watervulnerability

Chequamegon-­‐Nicolet National Forest Watershed Vulnerability Assessment, Eastern Region (R9)
RESULTS
Wetlands
For the historic period, the PHIM produced an average monthly snowpack that peaks in March at 2.2
inches of water equivalent and normally melts by mid-April (Figure 7). With warmer winters in the
future, PHIM projects that average monthly snow water equivalent would peak in February at 1.7 inches
and melt by mid-March. This represents a decline in average snow water of nearly 25 percent with melt
occurring about one month earlier.
The modeling results indicate average annual evapotranspiration from the upland-peatland complex
would increase by 3.2 inches (from 21.7 to 24.9 inches), a 15 percent increase (Table 1). Average annual
runoff would decline by 1.3 inches (from 5.5 to 4.2 inches), which represents a 24 percent decline. From a
seasonal standpoint, runoff would remain the same in winter, increase in spring by 0.4 inches, and
substantially decline in summer and fall (Table 1).
Average annual water levels would decline only slightly in the bog but changes for individual seasons and
months would be much greater. Average annual water levels in the bog would decline from 9.5 to 8.1
inches, or about 15 percent (Table 1). Monthly water levels would be unchanged in Jan-Feb, increase 0.5-
1.25 inches in Mar-May, and decline 0.5-4.5 inches in Jun-Dec (Figure 8). No flow days were predicted
to occur 4.4 percent of the time (16 days/yr) for the current climate but would increase to 23.4 percent of
time (85 days/yr) under the climate change scenario. The 4.5-inch decline in water levels in August and
September and large increase in no-flow days could have a substantial effect on plant communities and
carbon processes in the bog.
Ave Snow Water Equivalnet (inches)
2.5
2.0
1.5
1.0
0.5
0.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
1960-­‐2000
2046-­‐2065
Figure 7. PHIM average monthly watershed snow water equivalent for 1961-2000 and 2046-2065
The results indicating earlier snowmelt and higher initial water levels in the spring are similar to the
results obtained by McAdams et al. (1993) who used PHIM to model streamflow and water table changes
in the S2 bog due to climate change. S2 is an experimental peatland watershed located on the Marcell
Experimental Watershed in northern Minnesota. The researchers used temperature and precipitation
244 Assessing the Vulnerability of Watersheds to Climate Change
Peatland Hydrologic Impact Model
Calibrated S2 Bog WS
from Marcel Exp Forest in MN
WICCI Climate Data
longitude -­‐90.1, ladtude 45.8
(located on Park Falls unit
of Chequamegon-­‐Nicolet NF)
GFDL_CM2.0 Model, Scenario A1B