Exam 3 part 2 Flashcards
How does gradient effect velocity/stream flow?
The steepness of the gradient will determine how fast it goes because gravity is controlling it
How does roughness effect velocity/steam flow?
Smooth beds will be faster than rough beds
What is the highest point of velocity in a river?
The middle
What is discharge?
The volume of water moving past a given point in a certain amount of time
What is base level?
Base level is the lowest point to which a stream can erode
What is a graded stream?
A stream that is not eroding but is only transporting
What happens when you lower the base level of a stream?
It will down cut and cause erosion
What are the two types of base level?
1) Ultimate (sea level)
2) local/temporary
What happens to sediment when you build a dam?
Sediment will build up behind the dam and get polluted
what is stream erosion?
Lifting loosely consolidated particles by stronger currents
What are two types of erosion?
1) Abrasion
2) Dissolution
What is dissolution in stream erosion?
Dissolution is when something dissolves
What is abrasion in stream erosion ?
This is when something is broken down over time like sandpaper over wood
What is the stream’s load?
The transport of sediment by streams
What are the 3 types of stream load?
1) Dissolved load
2) Suspended load
3) Bed load
What does the dissolved load of a stream look like?
It’s practically invisable to the human eye, the smallest form of particles
What does the suspended load of the stream look like?
These are particles that are too small to roll at the bottom of a stream but too big to be dissolved. They make the water look muddy
What does the bed load of the stream look like?
These are large particles that roll at the bottom of a stream
What is the capacity of a stream?
It’s the maximum load a stream can carry
What is the comptetence of a stream?
The maximum particle size a stream can transport
How is the comptetence of a stream measured?
Through the stream’s velocity
What causes a stream to have deposition?
When the velocity is decreased and the comptetence is also decreased
Stream sediment is generally ______?
Well sorted
Stream sediment is known as?
Alluvian
What are point bars?
The opposite of cut banks, where sediment is deposited at the side of a river
What are braided streams?
They are multiple streams together with lots of sediment, they have sediment islands form when their velocity slows down making the streams braided
What are natural levees?
These form parallel to the stream channel by successive floods over many years
What are yazoo tributaries?
A tributary that runs parallel to a river, especially when separated by a natural levee
What is a flood plain?
a marshy area where floodwater may be contained between valley walls
What are backswamps?
poorly drained oval shaped depression located between the natural levees and the edge of the floodplain
What is an alluvial fan?
They are slopes in a broad arc that have been developed by a high gradient stream that leaves a narrow valley
What are the 3 types of beds in a delta?
1) Bottom beds
2) Forest beds
3) Topset beds
What is the most common landforms on the Earth’s surface?
Stream valleys
What are the two types of stream valleys?
1) Narrow valleys
2) Wide valleys
What is the base level of a stream?
the lowest point to which it can flow, often referred to as the ‘mouth of the river’.
What is a terrace?
It’s a step like formation: remnants of a former flood plain
What is a drainage basin?
A watershed: an area of land that separates waters flowing to different rivers, basins, or seas
What is the ‘Divide’ of a drainage basin?
It is an imaginary line separating one basin from another
What are the four common drainage patterns?
1) Dendritic
2) Radial
3) Rectangular
4) Trellis
What does a dendritic drainage pattern look like and how does it develop?
It looks like a tree, many branches, it develops on highly uniform bedrock
What does a Radial drainage pattern look like and how does it develop?
It’s a star like pattern, develops on isolated volcanic cones or domes.
What does a Rectangular drainage pattern look like and how does it develop?
It looks rectangular/brick like, developed on highly jointed bedrock
What does a Trellis drainage pattern look like and how does it develop?
it’s like a river with horizontal lines going out the sides, developed in areas of alternating weak and resistant bedrock
What is stream piracy?
This is where the headward erosion will cut back in the stream far enough that it might intersect with another stream and steal water from it to the point that it diverts the stream it stole from
What is an example of stream piracy in OHIO?
The cuyahoga river
What is a water gap?
A notch where a river cuts through a ridge that lies in its path
What is headward erosion?
When the stream gains enough water (Rain) to start run off and may have the stream erode at it’s head
What’s the difference between erosional floodplains and depositional flood plains?
depositional flood plains are when the river meanders around the flood plain, not really cutting into it, while erosional flood plains will cut into the flood plain and begin downwards a slope
