Deck 8: Streams and Flooding

Question 1

Which of the following statements is NOT true regarding artificial levees?

A) used to help keep the channel straight so water flows faster
B) raises the height a stream must reach before overflowing its banks
C) creates the potential for catastrophic flood in areas downstream
D) makes flooding worse in areas upstream
E) can be made of concrete or earthen materials

Answer 1

A

Question 2

What best describes the headwaters of a drainage basin?

A) collection of small channels in the upper part of a basin that merge into larger streams.
B) collection of streams that empty into a body of water.
C) those parts of a drainage basin where water infiltrates into the groundwater system.
D) those parts of a drainage basin where groundwater discharge into streams.
E) those parts of a drainage basin that lie above base level.

Answer 2

A

Question 3

Which of the following is NOT part of the hydrologic cycle?

A) sequestration
B) evaporation
C) transpiration
D) infiltration
E) overland flow

Answer 3

A

Question 4

Which of the following terms is used to describe the volume of water flowing past a specific point in a stream over a given time period?

A) discharge
B) flux
C) square volume
D) specific capacity
E) overland flow

Question 5

What best explains why stream valleys become wider over time?

A) meandering streams undercut their banks and cause mass wasting.
B) deposition of sediment creates a valley floor.
C) tectonic uplift causes valleys to widen naturally.
D) stream velocity becomes greater over time.
E) streams get further above base level.

Question 6

Streams located near the mouth of a river are quite different compared to those near the headwaters. What best characterizes streams near the mouth?

A) low velocity, high discharge, and meandering channels
B) low velocity, low discharge, and meandering channels
C) high velocity, high discharge, and straight channels
D) high velocity, low discharge, and straight channels
E) low velocity, high discharge, and straight channels

Question 7

Which of the following statements best describes losing streams?

A) common in arid regions where some of the stream water flows into the groundwater system.
B) common in arid regions where groundwater flows into streams.
C) common in humid regions where some of the stream water flows into the groundwater system.
D) common in humid regions where groundwater flows into streams.

Question 8

Some rivers naturally carry more water than others. Which of the following best explains why the Amazon River in South America carries 12 times more water than the Mississippi?

A) the Amazon's drainage basin lies mostly within a tropical rainforest
B) the Amazon has a much larger channel
C) there is much less human development along the Amazon
D) the Amazon is a much longer river
E) all of the answers listed here

Question 9

How do hydrologists measure the severity of floods?

A) the height (stage) above which a stream overflows its banks
B) the number of people that are impacted along a floodplain
C) the amount of land area that is inundated along a floodplain
D) how fast the water rises in the channel
E) the amount of land area that collects water from a rain event

Question 10

What best describes the basic role of streams in the Earth system?

A) drain water from the landscape and transport sediment
B) transport sediment and create valuable gold deposits
C) link the atmosphere to the oceans in the hydrologic cycle
D) help remove carbon dioxide from the atmosphere
E) provide water to the interior of continents

Question 11

Which of the following natural factors affect the degree or severity of flooding?

A) rainfall volume and infiltration capacity of the ground
B) size of the raindrops and wind speed
C) slope of the land and wind speed
D) rainfall volume and wind speed
E) size of raindrops and slope of the land

Question 12

What best explains why groundwater baseflow is important to maintaining a healthy stream ecosystem in humid climates?

A) provides streams with a steady flow of water during dry periods
B) removes bacteria and viruses that are harmful to plants and animals
C) reduces the intensity and duration of floods
D) decreases stream erosion
E) provides dissolved ions necessary for plant growth

Question 13

What best characterizes downstream flooding?

A) large volume flood that slowly rises and falls
B) small volume flood that slowly rises and falls
C) fast moving floodwaters that follow small tributaries
D) slow moving floodwaters that follow small tributaries
E) floodwaters that rapidly rises and falls

Question 14

In addition to cutting laterally, streams can also cut downward in their channels to form deep valleys and canyons. What best explains how streams can cut downward through solid rock?

A) transported sediment causes abrasion of bedrock.
B) water flowing rapidly over the bedrock causes erosion.
C) acidic water causing chemical weathering of the bedrock.
D) physical weathering of bedrock by freeze and thaw action.
E) occurs in areas where streams encounter weaker layers of bedrock.

Question 15

Why is hydraulic sorting of sediment important in environmental geology?

A) it produces relatively pure deposits of sand and clay
B) it separates those streams that are flood prone from those that are not
C) it produces elevated terraces that are less likely to be flooded
D) it causes streams to reach base level more rapidly
E) all of the answers listed here

Question 16

What best explains how hydrologists determine the frequency of flooding?

A) calculate recurrence intervals from historical discharge records
B) locate the 100-year floodplain on maps
C) predictions based on rainfall duration and intensity data
D) predictions based on rainfall volume and wind speed data
E) predictions based on topographic maps and precipitation data

Question 17

What best describes a drainage basin?

A) the land area that collects water for a given network of streams.
B) a circular depression in the topography where water accumulates.
C) a circular depression in the topography where sediment accumulates.
D) a part of the landscape where water is rapidly drained away.
E) a part of the landscape that stays above freezing and water remains a liquid.

Question 18

Which of the following are effective ways of reducing the effects of flooding?

A) all of the answers listed here
B) channelization
C) wetlands restoration
D) artificial levees
E) erosion controls

Question 19

Which of the following best explains why urbanization has led to larger and more frequent floods?

A) large areas of land are covered with impermeable surfaces
B) rainwater tends follow roadways and becomes more concentrated
C) heat island effect of cities produces more frequent rains
D) rainfall volume is naturally higher over areas where vegetation is more sparse
E) irrigation of yards and landscaping

Question 20

Which of the following statements is NOT true with respect to dams and reservoirs?

A) dams are generally not effective at flood control and are mainly used to generate electricity.
B) water released from reservoirs is cooler than a natural stream, which harms aquatic ecosystems.
C) sediment is trapped behind dams and slowly fills in reservoirs.
D) reservoirs serve as an important source of fresh water.
E) stream discharge becomes fairly uniform, which harms aquatic ecosystems.