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ESC1000 Chapter 3 HW

Terms in this set (47)

What is a stream's longitudinal profile?
What is a stream's longitudinal profile?
How do gradient, discharge, channel size, and channel roughness typically change from the head to the mouth of a stream?
From the head of a stream to its mouth, the gradient and channel roughness decrease while the discharge and channel size increase.
Is flow velocity usually greater at the head or at the mouth of a stream? Explain.
Flow velocity is usually greater at the mouth of the stream than the head of the stream due to an increase in channel size, an increase in channel discharge, and a decrease in channel roughness near the mouth.
Which of the following choices correctly describes two processes that cut channels into bedrock?
During abrasion, the bed and the banks of the river are constantly bombarded by the particles carried in the water. During corrosion, soluble bedrock such as limestone is gradually dissolved by the flowing water.
In what ways does a stream transport its load, and which part of the load moves most slowly?
as a bed load, which is the slowest mode of particle transport in streams

as a dissolved load

as a suspended load
What is the difference between capacity and competence?
Capacity is the maximum load of solid particles a stream can transport per unit time, whereas competence is a measure of a stream's ability to transport particles based on size rather than quantity
What is alluvium?
any sediment that is deposited by a stream
Where are bedrock channels more likely to be found?
Bedrock channels are typically found in the headwaters of river systems where streams have steep slopes.
How does an oxbow lake form?
On oxbow lake forms when the bend of a meandering river is isolated from the river due to erosion forces creating a cutoff in the main river channel. This isolated bend becomes the oxbow lake.
How might a stream channel become braided?
If a large portion of a stream's sediment load consists of coarse material and the stream has a highly variable discharge, a stream channel can become braided.
Which of the choices below correctly defines base level and differentiates between ultimate base level and local (temporary) base level?
Base level is generally defined as the lowest elevation to which a stream can erode its channel. The ultimate base level is sea level, whereas local base levels are lakes, resistant layers of rock, and rivers that act as base levels for their tributaries.
Why do V-shaped valleys often contain rapids and waterfalls?
In many V-shaped valleys, resistant bedrock upstream creates rapids by acting as a local base level while downcutting occurs in less resistant bedrock downstream.
Which choice describes how an erosional floodplain develops?
A stream approaches a level orientation, stops eroding, and starts meandering. As the stream meanders, it widens the valley by continuously eroding the banks on both sides. This widened valley is an erosional floodplain.
How do the formations of incised meanders relate to stream terraces and base level?
When the base level drops, the incised meander erodes both downwards and back and forth across the flood plain. After several reoccurrences of base level drops, stream terraces are left as evidence of past base level drops.
What feature may form where a stream enters the relatively still waters of a lake, an inland sea, or an ocean?
a delta
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