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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