Streams and Floods
Streams and Floods 2
Streams and Floods 3
Streams and Floods 4
Streams and Floods 5
100
Factors that control a stream's velocity
Gradient, Channel Shape and Roughness
100
How a meander neck cutoff from on oxbow lake
After the meander neck cutoff occurs, the old meander may be abandoned as sediment separates it from the new, shorter channel. The cutoff meander becomes an oxbow lake.
100
How a stream widens its valley
After a stream has become graded, lateral erosion widens a valley.
100
Typical units of discharge
cubic feet per second
100
4 drainage patterns
1) dendritic 2) radial 3) trellis 4) rectangular
200
How bar deposition creates a braided stream
deposition of a bar in the center of the stream diverts the water toward the sides where it washes the stream with greater force, eroding the banks and widening the stream. If the stream is heavily loaded with sediment will deposit many bars in its channel, causing the stream to widen as more bars are deposited. The stream may fill its main channel with sediment and become a braided stream.
200
How a natural levee forms
built up beside streams by flood deposition
200
A base level is
a theoretical downward limit for stream erosion of Earth's surface
200
Hydraulic action, solution, and abrasion are all examples of stream ______.
erosion
200
The broad strip of land built up by sedimentation on either side of a stream channel is _____.
flood plain
300
The part of an alluvial fan where sediment is the coarsest
nearest the mountains because in large fans deposits are graded in size within the fan
300
How stream terraces form
by erosion of rock benches OR dissection of thick valley deposits during down cutting
300
The total area drained by a stream and its tributaries is called the _______.
Drainage Basin
300
Cobbles are more likely to be transported in a stream's _____.
bedload
300
The average time between floods of a given size is _____.
reoccurrence interval
400
What a trellis drainage pattern tells about the rock underneath it
there are tilted layers of resistant rock such as sandstone alternate with nonresistant rock such as shale
400
3 ways in which a river erodes its channel
1) Hydraulic action=the ability of flowing water to pick up and move rock and sediment 2) Solution= dissolving of rock by water constantly flowing over rocks 3) Abrasion=the grinding away of the stream channel bu the friction and impact of sediment load
400
Stream erosion and deposition are controlled primarily by a river's _________.
Velocity
400
A river's velocity is _____ on the outside of a meander curve compared to the inside.
higher
400
A platform of sediment formed where a stream flows into standing water is _____.
delta
500
One way that incised meanders form
form as river meanders are cut vertically downward following uplift OR lateral erosion and down cutting proceed simultaneously
500
Name and describe 3 ways in which a stream transports sediment
1) Bed Load= the large and heavy sediment particles that travel on the stream bed. Movement by rolling, sliding, or dragging (traction). Movement by a series of short leaps or bounces of the bottom (saltation) 2) Suspended Load= sediment that is light enough to remain lifted indefinitely above the bottom by water turbulence 3) Dissolved Load= soluble products of chemical weathering processes
500
The gradient of a stream that drops 10 vertical feet over a 2-mile horizontal distance
5 ft./mile
500
Sandbars deposited on the inside of meander curves are called _____.
point bars
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