watervulnerability

Shasta Trinity National Forest Watershed Vulnerability Assessment, Pacific Southwest Region (R5)
Figure 15. Percentage of hydrologic units in volcanic and limestone geologies; representing groundwater influence.
While geologies that promote infiltration and groundwater may tend to buffer climate change effects,
areas that are currently dominated by snowmelt processes are likely to be most susceptible to change.
Snowmelt-Dominated Hydrology
An evaluation of the climatic subsections (Ecomap 1997) was used to rate areas most susceptible to
hydrologic transitions based on elevation and snow dominated runoff (Figure 16). Ecological subsections
on the Forest were ranked based on the amount of snow dominated runoff. The percentages of each
hydrologic unit containing the ranked climatic subsections determined the overall sensitivity of the
hydrologic units.
199 Assessing the Vulnerability of Watersheds to Climate Change