Lec 7: Fluvial Systems Rivers

Question 1

Which of these rocks was subjected to low grade metamorphism?

A: Gneiss
B: Schist
C: Phyllite
D: Shale
E: Slate

Answer 1

E: Slate

Question 2

Lecture’s goals:

1_ Describe the process of fluvial erosion and sediment transport

2_ List and describe 5 depositional environments, including 2 end-member river channel types

3_ Define graded (equilibrium) streams and the concept of base level

4_ Discuss 4 occasions for river engineering, the techniques employed for each occasion, and impacts of each technique

Answer 2

Lecture’s goals:

1_ Describe the process of fluvial erosion and sediment transport

2_ List and describe 5 depositional environments, including 2 end-member river channel types

3_ Define graded (equilibrium) streams and the concept of base level

4_ Discuss 4 occasions for river engineering, the techniques employed for each occasion, and impacts of each technique

Question 3

Lecture’s goals:

1_ Describe the process of fluvial erosion and sediment transport

Answer 3

Terminology:
_ Fluvial: processes associated with streams and rivers
_ drainage basin (or watershed): the movement of fluid from higher elevations to lower
_ gradient: elevation over distance

Fluvial processes: sediment erosion.
-> Sediments are eroded due to dissolution, abrasion, and entrainment

Sediment is transported by water in 3 main ways:
1_ rolling, sliding, or saltation
2_ suspended load
3_ dissolved load transport

Question 4

How could the amount of water in a stream increase?

A: snowmelt
B: Surface water runoff after a rain event
C: Water percolating up from underground
D: Increase flow from upstream tributary
E: ALL

Answer 4

E: ALL

Question 5

Lecture’s goals:

2_ List and describe 5 depositional environments, including 2 end-member river channel types

Answer 5

1_ braided streams
-> means streams that flow in broad, shallow channels and consist of multiple subchannels

2_ meandering streams
-> meandering streams follow a sinuous course. Channels tend to be narrow and deep

(plus floodplains, alluvial fans, and deltas)

When do streams follow a braided pattern or a meandering pattern?

Braided: if a stream is unable to transport all the available bed load continuously.
_ high sediment supply

Meandering: common in areas where elevation changes in low
_ sediment supply is low

Question 6

Lecture’s goals:

3_ Define graded (equilibrium) streams and the concept of base level

Answer 6

Fluvial systems will eventually establish equilibrium. (smooth and concave upwards)

Sediment size decreases uniformly downstream

The base level is the lowest point to which it can flow (referred to as the mouth of the river)

sea level is the ultimate base level

Question 7

Lecture’s goals:

4_ Discuss 4 occasions for river engineering, the techniques employed for each occasion, and impacts of each technique

Answer 7

1_ flood protection
2_ ease of transportation
3_ hydroelectric power production
4_ water storage