Download Meixner et al., 2004

Science issues
Water balance/cycling in snowmelt dominated
catchments
– remote sensing: SCA mapping
– ground based: SWE network design
Implications for understanding & modeling:
– Hydrology: partitioning of snowmelt
– water resources: tools to estimate amount & timing
of snowmelt
– nutrient & energy cycling, aquatic system response
Emerald lake, 1985-98
(Sierra Nevada)
Outflow N greater when snowmelt
occurred later in the year
Sickman et al., 2001
DIN retention less in years
with deep, late snowpacks
Modeling N cycle at Emerald lake
g m-2 a-1
plant uptake
leached
denitrification
net mineralization
discharge
Meixner & Bales, 2002
Emerald lake: discharge ANC
1950
1960
1970
1980
1990
– Multi-decadal simulations of basin hydrochemistry using
47-year reconstructed streamflow record & snowpack
depletion curves
– Multi-year wet periods lead to lower stream ANC
Meixner et al., 2004
… & lower soil pH
Climate variability
(5-10 fold changes
in snowpack) much
more important
than doubling of
acids in precipitation
(10 vs 1 µeq L-1)
Meixner et al., 2004
Research needs & advances
– Continuous (hourly or so) measurements as a
diagnostic tool
– flowpaths & water balance
– biogeochemical processes
– Integrated studies of water, C/N & energy cycles –
as climate changes
– disciplinary integration
– integration across landscape
– modeling as well as measurements
Instrumentation:
water, energy &
carbon cycling in
SW subalpine
forests
Canopy
Mt Bigelow 30 m tower
Eddy correlation system
Research infrastructure:
hydrologic observatories (HO’s)
– Address science questions at larger scales than current
research catchments (nested scales)
– Coordinated physical, chemical & biological measurements
over the long term
Consortium of Universities for the
Advancement of Hydrologic Science, Inc.
(CUAHSI)
Concept for a Sierra Nevada HO
HO made of 3-5 clusters of
instrumented
(sub)catchments along
latitudinal transect
Will also include elevational
transects along one or more
of the locations
Include stand-alone intensive
research sites in between
Focus mainly above the
reservoirs
Need to also consider
gradients other than climatic
Scope of HO science
stimulate study where hydrologic & biogeochemical understanding of
the water cycle is currently most limited
facilitate this research by:
– measuring hydrologic phenomena over representative spatial
scales & long time periods
– creating a legacy of well-designed & documented long-term
observations & experiments
– providing baseline data & short-term process studies for
conducting major synthesis & theoretical efforts
– fostering emergent collaborations among scientists & decision
makers
– providing information for the identification, assessment & solution
of societal problems
Broad science driver for HO
What: hydrologic systems are subject to multiple
perturbations (jolts) that result in responses that we
are currently poorly equipped to predict (examples …)
– how pulses & changes propagate through the system
– time lags & delays of stresses in comparative systems are
compelling issues
Why: multiple factors are increasing the stresses on
these systems, e.g. climate variability & change, land
use change, water demand patterns …
How: HO science addresses this deficiency by providing
a platform for research into the controlling processes &
for testing predictive tools
Some specific science drivers that will
influence design of a Sierra Nevada HO
Climate warming perturbations on a climate system that
is already highly variable:
– patterns of precipitation & snowmelt
– patterns of vegetative water use
Habitat restoration efforts – aquatic & riparian – in a
variable climate
– coupled groundwater & stream response to changes
– patterns of nutrient spiraling in streams
The potential for long-term droughts
– patterns of rain/snowmelt partitioning, soil moisture, ET …
– patterns of groundwater recharge, stream baseflow ..
Increasing potential for damage from floods
– elevational patterns of changes in hydrometeorology
– patterns of sediment generation & transport
Measurement priorities
Continuous
–
–
–
–
–
Ground-based hydrometeorology instrument clusters
Extended snow & soil moisture instrument cluster
Flux towers along gradients
Electrical conductivity, nitrate, silica in selected streams
Stream stage & groundwater levels
Periodic
– Snowcover, snowpack, soil moisture
– Stream, snow, rain, dry deposition, spring, groundwater chemistry
– Something related to sediment
Characterization
– Topography, soils, forest canopy, landcover, geology
– LIDAR (vegetation properties)
Thoughts on HO management
• Lead PI (1-2 mo) – position could rotate, like LTER PI
• Institutional Co-PI’s – makes decisions (may need
subset as excom) – institutional contribution to
leveraging, responsibility for some aspect (0.5-1.0 mo)
• Affiliated investigators (any institution or agency) –
must agree to data sharing policy (TBD)
• Advisory committee (2-4 persons)
• Ad hoc committees for distribution of special funds
• Project manager (Ph.D. level scientist) – full time
• Admin assistant – full time
• Business manager – full time
Thoughts on HO budget
Personnel
Equipment & supplies
Laboratory analyses
TOTAL
$1.2 M
$1.0 M
$0.8 M
$3.0 M