Rivers and Streams

Chapter 18

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

Leadville

Steamboat

Durango

Colorado Rivers

Arkansas

RioGrande

Colorado

S. Platte

N. Platte

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

• 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

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

• 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

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

Leadville

Steamboat

Durango

Colorado River

DrainageBasin

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.

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

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.

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).

V-shaped Valley (Byers Canyon)

V-shape: No Flood Plain

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.

Point Bars, Cut Banks, Meanders, and Oxbows

Flood Plain (Yampa)depositional

Flood Plain (Rhône)depositional

Flood Plain

(Yampa)

Braided Stream

Antecedent Stream

Antecedent StreamGreen River

Antecedent Stream:Green 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

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