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Exam 4 Geology
Streams (4-27)
37
Geology
Undergraduate 1
04/28/2009

Additional Geology Flashcards

 


 

Cards

Term

Streams

 

Definition

-body of water flows downslope (on passageway)

-transports detrital particles & dissolved substance

(weather off rocks & landscape)

-transports to ocean

Term
Stream Components
Definition

-channel

-load=material

-discharge=how fast the stream is flowing

Term
Human uses of Streams
Definition

-transportation

-fertile soil=when it floods

-Available water=freshwater

Term
Drawbacks of Streams
Definition

-floods

-pollution

Term
Geologic Agents (more)
Definition

-hydrologic cycle

-sediment transport

Term
Cross-Sectional Shape
Definition

-stream channels

-measuring the streams 

 

-volume of water moving through channel ↑ downstream

-ratio of channel width to depth changes downstream

 

 

Term
Long Profile
Definition

-streams channel

-determining long profile=is a line drawn along surface of a stream (from source to mouth)

-curve that ↓ in gradient downstream

 

Term
Long Profile irregularities
Definition

not perfectly smooth curve bc gradients 

produced by:

-beds of resistant

-landslides

-lava flows

-hydroelectric dams

Term
Factors in Streamflow
Definition

-gradient=(m/km) slope

-stream-cross-sectional area=(A;m2) width & average depth

-average velocity=(V;m/s) velocity

-discharge=(Q;m3/s) how much water moving past certain point

-load=(kg/m3) dissolve material being carried

Term
Q=VxA
Definition

relationship b/w 

-discharge

-velocity

-channel shape

 

Term
Changes Downstream
Definition

from head to mouth

-discharge  ↑

-stream cross-sectional area ↑

-velocity  ↑

-gradient ↓

Term
Flood
Definition

stream discharge becomes so great that it exceeds capacity of channel; causing stream to overflow its banks

-hydrograph

-during a flood=velocity ↑ as discharge ↑ resulting in stream carrying

(greater load, larger particles)

Term
Hydrograph
Definition

graph that plots stream discharge with time

 

Term
discharge
Definition
quantity of water passing by a point on the steambank in a given interval of time 
Term

Recurrence Interval

(flood prediction)

Definition

-measure of how often a flood at given magnitude is likely to occur

-flood having recurrence interval of 10 years "10- year flood"

 

Term
Base Level
Definition

-limiting level below which a stream cannot erode the land 

-most streams is global sea level

Term
Straight Channel
Definition
-highest velocity segment found near surface in mid-channel
Term

Meanders

(common channel pattern)

Definition

loop-like bend in a stream channel

while meander upstream migrating more rapidly, intersect the slower moving meander (migrate down)

-point bar

-meanders cut off

-oxbow lake

(picture)

Term
Point Bar
Definition

arcuate deposit of sand or gravel along the inside of bend of meaner loop

(picture)

Term
Oxbow Lake
Definition

cut off meander that is crescent shaped lake

(picture)

Term

Braided Channels

(common channel patterns)

Definition

channel system conisting of tangled networks of 2 or more smaller branching & reuniting channels, seperated by islands or bars

(found near glaciers)

-high discharge

-lots of sediment

-easily eroded banks

Term
Stream Load
Definition

-bed load

-suspended load

-dissolved load

-placier deposits

-downstream changes

Term
Bed Load
Definition
course particles move along stream bed
Term
Suspended Load
Definition
fine particles suspended in water
Term
Dissolved Load
Definition
streams carry dissolved substances
Term
Placer Deposits
Definition

deposit of heavy minerals concentrated mechanically

-behind rock bars

-in bedrock holes

-below waterfalls

-inside of meander bed

(density-big part/orginal places of mountains)

Term
Downstream Changes
Definition

-sediment size decrease

-in mountainous headwaters, rivers transport large boulders

-stream reaches sea, bed load may consist of sediments no coarser than sand

 

Term

Floodplain

(stream deposits)

Definition
flat area about level with top of the channel, lies on either side of channel
Term

Terraces

(stream deposits)

Definition
erosional remnants of former floodplains, meaning change in baselevel
Term
Delta
Definition

location of significant sedimentatiton, where river meets the sea

 

Term
Drainage Basin
Definition
area of land, surronded by topographic divides, which all water is directed to single point
Term
runoff
Definition
portion of precitoptation that flows over the land surface
Term
gradient
Definition
measure the vertical distance that a stream channel falls b.w two points a known distance apart along its course
Term
overland flow
Definition
water initally tends to move down slope in broad, thin sheets
Term
streamflow
Definition
overland flow begins to concentrate into well defined channels 
Term
laminar flow
Definition

(eriosion of running water)

waver very slow, water particles travel parrallel layers of motion

Term
turbulent flow
Definition
increasing velocity, the movement becomes more erratic and complex, rise of swirls and eddies
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