Deck 9: River Flooding

Question 1

The flood fringe is a zone in Canada that is at risk from flooding and is defined as

A) the region along the river where the most destructive floods occur.
B) the region where overbank flow occurs.
C) the region in the floodplain with deep, fast water.
D) the region in the floodplain where water is shallow and slow moving.
E) the region where 100 year floods occur.

Answer 1

D

Question 2

An anastomosing river channel is characterised by

A) a large number of intersecting active channels.
B) a single channel shaped like a snake.
C) a curving channel that migrates back and forth.
D) two or more channels and intervening stable islands.
E) avulsing channels and riffles.

Answer 2

D

Question 3

Urbanization can affect flooding by

A) increasing the lag time between rainfall and stream flow.
B) reducing stream flow during the dry season.
C) increasing stream flow during the dry season.
D) improving the water quality of a stream.
E) decreasing flood frequency.

Answer 3

B

Question 4

Ions in sewage and chemical effluent will make up part of a river's

A) bed load.
B) suspended load.
C) dissolved load.
D) sliding load.
E) floating load.

Question 5

An important lesson learned from the 1993 Mississippi flood was

A) levees remove land from the floodplain.
B) levees eliminate flood risk.
C) levees help the floodplain "soak up" flood waters.
D) the construction of levees produces a false sense of security.
E) levees built by farmers performed as well as government-built levees.

Question 6

River discharge is the volume of water that moves through a cross-section of a river per unit of time and is reported in units of

A) metres per second.
B) metres² per second.
C) metres³ per second.
D) metres².
E) metres³.

Question 7

When a river is in flood,

A) point bars begin to form.
B) it begins to meander.
C) bedload decreases.
D) avulsion can take place.
E) discharge decreases.

Question 8

When a flood warning has been issued

A) only walk in water up to your waist.
B) enquire about the risk of flooding where you live.
C) purchase flood insurance if you property is at risk.
D) find out where to turn off your gas and electricity.
E) do as much as you can in the daylight.

Question 9

Outburst floods are associated with

A) the breaching of moraine-dammed lakes.
B) upstream floods.
C) flash floods.
D) urbanization.
E) ice jams on rivers.

Question 10

The construction of levees can result

A) in the widening of the floodplain.
B) in an increase in wetlands.
C) in a false sense of security from flooding.
D) in an elimination of flood risk.
E) in an increased ability to absorb flood waters.

Question 11

The centre of the most recent ice sheet to cover most of Canada was to the north and northeast of southern Manitoba.All else being equal,which of the following rivers in southern Manitoba would be most prone to flooding?

A) a river flowing to the north
B) a river flowing to the south
C) a river flowing to the southwest
D) a river flowing to the west
E) a river flowing to the southeast

Question 12

The phrase "The Gift of the Nile" refers to

A) the fresh water the Nile provides.
B) the Aswan Dam built on the Nile in 1970.
C) flooding of the Nile.
D) transportation along the Nile.
E) the dissolved load the Nile transports.

Question 13

A downstream flood is characterised by

A) lots of flooding but little destruction.
B) a large, slow rise in discharge at a particular location.
C) a large, rapid rise in discharge at a particular location.
D) little or no warning.
E) a rapid rise in discharge at all locations.

Question 14

A unique characteristic of flash floods is

A) they are commonly much more deadly than downstream floods.
B) they only occur in the lower parts of drainage basins.
C) they only occur in desert regions.
D) most people who die are in automobiles.
E) they are always associated with violent thunderstorms.

Question 15

Downstream floods

A) are generally produced by intense rainfall of short duration.
B) are most common in arid environments.
C) are most common in areas of steep topography.
D) affect larger areas than flash floods but are commonly less deadly.
E) affect larger areas than flash floods and are commonly more deadly.

Question 16

Developing countries suffer greater loss of life from flooding because of

A) higher population.
B) the lack of monitoring and warning capabilities.
C) a greater degree of urbanization.
D) a greater degree of river channelization.
E) a higher frequency of flash floods.

Question 17

Which of the following is NOT a benefit of dam construction?

A) a reduction in the suspended load of the river
B) the creation of a reservoir for irrigation
C) recreational opportunities provided by artificial reservoirs
D) a reduction in flood risk downstream of the dam
E) the production of hydroelectric power

Question 18

An example of a primary effect of flooding is

A) damage to farms and homes.
B) water pollution.
C) displacement of people.
D) loss of services and income.
E) hunger

Question 19

The 2010 flood in Pakistan

A) could be classified as a downstream flood.
B) occurred very rapidly.
C) was associated with a large cyclone.
D) displaced 21 million people.
E) killed over 1 million people.

Question 20

Floodplains are usually built

A) in the summer.
B) by bedload.
C) during channel avulsion.
D) at times of overbank flow.
E) by dissolved load.

Question 21

Consider a stream that begins at 1000 m elevation in the mountains and flows to sea level over a distance of 500 km.What is its base level?

A) 0 m
B) 100 m
C) 250 m
D) 500 m
E) 1000 m

Question 22

What is a typical cause of flash floods?

A) melting snowpack
B) a prolonged rainy season
C) steep slopes and wet soil
D) logjam breakup
E) intense rainfall

Question 23

In Canada,the federal criterion for defining the flood risk in an area is based on

A) the average magnitude of the annual flood.
B) the 1-in-10 year flood.
C) the 1-in-50 year flood.
D) the 1-in-100 year flood.
E) the 1-in-200 year flood.

Question 24

Which of the following categories accounts for most of the material transported by rivers?

A) bed load
B) suspended load
C) sliding load
D) effluent load
E) dissolved load

Question 25

At what time of year do most large rivers in North America flood?

A) late spring
B) summer
C) early fall
D) late fall
E) winter

Question 26

If you were planning a hiking trip to the southwestern United States in an arid region with steep topography and little vegetation,what type of flooding hazard should you anticipate?

A) major flooding of large rivers
B) snowpack flooding
C) floods from failure of human-built dams
D) flash floods
E) downstream floods

Question 27

Which of the following is NOT a flood-proofing technique?

A) constructing flood walls around buildings
B) placing dykes along the river to divert flood waters
C) installing drains with pumps to remove the water
D) installing ground level windows that open to allow flood waters to pass through the building
E) using waterproofed doors and windows

Question 28

If you hear on the news that a river has reached "flood stage," what does this statement mean?

A) that the river has overflowed its banks
B) that the river has just reached bankfull discharge
C) that the water level has topped a levee
D) that the river discharge has peaked and is expected to decrease
E) that the water level is likely to cause property damage

Question 29

Which of the following is NOT a channel restoration technique?

A) reestablishing deeper pools
B) protecting channel banks by planting native trees
C) removing urban waste from stream channels
D) straightening of the river channel
E) reestablishing shallower riffles

Question 30

What type of channel pattern would you expect in a region of tectonic uplift with high sediment supply and large diurnal variations in water discharge?

A) meandering
B) anastomosing
C) braided
D) deluvian
E) alluvial

Question 31

Consider a river with a cross-sectional area of flow equal to 100 square metres and a flow velocity of 2 metres per second.What is this river's discharge?

A) 50 cubic metres per second
B) 100 cubic metres per second
C) 200 cubic metres per second
D) 400 cubic metres per second
E) There is not enough information given to determine the discharge.

Question 32

A stream in its natural state (unmodified by human infrastructure)will reach bankfull discharge on average

A) 5 times per year.
B) 2 times per year.
C) once per year.
D) once every 1-2 years.
E) once every 5-6 years.

Question 33

If you saw an aerial photograph of a river that had multiple active channels intersecting one another,how would you classify that type of channel pattern?

A) meandering
B) anastomosing
C) braided
D) deluvian
E) alluvial

Question 34

Peak discharge in flash floods can be reached in

A) less than 10 minutes.
B) 10-20 minutes.
C) 30-60 minutes.
D) 1-2 hours.
E) 2-3 hours.

Question 35

If you were a canoeist and you wanted to make maximum speed down a meandering river,what strategy might you adopt?

A) Keep to the outside of meander bends in order to decrease the distance you have to travel.
B) Keep to the inside of meander bends in order to decrease the distance you have to travel.
C) Keep to the outside of meander bends in order to maximize your speed.
D) Keep to the inside of meander bends in order to maximize your speed.
E) Keep to the centre of the river in order to avoid running aground and losing time.

Question 36

Of the following choices,in which situation would the timing of flooding be most difficult to predict?

A) spring flooding from melting snowpack
B) flash flooding from intense downpours
C) flooding from heavy rainfall over a few days
D) flooding from melting glaciers on volcanoes
E) flooding from failure of natural dams

Question 37

At which of the following places along a stream will erosion be the greatest?

A) on the floodplain
B) near the headwaters
C) near the river mouth
D) at the base level
E) on the inside curve of river meanders

Question 38

If you were hiking in the wilderness,at which of the following locations would you be at a drainage basin boundary?

A) when crossing a stream
B) at the mouth of a tributary
C) at a spring, where water is coming out of the ground
D) on a ridge
E) just below a mountain pass

Question 39

The worst flood disasters in human history (based on numbers of casualties)have occurred in

A) Indonesia.
B) Thailand.
C) India.
D) Canada.
E) China.

Question 40

What is the best way to reduce risks due to river flooding?

A) Build dykes.
B) Build diversion channels.
C) Build flood control dams.
D) Create good evacuation plans.
E) Don't build on floodplains.

Question 41

Alluvial fans often form where a stream leaves a steep canyon and flows onto a plain.

Question 42

The root cause of the severe flooding on the Yellow River in China is

A) the porosity of the soil.
B) susceptibility to monsoons.
C) levee and dyke construction.
D) geologic.
E) geologic, coupled with dyke and levee construction.

Question 43

The gradient of a stream is greatest at the river mouth.

Question 44

A river which contains a curving channel and multiple floodplains is known as a ________ river.

A) anastomosing
B) braided
C) meandering
D) avulsing
E) ox bow

Question 45

Flooding is Canada's most common natural hazard.

Question 46

Ice-jam floods only occur in the fall when rivers begin to freeze.

Question 47

The base level of a stream is at the river mouth.

Question 48

Canada's worst flood disaster,measured as lives lost,occurred in

A) Toronto, Ontario in 1954.
B) Saguenay, Quebec in 1996.
C) Red River, Manitoba in 1997.
D) Fredericton, New Brunswick in 2008.
E) Calgary, Alberta in 2013.

Question 49

Floodplains are only built at times of overbank flow.

Question 50

Spring discharges can be estimated and a warning provided

A) several days in advance.
B) only hours beforehand.
C) seasonally-annually.
D) in 100-year models.
E) cannot be estimated

Question 51

Which of the following is a secondary effect of flooding?

A) loss of life by drowning
B) damage to infrastructure
C) hunger
D) damage to crops
E) sediment deposition

Question 52

Anastomosed channels have a large number of intersecting active channels.

Question 53

The Calgary flood of 2013 was primarily the result of

A) heavy rainfall in the Rockies.
B) ice-jams.
C) an outburst from a glacial melt.
D) a rain-on-snow event.
E) an earthquake.

Question 54

Riffles are deep areas created by scour at high flow.

Question 55

Within a river,deep areas produced by scour at high flow are known as

A) pools.
B) runs.
C) riffles.
D) point bars.
E) cut banks.

Question 56

The flooding in Pakistan in 2010 was catastrophic,with over 2000 people dead and 21 million people homeless.The reason this was so devastating was

A) it happened quickly and caught people unaware.
B) it was a secondary effect of an earthquake, which damaged infrastructure.
C) the country is heavily populated in flood risk areas.
D) the country lacked sufficient flood monitoring and warning, has poor transportation systems and inefficient resources for disaster relief.
E) FEMA did not mobilize quickly enough.

Question 57

Which of the following is NOT a factor in determining the amount of damage caused by floods?

A) land use in floodplains
B) strength of dykes
C) depth and velocity of floodwaters
D) season of flooding
E) size of the watershed involved

Question 58

The northern Ontario town of Winisk was completely destroyed by flooding in 1986.This flooding was a result of

A) a hurricane.
B) ice-jams.
C) an outburst from a glacial melt.
D) a rain-on-snow event.
E) an earthquake.

Question 59

Flash floods occur in the upper parts of drainage basins and in small tributary basins of a larger river.

Question 60

The total load of a stream refers to the particles of sand and gravel that roll and slide along the river channel.

Question 61

Point bars are found on the inside of meander bends.

Question 62

The base level of a river is the lowest elevation to which it may erode.

Question 63

In a meandering channel,erosion occurs on the outside of a meander bend and deposition occurs on the inside.

Question 64

Floods have been known to cause fires in populated areas.

Question 65

Urbanization decreases surface runoff.

Question 66

Outburst floods and flash floods are essentially the same thing.

Question 67

If you were in a car and encountered fast-moving flood waters crossing the road in your path,it would be safe to drive through as long as the water is less than 1 metre deep.

Question 68

Stream erosion is a common occurrence upstream of a dam.

Question 69

Building human infrastructure on alluvial fans is safe because floods are contained within known distributary channels.

Question 70

For flooding to occur,heavy rain must fall within a few days prior to the flood event.

Question 71

Urbanization greatly reduces stream flow during the dry season.

Question 72

Smaller floods occur more frequently than larger floods.

Question 73

Southward flowing rivers in Canada routinely produce ice-jam flooding in the spring.

Question 74

Small streams can flood at any time of the year.

Question 75

Flooding is more likely after heavy rain falls on water-saturated soil,compared to heavy rain falling on dry soil.

Question 76

Flash floods are the deadliest type of flood.

Question 77

Meandering channels tend to be narrower and deeper than braided channels.

Question 78

Urbanization increases the lag time between the time of peak rainfall and the time of flooding.

Question 79

Floods can be a secondary effect of earthquakes and landslides.

Question 80

The flood stage of a river refers to the level of a river when the water flows out of the channel.