Question 1

Briefly explain how a stream might adjust toward an equilibrium state following a heavy rain.

Accepted Answer

A heavy rain will increase stream volume and velocity.The channel and gradient will be temporarily too small and low,respectively,for the increased volume.Stretches of the stream with a low gradient will experience erosion,and stretches farther downstream may experience deposition as the gradient of the upstream portion is adjusted (increased).

Question 2

Describe the major drainage patterns.

Accepted Answer

In dendritic drainage,a network of channels resembles tree branching.The pattern develops on gently sloping surfaces underlain by material that erodes roughly equally.Tributaries join larger channels at various angles.In rectangular drainage,tributaries join larger channels at right angles;this pattern is controlled by geologic structures,such as joints.Trellis drainage is a network of nearly parallel streams with tributaries joining them at right angles because the streams follow easily eroded rocks and are separated by resistant rocks.In radial drainage,streams flow outward from a high point like a volcano.Deranged drainage patterns are irregular,with streams flowing into and out of swamps and lakes.

Question 3

What are braided streams,and where do they form?

Accepted Answer

A braided stream has an intricate network of dividing and rejoining channels separated from one another by sand and gravel bars.Braided streams form when there is an excess of sediment load for the amount of water available and the depth of the stream channel.Braided streams have broad,shallow channels and carry a lot of bed load of mostly sand and gravel.

Question 4

How and where do alluvial fans form?

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Question 5

Describe the hydrologic cycle.

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Question 6

Briefly explain how a meandering stream can become incised in solid bedrock.

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Question 7

Is it possible to change the velocity of a stream but have it maintain the same discharge? Explain.

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Question 8

What happens when a stream overflows its banks?

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Question 9

What is stream piracy? What happens when one stream pirates another?

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Question 10

How often will a flood of a 20-year magnitude occur?

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Question 11

What is a 20-year flood?

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Question 12

Briefly explain what will happen to a stream's behavior if one drains a lake that is a temporary base level for that stream.

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Question 13

What causes a stream to meander?

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Question 14

Briefly explain the trade-offs that accompany any flood control project.

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Question 15

Describe where flow velocity is highest in a semi-straight channel.Why is this the case?

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Question 16

What is the infiltration capacity of a surface? On what factors does the infiltration capacity of a surface depend?

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Question 17

What are some of the techniques used to try to control floods?

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Question 18

What are the three main types of marine deltas based on? What are they,and how are they different from each other?

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Question 19

Describe the evolution of valleys.

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Question 20

What is a superposed stream?

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Quiz 11: Running Water