watervulnerability

Gallatin National Forest Watershed Vulnerability Assessment, Northern Region (R1)
SUMMARY
The physical characterization of watersheds was the most time-consuming step of the WVA. We felt it
was most important to first develop a robust analysis to characterize the geophysical reactivity of each
subwatershed. We hoped to utilize the most up-to-date and readily available datasets. After our initial run
using existing datasets of lower quality, we developed a repeatable method for the physical
characterization of watersheds. The results appear to be reasonably accurate, although additional
validations are needed. The terrain and geology sensitivity datasets may be used to derive other datasets,
such as soils, for use in future iterations of this assessment and other Forest analyses.
We expect this to be an iterative process that is never truly “complete.” The WVA was designed to be
easily updated with the latest datasets as they are developed. This design allows different resource areas
to be assessed together or separately, by incorporating the relevant datasets. Even as climate change
projections are refined in the future, the physical characterization of our subwatersheds should remain the
same, enabling quick evaluation of the subwatersheds through the latest climate scenarios without
additional analysis.
APPLICATIONS
Management
These results may aid GNF managers in prioritizing subwatersheds for resource conservation and
restoration efforts. The results can also be used to validate priorities identified by the rapid assessments
and landscape assessments on the Forest.
Monitoring
The identification of the potentially most sensitive and most vulnerable subwatersheds can be used to
prompt monitoring in those areas at risk.
Collaboration, Education and Outreach
This analysis, and others like it, will hopefully provide more reason and opportunity for the USFS to
educate the general public on climate change and our adaptive management strategies to address it. In
addition, these analyses will provide opportunities to collaborate with other state, federal, and tribal
agencies and non-governmental organizations (NGOs) to address climate change.
CRITIQUE
What important questions were not considered?
Currently, the WVA should not be considered valid beyond the Forest boundaries. The terrain sensitivity
analysis will need to be further refined to characterize the subwatersheds beyond the Forest boundaries.
What were the most useful data sources?
1. National datasets which do not end at the Forest boundaries (NHD, NED).
− NED was very useful for deriving other datasets as well.
2. Ecoshare (website) is a well-organized source for climate projections data for Region 1.
3. Montana NRIS provided statewide datasets.
43 Assessing the Vulnerability of Watersheds to Climate Change