HYDROLOGY IN A
CHANGING CLIMATE:
MOUNTAINS AS WATER
TOWERS
Mark Williams
University of Colorado
Geography and INSTAAR
What Do We Really Know about
the Water Cycle?
• Water flows towards money
• Whiskey’s for drinkin’, water’s for fighten’
WATER CYCLE
HYDROLOGIC EQUATION
Q = P – ET +- DS
Q is discharge
P is precipitation
ET is evapotranspiration
S is storage (usually groundwater)
GLOBAL WATER USERS
INCREASING GLOBAL USE
OF WATER
We aren’t making new water!
WATER RESTRICTIONS
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Apply only to municipal water users
They use <10% of all water
Why are municipal water users picked on?
Should municipal water users adhere to
voluntary water restrictions?
• Or by doing so do they provide aid and
comfort to water abusers?
MOUNTAINS AS WATER
TOWERS
AREAS DEPENDENT ON
MOUNTAIN DISCHARGE
DANIEL VIVIROLI, ROLF WEINGARTNER and BRUNO MESSERLI
GLOBAL VIEW OF MOUNTAIN
DISCHARGE
DANIEL VIVIROLI, ROLF WEINGARTNER and BRUNO MESSERLI
Headwaters of almost all Major
Rivers in Mountains
Gravity is Free: The ColoradoBig Thompson diversion project
Transfers water 13 miles from Lake Granby, Shadow Mountain Lake and
Grand Lake (in the Colorado River basin) to the Big Thompson River
for use on the east slope of the Front Range, under Rocky Mtn NP via
Adams tunnel
Most water users prefer “mountain stream water” because gravity delivers
it for free.
Potable Drinking Water
• Dependable, potable water as a
renewable resource is one of the global
environmental obstacles that has grown
more acute as a result of population
increase and changes in global climate
patterns.
WATER QUALITY
New York City
Storage capacity of 550 billion gallons.
1.5 billion gallons per day delivered
to 9 million customers
97 percent reaches homes and
businesses through gravity alone
90% of water unfiltered.
Chlorine is added to the water to kill
bacteria, and fluoride is added to help
prevent tooth decay.
ALL WATER FROM MOUNTAINS!
Brewed with Pure Rocky
Mountain Spring Runoff
Benefits of Mountain Runoff
• Mountain runoff provides 65-90% of
usable water in arid and semi-arid regions
• The high quality of mountain runoff is
preferred for drinking water, beer making
• Mountain runoff is “free” to downstream
users because of gravity flow
• Water available when needed: spring and
summer months
WHY MOUNTAINS ARE WATER
TOWERS
Precipitation Amount Increases
with Elevation
Loch Vale
Great Plains
Chemical loading also
increases with elevation
Transect from plains to ROMO
Percentage of Snow as Precipitation
Increases with Elevation
More snow stored longer at highelevation
Less ET with Higher Elevations
• Trees intercept snow
• Less snow reaches
ground
• High ET loses in both
winter and summer
for forested areas
• Less tress with higher
elevations
• Colder air temps with
higher elevations
Drip Irrigation System
•Melting snow is similar to a drip-irrigation system
•Snow melts slowly and steadily
•Snow melt generally stops at night
•Maximum infiltration occurs
•Little overland flow, flooding, or sediment transport
Less Subsurface Storage
A higher percent of snowmelt converted to streamflow
with increasing elevation, because less subsurface storage to fill
Don’t Eat the Snow!
• Snowmelt runoff has
the best water quality
• Snow generally has
much less solutes
than any streamwater
• Snow generally has
little anthropogenic
contamination
Alps case study
With mountains
No mountains
•Precip doubles
•ET: little change
•Runoff: 4x greater
Adapted from Baumgartner et al., in press
Climate Change and Mountain
Runoff
Larger temp increases in mountains
Mean change in temperature for 2xCO2 runs from 7 climate models.
Black triangles are high mountains for that latitude. White line connects
the highest elevations in each grid cell. North American summer months.
Note that the climate models suggest increasing temperature change
with increasing elevation (Bradley et al., 2004, GRLs).
Albedo of Snow
• Highest values on earth
• Why you get sunburn
twice when skiing
• Why you sunburn weird
places (ears, inside nose)
• Lack of snow decreases
albedo
• Increases warming
• Positive feedback
• Threshold effect
• Very sensitive to climate
changes
Snowline sensitive to 0oc Isotherm
Less Snow, Earlier Melt
CIG (www.cses.washington.edu/ cig/figures)
Climate-Snow Feedbacks
• Amount of snow stored in mountain areas
changes dramatically with just a small change in
temperature
• A small change in snow-covered area results in
a large decrease in albedo
• More snow melts
• Albedo decreases
• Positive cycle run amuck
• Less total discharge (more ET loss)
• Earlier discharge peak
• Less summer discharge
Western US 1950-2000
SNOWPACK
(Mote and others)
STREAMFLOW
(Stewart and others)
Problems with Hydroelectric
Power
• In the past two decades, the amount of power
that Idaho Power Co. has generated cheaply
from its 17 hydroelectric dams on the Snake
River has dropped.
• A drop in July-to-September streamflows, as
predicted in the climate models, would reduce
power production by 10 to 15 percent, according
to the Climate Impacts Group.
• Since summer is a peak period for power, the
wholesale rates could be high. Idaho Power is
allowed to pass on its annual power costs to its
423,000 customers so electricity bills would rise.
Glacial Retreat: South Cascade
Snow line and glacial extent moving uphill
Global Problem
Mark Dyurgerov, INSTAAR
Global warming threatens ski resorts
* 16:25 02 December 2003
* NewScientist.com news service
* Duncan Graham-Rowe
Hundreds of ski resorts will go out of business
because of global warming,
according to research published
by the United Nations Environment Program
on Tuesday.
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Ski Areas in a Changing
Climate
Great uncertainty of
future patterns
Low elevation ski
areas at risk
Risk of shortened
seasons from early &
late rains (winter &
spring
holidays=$$$$)
Number one ski day
is Saturday after
Thanksgiving
Too warm to make
snow?
Climate Related Stresses on
Ski Area Operations
Increased Snowmaking to
maintain length of season
Increased pressure for yearround operations to offset
reduced winter revenues
Increased value of shrinking
alpine ecosystems might
limit expansion
Warmer temperatures could
make skiing mor enjoyable…
From the Proceedings of the Rocky Mountain / Great Basin Regional Climate-Change Workshop
Trading snow boards for water
skiis
• The warmer winter temperatures projected
by the climate models mean ski resorts
would open later and closer earlier.
• Temperatures at Bogus Basin in Idaho
(outside fast-growing Boise) have
averaged 15 to 20 degrees above normal
for the last three years, said Mike Shirley,
Bogus Basin general manager.
A Snoball’s Chance in …
• John Harte, UC Berkeley prof at RMBL near
Crested Butte "It's very difficult for me to believe
that 40 years from now, or even 20 to 30 years,
the ski industry is going to be any kind of healthy
recreational industry“
• Vail Mountain chief operating officer Bill Jensen
replies, "Hogwash. I don't believe that at all.
People will be skiing in Colorado 50 to 100 years
from now. I'll let the jury decide about 200 years
from now."
• From Allen Best, Aspen Times, 30 September 2004
How is Snow Made?
• Water withdrawn from river or lake
• Pumped up to holding reservoir
http://www.ist-snow.com/Page1
Problems with Making Snow
• Take water from streams in fall months
• These are low-flow times of year
• Result is aquatic damage
– Benthic invertebrates killed (fish food)
– Not enough water, oxygen for fish
• No water for downstream users
• More pollution: concentrations of
pollutants goes up because no water to
dilute
Whiskey’s For Drinkin’,
Water’s For Fightin’
• Legal right to divert water
– Senior rights
– Vail has spent >$1,000,000 acquiring senior
water rights
• Legal rights for water left in rivers aren’t
recognized in many states
• Highest priority to people that hold oldest
rights
• In conflict with “ecosystem services” such
as trout fisheries, kayaking, rafting
ALPS: Dark view of white snow
• 85 percent of Swiss resorts today are
"snow reliable."
• Only 44 percent of skiing regions will be
“snow reliable” in 2030
• Germany and Austria, with more lowerelevation resorts, would have even fewer
ski areas remaining in business.
• Rolf B?rki, Hans Elsasser, and Bruno Abegg, quoted by A Best in
Aspen Times, 30 September, 2004.
Swiss wrap glacier to slow ice melt
• (Reuters) -- Alarmed by the
retreat of its Alpine glacier, a
Swiss ski resort on Tuesday
wrapped part of the shrinking
ice-cap in a giant blanket in a
bid to reduce the summer melt.
• If successful, officials at the
Gemsstock resort above
Andermatt in central
Switzerland expect the
example to be followed
elsewhere in the Alps, where
scientists say glaciers are
under threat from global
warming.
• 2005