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

100 East River at Almont

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Figure 7: Effect of temperature increases on the average hydrograph (East River model). A
temperature increase of 40C shifts peak runoff from June to May.

temperature cause the distribution to narrow. Whereas in the base case, June runoff ranges from

approximately zero to 400 thousand acre-feet (taf) , a temperature increase of if C cuts this range in half,

from zero to 200 taf.

Figure 10 illustrates mean runoff as it varies between high- and low-flow seasons for the White

River. Spring runoff is averaged over three months of high runoff (April, May, June) and fall runoff over three

months of low runoff (October, November, December). These results suggest less extreme seasonal flows

as a result of climate change in most cases. The effect of an evenly applied increase in temperature is to

reduce the seasonal variation in runoff, primarily as a result of reduced streamflow in the spring. In the

Animas River model, climate scenarios diminish the difference between spring and fall flows because spring

runoff decreases in all cases. When substantial precipitation increases are incorporated into the model,

however, seasonality becomes more pronounced. In the White and East River models, climate scenarios

do not decrease spring runoff as dramatically, while scenarios that incorporate precipitation increases of

20% augment spring runoff substantially.

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