1.
Usually the largest floods in a stream occur
A
very frequently, several times in one year
B
frequently, every few years
C
rarely, about every ten years
D
rarely, or once every few 100 years
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Usually the largest floods in a stream occur
very frequently, several times in one year
frequently, every few years
rarely, about every ten years
rarely, or once every few 100 years
In the future, which of the following is unlikely?
there will be an increased chance of flash flooding and coastal inundation
flood risk will increase due to population growth and urbanisation
improvements in flood forecasting and warning technologies will reduce the impacts of floods
we will be able to eliminate the risk of flooding.
What factors contribute to flooding?
Rainfall intensity
Rainfall duration
BOTH of the above; rainfall intensity and rainfall duration.
Urbanization usually results in an increase in flood frequency because
less water is able to runoff in streams
less water is able to infiltrate into the ground,so instead is discharged rapidly i ntostreams
more water is used by humans and then discharged to streams
rainfall is greater in urban areas than in rural areas
A flash flood is a flood that Flood
is caused by heavy rain rather than from the flooding of a river
occurs in urban areas
occurs suddenly and unexpectedly and for a short duration
is caused by the blocking of drains
The process of avulsion is caused by
erosion of the river channel
buildup of sediment in the river channel
widening of the channel
destruction of natural levees
The process of avulsion causes
downcutting of the riverbed
wider floodplains for the river
slow shifting of the rivers channel
formation of a new course for the river channel
In ancient Egypt the Nile River
changed its course almost every year
destroyed large areas of farming land every year
had to be regulated because it carried too much water
brought nutrients that made the fields fertile
Which of the following is not a characteristic of a braided stream?
constant discharge
branching channels
high gradient
abundant bed load
The Probable Maximum Flood is:
the maximum flood experienced since flood records have existed
an estimation of the largest possible flood that could occur at a particul ar location
the maximum flood experienced in the last 100 years
the maximum flood experienced in the last 200 years
The flooding of New Orleans in 2004 was caused by
a tornado
an earthquake
a tsunami
a hurricane
Flooding in London is prevented by
high dams along the Themes
a barrier that is raised and lowered
gates in the western part of the city
westerly winds
How many inches of fast-moving flood water can knock you off your feet?
6 inches
8 inches
10 inches
The largest floods in prehistoric times were probably the result of
very heavy rainfall
hurricanes
ice dam failures
meteorite impacts
What causes most flash flooding?
Tornadoes
Slow-moving thunderstorms, thunderstorms repeatedly moving over the same area, or heavy rains from hurricanes and tropical storms.
Hailstorms
Dikes and dams are lined up along the coast of the Netherlands
to generate electricity for its population
to change the course of rivers that flow into the North Sea
to keep storms away from the country
to keep ocean w ater out of the lower lying land
When a rivers water level reaches 10 metres, this means that:
the water level is 10 metres above an arbitrary zero level
the water level is 10 metres above mean sea level
the water level is 10 metres above mean sea level or an arbitrary 'zero level
it will flood.
Which of the following is associated with a La Niña event?
the Southern Oscillation Index (SOI) is strongly negative
the ocean surface off the coast of South America is warmer than usual
there is an increased chance of above average rainfall in easte rn Australia
all of the above.
Which of the following measurements is not needed to estimate stream discharge?
stream velocity
width of stream
bed load of stream
depth of stream
A stream with too much bed load will usually have what type of channel pattern?
straight
meandering
braided
dendritic