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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