Geol-111 Rivers

Front 1

Including offshore outer continental shelf production, where does Louisiana rank in the production of natural gas compared to the other 49 states in our country?

Back 1

2nd

Front 2

What is associated w/ changes in LA’s sea level during the Ice Ages?

Back 2

Terraces

Front 3

What formed as a distributary of the Mississippi River?

Back 3

The Atchafalaya River

Front 4

Shallow/wide streams:

Back 4

Braided streams

Front 5

A delta that is not strongly influence by waves or tides:

Back 5

River-dominated delta (Mississippi River Delta)

Front 6

Drainage pattern that develops when relatively flat-lying material erodes uniformally:

Back 6

Dendritic

Front 7

What often forms in areas w/ a lot of flash flooding?

Back 7

Braided streams

Front 8

What are the 5 main depositional features of meandering streams?

Back 8

1) point bar/cut bank
2) oxbow lake
3) floodplain
4) natural levee
5) terrace

Front 9

Where do streams usually have deposition?

Back 9

On the shallow side (inside)

Front 10

The “swirling” process which drills out circular holes in the bottom and sides of streams:

Back 10

Abrasion

Front 11

What types of streams migrate over time?

Back 11

Meandering streams

Front 12

What percentage of Louisiana's population (approximately 4 million people) live in coastal parishes?

Back 12

Just over 50%

Front 13

What 4 characteristics will produce the slowest stream velocity?

Back 13

Gentle gradient; shallow, wide channel; rough bottom

Front 14

What marks the floodplain where it used to flow when it was at a higher elevation?

Back 14

Terrace

Front 15

Drainage pattern that forms where there are mountain ridges separated by valleys:

Back 15

Trellis

Front 16

What prevents a river’s ability to flood and spread sediment out into the ocean?

Back 16

Artificial levees

Front 17

All material that is deposited by a stream:

Back 17

Alluvium

Front 18

During periods low water (i.e. little or no rainfall), streams will undergo a large amount of ____.

Back 18

Deposition

Front 19

The sand and gravel fractions of a stream’s load:

Back 19

Bedload

Front 20

What resource does the Western U.S. obtain from braided stream deposits and alluvial fans?

Back 20

Groundwater

Front 21

What 2 river/stream features are commonly found in LA?

Back 21

Meandering streams and deltas

Front 22

Narrow/ deep streams:

Back 22

Meandering streams

Front 23

Channels with the fastest velocity are usually ____.

Back 23

Semicircular

Front 24

What are the 4 types of drainage patterns?

Back 24

1) Dendritic
2) Radial
3) Rectangular
4) Trellis

Front 25

How much of the United States’ wetland loss occurs in LA?

Back 25

80%

Front 26

How does roughness affect a stream’s velocity?

Back 26

Any obstructions (i.e. “roughness”) in a stream will slow down the stream’s velocity.

Front 27

A fan-shaped deposit of alluvium that forms when mountain streams empty onto valley floors:

Back 27

Alluvial fans

Front 28

Explain the structure of the Mississippi River and the Red River before the 15th century:

Back 28

The Red River and Mississippi River were separate rivers, and were positioned parallel to each other.

Front 29

Streams with very high amounts of bed load tend to:

Back 29

Become braided

Front 30

What erosional process is not usually seen in LA and why?

Back 30

Abrasion – not usually seen in LA b/c it requires a lot of sand and gravel, and LA’s water is mostly muddy.

Front 31

Why hasn’t the Mississippi River changed its course through avulsion in a long time?

Back 31

Because of artificial levees

Front 32

If a stream channel is 20 feet wide, 10 feet deep, and flowing at a velocity of 10 feet/sec, what is its discharge? Hint: Area = width x depth.

Back 32

2000 cubic feet/sec

Front 33

The portion of a stream’s load that cannot be seen in the water:

Back 33

Dissolved load

Front 34

What process creates point bars?

Back 34

Deposition

Front 35

What percentage of the Earth’s water consists of rivers, streams, creeks, bayous, lakes, groundwater, etc.?

Back 35

Only 1%

Front 36

What did Capt. Henry M. Shreve, do to the Mississippi River?

Back 36

The entrance to the Atchafalaya River was blocked by a log jam, so Capt. Shreve dug a canal through the Turnbull's Bend and shortened the river’s travel time.

Front 37

The slope of a stream bed:

Back 37

Gradient

Front 38

What type of bed load is most commonly seen in LA?

Back 38

Suspended load

Front 39

Curves and bends in a stream channel:

Back 39

Meanders

Front 40

Why are stream channels steeper on one side than on the other?

Back 40

They are asymmetrical

Front 41

What is one way to measure the discharge in large bodies of water?

Back 41

Find out the elevation of the water surface

Front 42

Transportation of sand downstream through a series of hopping, skipping, and leaping motions:

Back 42

Saltation

Front 43

What erosional process requires the most energy?

Back 43

Scouring

Front 44

Small stream that flows into a large stream:

Back 44

Tributary

Front 45

As a stream increases its channel length by developing a mature meander pattern, it also:

Back 45

Decreases its discharge

Front 46

How much of the U.S. wetlands are in LA?

Back 46

40%

Front 47

What erosional process produces potholes?

Back 47

Abrasion

Front 48

Where are point bars deposited?

Back 48

On the INSIDE of the meander bend

Front 49

All material transported by a stream:

Back 49

Load

Front 50

Where are rectangular drainage patterns found?

Back 50

On fractured rock

Front 51

What 2 factors control a stream’s functions?

Back 51

1) velocity
2) discharge

Front 52

An area that is covered by water in a flood:

Back 52

Floodplain

Front 53

Channels with the slowest velocity usually have what characteristics?

Back 53

1) wide/shallow
2) narrow/deep

Front 54

Where do streams usually have erosion?

Back 54

On the steep side (outside)

Front 55

How can you measure a stream’s velocity?

Back 55

Measure velocity w/ a current meter

Front 56

What are the 2 types of erosion?

Back 56

1) Scouring
2) Abrasion

Front 57

Outside part of meandering stream that is created by erosion of the channel wall:

Back 57

Cut bank

Front 58

What forms when a river empties into a standing body of water?

Back 58

Delta

Front 59

What are the 3 main functions of streams/rivers?

Back 59

1) Erosion( removes material)
2) Transportation (transports material)
3) Deposition (deposits the transported material)

Front 60

What generally decreases downstream along the length of a stream?

Back 60

Gradient

Front 61

What formed Louisiana?

Back 61

Deltas

Front 62

How much of the Earth’s water is in the oceans?

Back 62

97%

Front 63

Particles that roll and slide along the bottom of streams:

Back 63

Bed load

Front 64

Streams with very high amounts of bed load tend to:

Back 64

Become braided

Front 65

How many different periods of avulsion has the Mississippi River Delta undergone in its lifetime?

Back 65

7

Front 66

How do you calculate stream/river discharge?

Back 66

Q = A x V
Discharge = cross-sectional area x velocity

Front 67

The cycling of water from the atmosphere, to the Earth, and back to the atmosphere:

Back 67

The hydrologic cycle

Front 68

Where does the Western U.S. acquire a large amount of its groundwater?

Back 68

From braided stream deposits and alluvial fans

Front 69

Transport of gravel through a series of rolling, sliding motions:

Back 69

Traction

Front 70

What process primarily occurs during floods?

Back 70

Erosion

Front 71

As a stream increases its channel length by developing a mature meander pattern, it also:

Back 71

Decreases its discharge

Front 72

How does gradient affect a stream’s velocity?

Back 72

The steeper the slope of the stream, the faster the velocity.

Front 73

Bed load that gives water its taste:

Back 73

Suspended load

Front 74

Including offshore outer continental shelf production, where does Louisiana rank in crude oil production compared to the other 49 states in our country?

Back 74

1st

Front 75

What are the terraces in Louisiana associated with?

Back 75

Changes in the sea level during the Pleistocene epoch (Ice Age)

Front 76

Slightly elevated land surfaces on either side of a river channel that form from the accumulation of sediment deposits:

Back 76

Natural levee

Front 77

Drainage pattern that forms on cone-shaped mountains (volcanoes):

Back 77

Radial

Front 78

The speed at which the water in a stream/river is moving:

Back 78

Velocity

Front 79

All land area drained by a stream and its tributaries:

Back 79

Drainage basin

Front 80

Streams that flow as single, sinuous, S-shaped channels:

Back 80

Meandering streams

Front 81

An abandoned meander that has been cut off from the river:

Back 81

Oxbow (if it is dry)

Oxbow lake (if it is filled w/ water)

Front 82

Where does 2% of the Earth’s water reside?

Back 82

In icecaps and glaciers

Front 83

What is transported either along or close to the streambed?

Back 83

Bedload

Front 84

What causes a stream to deposit its load, and what type of load is deposited first, and which is last?

Back 84

The stream’s velocity slows down and causes a decrease in flow energy, depositing the bed load first and the suspended load last.

Front 85

Narrow/deep streams:

Back 85

Meandering streams

Front 86

Where are cut banks located?

Back 86

On the OUTSIDE of the meander bend

Front 87

Where do braided streams usually form?

Back 87

In areas w/ a lot of flash flooding

Front 88

What is the impact of Louisiana’s loss of wetlands?

Back 88

1) Oil and gas industries (coastline is moving northward and exceeding 3 mile limit)
2) Seafood industries
3) Coastal wetlands are Louisiana’s first line of defense against hurricanes

Front 89

Process in which running water picks up loose material from the bottom of a streambed; requires the most energy:

Back 89

Scouring

Front 90

Ancient or abandoned floodplains:

Back 90

Terrace

Front 91

What happens as more water comes in contact w/ the bottom and sides of the stream’s channel?

Back 91

The slower it makes the stream’s velocity

Front 92

What 3 things control a stream’s velocity?

Back 92

1) GRADIENT (slope) of stream bed
2) SHAPE of channel
3) ROUGHNESS in bottom of stream

Front 93

The volume of water flowing past a point in a given period of time:

Back 93

Discharge

Front 94

Drainage pattern that contains right-angled bends:

Back 94

Rectangular

Front 95

What is causing the coastal wetlands of LA to erode at such an extreme rate?

Back 95

Avulsion

Front 96

When does erosion usually occur?

Back 96

During periods of high velocity and discharge; primarily during floods

Front 97

What process creates cut banks?

Back 97

Erosion

Front 98

What 2 factors cause the meandering motion of streams?

Back 98

1) Corkscrew motion of channel
2) Asymmetry of channel

Front 99

What forms when mountain streams empty onto valley floors?

Back 99

Alluvial fans

Front 100

Shallow/wide streams:

Back 100

Braided streams

Front 101

What causes rivers to change coarse?

Back 101

Avulsion

Front 102

What type of drainage pattern is commonly found in LA?

Back 102

Dendritic

Front 103

In 2004, the commercial fish harvest in Louisiana exceeded 1 billion pounds with a dockside value of $274 million. What percentage of the commercial fish harvest does this represent for the lower 48 states in our country?

Back 103

26%