watervulnerability

White River National Forest Watershed Vulnerability Assessment, Rocky Mountain Region (R2)
Figure 4. Predicted changes in Colorado River basin snowpack (Christensen and Lettenmaier 2006)
Lastly, Figure 5 shows the predicted decrease in annual runoff for the Colorado River Basin. Median
estimates from the multi-model runs approach 10% by mid and late century. Multiple studies in the
Colorado River basin show predicted decreases in runoff between 6% and 20% by 2050 (Ray et al. 2008).
Lower runoff is also coupled with a shift in the peak flow hydrograph. The peak is anticipated to occur
earlier by two to four weeks, perhaps more, depending on the influence of dust on the snow surface.
Recent research in Colorado has suggested that peak flows occur up to 3 weeks earlier than they did
historically. This is at least partially due to dust layers on the snow surface that reduce snow reflectivity
and increase the amount of solar radiation absorbed in the snowpack (Painter et al. 2010). Thus, not only
will there be less water in streams and available for water uses, but the peaks flows will likely be
occurring before the irrigation season begins. This would surely lead to an increase in the number of
proposals for water storage.
118 Assessing the Vulnerability of Watersheds to Climate Change