potential impactsof climate change and population growth ...water supply and demand must be...
TRANSCRIPT
SGCP
Potential Impacts of Climate Change and
Population Growth on U.S. Water Supply
and Demand in the Next 50 Years
Steve McNulty, Ge Sun, Jennifer Moore Myers, Erika Cohen, and
Emrys Treasure
Southern Global Change Program
Eastern Forest Environmental Threats Assessment Center
Southern Research Station
USDA Forest Service, Raleigh NC
SGCP
• Forests provide the best water
quality among all land uses
• Forest lands (30% of land area)
provide >50% of water supply
in the US
• Climate change, disturbances,
population growth, urbanization
and land use change could
impact water quantity
Why is the Forest Service Interested in
Water and Climate Change?
SGCP
Water Supply and Demand
Supply Demand
Climate Landuse
change Population
Reservoirs,
Groundwater
Facilities
Envir flow
Water price,
Economics.
SGCP
Water Supply Stress Index
(WaSSI):
SupplyWater
DemandWater WaSSI =
(Sun et al. JAWRA, 2008 44(5):1073-1075)
SGCP
Water Supply at Hydrologic Unit Code (HUC)
Scale (Watersheds)
= Precipitation - Evapotranspiration +
Groundwater Supply + Returnflow from Water
Users - Environmental Flow
Water Demand by Humans at HUC Watershed
Scale
= Water Use by Sector (Thermoelectric,
Commercial, Domestic, Irrigation, Livestock,
Industrial, Mining, Public Supply Use/Loss)
Definitions
SGCP
Current Water Supply (MGD)
Water Supply0 - 100100 - 500500 - 10001000 - 20002000 - 40004000 - 80008000 - 1200012000 - 2000020000 - 60000
States
SGCP
Current Water Demand (MGD)
ater Demand0 - 100100 - 200200 - 400400 - 800800 - 16001600 - 32003200 - 6620
States
SGCP
Water Demand / Water Supply (WaSSI) (1974-1993)
WaSSI0 - 0.010.01 - 0.050.05 - 0.10.1 - 0.20.2 - 0.40.4 - 0.60.6 - 0.80.8 - 1>1.0
States
SGCP
Projections
SGCP
SGCP
SGCP
• Scenario 1 = Baseline
– 1992 landcover, historic climate and water use
• Scenario 2 = Historical climate+Pop change (2050)
• Scenario 3 = Historical climate + Deforestation 10%
• Scenario 4 = Historical climate + Irrigation -10%
• Scenario 5 = climate change (HadCMSul2, CGC1)
• Scenario 6 = Climate change + Population growth
Hypothetical Scenarios Examined
SGCP
% Changes in Water Demand / Water Supply (WaSSI) due to:Population Growth (2050)
Ushuc.shp-7.8 - 00 - 2525 - 5050 - 100100 - 200200 - 1340.9
States_alb.shp
SGCP
Climate Change (Hadley2)
WaSSI Change %-95.3 - -30-30 - -10-10 - 00 - 5050 - 100100 - 447.8
States
SGCP
Climate Change (Hadley2) + Population Growth
WaSSI Change %-95.3 - -30-30 - -10-10 - 00 - 5050 - 100100 - 447.8
States
SGCP
Climate change only (1994-2050) Climate change + Population growth
Climate Change (Hadley2)
%0
8
Climate Change (Hadley2) + Population Growth
WaSSI Change %-95.3 - -30-30 - -10-10 - 00 - 5050 - 100100 - 447.8
States
SGCP
National Overall Pictures
SGCP
National Average Water Supply and Demand
0
1000
2000
3000
4000
5000
His
torica
l His
+Pop
Cha
nge
His
+Def
ores
tHis
+Irrig
atio
n
Had
ley2
CGC1
Had
ley2
+Pop
CGC1+
Pop
Scenarios
0
0.05
0.1
WaSSI (Demand/Supply)
Supply
Demand
Demand/Supply
SGCP
Seasonal Distribution of WaSSI
0
0.05
0.1
0.15
0.2
1 2 3 4 5 6 7 8 9 10 11 12
Month
WaSSI
Base
Population
Deforest
Irrigation
Hadley2
CGC1
SGCP
Model Expansion
Flow Routing
SGCP
Mississippi River Flow Under Two Climate Change Scenarios
0
50000
100000
150000
200000
250000
1974 1984 1994 2004 2014 2024 2034 2044 2054 2064 2074 20842094
Year
Canadian
Hadley2
Linear (Canadian)
Linear (Hadley2)
SGCP
Model Expansion
WaSSI-CB (Carbon and Biodiversity)
- Applying other equations to the WaSSI database
SGCP
SGCP
Carbon
SGCP
SGCP
SGCP
Biodiversity
SGCP
SGCP
SGCP
SGCP
SGCP
Water supply and demand must be addressed together at the basin scale (upstream and downstream; and seasonal scale)
Regardless of climate change, population growth will cause waterstress problems in metropolitan areas
Climate variability will likely have a larger impact on episodic water shortages than will climate change over the next several decades
The ability to synergistically examine tradeoffs between water availability, forest carbon sequestration and biodiversity is animportant addition to our assessment capabilities
Summary