watervulnerability

Grand Mesa, Uncompahgre and Gunnison National Forest Watershed Vulnerability Assessment, Rocky
Mountain Region (R2)
Projected Climate Change Anticipated Hydrologic Response
More intense storms
Warmer atmosphere has potential for
increase in frequency and magnitude of
big storms.
More frequent and longer periods of
drought
Increase winter dust deposition on
snowpack
• Localized flooding
• Increased debris flows
• Increased hillslope and channel
erosion
• Less soil moisture
• Reduced groundwater recharge
• Lower summer and fall
baseflow
• Accentuate changes to
snowpack melt
91 Assessing the Vulnerability of Watersheds to Climate Change
Potential Consequences to
Resource Values
• Increased risk to channel and
floodplain infrastructure
from sediment and high
flows
• Increased concern for public
safety
• Increased selenium load in
streams where Mancos Shale
exposure is significant.
• Increased erosion associated
with natural disturbances
associated with drought (e.g.,
fire)
• Increased plant stress and
susceptibility to insect and
disease mortality
• Reduced groundwater
contribution to baseflows
• Reduced discharge from
springs
• Reduced wetland/riparian
function
• Similar to warmer winter
consequences
Table 4. Projected climate changes to the GMUG NF, anticipated hydrologic response and potential consequences
to aquatic resource values
WATERSHED RISK
Inherent characteristics and past management of watersheds influence how a watershed is likely to be
affected by climate change, and when combined, can be considered as contributors to watershed risk.
Some characteristics and/or impacts from past activities may exacerbate the anticipated impacts of
climate change (stressors), while others may reduce the impacts of climate change (buffers).
Inherent characteristics of watersheds were evaluated as two types of sensitivities on the GMUG: 1)
sensitivity to erosion or sediment production, and 2) sensitivity to runoff response. Existing condition was
evaluated based on past management activities. (The GMUG has not yet completed the new watershed
condition classification, as directed by the Washington Office.)
Sensitivities are described below.
Erosion or Sediment Production Sensitivity
The erosion or sediment production sensitivity was initially developed as part of the watershed
assessment completed for the Forest plan revision. Characteristics of geology, soils, landforms and
topography that affect the erosion potential or amount of sediment production from a given subwatershed
were evaluated. Due to data limitations of some information, this evaluation was limited to lands within
the GMUG Forest boundary. Mass wasting potential was not available at the time of the Forest plan