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Climate Change Impacts on California’ s Wa t e r S y s t e m
Andrew Schwarz P.E.Division of Statewide Integrated Water Management
Water Policy for Food SecurityUC-Davis October 5th, 2015
Statewide Water Management Systems
Year 2000 data. Does not include re-use. Quantities vary by year.
High inter-annual variability –drought and flood prone Mountain ranges in the 8,000-12,000 foot range Highly dependant on snowpack storage with limited
reservoir capacity Steep mountain rivers draining into a flat valley Leveed river channels to convey flood waters and
water supply Tidally influenced delta as the hub of conveyance
system
the Perfect Water System to Demonstrate Climate Change Impacts
High Inter-annual Variability
1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Water Year Type
Wet
Critical
Dry
Below Normal
Above Normal
1/3 of California’s Water Supply comes from Snowpack
We need that snow to stay high in the watershed until after the flood season has passed
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
1901 1911 1921 1931 1941 1951 1961 1971 1981 1991 2001
Run
off V
olum
e (tA
F)
Water Year (October 1 - September 30)
April-July Runoff
Historical Trends – Runoff TimingSacramento River System
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep0.0
0.5
1.0
1.5
2.0
2.5
3.01906-19551956-2014
Monthly Average Runoff Sacramento River System
Run
off in
Mill
ion
Acre
-Fee
t (M
AF)
Month
San Francisco
You are here
Pumps Pumps
Temperature• Up to 8 degrees C
by end of century• Summer warming
will be more significant than winter warming
• Inland areas will experience more warming than coastal areas
• Evening and nighttime warming more significant than daytime warming
Projected Climate Changes
Projected Climate Changes Precipitati
on
• Projections nearly evenly split between more precip and less
• Trend toward more extreme years
• SoCal tending drier, NorCal maybe slightly wetter
Projected Climate Changes
• 30-40% Reduction in Snow Water Equivalent across the Sierras by mid-century
• 65% Less snowpack by end of century
• Changed runoff patterns lead to less summer runoff
• 15-20% Lower soil moisture
Snow Pack and Water Supply
Projected Climate Changes
Sea Level2030: 1.6 - 11.8 in (1 ft)2050: 4.5 - 24 in (2 ft)2100: 16.5 - 65.7 in (5.5 ft)
Higher storm surges on top of higher mean SLR
Is this Drought a Window into the Future?
Is Groundwater the Answer?
