7997

• UCREFRP Catalog Number: 7997
• Author: Nash, L. L. and P. H. Gleick.
• Title: The Colorado River Basin and Climatic Change, The Sensitivity of Streamflow and Water Supply to Variations in Temperature and Precipitation.
• USFW Year: 1993.
• USFW - Doc Type: EPA 230-R-93-009,
• Copyright Material: NO

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Mean (thousand acre-feet]

Figure 6: Point estimates of annual flow (mean and standard deviation) for the White River,
with approximate 90% confidence regions for the base case and selected hypothetical
scenarios.

East River also undergoes a distinct shift in the timing of peak runoff, from June to May. The UKMO

scenario for the Animas and White rivers shifts peak runoff from June to April, which reflects the 6.8' C

temperature rise. Figure 7 illustrates the general effect of temperature on the timing of peak runoff for the

East River. In all cases, the sub-basins remain snowmelt-driven, although peak runoff is occurring earlier

in the year.

Histograms of January and June runoff are presented for the Animas River in Figures 8 and

9. The distribution of January runoff becomes much more flat as a result of increases in temperature and/or

precipitation. This is indicative of the higher flows which are occurring during the winter, as more

precipitation falls as rain rather than snow. Still, flows in January are very low compared to typical spring

or summer flows. The impact of climate-change scenarios on June runoff is the opposite. Increases in

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