1. Presentation - Streams
Stream Transport

2. Presentation - Streams
Stream Transport
Suspended Load
Sediment that is held up and carried by the motion of the moving water
Bed Load
Sediment that is pushed, rolled or bounced along the stream bed
Stream Capacity
The overall ability of a stream to carry (transport) sediment
Depends on velocity and total flow

3. Presentation - Streams
Erosion
The removal of sediment particles
Occurs when a stream could carry more sediment than it is carrying.
Increasing a stream’s capacity results in erosion
Increasing the rate of flow (velocity)
Increasing the total volume of flow
Any sediment that can be picked up and carried, or pushed/rolled along

4. Presentation - Streams
Deposition
The placement of sediment particles
Occurs when a stream has been carrying more sediment than it is now able to carry.
Decreasing a stream’s capacity results in deposition
Decreasing the rate of flow (velocity)
Decreasing the total volume of flow
The largest and heaviest particles are deposited first

5. Presentation - Streams
Stream Erosion
Down-Cutting
Downward erosion of the stream bed
Deepening of the stream channel
Lateral Erosion
Sideways erosion of the stream banks
Widening of the stream channel

6. Presentation - Streams
Down-Cutting
Source:

7. Presentation - Streams
Lateral Erosion
Lateral erosion occurs when the zone of maximum velocity moves against the side of the channel because of the curve in the channel direction.

8. Presentation - Streams
Lateral Erosion
As the channel curve develops, sediment is deposited as a “point bar” on the inside of the curve at the same time erosion occurs on the outside of the curve.

9. Presentation - Streams
Down or Sideways?
If it can, a stream will erode downward.
The ability of a stream to down-cut is limited by its need to maintain a downward profile – the stream can not erode below its base level.
If it cannot erode downward, the stream will erode sideways.

10. Presentation - Streams
Base Level
The ultimate base level is the ocean.
Local base levels can be created by manmade and natural blockages of the stream channel (e.g., dams) or by strong rock that resists down-cutting

11. Presentation - Streams
Stream Profile
The change in elevation measured along the stream channel

12. Presentation - Streams
Changes to Base Level
If a base level is lowered, the stream profile is also lowered.
Lowering of a profile happens by down-cutting erosion.
If a base level is raised, the stream profile is also raised.
Raising of a profile happens by the deposition of sediment.

13. Valley Shape and Erosion
Presentation - Streams
Valley Shape and Erosion
Down-cutting produces V-shaped valleys.
Down-cut valleys sides come together as the edge of the stream.
Lateral erosion produces valleys with flat areas beside to the stream.
The flat areas on the sides of lateral cut valleys are called floodplains.

14. Presentation - Streams
Down-Cutting
Source: 14

15. Presentation - Streams
Lateral Erosion
Source: accessed on March 7, 2010 15

16. Presentation - Streams
Floodplain Features
As the channel moves back and forth across the valley floor, the valley walls are eroded back and a floodplain is formed.

17. Human Impacts to Streams
Presentation - Streams
Human Impacts to Streams
How do human decisions affect the quality of water in streams?
How do we plow our fields?
How do we manage the areas adjacent to our streams?

18. Presentation - Streams
Non-Contour Plowing
Source: Accessed

19. Presentation - Streams
Contour Plowing
Source: Accessed 03/02/09

20. Presentation - Streams
No Riparian Buffer
Source: Accessed 03/02/09

21. Presentation - Streams
Good Riparian Buffer
Source: Accessed 03/02/09

22. Best Management Practices
Presentation - Streams
Best Management Practices
Contour Plowing
Follows the shape of the land.
Slows down the velocity of runoff.
Reduces the carrying capacity and (therefore) the amount of erosion.
Riparian Buffer
Slows down the velocity of runoff before it enters the stream.
Reduces the carrying capacity; causes the deposition of sediment in the bank areas instead of allowing it to enter the stream.
Can also be used to reduce the impacts of subdivisions, feed lots, and logging.

23. Presentation - Streams
Estuaries
Estuaries in North Carolina: A Primer
Estuaries are bodies of water where freshwater and saltwater mix
The wide and varied range of mixing conditions creates very diverse habitats for plants and animals.
Estuaries also buffer the impacts of coastal storms on inland areas, act as an environmental filter, and support migratory wildlife.
Threats to estuaries include sea level rise from global warming, excess nutrients, and high levels of suspended sediment.

24. North Carolina’s River Basins
As you read through your pamphlet, make a list of 10 facts about your river basin that you find interesting.
Share your list with the other students who have the same river basin, and mark the facts that you have in common.
Select 10 facts that are the most interesting to you and make a mini-poster promoting (advertising) the attractive and/or beneficial features of your river basin. Use color and be creative!
Turn in at the end of class: your list of 10 facts and your mini-poster.