Question 1

The size of clasts that a stream can carry is primarily controlled by:
A)the water temperature
B)the dissolved and suspended load of a stream
C)how close the stream is to the ocean
D)the velocity and turbulence of the current
E)whether it is a permanent or ephemeral stream

Accepted Answer

The velocity and turbulence of the current are the primary controlling factors on the size of clasts that a stream can carry. A faster-moving and more turbulent stream can carry larger and heavier clasts, while a slower-moving and less turbulent stream can only carry smaller and lighter clasts.

Question 2

Which of the following is true about how a stream erodes material?
A)abrasion is concentrated on the upstream side of obstructions
B)turbulence of the water is less important than the temperature,which affects viscosity
C)erosion occurs equally on two sides of a bend
D)water cannot erode unless it is carrying sediment
E)all of these

Accepted Answer

Abrasion is concentrated on the upstream side of obstructions because the faster moving water on this side carries more sediment and creates more turbulence and erosion. The other options are not true statements about stream erosion.

Question 3

What is the pattern of discharge shown by this hydrograph? 
A)discharge gradually increases and quickly decreases
B)discharge quickly increases and gradually decreases
C)discharge gradually decreases and quickly increases
D)discharges quickly decreases and gradually increases

Accepted Answer

The hydrograph shows a quick increase in discharge followed by a gradual decrease. This pattern is typical of a storm event where precipitation causes a rapid increase in water flow, which then gradually subsides as the precipitation stops and the water drains away.

Question 4

Which of the following does NOT influence whether sediment is picked up by a stream?
A)size and density of the sediment
B)turbulence of the moving water
C)location of the sediment in the stream
D)whether the stream flows north-south or east-west

Accepted Answer

The orientation or direction of the flow of the stream does not affect the ability of the water to pick up sediment. The other factors listed - size and density of sediment, turbulence of water, and location of sediment within the stream - all play a role in whether sediment is picked up or not.

Question 5

What happens to water velocity downstream? It generally: 
A)Decreases
B)remains the same
C)increases
D)there is no way to tell because discharge cannot be determined

Accepted Answer

The answer of What happens to water velocity downstream? It...

Question 6

What is a reasonable interpretation for the flow event recorded by this hydrograph? 
A)there were two pulses of runoff because there were two storms
B)the drainage basin has several distinct parts
C)one pulse could be due to snowmelt and the other to rain
D)all of these

Accepted Answer

The hydrograph shows two distinct pulses of runoff, which could be due to two separate storms or due to a combination of snowmelt and rainfall. The fact that the second pulse continues at a lower magnitude for a longer period of time suggests that the drainage basin has several distinct parts with varying runoff characteristics. Therefore, all of the given options are reasonable interpretations for the flow event recorded by this hydrograph.

Question 7

Which of the following is a condition favoring deposition of sediment?
A)an increase in water velocity
B)a decrease in gradient of the stream
C)an increase in turbulence of the water
D)an increase in the salt content of the water
E)a decrease in grain size as a clast breaks into two pieces

Accepted Answer

A decrease in gradient of the stream would result in a decrease in water velocity, which would favor deposition of sediment. Higher velocity and turbulence would instead favor erosion and transport of sediment. The salt content of the water is not necessarily a significant factor in sediment deposition, and the decrease in grain size due to clast breakage does not directly relate to deposition.

Question 8

Compared with curve 2 on this hydrograph,what is a possible explanation for curve 1? 
A)the basin for curve 1 has steeper slopes than the basin for curve 2
B)the storm recorded by curve 1 was shorter and more intense than the storm represented by curve 2
C)curve 1 shows the same area as curve 2 but after urbanization
D)all of these are possible

Accepted Answer

The answer of Compared with curve 2 on this hydrograph,what...

Question 9

Which of the following is true about transport of sediment in a stream?
A)Pebbles and cobbles are mostly transported by suspension.
B)Sediment that is deposited within a stream bed is unlikely to be transported again.
C)Sand can be transported in a series of bounces along the stream bed.
D)Slower current can carry larger clasts because the water is in contact with each clast for a longer time.
E)Sand grains are converted into salt by the process of saltation.

Accepted Answer

Sand can be transported in a series of bounces along the stream bed, a process known as saltation. Pebbles and cobbles are too heavy to be transported by suspension, and sediment deposited within a stream bed can be remobilized during high flow events. Slower current cannot carry larger clasts because they require a higher velocity to be transported, regardless of the water's contact time with each clast. Sand grains are not converted into salt during transportation in a stream.

Question 10

What is the mostly likely setting for this drainage pattern? 
A)the rocks have a relatively equal resistance to erosion
B)drainages have followed a series of fractures that branch off of one another
C)the area has folded or faulted rocks with different resistances to erosion
D)a volcano once existed here but has been partly eroded away

Accepted Answer

The answer of What is the mostly likely setting for...

Question 11

Which of the following sediment sizes is likely to be transported mostly on the bottom of the stream bed?
A)fine sand
B)sticky clay particles
C)pebbles and cobbles
D)dissolved materials

Accepted Answer

Pebbles and cobbles are larger in size and weight, so they are more likely to be transported on the bottom of the stream bed through traction, rolling, and sliding. Fine sand and sticky clay particles can be transported in suspension or as bed load during high flow, but they can also be transported above the stream bed. Dissolved materials are not sediment and are carried within the water itself.

Question 12

Which event is best represented by the hydrograph shown here? 
A)a summer thunderstorm
B)a very long period of steady light rain
C)a long drought with no rain for months
D)a winter snowstorm followed by very cold weather

Accepted Answer

The answer of Which event is best represented by the...

Question 13

What units of measure would most likely be represented by letters A-E on the bottom of the accompanying hydrograph? 
A)meters
B)hours
C)kilograms
D)miles

Accepted Answer

The most common units of measure for hydrographs are time (usually in hours or days) on the x-axis and flow rate (usually in cubic feet per second or cubic meters per second) on the y-axis. Since the question specifically asks about the units represented by letters A-E on the bottom of the hydrograph, and meter, kilogram, and miles are not units typically used in hydrographs, the most likely answer is hours.

Question 14

What is the mostly likely setting for this drainage pattern? 
A)the rocks have a relatively equal resistance to erosion
B)drainages have followed a series of fractures that branch off of one another
C)the area has folded or faulted rocks with different resistances to erosion
D)a volcano once existed here but has been partly eroded away

Accepted Answer

The answer of What is the mostly likely setting for...

Question 15

Based on the accompanying hydrograph,what was the stream discharge when the data period shown in the graph ended? 
A)1.8 meters per second
B)4 meters per second
C)4 cubic meters per second
D)9 cubic meters per second
E)10 cubic meters per second

Accepted Answer

The answer of Based on the accompanying hydrograph,what was the...

Question 16

A delta forms when:
A)ocean waves,especially during storms,pile up sediment along the coast
B)a steep mountain front collapses sending sediment out into the sea
C)a river slows and deposits sediment as it enters a lake or sea
D)windblown dust slides down steep hillsides and into a lake

Accepted Answer

A delta forms when a river slows and deposits sediment as it enters a lake or sea. The sediment eventually accumulates and creates a fan-shaped landform.

Question 17

What typically happens when tributaries join the main river? 
A)channel size increases
B)water velocity increases
C)the amount of discharge increases
D)total sediment load increases
E)all of these

Accepted Answer

When tributaries join the main river, the channel size increases due to the addition of water and sediment, water velocity increases due to the extra volume of water, and the amount of discharge increases as the tributaries add more water to the main river. Additionally, the total sediment load increases as sediment from the tributaries is transported downstream.

Question 18

If erosion and deposition occur at the same rate,how can we best describe the particles of sediment on a streambed?
A)only very small particles will be present along the stream bottom
B)particles neither move in,nor move out of this part of the stream
C)as the sediment moves downstream,it is replaced by a similar volume of sediment
D)pebbles and cobbles carried away are replaced by the same number of smaller particles

Accepted Answer

The answer of If erosion and deposition occur at the...

Question 19

Bedrock and sediment in a stream is most susceptible to erosion if it is:
A)in slow-moving water in an eddy
B)in a site that is sheltered from oncoming clasts
C)located in a turbulent part of the river
D)composed entirely of large clasts that affect stream flow
E)all of these

Accepted Answer

Sediment in a turbulent part of the river is exposed to higher velocity flow, which increases the likelihood of erosion. Slow-moving water in an eddy and sites that are sheltered from oncoming clasts are less likely to erode sediment. Clasts that are too large can actually help protect the bedrock from erosion. Therefore, option E is incorrect.

Question 20

Which particles of sediment are most likely to be transported as suspended load?
A)small,low density particles
B)pebbles of average density
C)sand and gravel of relatively high density
D)dissolved ions in solution
E)all of these

Accepted Answer

Small, low density particles are most likely to be transported as suspended load because they are easily moved by water currents and can remain in suspension for longer periods of time.

Quiz 16: Streams and Flooding

The size of clasts that a stream can carry is primarily controlled by:

Which of the following is true about how a stream erodes material?

What is the pattern of discharge shown by this hydrograph?

Which of the following does NOT influence whether sediment is picked up by a stream?

What happens to water velocity downstream? It generally:

What is a reasonable interpretation for the flow event recorded by this hydrograph?

Which of the following is a condition favoring deposition of sediment?

Compared with curve 2 on this hydrograph,what is a possible explanation for curve 1?

Which of the following is true about transport of sediment in a stream?

What is the mostly likely setting for this drainage pattern?

Which of the following sediment sizes is likely to be transported mostly on the bottom of the stream bed?

Which event is best represented by the hydrograph shown here?

What units of measure would most likely be represented by letters A-E on the bottom of the accompanying hydrograph?

What is the mostly likely setting for this drainage pattern?

Based on the accompanying hydrograph,what was the stream discharge when the data period shown in the graph ended?

A delta forms when:

What typically happens when tributaries join the main river?

If erosion and deposition occur at the same rate,how can we best describe the particles of sediment on a streambed?

Bedrock and sediment in a stream is most susceptible to erosion if it is:

Which particles of sediment are most likely to be transported as suspended load?