watervulnerability

Chequamegon-­‐Nicolet National Forest Watershed Vulnerability Assessment, Eastern Region (R9)
increases projected for northern Minnesota by the GISS global climate model at the time of their study.
These included monthly increases of 3 to 6 o C for temperature and 5 to 25 percent for precipitation. In
their case, though, growing-season water levels in the bog were projected to decline by only 0.2-0.6
inches because higher evapotranspirational losses would be offset by higher summer precipitation.
There was one modeling problem that remained unresolved. The spring runoff hydrograph for the historic
period appears to peak at about 25 to 50 percent of expected runoff during the spring snowmelt season
(Figure 9). It also appears to produce slightly higher runoff than expected in the fall.
While this modeling problem causes some concern, the overall results seem to provide reasonable
estimates of the potential impacts of climate change on bog hydrology in northern Wisconsin. These
include future increases in average annual evapotranspiration of about 3.2 inches, decreases in runoff of
1.3 inches (about 25 percent) with an increase in spring and decreases in summer and fall, and lower
water levels in the bog in summer and fall of 2-4.5 inches with an increase in no-flow days.
Although the ecological implications of these potential changes in wetland hydrology need further
evaluation, for the purposes of this analysis they were considered sufficient to conclude that climate
change poses some risk to the Forest’s wetlands in general and to bogs in particular. These risks include
loss of wetland area, changes in wetland plant communities, and alteration of wetland processes such as
water chemistry, peat accumulation, and geochemical cycling.
Season
Time
Period
Air
Temp.
( o C)
Ppt.
(in)
ET
(in)
245 Assessing the Vulnerability of Watersheds to Climate Change
RO
(in)
Water
Level
(in)
Winter 1961-2000 -10.3 3.2 0.2 0.4 8.6
2046-2065 -7.0 3.9 0.4 0.4 8.2
Spring 1961-2000 4.3 7.5 4.7 1.6 9.5
2046-2065 7.6 9.7 6.0 2.0 10.3
Summer 1961-2000 17.9 11.7 12.5 1.3 9.3
2046-2065 22.3 10.3 14.8 0.8 6.7
Autumn 1961-2000 6.3 8.7 3.7 2.1 10.5
2046-2065 9.2 8.0 4.4 0.8 7.3
Annual 1961-2000 4.6 31.1 21.7 5.5 9.5
2046-2065 8.1 31.9 24.9 4.2 8.1
Table 1. Average seasonal and annual water balance components from modeling of potential climate change
impacts to wetlands on the Chequamegon-Nicolet National Forest. WICC climate data for longitude 90.1, latitude
45.8 located on Park Falls Unit of Chequamegon-Nicolet NF, GFDL_CM2.0 Model, A1B scenario. Water level
estimates from Peatland Hydrologic Model (PHIM).