TreeFlow - Clear Creek near Golden, CO

Clear Creek near Golden, CO

Calibration & Validation

Long-term Reconstruction

Background

Clear Creek is an important tributary of the South Platte River and provides water for several municipalities, including Golden and Westminster. A reconstruction (1685-1987) was first developed for Clear Creek in 1999 by Connie Woodhouse for the City of Westminster. An updated reconstruction (1635-1987) was developed by Woodhouse in 2003 for Wright Water Engineering, consultants for Coors Brewing Company, which obtains water for its brewery from Clear Creek. The latest reconstruction (1566-2002) was developed by Woodhouse and Jeff Lukas, for the City of Westminster. The calibration period includes the extreme drought year of 2002. This reconstruction is shown here.

Reference:

Woodhouse, C., and J. Lukas. Tree-ring reconstruction of Clear Creek annual streamflow, 1566-2002. Report to City of Westminster, August 2006.

Metadata

Observed Record

Location: Clear Creek above Welch Ditch, near Golden, CO
USGS Gage: 06719505

Source: City of Westminster

Adjustment: Undepleted flow record, extesively adjusted to account for depletions

Observed Flows

Period: 1912-2002

Mean flow:	162 KAF
Median flow:	157 KAF
Minimum:	61 KAF
Maximum:	309 KAF

Reconstructed Flows

Period: 1566-2002

Mean flow:	158 KAF
Median flow:	157 KAF
Minimum:	27 KAF
Maximum:	275 KAF

Calibration & Validation

Methods

A forward stepwise regression procedure was used to calibrate the observed flows with a pool of potential predictors consisting of 21 tree-ring chronologies from Colorado (both east-slope and west-slope). The residual chronologies, with the low-order autocorrelation removed, were used. Four predictor chronologies were selected by the stepwise procedure for the reconstruction model. Validation statistics were computed using a leave-one-out (cross-validation) approach.

Predictor Chronologies: Van Bibber Update (CO), Dillon (CO), McPhee-Dolores (CO), Cochetopa Dome (CO), Chokecherry Canyon (CO)

Statistic	Calibration	Validation
Explained variance (R2)	0.70
Reduction of Error (RE)		0.66
Standard Error of the Estimate	27,439 AF
Root Mean Square Error (RMSE)		28,316 AF

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

Figure 1. Scatterplot of observed and reconstructed Clear Creek annual flow, 1912-2002.

Figure 2. Observed (black) and reconstructed (blue) annual Clear Creek annual flow, 1912-2002. The observed mean is illustrated by the dashed line.

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Long-Term Reconstruction

Figure 3. Reconstructed annual flow for Clear Creek (1566-2002) 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 Clear Creek flow, 1566-2002. 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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