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Rivers and Streams
Chapter 18Streams: Outline
• Definition• Basins and divides: Colorado Rivers• Floods & Gradients
Hydrologic Cycle Streams• A stream is a body of water that is
confined in a channel and moves downhill under the influence of gravity.
• This definition includes all sizes of running water from a tiny trickle to the Amazon.
• The total area drained by a given stream is its drainage basin.
Drainage Basins and Divides
• The line separating one drainage basin from another is a drainage divide.
• The Continental Divide separates drainage basins of rivers that flow to the Atlantic and Gulf of Mexico from those flowing to the Pacific and Gulf of Cortez (Gulf of California).
Colorado Drainage Basins
Pueblo
Boulder
Alamosa
Steamboat
Durango
Colorado Rivers
Arkansas
RioGrande
Colorado
S. Platte
N. Platte
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Clicker Question
• Water falling on Boulder goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Water falling on Boulder goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to
Mississippi River to Gulf of Mexico at New Orleans
– C. Arkansas River to Mississippi River to Gulf of Mexico at New Orleans
– D. Rio Grande To Gulf of Mexico at Brownsville, TX
Clicker Question
• Water falling on Pueblo goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Water falling on Pueblo goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to
Gulf of Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Water falling on Alamosa goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Snow melting at Leadville goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
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Clicker Question
• Snow melting at Leadville goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to
Gulf of Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Snow melting at Breckenridge goes down which river system?– A. Blue River to Colorado River to Gulf of
California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Snow melting at Breckenridge goes down which river system?– A. Blue River to Colorado River to Gulf of
California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Snow melting at Steamboat Springs goes down which river system?– A. Blue River to Colorado River to Gulf of
California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. Yampa River to Green River to Colorado River
to Gulf of California – D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Snow melting at Steamboat Springs goes down which river system?– A. Blue River to Colorado River to Gulf of
California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. Yampa River to Green River to
Colorado River to Gulf of California – D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Water falling on Alamosa goes down which river system?– A. Colorado River to Gulf of California– B. North Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans – C. South Platte to Missouri River to Mississippi
River to Gulf of Mexico at New Orleans– D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
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Clicker Question
• Snow melting at Durango goes down which river system?– A. Blue River to Colorado River to Gulf of
California– B. Animas River to San Juan River to Colorado
River to Gulf of California – C. Yampa River to Green River to Colorado River
to Gulf of California – D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Clicker Question
• Snow melting at Purgatory (Durango) goes down which river system?– A. Blue River to Colorado River to Gulf of
California– B. Animas River to San Juan River to
Colorado River to Gulf of California – C. Yampa River to Green River to Colorado River
to Gulf of California – D. Arkansas River to Mississippi River to Gulf of
Mexico at New Orleans– E. Rio Grande To Gulf of Mexico at Brownsville,
TX
Colorado Drainage Basins
Pueblo
Boulder
Alamosa
Steamboat
Durango
Floods• Flash floods can occur in a
matter of hours as a result of a single storm.
• Flash floods are most likely in areas of high gradients.
• Annual floods result from snowmelt or annual rain patterns (monsoons).
Annual Floods Flash Flood, Boulder, 1894
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Flash Flood, Boulder, 2013 Gradient• Gradient is the drop per mile (km).• Boulder Creek drops from 8000ft at
Nederland to 5600’ in Boulder and has a gradient of 160 ft/mi (~30 m/km).
• The Colorado River through Grand Canyon has a gradient of about 10 ft/mi (~2 m/km)
• The lower Mississippi has a gradient of less than 0.5 ft/mi (~0.1 m/km).
• Gradients usually decrease downstream.
Gradient Decreases downstream Stream Velocity
• Velocity is controlled by both gradient and channel size.
• Steep gradients cause high velocities• Constricted channels cause high
velocities.
Discharge• Discharge is the total flow in ft3/s (cfs)
or m3/s.• 1 m3/s = ~35 ft3/s (cfs). • In a section of stream with no
tributaries, the discharge is constant while the velocity and channel size may vary along the bed.
Discharge• Boulder Creek is typically 10-25 cfs,
but may be 500 cfs or greater in May and June.
• The Colorado at Grand Junction is typically 2000 cfs, but may exceed 30,000 in May and June.
• The lower Mississippi is typically 250,000 cfs but exceeded 3 million cfs in 1993 flood.
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Load• The load is the amount of material
transported by a stream.– Dissolved load is the material in
solution.– Suspended load is the material in
suspension.– Bed load is the material on the bed
•Saltation load is the material bouncing along the bottom.
•Traction load is the material dragged along the bottom.
Load
Deposition and Erosion• The amount of bed load and
suspended load vary with velocity.– Where a stream widens and slows,
it deposits material.– Where a stream narrows and
quickens, it erodes material.
Deposition, Erosion, and Valley Profiles
• Actively eroding streams valleys have a charac-teristic V-shape (no flood plain).
• Actively depositing stream valleys have flat bottoms (flood plain).
Bedrock channels Yellowstone
River
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V-shaped Valley (Byers Canyon)
Incised Meanders – meandering streams that were once “alluvial channels” near base level, but base level changed so they began to downcut again…what happened here? – rise of the Colorado Plateau
San Juan River, UT
U-shaped Valley (Arlberg, Austria)
U-shaped/V-shaped Valley (Val Feret, Suisse)
Flood Plain
(Yampa)
Bars• Bars are material deposited by
streams.– A point bar is a bar on the side of a
stream.– A channel bar is a bar in the middle of a
stream– A braided stream has many channels
bars.• The presence of bars indicates that
the steam is depositing.
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Point Bars, Cut Banks, Meanders, and Oxbows
Flood Plain (Yampa)depositional
Flood Plain (Rhône)depositional Flood
Plain(Yampa)
Braided Stream Antecedent Stream
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Antecedent StreamGreen River
Victoria Falls (Zambesi)
Mississippi Delta Stream Terms• Stream• Hydrologic Cycle• Drainage divide• Drainage basin• Gradient• Discharge• Load
– Suspended– Dissolved– Bed
• Saltation• Traction
• Flash flood• Annual flood• Point bar• Channel bar• Cut bank• Meander• Oxbow• Braided stream• Antecedent
stream• Delta
Profile:a: V-shapeb: U-shapec: Flat floord: braided
Profile:a: V-shapeb: U-shapec: Flat floord: braided
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Profile:a: V-shapeb: U-shapec: Flat floord: braided
Profile:a: V-shapeb: U-shapec: Flat floord: braided
Profile:a: V-shapeb: U-shapec: Flat floord: braided
Profile:a: V-shapeb: U-shapec: Flat floord: braided
Colorado River
DrainageBasin
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Links• Colorado River Basin
– www.cbrfc.noaa.gov
• Colorado River Data–waterdata.usgs.gov/co/nwis/rt
• Colorado Water Law–http://www.waterinfo.org/colorado-
water/colorado-water-rights
Colorado River Compacts, 1922, 1948
• Divides flow above and below Lee’s Ferry (below Lake Powell)
• Upper Basin (“50%”):– Colorado(52%), Wyoming(14%),
Utah(23%), New Mexico (11%)• Lower Basin (50%)
– California, Arizona, Nevada• Upper Basin states have never
used their allocation.
Water Law
• Land owners do not own the water.
• Prior users have precedent.• You may not restrict flow to
deprive prior users downstream.
V-shape: No Flood Plain
Antecedent Stream:Green River