watervulnerability

Coconino National Forest Watershed Vulnerability Assessment, Southwest Region (R3)
The CIG applied the Variable Infiltration Capacity (VIC) (Liang et al. 1994) model to their modeled
changes in temperature and precipitation, to predict changes to different hydrologic characteristics. Of
most interest to the ID team were changes to snow, and runoff (Figures 14-15). Predictions again show
fairly uniform changes across the forest, but with more change at higher elevations. This is logical, as this
is where the most snow currently falls. If temperatures increase, a decrease in snow could be expected,
with resultant changes in runoff timing and amount.
Figures 14 and 15. Left, Predicted changes in Snow Water Equivalent (mm) between modeled historic and modeled
conditions in 2070, based on the CIG composite model. Right, Predicted changes in runoff (mm/acre) between
modeled historic and modeled conditions in 2030, based on the CIG composite model.
The CIG composite model predicts almost no change in the annual precipitation, but does predict changes
in the timing, with less precipitation falling in the spring, and more delivered by monsoons in the fall.
Results of this modeling are shown in Table 4, and are averages for all the watersheds in the analysis area.
Month Historic 2030 2030 2080 2080
January 2.4 2.5 0.1 2.3 -0.2
February 2.4 2.5 0.1 2.5 0.2
March 2.4 2.0 -0.4 1.9 -0.5
April 1.4 1.1 -0.3 0.9 -0.5
May 0.6 0.4 -0.2 0.3 -0.2
June 0.4 0.4 0.0 0.4 0.0
July 2.3 2.3 0.1 2.8 0.6
August 3.1 3.3 0.2 3.9 0.8
September 1.9 2.5 0.6 2.6 0.8
October 1.6 2.0 0.4 2.1 0.5
November 1.6 1.5 -0.1 1.3 -0.3
December 2.4 2.2 -0.2 2.3 -0.1
144 Assessing the Vulnerability of Watersheds to Climate Change