Deck 11: Running Water

Question 1

Briefly explain what will happen to a stream's behavior if one drains a lake that is a temporary base level for that stream.

Answer 1

Drainage of a lake that serves as a temporary base level will lower the base level for the part of the stream above the lake. The stream may respond by eroding, in an attempt to reach its new base level.

Question 2

What is the hydrologic cycle?

Answer 2

The hydrologic cycle is recycling of water in the Earth's system. Water is evaporated from the ocean, lakes, and streams and becomes water vapor in the atmosphere held by clouds, which subsequently results in precipitation and ends up back on Earth. On land, it may end up in glaciers, in the oceans, in lakes or streams, or it may be infiltrated underground as groundwater. Water also works its way through plants by evaporation and transpiration.

Question 3

Briefly explain how a stream might adjust toward an equilibrium state following a heavy rain.

Answer 3

A heavy rain will increase stream volume and velocity. The channel and gradient will be temporarily too small and low, respectively, for the increased volume. Stretches of the stream with a low gradient will experience erosion, and stretches farther downstream may experience deposition as the gradient of the upstream portion is adjusted (increased).

Question 4

Define drainage pattern and describe the major drainage patterns.

Question 5

Briefly explain the trade-offs that accompany any flood control project.

Question 6

What are braided streams, and where do they form?

Question 7

What is stream piracy? What happens when one stream pirates another?

Question 8

What are incised meanders?

Question 9

How often will a flood of a 50-year magnitude occur?

Question 10

What is a graded stream?

Question 11

What causes a stream to meander?

Question 12

Is it possible to change the velocity (speed) of a stream but have it maintain the same discharge? Explain.

Question 13

Describe base level.

Question 14

What is the infiltration capacity of a surface? On what factors does the infiltration capacity of a surface depend?

Question 15

Describe where flow velocity is highest in a semi-straight channel and why?

Question 16

What is a 20-year flood?

Question 17

How and where do alluvial fans form?

Question 18

What is progradation?

Question 19

What are some of the techniques used to try to control floods?

Question 20

What happens when a stream overflows its banks?

Question 21

Give a few examples of bed load.

Question 22

How is the discharge of a stream calculated?

Question 23

What is the difference between the velocity and the discharge of a stream?

Question 24

Distinguish sheet flow from channel flow.

Question 25

What are the different sources of water on the Earth?

Question 26

What is meant by the term "divide" as in the continental divide along the Rocky Mountains?

Question 27

What is the gradient of a stream?

Question 28

Briefly explain the physical properties of water instrumental in the hydrologic cycle.

Question 29

In addition to dams and levees, what are two other measures that may be taken to control flooding?

Question 30

Why does the velocity of a stream generally increase downstream even though the gradient decreases?

Question 31

In what ways can water be temporarily stored, from a few years to a few thousand years, on the land areas before returning to the oceans?

Question 32

How is the gradient of a stream calculated?

Question 33

What are the three types of beds characteristically exhibited by a prograding delta?

Question 34

What are some of the reasons why running water is important to humans?

Question 35

The ideal graded stream has a balance among what five factors?

Question 36

What causes a delta to form?

Question 37

What powers the hydrologic cycle?

Question 38

In the hydrologic cycle, what happens to the precipitation that falls on the land?

Question 39

How do oxbow lakes form?

Question 40

Provide an example of a continental divide for the United States?

Question 41

Ridges of alluvium left along stream's margins by repeated deposition during floods are called ____________________.

Question 42

An uplifted erosional remnant of a floodplain that formed when a stream was flowing at a higher level is called a(n) ___________________

Question 43

Water that returns to the oceans as surface flow from streams is ____________________.

Question 44

The renewal of erosion that results in formation of stream terraces is generally attributed to a change in ____________________ level, or a change in climate resulting in greater ____________________, and thus, discharge.

Question 45

The types of marine deltas that are recognized, based on the relative importance of the processes involved in their formation, are ____________________-dominated, ____________________-dominated, and ____________________-dominated.

Question 46

When infiltration capacity is exceeded and water begins to move rapidly downslope, a continuous film of water known as ____________________ flow develops. This type of flow can result in ____________________.

Question 47

The total surface region that provides runoff to a stream system is known as a(n) ____________________.

Question 48

When flow is restricted to long, trough-like depressions, the flow is known as ____________________ flow.

Question 49

The gradient of streams tends to be ____________________ in their upper reaches and ____________________ in their lower reaches.

Question 50

Water enters the atmosphere by ____________________ from the ocean surface. Most of this water condenses and returns to the ocean as ____________________.

Question 51

The lower limit to which the stream can erode is its ____________________.

Question 52

The process by which water vapor reenters the atmosphere by evaporation from plants is called ____________________.

Question 53

Lateral erosion forms conditions along a stream valley that promote movement of material by a geologic process known as ____________________.

Question 54

Former meanders that have been cut off from the stream are called ____________________.

Question 55

A change in base level leading to the formation of stream terraces can come about by ____________________ of the land over which the stream flows, or a(n) ____________________ of sea level.

Question 56

The outer bank of a meander in a meandering stream is called the ____________________, where (erosion/deposition) ____________________ takes place. The deposit on the opposite side (inner bank) of the channel is called the ____________________, which is where (erosion/deposition) ____________________ occurs.

Question 57

In meandering streams, the water velocity tends to be greatest in the ____________________ portion of the meander.

Question 58

A stream that cuts directly through ridges that lie in their paths are called ____________________.

Question 59

A fan-shaped deposit of alluvium that forms adjacent to highlands in arid or semiarid climates is called a(n) ____________________.

Question 60

If a superposed stream erodes downward into resistant rock and cuts narrow canyons, the resulting feature is called a(n) ____________________.

Question 61

A rill is the precursor to a brook, creek, stream, or river.

Question 62

Dissolved load is the:

A) invisible load of a stream.
B) abrasive load of a stream.
C) suspended load of a stream.
D) invisible and abrasive load of a stream.
E) abrasive and suspended load of a stream.

Question 63

A dry surface has a higher infiltration capacity than a moist surface.

Question 64

A delta that has islands reworked by waves on the seaward side, such as the Nile delta, is typically formed as in a(n) ____-dominated delta.

A) avian
B) stream
C) wave
D) tide
E) sediment

Question 65

The approximate percentage of the Earth's surface that is covered by water is about:

A) 10%.
B) 30%.
C) 50%.
D) 70%.
E) 100%.

Question 66

The crescent-shaped feature of meandering streams that is formed during a flooding event where the slender neck of land is cut off from the meander is called _____.

A) point bar
B) cut bank
C) oxbow lake
D) alluvial fan
E) delta

Question 67

The solid particles of a stream include:

A) bed load.
B) suspended load.
C) solution load.
D) bed load and suspended load.
E) suspended load and solution load.

Question 68

Streams or rivers possess two kinds of energy. Potential energy is the energy of:

A) water molecules.
B) position.
C) gravity.
D) motion.
E) channeling.

Question 69

The ultimate base level for a stream is:

A) sea level.
B) the nearest lake.
C) the nearest stream.
D) the nearest spring.
E) the nearest valley.

Question 70

The Mississippi River is an example of channel flow.

Question 71

The approximate percentage of Earth's water that is in the oceans is:

A) 100%.
B) 97%.
C) 93%.
D) 55%.
E) 50%.

Question 72

The percentage of atmospheric water that comes directly from the ocean is:

A) 95%.
B) 85%.
C) 65%.
D) 35%.
E) 15%.

Question 73

Particles move along a streambed by:

A) rolling.
B) sliding.
C) saltation.
D) rolling and sliding.
E) rolling, sliding, and saltation.

Question 74

Streams or rivers possess two kinds of energy. Kinetic energy is the energy of:

A) water molecules.
B) position.
C) gravity.
D) motion.
E) channeling.

Question 75

A stream erodes material from its banks and bed by:

A) suspension.
B) hydraulic action.
C) abrasion.
D) suspension and hydraulic action.
E) hydraulic action and abrasion.

Question 76

A stream's velocity varies only along its length.

Question 77

Deep, meandering canyons cut into bedrock are called:

A) hard rock meanders.
B) oxbows.
C) incised meanders.
D) eroded meanders.
E) floodplains.

Question 78

A delta with long fingerlike sand bodies, each deposited in a distributary channel that progrades far seaward, such as the Mississippi River, is typically formed as in a(n) ____-dominated delta.

A) avian
B) stream
C) wave
D) tide
E) sediment

Question 79

Surface runoff is confined to trough-like depressions of various sizes in channel flow.

Question 80

The percentage of the Earth's water that is fresh water that is not frozen is:

A) 5%.
B) 3%.
C) 2%.
D) 0.65%.
E) 0.01%.