Paleo-reconstruction of summer streamflow

and seasonal uncertainties using the VIC hydrologic model

Eric LutzAlan Hamlet

Jeremy Littell

JISAO CSES Climate Impacts GroupCivil and Environmental Engineering

University of Washington

Climate science in the public interest

Acknowledgments

FundingNOAA CPO SARP (N. Mantua, J. Littell, A. Hamlet, C. Woodhouse)

JISAO

ContributorsJ. Deems ~ Meteorological data processingM. McGuire Elsner ~ VIC implementation

P. Carrasco ~ Programming supportG. Pederson (USGS) ~ Chronologies of the Northern Rockies

Contributors of the International Tree-Ring Data Bank

GoalsI. Reconstruct Seasonal Streamflow

Exploit PNW character: Summer Streamflow driven by Winter Precipitation

Use a physically based hydrologic model (VIC)

Summer Streamflow ~ Winter Precipitation Yakima Basin

r2 = 0.65r2 = 0.73; w/o outlier (1934)

GoalsI. Reconstruct Seasonal Streamflow

Exploit PNW character: Summer Streamflow driven by Winter Precipitation

Use a physically based hydrologic model (VIC)

Summer Streamflow ~ Winter Precipitation

r2 = 0.65r2 = 0.73; w/o outlier (1934)

Goals

II. Quantify Streamflow Uncertainty

Integrate historic meteorological variability into tree-ring based streamflow reconstruction

Develop a physically-based framework for assessing streamflow uncertainty caused by various

factors (Land use change, vegetation dynamic, etc.)

Methods

1. Reconstruct cool season (October-March) precipitation from proxy relationships between historic meteorological data and tree-ring chronologies

2. Create an extended historic meteorological dataset that contains natural variability of the historic record combined with the winter precipitation estimates from the paleo reconstruction.

3. Reconstruct summer streamflow for the period 1600-1981 by driving VIC hydrologic model with the extended historic meteorological datasets.

4. Demonstrate how summer streamflow may be systematically influenced by a climate-change scenario.

Tree-ring Reconstruction of Basin-Average Winter Precipitation

Meteorological RecordMeteorological Record

EOF/PCA, RegressionEOF/PCA, Regression

Historic Record (1916-2006)Paleo Period (1600-1915)

Reconstructed Basin-Average Winter PrecipitationReconstructed Basin-Average Winter Precipitation

Dendrochronological Record (Tree-rings)Dendrochronological Record (Tree-rings)

91 years ofBasin-Average

Winter Precipitation

91 years ofBasin-Average

Winter Precipitation

Tree-ring Reconstruction of Basin-Average Winter Precipitation

‘1937’ ‘1953’ ‘1983’ ‘1933’ ‘1926’

Disaggregate onto multiple winter precipitation patterns

Ensemble of Extended Meteorological Forcings for VIC

High Flow

Pattern

Low Flow

Pattern

Ave. Flow

Pattern

Summer Streamflow ReconstructionHistoric Period (VIC-generated)

Historic Meteorological Patternassociated with

Very high summer flow

Very low summer flow

Average summer flow

Summer Streamflow ReconstructionPaleo-Reconstruction (VIC-generated)

Historic Meteorological Patternassociated with

Very high summer flow

Very low summer flow

Average summer flow

r2 = 0.3

Dalles Streamflow observations (thin black) and long-term linear trend (bold black, p =0.005) compared with reconstructed streamflow (thin red) and long-term linear trend (bold red, p = 0.08).

1860 1880 1900 1920 1940 1960

1500

0025

0000

3500

00

YEAR

Stre

afm

lwo

[cfs

]

Summer Streamflow ReconstructionClimate Change Scenario (VIC-generated)

Historic Meteorological Patternassociated with

Very high summer flow

Very low summer flow

Average summer flow

Summer Streamflow ReconstructionClimate Change Scenario (VIC-generated)

Paleo

Future

Ave. Paleo

Ave. Future

Appendix

Study Design

Meteorological RecordMeteorological RecordEOF/PCA, RegressionEOF/PCA, Regression

Historic Record(1916-2006)

Paleo Period(1600-1915)

Reconstructed Basin-Average Winter PrecipitationReconstructed Basin-Average Winter Precipitation

Reconstructed StreamflowReconstructed Streamflow

Dendrochronological Record (Tree-rings)Dendrochronological Record (Tree-rings)

Winter PrecipitationSensitivity AnalysisWinter PrecipitationSensitivity Analysis

Spatial & temporal re-distribution of cool-season precipitation

Spatial & temporal re-distribution of cool-season precipitation

Macro-scale hydrological model (VIC)Macro-scale hydrological model (VIC)

Met. Ensemble Representative of Historic Variability

Met. Ensemble Representative of Historic Variability

Extended Distributed Meteorological Data(perturbed independently for Climate Change scenario)

Extended Distributed Meteorological Data(perturbed independently for Climate Change scenario)