TreeFlow - Fraser R. at Winter Park, CO

Upper Colorado Basin

Fraser River at Winter Park, CO

Calibration & Verification

Long-term Reconstruction

Background

The Fraser River at Winter Park gage measures a key component of Denver Water's water supply. A reconstruction for this gage was first developed by Connie Woodhouse in 2002, and then re-calibrated in 2004 using new tree-ring chronologies that end in 2002. The 2004 re-calibration is shown below. This reconstruction was used in analyses described in Woodhouse and Lukas (2006).

Reference:

Woodhouse, C.A. and J.J. Lukas. 2006. Multi-century tree-ring reconstructions of Colorado streamflow for water resource planning. Climatic Change 78: 293-315.

Metadata

Observed Record

Location: Fraser River at Winter Park, CO
USGS Gage: 09023750

Source: Denver Water

Adjustment: "Natural flow" record extensively adjusted to account for depletions and diversions

Observed Flows

Period: 1916-2002

Mean flow:	28 KAF
Median flow:	28 KAF
Minimum:	11 KAF
Maximum:	46 KAF

Reconstructed Flows

Period: 1437-2002

Mean flow:	28 KAF
Median flow:	28 KAF
Minimum:	11 KAF
Maximum:	41 KAF

Calibration & Verification

Methods

A forward stepwise regression procedure was used to calibrate the observed flow record with a pool of potential predictors consisting of ~30 tree-ring chronologies from Colorado). The residual chronologies, with the low-order autocorrelation removed, were used. Four predictor chronologies were selected by the stepwise procedure for the reconstruction model for Fraser River at Winter Park. Validation statistics were computed using a leave-one-out (cross-validation) approach. Further details are provided in Woodhouse and Lukas (2006).

Predictor Chronologies: Dillon (CO), Pump House (CO), Cochetopa Dome (CO), Gould Reservoir (CO)

Statistic	Calibration	Validation
Explained variance (R2)	0.67
Reduction of Error (RE)		0.62
Standard Error of the Estimate	3802 AF
Root Mean Square Error (RMSE)		3931 AF

(For explanations of these statistics, see this document (PDF), and also the Reconstruction Case Study page.)

Figure 1. Scatter plot of observed and reconstructed Fraser River annual flow, 1916-2002.

Figure 2. Observed (black) and reconstructed (blue) annual Fraser River annual flow, 1916-2002. The observed mean is illustrated by the dashed line.

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Long-Term Reconstruction

Figure 3. Reconstructed annual flow for the Fraser River (1437-2002) is shown in blue. Observed flow is shown in gray and the long-term reconstructed mean is shown by the dashed line.

Figure 4. The 10-year running mean (plotted on final year) of reconstructed Fraser River flow, 1437-2002. Reconstructed values are shown in blue and observed values are shown in gray. The long-term reconstructed mean is shown by the dashed line.

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