Deck 13: Streams and Flooding

Question 1

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.

Answer 1

A

Question 2

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

Answer 2

B

Question 3

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.

Answer 3

A

Question 4

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.

Question 5

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.

Question 6

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.

Question 7

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

Question 8

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.

Question 9

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

Question 10

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.

Question 11

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.

Question 12

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

A)the water temperature.
B)the amount of 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.

Question 13

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

Question 14

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

Question 15

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.

Question 16

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.

Question 17

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

Question 18

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.

Question 19

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.

Question 20

In this diagram, water velocity downstream generally

A)decreases.
B)remains the same.
C)increases.
D)There is no way to tell because discharge cannot be determined.

Question 21

At which sites would this stream profile most likely be located?

A)A and C
B)B and D
C)C and D
D)D and A

Question 22

If a river originates 200 meters above sea level and travels 100 kilometers to the ocean, what is the average gradient in meters per kilometer?

A)0.2 meters per kilometer
B)0.5 meters per kilometer
C)2 meters per kilometer
D)5 meters per kilometer
E)None of these.

Question 23

Which of the following can influence a stream's profile?

A)a rise in sea level
B)a fall in sea level
C)tectonics
D)All of these.

Question 24

Which site along this stream would have the highest velocity for that segment of the stream?

A)A
B)B
C)C
D)D

Question 25

What happens to a river as it flows through a delta and encounters the sea?

A)The discharge and water velocity increase.
B)The maximum sediment grain size carried by the river increases.
C)The total sediment load carried by the river decreases.
D)All of these.

Question 26

Which of the following is true about the formation and migration of meanders?

A)most floodplains do not preserve evidence of the former position of meanders
B)flow velocity is highest when water takes a shortcut around the inside of a bend
C)meanders migrate inward as sediment is deposited on the inside bend
D)migration of meanders back and forth can help form a floodplain
E)None of these.

Question 27

What could cause a canyon to be deeper upstream than downstream?

A)The area upstream could be uplifted more than areas downstream.
B)The area upstream is higher above base level and so results in deep erosion.
C)A steeper gradient allows more erosion upstream.
D)All of these.

Question 28

On this graph of discharge versus season for a river in the Rocky Mountains, why is the highest runoff likely to be in the spring?

A)Winter snow melts in the spring.
B)The Rocky Mountains have many tornadoes during the spring.
C)The Rocky Mountains experience hurricanes in the spring.
D)All of these.

Question 29

Which of the following is NOT a common site for deposition of sediment?

A)point bar
B)distributary system
C)levee
D)cutbank
E)floodplain

Question 30

At which site along this stream would a cut bank form?

A)A
B)B
C)C
D)D

Question 31

What does a profile of a river from its headwaters to its mouth typically show?

A)an increase in gradient downstream
B)a straight-line profile reflecting a constant decrease in gradient
C)an abrupt increase followed by a gradual decrease
D)a curved shape that flattens out downstream
E)None of these.

Question 32

What could cause this stream to begin carving into the landscape?

A)if base level is lowered, such as a drop in sea level
B)if the land is uplifted relative to the sea
C)if a change in climate weathers and weakens the rocks
D)All of these.

Question 33

Which of the following is unlikely to cause deposition of sediment along a stream?

A)a decrease in gradient
B)a decrease in water velocity
C)a drop in sea level
D)None of these.

Question 34

Which of the following is true about the base level of a stream?

A)Base level indicates the normal (or base)flow level before flooding.
B)The flat top of a mountain is the ultimate base level for most streams.
C)A mountain is close to its base level if bedrock is close to the surface.
D)Most streams have lower gradient close to their base level.
E)Base level generally is near the steepest part of a stream's profile.

Question 35

Which of the following profiles does NOT match its position on the stream?

A)A
B)B
C)C
D)D

Question 36

If a stream drops 15 meters in 15 kilometers, what is its gradient?

A)100%
B)1 meter per kilometer
C)15 meters per kilometer
D)15 kilometers per meter
E)None of these.

Question 37

Which of the lettered sites would most likely be undercut by migration of a meander?

A)A
B)B
C)C
D)D

Question 38

At which site along this stream would a point bar form?

A)A
B)B
C)C
D)D

Question 39

Which of the following typically decreases downstream in a river?

A)flow velocity
B)discharge
C)channel size
D)maximum sediment grain size
E)None of these.

Question 40

What does the associated graph indicate about a stream?

A)Silt and clay are carried in suspension under most stream velocities.
B)Sand and gravel are deposited at low velocities but transported at higher velocities.
C)Sand is carried in suspension only at high velocities.
D)As fast-moving water slows down, fine sand can switch from transport by suspension to the bed load.
E)All of these.

Question 41

Which of the features on this aerial photograph is a point bar?

A)A
B)B
C)C
D)D

Question 42

If a stream-cut canyon is deep and narrow, which of the following is most likely to be true?

A)Rocks in the canyon walls are relatively hard and easy to erode.
B)The stream is probably close to its base level.
C)Downcutting is occurring faster than widening.
D)The stream contains mostly small clasts, such as silt.

Question 43

What type of stream is shown in this figure?

A)meandering stream
B)braided stream
C)a stream whose main channel has high sinuosity
D)an esker

Question 44

Where do mountain streams get most of their load of sediment?

A)landslides, slope failures, and erosion of the mountain sides
B)downward incision into bedrock
C)abrasion of bedrock along the bottom of the channel
D)alluvial fans

Question 45

What type of stream is shown in this figure?

A)braided stream
B)a stream whose channel has a low sinuosity
C)meandering stream
D)a stream that lacks point bars
E)All of these.

Question 46

Which of the features on this aerial photograph is a cutbank?

A)A
B)B
C)C
D)D

Question 47

Feature A, formed where the Nile River encounters the Mediterranean Sea, is

A)a landslide.
B)a series of waterfalls.
C)a delta.
D)All of these.

Question 48

Which of the following is NOT true about braided streams?

A)These streams form where the sediment is plentiful and dominated by clay and silt.
B)The amount of sediment is close to or exceeds the stream's capacity to carry it.
C)More than one channel can carry water and sediment.
D)They can have a fairly straight overall path or gentle curves.

Question 49

Which of the following features is NOT formed by stream deposition?

A)broad plains next to a braided stream
B)a floodplain
C)a delta
D)a waterfall

Question 50

Which of the features on this aerial photograph is an oxbow lake?

A)A
B)B
C)C
D)D

Question 51

Construction of a dam results in

A)an increase in the total amount of water flowing downstream of the dam.
B)increased erosion by clear water released from the dam.
C)the dam releasing water that contains more sediment than carried by the river before the dam was constructed.
D)increased erosion where the stream channel meets the reservoir.

Question 52

Which of the following features can be formed by deposition along a low-gradient stream?

A)point bar
B)oxbow lake
C)cutbank
D)None of these.

Question 53

Which of the following is commonly associated with tributaries?

A)rapids when the tributary joins the main river
B)delivery of sediment to the main river
C)an increase in the discharge in the main river
D)All of these.

Question 54

What type of stream is shown in this photograph?

A)meandering stream
B)braided stream
C)a stream whose main channel has high sinuosity
D)an esker

Question 55

Which of the following statements about streams is NOT true?

A)Base level is the lowest elevation to which a stream can erode.
B)A steep stream high above base level generally will be eroding its channel.
C)Some streams can simply transport material instead of eroding or depositing material.
D)Streams typically do not respond to a change in climate.

Question 56

Which of the following is NOT associated with braided streams?

A)an abundant supply of sediment
B)a broad sediment-covered plain
C)a range of sediment sizes, including sand and gravel
D)cutoff meanders

Question 57

Which of the following features is most related to erosion along a low-gradient stream?

A)point bar
B)floodplain
C)levee
D)None of these.

Question 58

When water in a stream or desert wash decreases in velocity, sediment that the stream carries can be deposited in

A)a delta.
B)an alluvial fan.
C)a floodplain.
D)All of these.

Question 59

How is an alluvial fan formed?

A)A stream erodes down through older terraces and entrenched meanders.
B)Sediment is deposited by debris flows and streams that decrease in velocity along the mountain front.
C)A landslide blocks the stream, causing sediment to accumulate upstream.
D)A dam increases the speed of currents below the dam.

Question 60

Which of the following features are generally NOT associated with mountain streams and rivers?

A)waterfalls
B)rapids
C)canyons incised into bedrock
D)meanders

Question 61

Which of the following is true about a delta?

A)A delta forms as channels merge and pile up sand.
B)A river keeps forming a delta in the exact same position along a coastline.
C)Deltas form some layers that are horizontal and form some that are inclined toward the ocean.
D)The total amount of sediment carried by the river increases from the start to the end of the delta system.

Question 62

Formation of entrenched meanders can result from a

A)low-gradient river followed by downcutting.
B)braided river that later exceeds its capacity to carry sediment.
C)braided river followed by regional uplift.
D)steep-gradient mountain stream following by an increase in precipitation.

Question 63

What would happen if the amount of ice in this area increases?

A)The land near the ice would rise.
B)The area near the ice would experience isostatic rebound.
C)The weight of the ice depresses the land, possibly causing river to change direction.
D)None of these.

Question 64

This figure shows four numbered river terraces, with 1 being the highest and 4 being the lowest.Which is the oldest terrace?

A)1
B)2
C)3
D)4

Question 65

Which of the following is the most common cause of river and stream flooding?

A)the onset of cold weather
B)failure of levees
C)intense precipitation
D)overgrazing
E)global warming

Question 66

The type of feature shown in this figure is

A)a braided stream.
B)river terraces.
C)alluvial fans.
D)entrenched meanders.
E)None of these.

Question 67

Which of the following can have a significant effect on a river?

A)rises and drops in sea level
B)tectonics
C)types of bedrock in the river
D)changes in climate
E)All of these.

Question 68

Which of the following is NOT true about rivers?

A)Major rivers, like the upper Mississippi near the Great Lakes, must be relatively old rivers.
B)The boundary between hard rocks and soft rocks can be marked by waterfalls.
C)Loading and unloading of the crust by ice sheets can change the direction that rivers flow.
D)Different parts of a river can be different ages.

Question 69

What is NOT true about terraces?

A)Most terraces were once part of a floodplain.
B)According to superposition, the lowest terrace is the oldest.
C)Terraces develop along a river that is incising (eroding)downward.
D)A river can have more than one level of terraces.

Question 70

This figure shows four numbered river terraces, with 1 being the highest and 4 being the lowest.Which is the youngest terrace?

A)1
B)2
C)3
D)4

Question 71

What would happen if the ice in this area melted away?

A)The land near the ice would drop due to isostatic rebound.
B)Rivers could change direction and flow away from the area once covered by ice.
C)The land subsides because the ice is removed.
D)All of these.

Question 72

What can you conclude by comparing the left and right hydrographs, each of which depict the same amount of time?

A)The left diagram has a higher peak discharge.
B)The right diagram represents a quicker event, like a flash flood.
C)Neither graph shows a true flood.
D)None of these.

Question 73

What are some effects of building a dam?

A)A stream has more sediment below the dam and so can erode more efficiently.
B)The reservoir (lake)traps sediment that over time fills up part of the reservoir.
C)A dam, whether constructed by nature or by humans, represents a permanent change in base level.
D)The stream erodes into the land instead of depositing sediment, where it enters the reservoir.

Question 74

How did the entrenched meanders shown in this figure form?

A)Rising seas flooded a meandering river valley.
B)The land subsided and the river deposited sediment.
C)A meandering river carved into the land due to uplift or falling base level.
D)None of these.

Question 75

Which of the following influences whether a flood occurs?

A)the height of levees
B)the amount of discharge
C)urbanization (replacing farms or natural land with buildings)
D)the width of the channel
E)All of these are influences.

Question 76

Which of the following is properly called a flood?

A)when a meander is cut off and forms a lake
B)when the entire bottom of the channel is covered with water
C)if water spreads out over the floodplain
D)when water is 1 meter below the top of the channel

Question 77

Which of the following accompanies urbanization (replacing farms and open areas with cities)?

A)The discharge pattern of streams in the area does not change.
B)Runoff occurs more quickly and produces a higher peak flow.
C)Runoff becomes more spread out in time, increasing the amount of flooding.
D)Runoff becomes more spread out in time, reducing the amount of flooding.
E)None of these.

Question 78

Which of the following sites is most likely to be flooded if all other factors are held constant?

A)a site that is higher but closer to the river than a site that is lower but farther from the river
B)a site next to the river where the main channel is wider and deeper than other segments of the river
C)a site on the floodplain instead of a site on an older terrace
D)All of these.

Question 79

Which of the following is the main reason that a delta forms when a stream flows into a lake or sea?

A)The stream flows backward during high tide.
B)Ocean waves push the sediment up onto the beach.
C)The velocity of the stream decreases.
D)The stream began downcutting during the ice ages.
E)None of these.

Question 80

Stream terraces represent

A)older floodplains of a river that has incised downward.
B)cutoff meanders of a meandering stream.
C)areas where sea level has risen and waves beveled across the coast.
D)None of these.