Week 8: Rivers Flashcards
What is a stream?
Any flowing body of water, regardless of size
What is a river?
A major branch of a large stream system
What is a channel?
The stream passageway
What is a load?
The sediment carried by the stream
What is discharge?
The quantity of water passing a given point
Name and describe the two processes by which water in a stream moves.
Laminar Flow:
Straight or gently curved streamlines that run parallel to one another without mixing or crossing
Turbulent Flow:
A complex pattern of movement with streamlines crossing and forming swirls and eddies
What is a suspended load?
All the material temporarily or permanently suspended in the flow
What is a bed load?
The material carried by the stream along its bottom by sliding and rolling
What is saltation?
The intermittent jumping of sand grains as they are lifted off the bottom, carried a short distance and then settle out
What is abrasion?
A sandblasting action from sediments in the suspended and bed load that cause erosion on rocks the stream runs over or alongside.
What is a stream valley?
The entire area between tops of the slopes on both sides of a river
What is a stream channel?
A channel that carries all the water during normal, nonflood times.
What is a flood plain?
A flat area about level with the top of the stream valley
List the 2 common stream channel patterns.
- Meanders
- Braided Streams
What are Meanders?
- Curved and bent river channels that wind across a floodplain
- Common in streams with a low gradient that typically cut through unconsolidated material
- Migrate over years, eroding the outside banks of the stream where current is strongest
What are point bars?
Curved sandbars that deposit on the inside bank where current is slower in a meandering stream channel.
What is an oxbow lake?
The crescent-shaped, water filled loop that is created when the meander loop neck becomes so narrow that the loop is bypassed by the river
What are braided streams?
- High energy streams that have many channels instead of one single channel
- Channels split apart and then rejoin in a patter resembling braids of hair
What is the gradient of a stream?
The distance the stream falls between two points
What is a stream’s Long Profile?
- A line drawn along the surface of the stream from its source to its mouth
- It is a concave upward curve due to decreases in gradient downstream
What is the base level?
It occurs where a river enters a body of standing water
What is the discharge?
The amount of water in m3/s that passes down the river
Why does the velocity of streams increase downstream?
Because the streams are deeper downstream and have less resistance from the stream bed, even though the gradient has decreased
When does a flood occur?
When a stream’s discharge exceeds the capacity of the channel and the stream overflows its banks.