1c. determine reach potential 1b. review existing information & delineate & stratify reaches...
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1c. Determine Reach Potential
1b. Review Existing Information & Delineate & Stratify Reaches
1a. Identify Assessment Area & Assemble ID Team
1d. Complete PFC Assessment
Integrated Riparian Management Process
Steps 1a through 1d (7-step process)
Identify Assessment Area and assemble an ID team with:
• Strong observation and interpretation skills• Knowledge of quantitative sampling that supports
PFC• Knowledge of hydrology, vegetation, and
geomorphology attributes and processes.• Knowledge of reference conditions• Ability to communicate findings.
Step 1: Assess Riparian Resource Function Using PFC
Step 1:1b. Review existing information:
•Riparian concepts•The importance of uplands and
tributaries•Recovery process
http://www.blm.gov/or/programs/nrst/tech_refs.php
Step 1:
• 1b. Review Existing Documents• Information specific to the
drainage basin.• Previous assessments,
inventories, monitoring data.
• Resource information• GIS data, etc.
1b. Delineate and stratify reaches: Delineate the riparian areas into
reaches/riparian complexes of similar character based on observable differences and/or similarities
May stratify reaches into groups with similar resource values, uses, geology etc.
Step 1:
Physiographic Processes and AttributesGeology and GeomorphologyTopography – elevation, relief, aspectSediment source, transport, storage capacity
Delineation:
Drainage area / Contributing areaMajor confluencesStreamflow duration
Perennial, intermittent Interrupted
Groundwater/surface-water interactionsHydrologic regime
Snow-melt, storm runoff (monsoon), spring-fed brook
Delineation: Hydrologic Processes and attributes
Geologic filters
VolcanicLimestone terrainGranitic terrain
Basin fill
Axial stream (perennial)Tributary stream (intermittent)
Mountainous terrain
Delineate Reaches
0 10 20
Miles
1c. Determining Potential of
Stream Reaches
Compare:1) Hydrology, 2) Vegetation, and 3) Geomorphology
Step 1:
Why is potential important?
Accuracy - for the PFC assessment to be accurate.
Realistic - to gauge the system against what it can actually be.
Potential Defined
Potential is the highest ecological status a riparian area (stream reach or complex) can attain and is often referred to as the potential natural condition (PNC).
Ecological status is the degree of similarity between existing conditions (hydrology, vegetation, and geomorphology) and the potential of a reach; the higher the ecological status, the closer the reach is to potential
A site does not have to be at potential for a “yes;” it only has to be evaluated against its potential.
Applying Potential to PFC
PFC PNC
Tim
e
NF FAR
DC
Unproductive Vulnerable
Fisheries ValuesLivestock ValuesRecreation ValuesWildlife ValuesWatershed Values
Sustainable
Eco
logi
cal
Thr
esho
ld
Decision Space
Reference Reach
Management Reach
Consider (as an ID team):Climate, landform, soil, hydrology, & vegetation relationships for clues
Regional and local riparian classifications & other literature Historic information and photos Species lists and habitat needs Past inventory and monitoring data Reference areas
Once stream potential is established, it should be documented!
Process/tools for determining potential
Numana Hatchery on Truckee River 6/1994
Numana Hatchery on Truckee River 8/2013
Factors that influence riparian plant species & communities:
Wetness: Height above the water surface
Substrate: Channel and bank particle size
Slope: Stream gradient in percent
Stream size: Channel width and depth
Valley morphology: Geomorphic valley type
Vegetation = sedge dominated banks and activefloodplain with willows, cottonwood and aspen occurring on less frequently flooded surfaces
E Type channel
C4 type channel. Gravel-dominated substrate.
Slope: < 2 %W/D: > 12Sinuosity: > 1.4Valley: broad/terraces
B type channel; gradient > 2%; bedrock / boulder controlled; large
wood important to channel complexity; vegetation = alder / fir
Example Riparian Complex
COMPLEX ANarrow Valley BottomSteep gradientCoarse SubstrateAlder/Dogwood
COMPLEX BWide Valley BottomLow gradientFine SubstrateTufted Hairgrass
Riparian ComplexesGroupings of potential plant communities that form vegetation patterns along the stream.From interaction of: hydrology, geomorphology and climate. Consider:
Valley bottom gradient and width (types);
Geology, deposition, and soil characteristics;
Elevation; and climate.
Delineation of Riparian Complexes
Valley bottom type (Rosgen 1996) Dominant soil family (USDA, NRCS)Entrenchment Stream profile or gradient – Stream type
(Rosgen 1996) Vegetation patterns along the stream, Land uses
Valley Types
Narrow, confined valley; Bedrock controlled
Broad, unconfined valley;Alluvial fill
Rosgen Valley Types
X
VIV
VIII
Gentle Canyon
Wide Floodplain
Glacial Trough
Broad Lakebed
From Rosgen 1996.
Land Uses -- Management/land-ownership boundaries
Capability – Old Concept Highest ecological status an area can attain given political, social, or economic constraints, which are often referred to as limiting factors.
Limiting factors include railroads, dams, diversions, channelization, levees, roads, ground-water pumping, and related permanent alterations that change the potential of the reach.
Applying Altered Potential to PFCChange in TR revision is to “altered potential”
instead of capability (for direct human alterations)
Capability simple to define but difficult to consistently apply
Capability precluded some altered streams from ever achieving PFC if gauged against historic potential or PNC
Altered Potential… New Approach
…Is the best possible ecological status and channel form that can be attained under permanent human alterations.
Permanent human alterations include railroads, dams, diversions, channelization, levees, roads, ground-water pumping, and related permanent alterations that change the potential of the reach.
Are direct alterations (i.e. limiting factors) present that have created predominantly artificial channel conditions for a large part of the reach? If so, Don’t do PFC.
Proposed Guidelines for Altered Systems
Are direct alterations present but the overall potential of the reach remains unchanged? Use potential.
Proposed Guidelines for Altered Systems
Are direct alterations present but the overall potential of the reach has been changed (but is not predominantly artificial)? Describe new potential.
Proposed Guidelines for Altered Systems
Example: Diversion of > 50% of low flows has caused a drop in water table and potential has shifted from hydric to more mesic plant types.
Prediction – e.g. potential; response to management actions
Efficiency/Extrapolation – sampling a subset; applying throughout study unit
Prioritization – doing the right work in the right place with limited dollars and people
Purpose of Delineation/Stratification:
If you do not spend the time to develop an understanding of the attributes and processes affecting an area, your judgment about PFC will be incomplete and may be incorrect.
Understanding Attributes and Processes - Determine Potential & Capability