Deck 9: Hydrologic Hazards at the Earthss Surface

Question 1

What do hydrologists call the volume-rate of flow of a river through its channel?

A) flow through
B) overdraft
C) gaining rate
D) velocity
E) discharge

Answer 1

discharge

Question 2

What is the local steepness of a river channel called?

A) base level
B) gradient
C) profile
D) slope
E) drop

Answer 2

gradient

Question 3

What is the term relating to the lowest elevation to which a stream can erode?

A) base level
B) gradient
C) grade
D) erosion limit
E) floodplain

Answer 3

base level

Question 4

What is the term that refers to all sediment deposited by running water?

A) mud
B) talus
C) regolith
D) alluvium
E) till

Question 5

What is the term for a broad, flat area adjacent to a meandering river where seasonal flooding occurs?

A) floodplain
B) inundation zone
C) overflow margin
D) delta
E) alluvial fan

Question 6

What is the feature that forms in coastal areas where rivers enter the ocean?

A) floodplain
B) inundation zone
C) overflow margin
D) delta
E) alluvial fan

Question 7

Which of the following is NOT a feature of a low gradient river?

A) floodplain
B) levee
C) alluvial fan
D) oxbow lake
E) point bar

Question 8

A hydrograph is a graph of a water body's discharge, velocity, stage, or other characteristic plotted against which of the following things?

A) distance
B) elevation above sea level
C) cost in dollars
D) human population
E) time

Question 9

On average, how many 100-year floods will occur in 500 years?

A) 0
B) 1
C) 3
D) 5
E) There is no way of knowing for sure.

Question 10

On average, how many 500-year floods would be expected to occur in 500 years?

A) 0
B) 1
C) 3
D) 5
E) There is no way of knowing for sure.

Question 11

A number of hydroelectric dams are now scheduled for dismantling. What is the main reason for this?

A) Their structure has weakened.
B) New findings about the potential for large earthquakes have been discovered.
C) Cheaper and cleaner sources of electrical power have been found.
D) Environmental concerns must be addressed before a dam can be relicensed.
E) The demand for irrigation water has decreased.

Question 12

What is the most environmentally diverse and continually destructive natural hazard in the United States?

A) earthquakes
B) volcanoes
C) river floods
D) hurricanes
E) landslides

Question 13

Where would you NOT be permitted to build a house in a U.S. Government-regulated floodway?

A) in the regulatory floodway
B) in the regulatory floodway fringe
C) on the river side of the standard project flood limit
D) on the side of the regulatory flood limit away from the river
E) outside of the standard project flood limit

Question 14

What dam failure caused the greatest loss of life in the U.S.?

A) Grand Coulee, Washington
B) Teton, Idaho
C) St. Francis, California
D) Johnstown, Pennsylvania
E) Buffalo Creek, West Virginia

Question 15

What is the statistical recurrence interval for a flood of rank 2 in a data set that is 99 years long?

A) on average, once every 10 years
B) on average, once every 20 years
C) on average, once every 30 years
D) on average, once every 40 years
E) on average, once every 50 years

Question 16

Judge the following sentence according to the criteria given below: Engineering solutions aimed at stabilizing rivers (e.g., channelization) typically fail over time BECAUSE they don't recognize the dynamic nature of flowing water.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct, but the reason is incorrect.
D) The assertion is incorrect, but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 17

Judge the following sentence according to the criteria given below: Deltas are not subject to deadly flooding by tropical storms BECAUSE their elevations are far above sea level.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct, but the reason is incorrect.
D) The assertion is incorrect, but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 18

Which of the following is NOT a factor in riverine flood occurrence?

A) topography
B) dissolved solids
C) antecedent rainfall
D) vegetation
E) intensity of rainfall

Question 19

Which of the following statements about the fifty-year flood is true?

A) The fifty-year flood has a 50% chance of happening in a given year.
B) The fifty-year flood has a one-in-fifty chance of happening in any given year.
C) Once a fifty-year flood occurs, the region is safe for 49 years from another fifty-year flood.
D) The fifty-year flood occurs once every fifty years.
E) The fifty-year flood cannot happen twice in the same year.

Question 20

Which of the following is NOT an example of flood proofing?

A) building fish ladders so adult salmon can migrate upstream to spawn
B) building floodwalls of reinforced concrete and continuous piles
C) employing water-resistant building materials in all construction
D) raising structures above the 100-year flood level with artificial fill
E) building artificial levees on top of natural river levees

Question 21

Coastal flooding is the most deadly of natural disasters.

Question 22

Meandering streams typically occur in areas of low gradient.

Question 23

The upstream part of a stream profile usually has a steeper gradient than the downstream part.

Question 24

River floods have caused the greatest number of deaths in the U.S. in comparison to hurricanes, flash floods, and dam failures.

Question 25

A drainage divide separates one drainage basin from another.

Question 26

More than one 100-year flood can occur in 100 years.

Question 27

It is a good idea to stay in your car in a flash flood because its weight will protect you from being washed away.

Question 28

Streams in mountainous areas normally have floodplains.

Question 29

Ice jam floodwaters tend to rise much more rapidly than do normal floodwater.

Question 30

Urbanization can alter the amount and timing of runoff and cause flood events to become more common.

Question 31

Coastal flooding is not as deadly as earthquakes.

Question 32

Flood hydrographs tend to peak sooner and higher downstream from urbanized areas than prior to urbanization.

Question 33

Flood-control structures such as flood-walls and artificial-levees can actually increase flood risk.

Question 34

Oxbow lakes occur along rivers in mountainous areas due to the formation of temporary base levels.

Question 35

Earthquakes can result in flooding only when they trigger a tsunami.

Question 36

Canyons are carved by the low-amplitude monotonous flow of water over rocks.

Question 37

Flood frequency data are more reliable for rivers with long periods of record.

Question 38

It is not possible to estimate the annual peak discharge of the 100-year flood if you do not have at least 99-years worth of data.

Question 39

The flow characteristics of rivers change over time.

Question 40

What is the difference between velocity and discharge of water through a river channel?

Question 41

What do Darcy's Law and river discharge have in common? How do they differ?

Question 42

What is the significance, in terms of geological time, of the word "temporary" in temporary base level?

Question 43

What is the ultimate base level, and why is it called that?

Question 44

What causes point bars and cut banks to form?

Question 45

Why is a longer historical record of peak discharge preferred for a given river when determining the statistical recurrence interval for flood events?

Question 46

Given a rank for a particular flood event of 25 and a record of 24 years duration, what is the recurrence interval for a flood of this size?

Question 47

What are two benefits and two negative aspects of large dams on rivers?

Question 48

Building artificial levees has been said to be self-perpetuating. Why does building a levee in one place along a river system prompt the construction of another downstream?