Deck 13: Floods

Question 1

Most flood-related deaths in the United States are caused by __________________.

A)flash floods from local thunderstorms
B)regional floods from abundant rainfall lasting for days
C)storm surges of tropical cyclones flooding the coasts
D)ice jam floods from the break-up of winter ice on rivers
E)collapse of man-made dams

Answer 1

A

Question 2

If a stream has a meandering section,that section is most likely to be ________________.

A)in its upstream section near its source or sources
B)in its downstream section,near its mouth
C)in its upstream section near its source or sources or in its downstream section,near its mouth
D)braided

Answer 2

B

Question 3

Between 1960 and 2006,floods in the United States resulted in an average of _______ deaths per year.

A)1.4
B)14
C)139
D)1,450
E)14,5000

Answer 3

C

Question 4

United States Geological Survey stream-gauging stations measure all but which of the following?

A)water depths
B)channel width
C)water velocity
D)amount of sediment being carried by the stream
E)All of these choices are correct.

Question 5

Between 1960 and 2006,floods in the United States produced an average of _______ in damage per year.

A)$459,000
B)$4.59 million
C)$45.9 million
D)$459 million
E)$4.59 billion

Question 6

Base level __________________.

A)is the level below which a stream cannot erode
B)for all streams is sea level
C)is the average annual flow level for a stream
D)is the minimum amount of flow possible for a stream
E)None of these are correct.

Question 7

What is the probability that a 100-year flood will occur at least once in 100 years?

A)1 percent
B)10 percent
C)50 percent
D)63 percent
E)0 percent

Question 8

Factor(s)that interact to make streams seek equilibrium include ________________.

A)the volume of water discharged by the stream
B)the amount of sediment waiting to be moved
C)the slope of the stream bottom
D)the sinuosity of the stream path
E)All of these choices are correct.

Question 9

If a stream is choked with sediment and has insufficient water to carry it away _______________.

A)the water will pick its way through as a braided stream
B)a peninsula is formed
C)a canyon is formed
D)a flood will occur
E)Any of these may happen

Question 10

In the late spring and summer of 1993,the upper Mississippi River basin experienced record high floods.However,the floodwater mass did not significantly affect the lower Mississippi River basin because _______________.

A)the input from the Ohio River flow was low
B)there was a drought in Louisiana
C)the southern levees were built higher during the summer before the water got there
D)All of these choices are correct.
E)None of these choices are correct.

Question 11

A hydrograph is a plot of _________________.

A)the volume of water or stream-surface height versus time
B)water quality versus time
C)sediment load versus time
D)stream elevation versus distance downstream

Question 12

On a given stream,small floods happen _____________________.

A)with the same frequency as large floods
B)more often than large floods
C)less often than large floods,which explains why we hear about large floods more often in the news
D)sometimes more often,sometimes less often than large floods,depending on long-term climate

Question 13

Statistically,the 100-year flood has a ______ percent chance of occurring any year.

A)1
B)10
C)50
D)63
E)0

Question 14

The __________ is reputed to have killed more people than any other natural feature.

A)Huang (Yellow)River in China
B)Mississippi River
C)Nile River in Egypt
D)Red River of the North
E)Amazon River in Brazil

Question 15

In the United States about 2.5% of the land is floodplain and home to about _________ of the population.

A)0.065 percent
B)0.65 percent
C)6.5 percent
D)65 percent
E)None of our population lives on floodplains because of flood zoning legislation

Question 16

Why are floods so common along the Red River of the North (in North Dakota,South Dakota,and Minnesota)?

A)The Red River valley is geologically young (about 9000 years old)and has not carved a deep valley.
B)The gradient or slope of the riverbed is very low.
C)River flow increases as winter snow melts and meltwater runs northward into still frozen parts of the river.
D)All of these choices are correct.

Question 17

Killer floods are caused by __________________.

A)local thunderstorms
B)abundant rainfall lasting for days
C)the storm surges of tropical cyclones flooding the coasts
D)the break-up of winter ice on rivers
E)All of these choices are correct.

Question 18

Efforts to control rivers include _____________.

A)dams
B)levees
C)channelization
D)All of these choices are correct.

Question 19

If a stream experiences more energetic water flow,the stream ___________________.

A)responds by increasing the sinuosity of its channel pattern through meandering
B)responds by decreasing the sinuosity of its channel pattern
C)will not change its sinuosity,but will erode sediment
D)will not change its sinuosity,but will deposit sediment
E)will not change its floe path

Question 20

About 50% of flash flood deaths ________________________.

A)are related to people swimming across flooded rivers
B)are related to people watching floods from bridges
C)are related to people trying to retrieve pets from flooded homes
D)are vehicle-related
E)are boat-related

Question 21

The 1993 flood in the central United States was caused by ___________________.

A)a single large rainstorm over a large area
B)rapid melting of record winter snows during the spring of 1993
C)several storms building up excess moisture over several months over much of the upper Mississippi River drainage basin

Question 22

A president is limited by the Disaster Relief and Emergency Assistance Act to declaring only one flood every year as a federal disaster.

Question 23

During the great flood of July 1993,the southeastern United States experienced ________________.

A)persistent low atmospheric pressure and a drought
B)persistent high atmospheric pressure and a drought
C)persistent low atmospheric pressure and a flood
D)persistent high atmospheric pressure and a flood

Question 24

A braided stream has ____________.

A)too much sediment to carry
B)too little sediment in suspension,causing erosion in a braided pattern
C)no relationship to the amount of sediment being transported

Question 25

Which of the following conditions led to the 1993 flood in the midcontinental United States?

A)the jet stream moving north and south more rapidly than normal
B)the jet stream locked in place over north-central plains for an unusually long time
C)an unusual amount of rainfall caused by the after-effects of Hurricane Andrew
D)one unusually large rainstorm over Iowa,Kansas,Nebraska,and Minnesota

Question 26

A longitudinal cross section of a stream will show a lower gradient near the stream source and a higher gradient near the stream mouth.

Question 27

Hydrographs from urban settings _____________________.

A)look just like those from rural settings
B)show higher rates of runoff than rural settings,for a given precipitation event
C)show floods are of shorter duration than in rural settings,for a given precipitation event
D)show floods are of longer duration than in rural settings,for a given precipitation event
E)Both show higher rates of runoff than rural settings,for a given precipitation event and show floods are of shorter duration than in rural settings,for a given precipitation event are correct

Question 28

If a flood has a recurrence interval of ten years,it means ____________________.

A)that a similar-sized flood will occur once every ten years
B)that a similar-sized flood has a greater probability of occurring every tenth year than during any one of the intervening years
C)that in any given year a similar flood has a 1/10 chance of occurring
D)that the flood must be bigger than any other flood during any given 10-year interval
E)None of these are correct.

Question 29

The "channeled scablands" of the state of Washington were caused by _________________.

A)the gentle,slow melting of glaciers
B)the failure of an ice dam during glacial melting
C)a large rainstorm
D)winds from an ancient volcanic explosion at Mt.St.Helens
E)None of these are correct.

Question 30

When flooding occurs along a river,as you go farther downstream _________________.

A)the flooding gets worse as water piles up
B)the flooding gets less severe as water spreads out in time and space
C)the flooding is the same because the amount of water is the same

Question 31

The largest flood known in an area is likely to be exceeded someday by a larger one,even in an area with a long history.

Question 32

Flood duration is not related to size of the drainage basin in which the flood is occurring.

Question 33

With respect to channelization,straightening the channel ____________________.

A)increases the gradient of the stream bottom,making the water flow faster
B)decreases the gradient of the stream bottom,making the water flow slower
C)increases the gradient of the stream bottom,making the water flow slower
D)decreases the gradient of the stream bottom,making the water flow faster
E)None of these are correct.

Question 34

Statistically speaking,the larger the floods,the shorter are the recurrence times between them.

Question 35

A meandering stream lengthens its flow path,lowering the stream's gradient,and thus increasing the speed of its water flow.

Question 36

It is possible to estimate the flow volume of a 100-year flood on a stream that has only 25 years of flow records.

Question 37

The most famous of the ice-dam failure floods is preserved in the "channeled scablands" topography in __________________.

A)Manitoba
B)Saskatchewan
C)Alberta
D)Montana
E)Washington State

Question 38

Excesses in stream discharge or stream-sediment load are managed by the stream changing dependent variables,such as gradient and channel pattern.

Question 39

When ice dams in front of the largest glacial lakes failed,stupendous floods resulted whose passage is still recorded _________________.

A)in lake sediments
B)by countryside stripped of all soil and sediment cover
C)by abandoned waterfalls
D)by a system of braided channels,now left mostly dry
E)by all of these

Question 40

Ignoring scale,the fact that most streams worldwide have the same longitudinal cross section is a testimony to the effectiveness of their negative-feedback mechanisms.

Question 41

If a dam is removed from a river,the river will respond by eroding sediment deposited in the former reservoir and transporting it downstream.

Question 42

Most flood-related deaths in the United States are caused by flash floods,and about 50 percent of these deaths are vehicle-related.

Question 43

The probability that a 100-year flood will occur at least once in 100 years is 1%.

Question 44

An effective mitigation strategy against flooding is to construct many sewers,gutters,and drainage channels to remove precipitation from city streets and get it to streams as quickly as possible.

Question 45

The biggest floods known on Earth within the past two million years occurred during the melting of the continental ice sheets.

Question 46

Large floods due to ice dam collapses are thought to have the potential to affect global climate,due to the massive influx to the ocean of cold water,which can disrupt deep-ocean circulation.

Question 47

When designing roads,bridges,and buildings,it is possible to save large amounts of money on initial construction costs by considering only smaller floods,but in the long run,it is commonly cheaper to build with large floods in mind.

Question 48

Even though a "150-year flood" may occur one year,it is still possible for another of the same size to come again in the following year,or even in the same year.

Question 49

Flood frequency can be accurately predicted with only a few years of stream discharge measurements.

Question 50

When a flood crest passes downstream,stream level falls more rapidly than it rose.

Question 51

The probability that a 100-year flood will occur at least once in 100 years is 100%.

Question 52

The weather pattern was remarkably similar for the big floods of 1927,1973,and 1993 in the upper Mississippi River basin.