA Waterworks System and Water Sources

Newport News, VA Waterworks System and Water Sources

Interconnected pumped storage reservoirs and one river intake

Chickahominy River is major water source

Surface water ----- 57 mgd safe yield based on 75-year record

Groundwater desalination ----- 6 mgd yield

– 1 mgd = 3,785 cubic meters per day

– 10,000 cubic meters per day = 2.64 mgd

Chickahominy River/IntakeChickahominy River/Intake

Brackish Groundwater DesaltingBrackish Groundwater Desalting

Climate Change Impacts to Coastal Water Supplies

Climate Change Impacts to Coastal Water Supplies

Warmer temperatures

Changing precipitation patterns

Rising sea level

Warmer TemperaturesWarmer Temperatures

Higher evaporation/lower yield

Higher demand

Increased biological activity and impacts on water quality/treatability

Changing Precipitation PatternsChanging Precipitation Patterns

More intense rainfall events/storms

– Increased turbidity/sediment/treatment required

– Faster reservoir refill – shoreline erosion

– Spillways must pass more water

– Storm damage to facilities – redundancy/reliability

issues?

More frequent, intense or prolonged droughts

– Higher irrigation demand

– Reduced surface system yields during drought

– Reduced groundwater recharge/yield

Rising Sea LevelRising Sea Level

Inundation of service area

Surge impacts to low lying areas during storms including water utility facilities are magnified

Salt water intrusion into surface supplies

Salt water intrusion into groundwater

Accelerated subsidence

Summary of Historical Drought Studies: Newport News

Summary of Historical Drought Studies: Newport News

Water supply planning in Eastern U.S. is typically based on most severe drought in 20th Century (e.g., 1930)

Firm Yield of 57 mgd for 78-year streamflow record estimated for surface system based on 1930-2008 record

Fort MonroeConstructed Between 1819 and 1834

Fort MonroeConstructed Between 1819 and 1834

Updating Drought Studies to Include 19th Century Records

Updating Drought Studies to Include 19th Century Records

Monthly rainfall records extend back to 1836 for Southeastern and Central Virginia

Standardized Precipitation Index (SPI) method was used to compare 19th and 20th Century rainfall records

Synthesized streamflows developed from rainfall records

Performed Firm Yield modeling with a 161-year streamflow record

Rain Gauge LocationsRain Gauge Locations

Fort Monroe, 1836-1890

Norfolk, 1871-1998

Hampton, 1869-1913

Fredericksburg, 1893-1998

Newport News, 1899-1927

Powhatan Hill, 1849-1876Richmond, 1872-1998

Hopewell, 1888-1998

Williamsburg, 1900-1998

19th and 20th Century Rainfall Data Show Similar Means and

Distributions

19th and 20th Century Rainfall Data Show Similar Means and

Distributions

1836-1899

1900-1998

1836-1998

Monthly Rainfall Datasets

0

5

10

15

20

Mon

thly

Rai

nfal

l (in

che

s)

Results of Firm Yield Modeling with 161-Year Streamflow Record

Results of Firm Yield Modeling with 161-Year Streamflow Record

Four 19th Century droughts are more severe than the worst 20th Century drought

Minimum Firm Yield is 42 mgd (1851-55 drought)

20th Century drought of record (1930): 57-mgd Firm Yield corresponds to a 22-year return period (rather than a 75-year return period)

Firm Yield for a 75-year return period is 44.5 mgd

Implications for Water Supply Planning Studies

Implications for Water Supply Planning Studies

Consideration of 19th Century droughts can significantly change evaluations of existing system reliability and future needs.

Recent droughts and storms indicate a return to precipitation conditions in the mid-Atlantic region more like the 1800s than the 1900s.

Are the 1800s a better model for climate change impacts with respect to yield?

Newport News Response CurvesNewport News Response Curves

position analysisNewport News Waterworks using 53 mgd average annual raw water demand

0

10

20

30

40

50

60

70

80

90

100

jan feb march apr may june july aug sept oct nov dec

simulation month

use

able

cap

acit

y (i

n %

)

5% risk of depleting useable capacity10% risk of system depletion161 year simulated average1930 drought, year 12002 actual

Distribution of possible "safe yields"; 1838-2001

30

40

50

60

70

80

90

100

110

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

probability of storage depletion

yield

in m

gd

1884-86 yield; 95% reliability

1863-66 yield; 98% reliability

From Zhang et al. (2004) Climatic Change 64: 41–58.

Relative Sea Level Rise Along the East Coast of North America

Estimated Sea Level Rise at NN – 3 to 4 mm/yearEstimated Sea Level Rise at NN – 3 to 4 mm/year

SLR 2008 SLR 2025

SLR 2050 SLR 2075 SLR 2100

Hurricane IsabelSep 18-19, 2003

Reagan Washington National Airport

Chesapeake Inundation Prediction System (CIPS)

Hampton Roads InundationEstimates Under Different Sea Level Rise Scenarios

Extent of flooding is a function of: - height of water - land elevation - land relief

With increasing sea level, additional flooding from storm surge effects will be greater than previously - smaller storms will have equivalent destruction potential as larger storms pre-SLR

Important implications for both human populations as well as living resources and coastal environments

From Titus and Wang (2008) EPA.

Conclusions for the futureConclusions for the future

Climate change will impact coastal water supplies in multiple ways

Regional modeling and downscaling of global models are needed to predict temperature, sea level rise, design storms and droughts

Combination of impacts must be considered

Existing yields and safety factors are almost certainly wrong – high or (more likely) low

Conclusions for the futureConclusions for the future

Diversification of water supplies will enhance reliability – Security Through Diversity

Looking further back in time may be a useful way of estimating the future climate

Integrated resource planning principles offer a roadmap

Redundancy/reliability concerns should be given more attention in the face of an uncertain future