Post on 04-Mar-2020
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Riparian Landforms and Riparian Landforms and Channel MorphologyChannel Morphology
Organizing the ChaoticOrganizing the Chaotic
N. Phil PetersonN. Phil Peterson
Forest & Channel Metrics, Inc.Forest & Channel Metrics, Inc.
Changing the Way We Think About Changing the Way We Think About Riparian SystemsRiparian Systems
StopStop Focusing OnFocusing OnFishFishRegulatory stream typesRegulatory stream typesTHE ordinary high water THE ordinary high water markmarkSet distancesSet distancesOne size fits all One size fits all prescriptionsprescriptions
Start Focusing OnStart Focusing OnBedrock and surficial Bedrock and surficial geologygeologyTopographic slope breaksTopographic slope breaksLandforms, their origins Landforms, their origins and processesand processesSurfaces and their soilsSurfaces and their soilsUnderstory plant Understory plant communitiescommunitiesProcess based channel Process based channel typestypes
Organizing the ChaoticGeologyGeology–– Bedrock and surficialBedrock and surficial–– Lithotopo unitsLithotopo units
Valley segments (xValley segments (x--sections)sections)–– Riparian landforms (topographic slope breaks)Riparian landforms (topographic slope breaks)
Valley floorsValley floorsValley wallsValley walls
Channel networkChannel network–– Patterns of segment linkagePatterns of segment linkage
Process based channel typesProcess based channel types–– SizeSize–– ConfinementConfinement–– Bed morphologyBed morphology
Benefits of process and ecologically based systemBenefits of process and ecologically based system–– Aquatic assemblagesAquatic assemblages–– DisturbancesDisturbances–– Natural plant potentialNatural plant potential
Lithotopo Units
Terrain units with fundamental differences in Terrain units with fundamental differences in watershed processes and inputswatershed processes and inputs
Valuable scale for integrating important Valuable scale for integrating important information and explaining significant variationinformation and explaining significant variation
For example:For example:–– Crescent UplandsCrescent Uplands–– Recessional Outwash PlainRecessional Outwash Plain–– Sedimentary Inner GorgesSedimentary Inner Gorges
Valley SegmentsValley cross sectionValley cross section
Riparian landformsRiparian landforms
–– Valley floors (channel migration and channel disturbance zones)Valley floors (channel migration and channel disturbance zones)FloodplainFloodplainLow terraceLow terraceHigh terraceHigh terraceAlluvial fansAlluvial fans
–– Valley wallsValley wallsUniform slopeUniform slopeCanyonCanyonInnerInner--gorgegorgeBreak in slopeBreak in slopeReverse break in slopeReverse break in slope
Channel Networks
DendriticDendriticLong unbranchedLong unbranchedTrellisTrellisShort lateralsShort laterals
Systematic patterns of segment linkages Systematic patterns of segment linkages vary by geology vary by geology (River Continuum Concept and (River Continuum Concept and Process Domain Concept diverge)Process Domain Concept diverge)
Process Based Channel Types
SizeSizeConfinementConfinementBed morphology Bed morphology (Montgomery and Buffington 1997)(Montgomery and Buffington 1997)
–– CascadeCascade–– Step poolStep pool–– Plane bedPlane bed–– Pool rifflePool riffle
Benefits of Process and Ecologically Based System
Significant amount of information embedded Significant amount of information embedded in the classificationin the classification
–– Predicts aquatic assemblagePredicts aquatic assemblage–– Identifies likely disturbance regimeIdentifies likely disturbance regime–– Identifies general temperature regimeIdentifies general temperature regime–– Associates natural plant potential with the siteAssociates natural plant potential with the site
Olympic Torrent Salamander(Rhyacotriton olympicus)
60C
hann
el s
lope
(%)
Basin area (ha)0
10
20
30
40
50
0 25 50 75 100 125 150 1750.00.10.20.30.40.50.60.70.80.91.0
Probability occupied
Temperature Regimes
Channel pattern
Riparian forest shade
Topographic shade and elevation
Groundwater0
0.2
0.4
0.6
0.8
1
8 12 16 20 24
Temperature
Tim
e ex
ceed
ance
Canyon R.Glenn Ck.Bell Ck.Gosnell Ck.Schafer Ck.North Mt. Ck.Save Ck. trib.Bingham Ck.Devils Club Ck.
Plant Associations
UplandsUplandsValley wallValley wallValley floorValley floorActive channelActive channel
TSHE / POMU / TITR
TSHE / OPHO / ATFI
Active Channel
TSHE / GASH / POMU
Hypotheses for Riparian Successional Pathways(Devils Club/Lady Fern Complex)
Red alder Devils club Lady fern
Devils club Lady fern
Western hemlockDevils clubLady fern
Alder senescenceAlder senescenceMass wastingMass wastingFireFireFloodFloodChanges in surface roughnessChanges in surface roughness
SummarySummaryGeology exerts a strong influence on valley segment Geology exerts a strong influence on valley segment morphology and channel typemorphology and channel type
Valley segment linkages transmit energy and materials Valley segment linkages transmit energy and materials downstream in predictable ways and create legacy downstream in predictable ways and create legacy conditions that influence riparian forestsconditions that influence riparian forests
Key associations exist between valley segment Key associations exist between valley segment morphology and natural plant potential, often characterized morphology and natural plant potential, often characterized by sharp boundaries at slope breaksby sharp boundaries at slope breaks
Integrating this kind of information provides a basis for Integrating this kind of information provides a basis for riparian management decisions and restorative strategies riparian management decisions and restorative strategies