1. Why Study A Stream’s Velocity?
Because the speed of stream can be used to predict and assess future events and give us valuable information
Flash floods amateur footage, arid climate
Homes float away
Nechako River (During high water)
Sooke River (Spring time)

2. A stream’s velocity (or speed) effects the rate of erosion
A stream’s velocity (or speed) effects the rate of erosion. Predicting erosion can predict floods and future changes in the stream channel.

3. A stream’s velocity effects the type of debris and material that it carries down the stream.
Damming and deposits of woody debris can have serious consequences.

4. The velocity of streams and rivers will also determine the type of sediment that is transported, called the stream load. This can be valuable info
for fisheries and the study
of spawning channels

5. Turbidity
Turbidity = cloudiness or particles in water
As turbidity rises, so does the risk of gastrointestinal illness .
While this might not be of great concern to most of us, the risk for the very young, the very old, and people with weakened immune systems can be higher.
Question: Is velocity the main cause of turbidity?
Turbidity = Boil Water Advisory

6. The velocity of streams and rivers gives data about what kind of changes might have to be made to the banks to prevent erosion and flooding

7. What Effects Velocity? The Stream Gradient or Slope Does!
The slope/gradient of the stream channel = the vertical drop over a certain distance.
Question: Do mountain streams tend to have a high or low gradient?
High Velocity
Low Velocity
Slopes change, THEREFORE a stream’s gradient also varies.
The steeper the gradient, the greater the energy.
The greater the velocity The greater the effects

8. What Other Factor Controls Velocity?
Shape, Size, and Roughness of the Channel Does!
The channel controls the flow of a stream and river.
Water experiences friction at the base and this will effect the velocity of the stream.
Large channels have more efficient flow because less water is in contact with the channel.
QUESTION: What else do you think can slow flow down?
Large boulders in a channel tend to slow water flow.
Velocity is less near the banks too!
Velocity varies around bends as well!

9. One More Factor Effecting Velocity
Stream Discharge or Volume of Flow
Discharge = Volume of water flowing past a certain point at a given time.
Crawford Ck. Discharge Rates
Discharge from streams is not constant and is controlled by other factors.
QUESTION:
What increases discharge?
Snowmelt
Rainfall and its runoff
Logging and land clearing.

10. How Will We Measure Velocity?

11. Do not go into the creek for any reason. No pushing or horseplay
Rules Around The Creek
There are 7 important Do’s and Don’ts. What are they?
No running.
Do not go into the creek for any reason.
No pushing or horseplay
Please do not litter or alter the landscape.
Get help right away
Stay with the group and the class
Listen to instructions.

12. Divide the meters by the seconds (10 / 5) = 2 10 / 6.1 = 1.64, etc.
Bob (thrower), Emily (Shouter at A), Dave (StopWatch at B), Steve (Time recorder and Calculator) 5 10 2
6.1 10
1.64 20
13.2
1.51
Find the average by summing the m/sec
(eg )
then divide by 4. In this case it equals
1.63 m/sec 20 14
1.4
1.63

13. Multiply the 200 m. by 1.63 seconds (the average calculated last day).
326
5 min 26 secs
Multiply the 200 m. by 1.63 seconds (the average calculated last day).
200 x 1.63 = 326 seconds
or 5 minutes and 26 secs.