18.01.2013 Views

watervulnerability

watervulnerability

watervulnerability

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Sawtooth National Forest Watershed Vulnerability Assessment, Intermountain Region (R4)<br />

WATER RESOURCE VALUES<br />

Columbia River Bull Trout<br />

• Threatened Species under Endangered Species Act since1998<br />

• Sawtooth NF Management Indicator Species<br />

• More specific habitat requirements than other salmonids<br />

• Associated with the coldest streams; upper tolerance limits appear to be 12-15°C<br />

• Climate change could lead to smaller and more isolated habitat patches and the loss of local<br />

populations in the Upper Salmon.<br />

• Embryos and juveniles are vulnerable to channel scour associated with the rain-on-snow events<br />

and winter peak flows.<br />

Infrastructure<br />

• Roads, campgrounds, water diversions, bridges, etc., with poor drainage or in riparian areas will<br />

be at increased risk from rain-on-snow events and winter peak flows.<br />

Water<br />

Resource Indicators<br />

Value<br />

Infrastructure Recreation Sites<br />

(Campgrounds)<br />

Water Diversions<br />

System Roads and<br />

Trails<br />

Private Ownership<br />

Projected Hydrologic<br />

Changes<br />

Rain-on-Snow Events<br />

Increased Winter Peak<br />

Flows<br />

Aquatics Bull Trout Rain-on-Snow Events<br />

Increased Winter Peak<br />

Flows<br />

Lower Summer Base<br />

Flows<br />

Increased Summer Water<br />

Temps<br />

Table 1. Water resource values, indicators, and analysis tools<br />

WATERSHED SENSITIVITY<br />

160 Assessing the Vulnerability of Watersheds to Climate Change<br />

Analysis Tools Potential Impacts<br />

VIC – Winter 95<br />

(# of days in the winter in<br />

which flows are among the<br />

highest 5% for year)<br />

VIC – Winter 95<br />

VIC – MeanSummer<br />

(Mean flow during June 1<br />

to September 30)<br />

Stream Temperature<br />

Model (Summer Maximum<br />

Weekly Temperature)<br />

Flood Damage<br />

Egg and Juvenile<br />

Scour<br />

Habitat Reduction<br />

Habitat<br />

Fragmentation<br />

Watershed sensitivity includes natural risks from increased sediment, debris flows, and landslides to fish<br />

populations. The following factors were considered.<br />

Subwatershed Vulnerability - Percent of a subwatershed with sensitive land types (e.g., inherent surface<br />

soil erosion, sediment yield, and mass stability) (Figure 2).<br />

Landslide Prone Terrain – Included are areas with a tendency for rapid soil mass movements typified<br />

by shallow, non-cohesive soils on slopes with shallow translational planar landsliding phenomena are

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!