Deck 6: Flooding

Question 1

In which cycle do rivers NOT play an important role?

A) hydrologic cycle
B) tectonic cycle
C) rock cycle
D) biogeochemical cycle

Answer 1

B

Question 2

What is avulsion?

A) A river overflows its banks and leaves pools of water behind in the floodplain.
B) A river turns and moves in the opposite direction due to uplift caused by a fault.
C) A river shifts its position after a flood.
D) A river overflows and completely fills the floodplain.
E) A river deposits sediment and creates a fan-like structure.

Answer 2

C

Question 3

Choose the best answer. Which would increase during a flood, discharge or velocity?

A) Discharge only because there is more water flowing
B) Velocity only because the water is flowing faster
C) Neither discharge or velocity because the stream will be doing more erosion during a flood
D) Neither discharge or velocity because both are constant for any given stream
E) Both discharge and velocity will increase because there is more water flowing and it is flowing faster.

Answer 3

E

Question 4

If you were running water through a hose, how would you increase the discharge of water coming from the hose?

A) Turn up the water at the faucet
B) Hold your finger over half of the opening in the hose
C) Connect the hose to a sprinkler
D) Connect the hose to a spray gun

Question 5

What happens to rivers when they reach their base level?

A) Their discharge decreases.
B) They erode sediment.
C) They fill the bottom of a v-shaped valley.
D) They often form alluvial fans or deltas.

Question 6

Which of the following loads are most likely to consist of heavy rocks and boulders?

A) Bed load
B) Suspended load
C) Dissolved load
D) Structural load
E) Buoyant load

Question 7

What is the role of a drainage basin?

A) Rivers empty into a drainage basin, which represents a lake or the ocean.
B) A drainage basin is the area drained by a river and all of its tributaries.
C) A drainage basin is very permeable soil into which flood waters seep instead of going into a river.
D) A drainage basin is very impermeable soil, where flood waters are held and eventually evaporate instead of going into a river.
E) A drainage basin is a set of underground tunnels that drain water into the ocean.

Question 8

In which of the following cases would you expect the LEAST amount of flooding due to a rainstorm? Assume all areas receive similar amounts of rainfall in the rainstorm and there are no flood control measures in any of the areas.

A) An area where soil is already saturated due to previous recent thunderstorms
B) An area where the ground is frozen
C) A short duration rainstorm falling on an area that is typically very dry such as a desert
D) A city with many houses, paved roads, and sidewalks
E) A long duration rainstorm falling on an area that consists of forest, grasslands, and no human development.

Question 9

Which rivers have the highest gradient?

A) Rivers near their base level
B) Rivers near the ocean
C) Rivers in gentle valleys
D) Rivers moving down mountains

Question 10

What is the stage of a river?

A) Volume of water that flows past a point over time
B) Height of water that is flowing
C) Age of the river
D) Elevation of the top of the river valley
E) Length of the river

Question 11

If you dip a glass of water into a river and passed the water through a very fine sieve that blocked all sediment grains from passing through, what will you be left with?

A) Bed load
B) Suspended load
C) Dissolved load
D) Structural load

Question 12

What is the floodplain?

A) The area around a river that is the ultimate limit to how far it will ever flood
B) A flat area next to the river carved out by the rivers
C) The steep sides of the river channel that holds in the water
D) Earthen mounds that run parallel to the river and hold in the water during floods
E) A triangular shaped deposit that forms when a river flows into the ocean

Question 13

Where on a river would you most likely find point bars?

A) On the outside of a bend
B) On the inside of a bend
C) At the mouth of the river
D) At the headwaters of the river
E) In the center of the river

Question 14

Which of the following will tend to REDUCE the size of a river flood?

A) High amount of precipitation in a drainage basin
B) High rate at which the precipitation soaks into the ground
C) Fast rate at which the runoff moves towards the river
D) High amount of moisture in the soil (water-saturated soil)

Question 15

Which of the following loads would make a river appear murky or dirty?

A) Bed load
B) Suspended load
C) Dissolved load
D) Structural load
E) Buoyant load

Question 16

What would the longitudinal profile of a river flowing from a gentle valley into an ocean look like?

A) A steeply downward sloping line
B) A steeply upward sloping line
C) A gently downward sloping line
D) A gently upward sloping line
E) An upward sloping and then downward sloping line

Question 17

Where does a meandering river run the fastest?

A) On the outside of a bend
B) On the inside of a bend
C) All parts of a meandering river run at similar speeds.
D) Near the point bars

Question 18

What two parameters are plotted in a hydrograph?

A) Cross-sectional area vs. stage
B) Stage vs. elevation
C) Discharge vs. time
D) Stage vs. gradient
E) Velocity vs. discharge

Question 19

Which of the following is NOT an example of a base level for a river?

A) Ocean
B) Lake
C) Rapids
D) Reservoir

Question 20

Where on a river would you most likely find cutbanks and why?

A) On the outside of a bend because that is where the river erodes most.
B) On the inside of a bend because that is where the river erodes most.
C) On the outside of a bend because that is where the river deposits most.
D) On the inside of a bend because that is where the river deposits most.
E) At the bottom of the river because that is where it moves the fastest.

Question 21

What distinguishes flash floods from downstream floods?

A) Flash floods are caused by thunderstorms, downstream floods do not involve lightning and thunder.
B) Flash floods occur in the upper part of a drainage basin, downstream floods occur in the lower part of a drainage basin.
C) Flash floods don't really involve any danger, downstream floods are extremely dangerous.
D) Flash floods are only common with large rivers, downstream floods generally involve much smaller rivers.

Question 22

How would the hydrograph of a large rainstorm change after urbanization of an area?

A) The hydrograph would become a straight line.
B) The peak of the hydrograph would become lower and wider.
C) The peak of the hydrograph would become higher and wider.
D) The peak of the hydrograph would become higher and narrower.
E) The peak of the hydrograph would become lower and narrower.

Question 23

What is the greatest hazard to people in a flash flood?

A) Sediment deposits
B) Erosion of farmland
C) People driving into floods and being carried away
D) Houses and other buildings being carried away
E) Fires

Question 24

Tributaries are smaller streams which drain into larger rivers.

Question 25

Which homes built on the floodplain are most likely to sustain the greatest damage?

A) Houses outside of the floodplain
B) Houses within the 100 year floodplain but outside the 20 year floodplain
C) Houses within the 20 year floodplain
D) All houses within the floodplain have an equal chance to sustain similar amounts of flood damage.

Question 26

The gradient of streams is higher at headwaters than at the mouth of a river.

Question 27

Which of the following is NOT an example of how urbanization influences a river or stream?

A) Urbanization decreases rainwater infiltration into the ground and therefore increases the frequency of floods.
B) Urbanization decreases rainwater infiltration into the ground and therefore increases the magnitude of floods.
C) Urbanization decreases flood lag time by the network of street sewers.
D) Urbanization increases rainstorm frequency and therefore increases the frequency of floods.

Question 28

Which of the following natural hazards is the number 1 disaster in the United States in terms of lives lost over the past century?

A) Floods
B) Volcanoes
C) Earthquakes
D) Landslides
E) Lightning

Question 29

Which of the following adverse effects of natural hazards is NOT associated with flooding?

A) Pollution
B) Disease
C) Destruction of buildings
D) Land upheaval
E) Economic loss

Question 30

What should you do during a flood?

A) Move to higher ground away from the river.
B) Wade into the water to see how deep it really is.
C) Drive your car through water to get to safety.
D) Swim across water to a safer location.
E) Go to a bridge and watch the water rise.

Question 31

How would a river in an area changed from forest to farmland react to changes?

A) Decreased amounts of sediment would increase the gradient of the stream.
B) Increased amounts of sediment would increase the gradient of the stream.
C) Decreased amounts of sediment would decrease the gradient of the stream.
D) Increased amounts of sediment would decrease the gradient of the stream.
E) The change in land use would have no effect on the stream.

Question 32

Which of the following are things that you should NOT do in preparing for a flood?

A) Buy flood insurance.
B) Place sandbags to block water from entering doors.
C) Make a flood kit and place it in your basement.
D) Make a flood plan with members of your household.
E) Find out how to turn off utilities in the event of a flood.

Question 33

Which of the following has the LEAST effect on flood damage? Assume that a moderate amount of development is available for flood damage.

A) People's use of the floodplain
B) Flood duration
C) Geographic region
D) Speed of the floodwaters

Question 34

Which statement is FALSE about the effects that floods can have?

A) Floods can supply nutrients to soils for farming.
B) Floods can clear ecosystems of debris.
C) Floods can supply sediments to build up the elevation of land.
D) Floods can bring nutrients to ecosystems.
E) Flooding has no positive effects; it is always bad for human interests.

Question 35

Does it have to be raining for a river to flood?

A) Yes. Only the rain that falls into the river fills it up and causes it to overflow.
B) Yes. Rain runs off over the ground and into the river causing flooding.
C) No. Snow and rain that fall into the river fill it up and cause it to overflow.
D) No. Rivers can flood after rain has stopped and tributaries have flowed into bigger streams.
E) No. Rivers can flood during droughts without any rain.

Question 36

Which of the following is NOT information that can be obtained by calculation of a recurrence interval for a flood?

A) How often on average floods of certain sizes occur
B) It can be used to make maps along rivers of flood risk.
C) It can be used to help city planners decide where and where not to build.
D) It can give homeowners help in making decisions about purchasing flood insurance.
E) Time of day when the maximum floodwaters will occur during a flood event

Question 37

In which of the following environments are flash floods LEAST common?

A) Higher elevations in a small drainage basin
B) Arid environments with steep slopes
C) Humid environments with large meandering rivers
D) Urban environments with poor drainage

Question 38

If you are standing in the middle of a river and look at either side, you might see tall earthen hills. What are they and what do they do?

A) They are levees and they hold in floodwaters.
B) They are drains and they drain water to the city.
C) They are dams and let water out slowly.
D) They are cutbanks and they hold in water.

Question 39

What is a hydrograph NOT able to tell you about a river?

A) The stage or discharge of a river at a particular time
B) Size of a river flood
C) How the stage or discharge of a river varies over time
D) The highest discharges or stages for rivers over a period of time
E) The amount of rainfall an area receives

Question 40

Does channelization of a stream completely prevent flooding?

A) No. Nothing can prevent flooding,
B) No. It increases flooding.
C) Yes. It is the best solution for flooding and it has no drawbacks.
D) Yes. However, it is not necessarily good for habitats.
E) No one actually knows because channelization of a stream has never been applied to the real world.

Question 41

A narrow river usually runs faster than a wider one.

Question 42

Flash floods are usually of short duration and therefore not very dangerous.

Question 43

One of the benefits of flooding is deposition of fertile soil.

Question 44

There are some places that have too high a flood risk for people to rebuild; these homes usually are better off abandoned.

Question 45

If the discharge of a river is constant and the river channel suddenly widens, then the velocity of the river will decrease.

Question 46

At a river meander, erosion occurs on the outside part of the bend, and deposition occurs on the inside part of the bend.

Question 47

A river in flood stage can erode and transport more sediment than the same river in normal flow.

Question 48

Rivers normally stay in a state of dynamic equilibrium between their flow velocity, their gradient, and their cross-sectional area.

Question 49

Flash floods are most common on the floodplains of large meandering rivers.

Question 50

If you live on the 100 year floodplain, it means that you are guaranteed to have one large flood once every 100 years.

Question 51

Virtually all areas of the U.S. have some risk of flooding.

Question 52

Insurance and building codes are two important ways that the government can protect property from disaster in a flood.

Question 53

An alluvial fan can be found at the base level of rivers.

Question 54

Construction of levees can actually make floods worse in areas upstream and downstream from the construction.

Question 55

The longitudinal profile of most streams is an upwardly curving line.

Question 56

Channelization is one of the more drastic solutions to flooding because it can cause the draining of wetlands, which can have a negative impact on the wildlife.

Question 57

Hydrographs are used to show the amount of water in the hydrologic cycle.

Question 58

Living near a dam is very safe because you will never have to worry about flooding.

Question 59

Paving over land decreases the amount of flooding because water can't soak into the soil.

Question 60

The bed load of a stream is involves the largest grains in the stream.

Question 61

Many major cities are on floodplains. Give three reasons why people would want to live in areas that have periodic flooding.

Question 62

During a flood, the safest place to be is behind a levee or floodwall.

Question 63

After a flood, you should be sure to wash anything that has been in touch with river water.

Question 64

Explain the role of rivers in the rock cycle.

Question 65

Explain how a floodplain forms.

Question 66

Give an example of something that acts as a base level for streams. Explain what happens to the river as it reaches this level and why it is a base level. Sketch a longitudinal profile for this stream.

Question 67

How does urbanization affect flooding?

Question 68

Imagine that you were put in charge of planning a public awareness campaign about flooding. What are some of the most important things that you would want people to know? Why are these important?

Question 69

What is the difference between stream discharge and stream stage? How are they related?

Question 70

Describe a hydrograph for a river that has experienced a flash flood and one that has experienced a downstream flood. What is the difference in the two hydrographs?