watervulnerability

Chugach National Forest Watershed Vulnerability Assessment, Alaska Region (R10)
areas, there is likely a need to collect simple baseline data, such as groundwater temperatures, that can be
monitored over time to detect or verify predicted changes.
Most of all, managers need to determine how the information is going to help make on-the-ground
decisions. Certainly, we would like to know that if fry develop faster and emerge earlier, their food
resources will also develop faster and will be available. But we need to be thinking about how we can
mitigate the situation if necessary. And this isn’t necessarily building enhancement structures or replacing
culverts. New information can be used to justify policies and management, such as a reduction in salmon
harvests or other conservation measures. The main point is that the complexity of climate change is
bringing up lots of questions, and managers would do well to establish specific needs and research
priorities before getting started.
CRITIQUE
General Approach
The initial steps that were suggested for this assessment follow a rational and logical progression –
defining the assessment area, identifying the resource values, describing the sensitivity of these values,
identifying stressors, and determining exposure. Identifying the resource values is especially important
because it focuses the analysis on the relevant issues.
The other Forests compared all of their watersheds to determine which were the most vulnerable but this
was not a priority for the Chugach. As mentioned earlier, most of the watersheds have little or no
development – 99% of the Forest is in roadless areas. Although climate change can affect resources in all
of the watersheds, I felt that it was unlikely that managers would conduct mitigation measures in pristine
areas.
Not ranking the relative vulnerability of the watersheds may be one weakness of this assessment. The
assessment does not show, for example, that the fisheries values of the Kenai River system (with
headwaters on National Forest land) far outweigh the Resurrection Creek fisheries. However, Chugach
managers don’t have more than a half dozen developed watersheds to look at, so they have the luxury of
being able to look closely at each watershed. Given the low levels of development in the Kenai area and
knowing that the climate change conditions will be similar, managers will still need to be working on a
site-specific scale, watershed by watershed, to develop meaningful plans and establish project priorities.
Data Availability
There is a good deal of climate change information available from the UAF SNAP program, from raw
GCM data to ready-made maps and graphs. Other websites have historic evapotranspiration estimates and
other parameters that could be useful in more extensive analyses.
Predicting change for streamflow and runoff timing in coastal Alaska is difficult due to several conflicting
factors. Climate change models predict warmer temperatures and increased precipitation for coastal
Alaska, but given the high elevations of the area, reductions in snowpack at lower elevations may be
offset by higher precipitation and more snow at higher elevations. Earlier melting of the snowpack may
be compensated for by increased glacial melting augmenting flows in late summer, – at least until the
glaciers are gone. Most of the literature agreed that glaciers were melting more rapidly, but increased
snowpacks in coastal Alaskan mountains was only mentioned as a possibility.
298 Assessing the Vulnerability of Watersheds to Climate Change