Question 1

In which cycle do rivers NOT play an important role? A) hydrologic cycle B) tectonic cycle C) rock cycle D) biogeochemical cycle

Accepted Answer

Rivers do not play a significant role in the tectonic cycle, which involves the movements and interactions of the Earth's lithospheric plates. Rivers do, however, play important roles in the hydrologic, rock, and biogeochemical cycles.

Question 2

What is avulsion?
A) A river overflows its banks and leaves pools of water behind in the floodplain.
B) A river turns and moves in the opposite direction due to uplift caused by a fault.
C) A river shifts its position after a flood.
D) A river overflows and completely fills the floodplain.
E) A river deposits sediment and creates a fan-like structure.

Accepted Answer

Avulsion refers to the sudden shifting of a river's position due to natural causes such as flooding. Option C accurately describes this process. Option A describes a floodplain, while option B describes a river changing direction due to tectonic activity. Option D describes a flood that completely fills a floodplain, and option E describes a fan-like structure created by deposition, neither of which accurately describe avulsion.

Question 3

Choose the best answer. Which would increase during a flood, discharge or velocity?
A) Discharge only because there is more water flowing
B) Velocity only because the water is flowing faster
C) Neither discharge or velocity because the stream will be doing more erosion during a flood
D) Neither discharge or velocity because both are constant for any given stream
E) Both discharge and velocity will increase because there is more water flowing and it is flowing faster.

Accepted Answer

During a flood, both the amount of water (discharge) and the speed of its movement (velocity) increase, so both factors contribute to the increased flooding.

Question 4

If you were running water through a hose, how would you increase the discharge of water coming from the hose?
A) Turn up the water at the faucet
B) Hold your finger over half of the opening in the hose
C) Connect the hose to a sprinkler
D) Connect the hose to a spray gun

Accepted Answer

By turning up the water at the faucet, more water will be flowing through the hose, resulting in an increase in the discharge of water coming from the hose. Holding your finger over half of the opening in the hose, connecting the hose to a sprinkler, and connecting the hose to a spray gun could all potentially decrease the discharge of water coming from the hose by restricting or directing the flow.

Question 5

What happens to rivers when they reach their base level?
A) Their discharge decreases.
B) They erode sediment.
C) They fill the bottom of a v-shaped valley.
D) They often form alluvial fans or deltas.

Accepted Answer

When rivers reach their base level, the lowest point to which they can erode, they lose the energy needed to carry sediment. This causes the sediment to be deposited, often forming alluvial fans or deltas.

Question 6

Which of the following loads are most likely to consist of heavy rocks and boulders?
A) Bed load
B) Suspended load
C) Dissolved load
D) Structural load
E) Buoyant load

Accepted Answer

Bed load consists of larger, heavier sediment particles such as rocks and boulders that roll, slide, or bounce along the stream bed.

Question 7

What is the role of a drainage basin?
A) Rivers empty into a drainage basin, which represents a lake or the ocean.
B) A drainage basin is the area drained by a river and all of its tributaries.
C) A drainage basin is very permeable soil into which flood waters seep instead of going into a river.
D) A drainage basin is very impermeable soil, where flood waters are held and eventually evaporate instead of going into a river.
E) A drainage basin is a set of underground tunnels that drain water into the ocean.

Accepted Answer

A drainage basin is the area drained by a river and all of its tributaries. It is also known as a watershed or river basin. It is responsible for collecting and carrying water from precipitation, such as rain or snowmelt, to a common outlet, such as a lake, river, or ocean.

Question 8

In which of the following cases would you expect the LEAST amount of flooding due to a rainstorm? Assume all areas receive similar amounts of rainfall in the rainstorm and there are no flood control measures in any of the areas. A) An area where soil is already saturated due to previous recent thunderstorms B) An area where the ground is frozen C) A short duration rainstorm falling on an area that is typically very dry such as a desert D) A city with many houses, paved roads, and sidewalks E) A long duration rainstorm falling on an area that consists of forest, grasslands, and no human development.

Accepted Answer

Forests and grasslands have natural vegetation that can absorb and slow down water, reducing the risk of flooding compared to urban areas or saturated/frozen grounds.

Question 9

Which rivers have the highest gradient?
A) Rivers near their base level
B) Rivers near the ocean
C) Rivers in gentle valleys
D) Rivers moving down mountains

Accepted Answer

Rivers moving down mountains have the steepest gradient as they are descending from high elevations to lower elevations in a short distance. As the water flows down the mountains, it cuts through the rock, creating a V-shaped valley with steep sides.

Question 10

What is the stage of a river?
A) Volume of water that flows past a point over time
B) Height of water that is flowing
C) Age of the river
D) Elevation of the top of the river valley
E) Length of the river

Accepted Answer

The stage of a river refers to the height of the water surface at any given point, which can indicate the level of flooding or water flow at that location.

Question 11

If you dip a glass of water into a river and passed the water through a very fine sieve that blocked all sediment grains from passing through, what will you be left with?
A) Bed load
B) Suspended load
C) Dissolved load
D) Structural load

Accepted Answer

The dissolved load consists of ions and other molecules that are dissolved in the water and cannot be filtered out, unlike the bed load (particles that roll or bounce along the stream bed) and the suspended load (particles that are suspended in the water and can be filtered out by a fine sieve). Structural load is not a relevant term in this context.

Question 12

What is the floodplain?
A) The area around a river that is the ultimate limit to how far it will ever flood
B) A flat area next to the river carved out by the rivers
C) The steep sides of the river channel that holds in the water
D) Earthen mounds that run parallel to the river and hold in the water during floods
E) A triangular shaped deposit that forms when a river flows into the ocean

Accepted Answer

The floodplain is a flat area next to the river that is carved out by the river's flow. This area is often subject to flooding during periods of high water flow.

Question 13

Where on a river would you most likely find point bars?
A) On the outside of a bend
B) On the inside of a bend
C) At the mouth of the river
D) At the headwaters of the river
E) In the center of the river

Accepted Answer

Point bars are depositional features formed on the inside of a meandering river bend where the velocity of water is lower, causing sediment to be deposited.

Question 14

Which of the following will tend to REDUCE the size of a river flood? A) High amount of precipitation in a drainage basin B) High rate at which the precipitation soaks into the ground C) Fast rate at which the runoff moves towards the river D) High amount of moisture in the soil (water-saturated soil)

Accepted Answer

When precipitation soaks quickly into the ground, there is less runoff into the rivers, reducing the size of a river flood. A high amount of precipitation in the drainage basin, a fast rate at which the runoff moves towards the river, and high moisture in the soil (water-saturated soil) can all contribute to an increase in river flood size.

Question 15

Which of the following loads would make a river appear murky or dirty?
A) Bed load
B) Suspended load
C) Dissolved load
D) Structural load
E) Buoyant load

Accepted Answer

Suspended load is made up of fine sediment particles that are carried by the water. When a river has a high suspended load, the water can appear murky or dirty. Bed load is made up of heavier sediment particles that are pushed along the bottom of the river, while dissolved load is made up of minerals and other substances that are dissolved in the water. Structural load and buoyant load are not related to the appearance of a river's water.

Question 16

What would the longitudinal profile of a river flowing from a gentle valley into an ocean look like?
A) A steeply downward sloping line
B) A steeply upward sloping line
C) A gently downward sloping line
D) A gently upward sloping line
E) An upward sloping and then downward sloping line

Accepted Answer

The longitudinal profile of a river typically shows a gradient that decreases from the source to the mouth, resulting in a gently downward sloping line, especially for a river flowing from a gentle valley into an ocean.

Question 17

Where does a meandering river run the fastest?
A) On the outside of a bend
B) On the inside of a bend
C) All parts of a meandering river run at similar speeds.
D) Near the point bars

Accepted Answer

A meandering river runs fastest on the outside of a bend because the water is forced to flow around a wider curve, increasing its velocity. As the river flows around the bend, erosion on the outer bank causes the channel to become deeper, creating faster water flow.

Question 18

What two parameters are plotted in a hydrograph?
A) Cross-sectional area vs. stage
B) Stage vs. elevation
C) Discharge vs. time
D) Stage vs. gradient
E) Velocity vs. discharge

Accepted Answer

A hydrograph plots the discharge (volume of water passing a point per unit time) on the y-axis and time on the x-axis. Therefore, the correct answer is C, which represents discharge vs. time. None of the other choices represent parameters commonly plotted in a hydrograph.

Question 19

Which of the following is NOT an example of a base level for a river? A) Ocean B) Lake C) Rapids D) Reservoir

Accepted Answer

Rapids are considered a feature within a river, not a base level. Base level refers to the elevation or level at which a stream or river flows into another body of water, typically the sea, lake, or ocean. A reservoir or lake can also serve as a base level if the river flows into it.

Question 20

Where on a river would you most likely find cutbanks and why?
A) On the outside of a bend because that is where the river erodes most.
B) On the inside of a bend because that is where the river erodes most.
C) On the outside of a bend because that is where the river deposits most.
D) On the inside of a bend because that is where the river deposits most.
E) At the bottom of the river because that is where it moves the fastest.

Accepted Answer

Cutbanks are found on the outside of a bend in a river because that is where the water flows the fastest, causing more erosion compared to other parts of the river.

Quiz 6: Flooding

In which cycle do rivers NOT play an important role?

What is avulsion?

Choose the best answer. Which would increase during a flood, discharge or velocity?

If you were running water through a hose, how would you increase the discharge of water coming from the hose?

What happens to rivers when they reach their base level?

Which of the following loads are most likely to consist of heavy rocks and boulders?

What is the role of a drainage basin?

In which of the following cases would you expect the LEAST amount of flooding due to a rainstorm? Assume all areas receive similar amounts of rainfall in the rainstorm and there are no flood control measures in any of the areas.

Which rivers have the highest gradient?

What is the stage of a river?

If you dip a glass of water into a river and passed the water through a very fine sieve that blocked all sediment grains from passing through, what will you be left with?

What is the floodplain?

Where on a river would you most likely find point bars?

Which of the following will tend to REDUCE the size of a river flood?

Which of the following loads would make a river appear murky or dirty?

What would the longitudinal profile of a river flowing from a gentle valley into an ocean look like?

Where does a meandering river run the fastest?

What two parameters are plotted in a hydrograph?

Which of the following is NOT an example of a base level for a river?

Where on a river would you most likely find cutbanks and why?