Integrated measurements & modeling of Sierra Nevada water budgets UCM PI: Roger Bales LLNL Co-PI: Reed Maxwell

Snowpack loss & water storage 13.5 MAF 11 MAF 14 MAF Likely loss of 3-5 million acre feet of snowpack storage in coming decades Sacramento Valley storageSan Joaquin Valley storage snowpack annual storage Data from DWR

California precipitation: more variable Coefficient of variation for annual average precipitation in California from 1890 to 2001 with trend line

Snowmelt runoff: occurring earlier in the year Annual April through July unimpaired runoff for four Sacramento Valley rivers compared to total unimpaired annual runoff

Specific aim : Develop strategies that integrate remote sensing & ground- based measurements with state-of-the-art models to achieve accurate estimates of snowpack, snowmelt & the partitioning of snowmelt into runoff, infiltration & evapotranspiration.

Research plan 1.Establish & maintain ground-based instrument clusters 2.Develop remotely sensed data for mountain snowcover & vegetation 3.Calibrate & evaluate advanced hydrologic model 4.Estimate spatial water balance components 5.Simulate climate & hydrology

Wolverton Project location Sierra Nevada boundary

Wolverton basin & meadow instrumentation

Stream stage & discharge Four pressure transducers installed in summer 2006 Rating curve in progress One more stage recorded to be added in summer 2007

Wolverton stream stage data, 2006

Wolverton stream detail, Nov 2006 Note inlet versus outlet daily & weekly patterns in response to temperature & evapotranspiration

Wolerton & Clover stream stage data, 2006

Wolverton meteorological stations Two stations installed in fall 2006, at Wolverton & Panther Meadow Telemetry in place on Wolverton station

Panther Meadow meteorological data,

Soil moisture & temperature Four locations Three pits per location Four depths per pit

Soil moisture & temperature, 2007

Snow depth sensors Four locations 10 per locations One over each soil pit

Meadow piezometers & wells Three lateral transects & one longitudinal transect Continuous logging

Soil matric potential Transect in meadow, in line with piezometers

Data sharing Currently data posted on internet in flat files & graphs: Digital library in place later this month Currently manual download of most data Matric potential data on telemetry; met station data to be added soon

Geophysical investigations Successful pilot test of ground penetrating radar by Reed & Stefan: plans to return in fall 2007 Proposal pending for additional geophysical investigation Expected results: bedrock depth & groundwater level

Satellite remote sensing of snowpack

2005, April 5

2005, April 14

2005, April 16

2005, April 21

2005, May 25

2005, May 26

2005, June15

2005, July 16

Depletion of snow covered area (SCA) vs. snow water equivalent (SWE), 2004

Depletion of snow covered area (SCA) vs. snow water equivalent (SWE), 2005

Melt season SCA: upper Merced basin 2004: less snow − ground became snow free relatively early Each higher elevation band requires ~1 mo longer to become snow free 2005: more snow – ground became snow free ~1 mo later than in Analysis for Kaweah in progress

Interpolated SWE (snow pillow) March 7, 2004 MODIS SCA March 7, 2004 Blended MODIS SCA & interpolated SWE +=

Depletion of snow covered area (SCA) vs. snow water equivalent (SWE), 2005

Plans for year 2 -Maintain instrument clusters & upgrade telemetry -Carry out geophysical surveys -Do meadow tracer tests -Extend remote sensing time series -Calibrate & evaluate hydrologic model -Analyze water balance data -Carry out water balance modeling

Wolverton Program expansion Sierra Nevada boundary Additional instrument clusters: NSF, DWR & USFS support NSF observatory planning grant funded Exploring O&M support from UC Sagehen Future