watervulnerability

Chugach National Forest Watershed Vulnerability Assessment, Alaska Region (R10)
can be used for the gaps. The system tests whether a statement is true (e.g., coho salmon habitat is
suitable), based on a number of dependent data inputs. The validity of this method is discussed by
Reynolds (2001), and the method was used for the Aquatic and Riparian Effectiveness Monitoring Plan
for the Northwest Forest Plan (Reeves et al. 2003). Some of the key benefits are that it forces managers to
analyze issues in a clear, rational method, and that the links between factors and conditions, the causes
and effects, can be clearly diagrammed.
Using this tool may seem easy in concept, but can become exceedingly complex, even for simple
biological questions. Summer coho salmon habitat, for example, will depend on water temperature, cover,
food, water velocity, etc., all of which may depend on multiple subfactors. Temperature could depend on
riparian vegetation, groundwater input, stream width, and so forth. At each step, one has to determine
how much to weigh each factor in relation to other factors and how to evaluate each factor. The degree of
uncertainty seems to accumulate with every estimation, opinion, or assumption. Thus, one can spend a lot
of time working out the details of this analysis method and never reach a conclusion with which one feels
comfortable. This was my experience.
If one wants to use NetWeaver or some similar method, it would be best to have experienced users to
point out the limitations, particularly as to the level of investigation. Deriving broadscale conclusions for
the Northwest Forest Plan is probably more appropriate than trying to analyze conditions in a small
watershed, where you would want more detailed answers. Also, since many inputs may require expert
opinion, it would be best to have a number of qualified people to present their views for each topic
(Reynolds 2001), not just a single person. Even though NetWeaver may reduce the need for some data, it
still requires a good deal of intellectual input and effort to get a satisfactory product.
So, as far as analysis is concerned, a general idea of the types and magnitudes of climate change – which
could be readily available from the internet – may be enough to get started. The key first step might not
be to obtain specific numbers, but to analyze how those changes might generally affect the resource
values in a given area. After that, one can determine if there is anything that can be done about the
problem, and how much more specific data is needed for project implementation. Again, local groups
with existing plans, such as the Kenai Peninsula Borough’s All Hazard Mitigation Plan or the Copper
River Watershed Project’s Million Dollar Eyak Lake program can provide direction or ready-made
solutions.
Direction for the Future
Once managers have looked at the resource values and how they might be affected by climate change,
there is the need to implement the mitigation proposals. Certainly, there is a laundry list of tasks that can
be applied to almost all areas and that should be implemented as a normal course of work. Some
examples include:
• Replacing “red” culverts that are inadequate for fish passage or flows. Replacement culvert sizes
will need to be adjusted for predicted flows under climate change scenarios and extreme events.
Utilize existing culvert prioritization protocols.
• Maintaining roads at least to current standards. In the long term, standards should be reviewed in
light of predicted climate changes, such as requiring more frequent drainage structures for areas
with increased precipitation.
• Examining infrastructure in riparian or other areas that may be subject to floods or snow
avalanches, in regard to public safety.
• Restoring existing damaged riparian areas, particularly in regard to floodplain connectivity in
areas susceptible to floods from rain-on-snow or extreme events.
295 Assessing the Vulnerability of Watersheds to Climate Change