1

Review: Summary Hydraulic Geometry In Two Equations

Q = (width) (depth) (λ) / (slope)

Examples of Q+ and Q-

Qsed = (width) (λ) (slope) / (depth) (p)

Examples of Qsed+ and Qsed-

Stream Classification

• Suspended Load (Vertical Accretion),• Bedload (Channel Aggradation), vs.• Mixed Load (Lateral & Vertical Accretion)

Schumm, 1963

Bloom, 2004, p. 221after Schumm, 1981

2

“Modern” Stream Classification

• One System Drawing Most Attention:

• Rosgen, David L. 1994. A classification of natural rivers. Catena 22 (1994) 169- 199.+ Rosgen, David L. 1996, Applied River

Morphology, Wildland Hydrology, Pagosa Springs. Co.

Dave Rosgen

After Montgomery & Buffington (1998)

Stream Classification Hierarchy

• Valley Segments (may be many miles)• Stream Reaches (~30 channel widths)• Channel Units (~1 channel width)

Rosgen Stream Classification Criteria

• Single Channel vs. Multiple Channels• Entrenchment Ratio• Width/Depth Ratio• Sinuosity• Slope• Bedload Texture

3

Rosgen Level II Classification: Cross-Sectional Delineating Criteria

Entrenchment Ratio(Flood-prone Width / Bank-full Width)

Floodplain Width = Width @ 2 Times Maximum Bankfull Depth

Width/Depth Ratio(Bank-full Width/Bank-full Depth)

If You Don’t Know Bank-Full, ...

Flow Width @ 2X Bank-Full Stage

Bank-Full Width

“Entrenchment” Ratio =Flow Width @ 2X Bank-Full Stage

Bank-Full Width

“C” Type Stream, Deckers Creek, Monongalia Co.

Width-Depth Ratio

~12:1

~20:1

~40:1

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Rosgen Level II Classification: Plan-Form Pattern Delineating Criteria

Sinuosity (P) =

(Stream Length / Valley Length)

Meander-Width Ratio =

(Meander Belt Width / Bank-Full Channel Width)

λ = MeanderWavelength

Sinuosity = P = River Distance Along Thalweg /

Straight-Line Distance

Sinuosity Rosgen Class

1.0 - 1.2 Low1.2 - 1.5 Moderate1.5 + High

Radius of Curvature

Mea

nder

-Be

lt W

idth

Rosgen Stream Classification, Fig 5-3http://www.r6.fws.gov/pfw/images/Class2.gif

5

Stream types: gradient, cross-section, plan view (from Applied River Morphology, Dave Rosgen and Hilton Lee Silvey, Wildland Hydrology, Pagosa Springs, Colorado, 1996.)

Longer Timescales

Review: Concept of Graded Stream

Unpaired Stream Terraces:

6

Paired Stream Terraces:

Strath =Erosional (Unpaired) Terraces

Strath Terraces near Parsons, WV

1840’+

1800’+

1800’+

1620’+

1640’+

1760’+

1640’+

1680’+

1720’+

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Depositional (Paired) Terraces

© Michael R. Marty Snake River Terraces, Teton National Park, Wyoming

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Maximum Turbulence

.

Erosionwith SlightDownward Component

Deposition = Accretion

Slip-Off Terrace

Slip-Off Terrace

Erosion

Slip-Off Surface

Meander Development

9

Slip-Off Terrace

Slip-Off Terrace

Slip-Off Terraces

Paw Paw, WV-MD

Photo

Slip-Off Terrace North of Paw Paw, WV

JS Kite Photo

10

Valley Type ClassificationThornbury, 1969

• Antecedent (Predates Structures)• Superposed (Super-imposed)• Consequent (Flows Down Bedding Dip)

–vs. Obsequent (Flows Opposite Dip)• Subsequent (Eroded into Weak Rocks)

THEORIES OF LANDSCAPE DEVELOPMENT

(after Higgins, 1975)

3 Theories

W.M. Davis: Geomorphic CycleW. Penck: Parallel Slope RetreatJ.T. Hack : Dynamic Equilibrium

Davis:First Systematic, Genetic Landscape Classification on a Descriptive Basis

Normal Cycle (= Fluvial Cycle)Rapid Uplift of Landscape, Followed

by Prolonged Tectonic StillstandLandscapes Reflect Process & Time

Stages:Youth - Maturity - Old Age

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YOUTH:Dominated by Vertical Erosion and

Ungraded Streams

1. Numerous Short, Straight Tributariesand Gullies Extending Headward.

2. V-Shaped Cross Profile3. Poorly Developed Floodplain4. Broad, Poorly Drained Interfluves5. Falls and Rapids at Crossing of

Resistant Rocks6. Few Meanders

Black Canyon of the Gunnison,

Colorado

MATURITY:Lateral Erosion Important; Graded Streams1. Well-Integrated Drainage2. Some Structural Control of Tributaries3. Sharp, Well-Drained Interfluves4. Waterfalls & Lakes Obliterated5. Floodplains Considerable, with Shifting

Meanders6. Valley Floor Width = Meander Belt Width7. Most of Landscape in Slope

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Maturity - View from Backbone Mtn.

OLD AGE:Lateral Erosion Dominant, Stream

Graded near Base Level, Little Erosion1. Valleys Broader than Meander Belt2. Large Floodplains

with Broadly Meandering Streams, Flood Basin, Swamps, etc.

3. Low Hills, Low Valley Slopes4. Effect of Lithology Obscure5. Extensive Areas at, or Near, Base Level:

Peneplain (Truncates Structure) -Monadnock (Resistant Bedrock Knob)

Old Age

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REJUVENATION

Large Meanders Juxtaposed withDeep V-Shaped Valleys

Interpretation:Development of PeneplainSubsequent Uplift

San Juan River

New River Gorge

Cheat Canyon,

WV

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Blackwater Canyon - Youth

Projected Peneplains: Cumberland - Ohio River.

Fridley, Harry M., and Nölting, John P., Jr., 1931, Peneplains of the Appalachian Plateau, The Journal of Geology, v. XXXIX, no. 8, p. 749-755

Geology Colloquium

Dr. Ellen HermanBucknell University

Interpreting Flow and Sediment Transport in Karst Springs

Thursday March 1stTalk at 4, refreshments at 345 PM

310 White Hall

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THEORIES OF LANDSCAPE DEVELOPMENT

(after Higgins, 1975)

3 Theories

W.M. Davis: Geomorphic CycleW. Penck: Parallel Slope RetreatJ.T. Hack : Dynamic Equilibrium

Do Davis’s Concepts Make Sense?

•Sure!

Geology: Epeirogeny• Continental-Wide Erosion Episodes in

Geological Record.• North American Craton - 6 Major

Unconformities in Last 600 My.– Base of Sauk - Tippecanoe - Kaskaskia -

Absaroka - Zuni - Tejas Sequences• Continent "Highstands"- Correlate with

Low Sea-Floor Spread Rates & Deep Ocean-Basin Geometry

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Peneplain Tracing Worldwide: 1899-1950

Dr. Harry M. Fridley, arrived WVU 1931Projected Profiles (1;62,500)

Accordant SurfacesFridley’s 2 Peneplains in This Area

Kittatinny (Schooley)Allegheny

Problems: Better Topo Maps Show Surfaces are Not Accordant?

Why Were Davis's Ideas Successful?

• Simple and Filled a Void.

Davis's Lasting Contributions

• Landforms Change in an Orderly Manner as Fluvial Processes Operate Through Time.

• Under Uniform Conditions, Orderly Sequences of Landforms Develop.

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Walther PENCK

"Die Morphologiche Analyse" 1924

- Translated by L.C. King.

PENCK

• Long Continued Crustal Movement• Parallel Slope Retreat

– Retreating Fluvial Knickpoints– Graded Slopes.

Canyonlands National Park

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Arches National Park, Utah

Walther PENCK

Long Lasting TectonicsParallel Slope Retreat

Retreating KnickpointsGraded Slopes.

Canyonlands National Park

Pediment

John T. HACK (1965)

Dynamic Equilibrium Concept: Much Inherited from Gilbert (1880s) &

Strahler (Columbia School of 1950s).Hack: Landforms Part of an Open

System Tending to Steady-State Equilibrium.

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Hack’s Assumptions:Balance Between Erosion & Rock

ResistanceAll Landscape Elements Down-

waste at the Same RateForm Is Explainable in Terms of

Bedrock Geology:“Accordant Summits” Have

Similar Structure and Lithology.

MacDonald Range,

Australia

Hack’s “Sequence”

• Short Early Ungraded Episode• Long Period of Uniform

Downwasting of Steady-State Landforms…

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Where Does Each Landscape Evolution Model Fit Best?

Davis: Cratons & Tectonic Landscapes

Not Rivers & Valleys of Appalachians Where He Came Up with Concepts.

Black Sea Coast near Varna, Bulgaria

Wasatch Range, Utah

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Where Does Each Model Fit Best?

Penck:

Arid & Semiarid Landscapes.

Canyonlands National Park

Canyonlands National Park© copyright nps.gov White Rim Road

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Where Does Each Model Fit Best?

Hack:

Erosional Landscapes with Varied Rock Types

Rivers and Valleys of Appalachians.

Ridge and Valley of PA

Ridge&

Valley of WV