watervulnerability

Umatilla National Forest Watershed Vulnerability Assessment, Pacific Northwest Region (R6)
Three categorical exposure values were summed for total exposure risk (from 3, least exposure to 7,
greatest exposure). The climate exposure risk rating for each HU6 subwatershed was then combined with
the Risk-Value rating.
Composite Watershed Vulnerability
Each step in the analysis is displayed below for the 162 HU12 subwatersheds using 5 categories for value,
sensitivity, and exposure, and combined into a simplified three-factor “composite watershed
vulnerability” rating.
Watershed values were ranked 10-50 in multiples of ten in an unequal distribution of arbitrary breaks based on the
total number of values. Rankings were based on the sum of all values categorized as follows: 3-4 values=10 (Low);
5 values=20 (Moderate/Low); 6 values=30 (Moderate); 7-8 values=40 (Moderate/High); 9-13 values=50 (High).
Watershed sensitivity was ranked 1-5 in an approximately equal distribution. Rankings were based on
sum of all values categorized as follows: 5-7=1 (Low); 8=2 (Moderate/Low); 9=3 (Moderate); 10=4
(Moderate/High); 11-14=5 (High).
216 Assessing the Vulnerability of Watersheds to Climate Change