Name: ________________________

Extra Credit On-line Stream Study (250 points)

 

This assignment will take you a few hours to complete.  It is best if you do it all at once at a computer with an internet connection (preferably fast!)  If you need to stop at some point and come back to it another time, write down the page’s internet URL you stop at and then retype this in when you return.

 

There is math involved, but the computer will prompt you if you get the answers incorrect and will help you understand how to fix them.  You may want to use your own calculator, though one will also pop up on the computer when you need to do a calculation.

 

Hit print to print out this assignment (it is about 6 pages long). 

On your internet browser URL address area, type in (or click below):

http://vcourseware3.calstatela.edu/VirtualRiver/Files/page01a.html

 

Now you are ready to begin answering the questions!  You will need to record your answers on this page as well as on the computer.  If you get the answer incorrect, the computer will tell you and not let you continue until you get it correct.

 

 

1.  Where do rivers get their water?

 

 

 

2. Discharge is an important concept. What statement best describes stream discharge?
It's a measure of stream volume per distance traveled

 It's a measure of stream velocity

 It's a measure of how much water is moving past a certain location along the stream each second.

3. If the stream above were moving twice as fast, what would the discharge be?
2.0 cubic meters/s 0.5 cubic meters/s 1.5 cubic meters/s

4.  In this diagram which side of the river is its left side?

Side A Side B


 

5.  Which part of the stream is flowing fastest?

    Near the top In the middle At the bottom of stream.

 

6.  Make each measurement twice to the nearest 0.2 seconds. Record your data in the top two rows of the table below. Then record the average of the two times.

Top of Form

Fraction of Depth

Time 1
(sec)

Time 2
(sec)

Average
Time (sec)

0.1 D

_____

_____

_____

0.4 D

_____

_____

_____

0.6 D

0.8 D

 

 

 

 

7.  Converting the time for the particles to move 5.0 meters into the velocity of the stream is easy.  Keep in mind that Velocity is Distance per unit Time (V = Distance / Time). Record your answer to the nearest 0.01m/sec.

 

Fraction of Depth

Distance
Traveled

Average
Time (sec)

Velocity
(= Distance
/ Time)

0.1 D

5.0 meters

11.9 sec

______m/sec

0.4 D

5.0 m

14.2 sec

______m/sec

0.6 D

5.0 m

17.2 sec

______m/sec

0.8 D

5.0 m

29.7sec

______m/sec

8.  Use your mouse cursor to drag the symbols representing each of the four points from the table on the right to the graph on the left. When the depth and velocity coordinates on the graph match those from the table release the mouse button. You may not be able to plot each point perfectly. Point # 1 has already been plotted for you.  You do not have to write anything here.


 

9.  The graph to the left shows that streams flow fastest near the water surface and slowest near the bottom of the stream. Use your mouse to move the "crosshairs" and read the velocity  (the x value at the bottom, also displayed in black box beneath the graph) at different depths. Record your results.

0.1D ______m/sec

0.2D ______m/sec

0.3D ______m/sec

0.4D ______m/sec

0.5D ______m/sec

0.6D ______m/sec

0.7D ______m/sec

 

0.8D ______m/sec


0.9D ______m/sec

 

Recall that we are trying to determine the average velocity of a stream at a particular spot. Now use the calculator tool and determine the stream's average velocity from these 9 velocity values.

Average = ______m/sec

 

 

 

 

 

 

 

10.  Move the cross hairs to the depth where the velocity in the stream is closest to the average velocity (.29 on the x axis). What is that relative depth value? ______

 

11. At what depth should a velocity sensor be placed to estimate a stream's average velocity if it's 12.5 meters deep?

_____meters

12. Same questions as above, but for a stream that's 2.0 meters deep.

_____meters

 

 

13. What is the velocity value at a sensor depth of 0.30 m at 6.2 m on the tape measure?

_____m/s

14. How does the velocity at 9.1 m on the tape (also at a sensor depth of 0.3) compare with that at 6.2 m and 0.30 sensor depth?

greater than less than
same as

 

15. What is the maximum depth of water in this hypothetical stream?

_____meters

16. At what actual depth should the velocity sensor be set to record the average velocity? ( Remember that the average velocity is best measured at 6/10th's of the total depth.)

_____m

17. What is the average velocity of this stream, as measured by the virtual stadia rod and velocity sensor?

_____m/sec

18. What is the distance on the tape of the left edge of stream? (Note that the edge of the stream is NOT at "0.0" on the tape.)

_____m

19. What is the distance on the tape of the right edge of the stream?

_____m

20. Compute the width of the stream. (This is the difference between the right and left sides.)

_____m

21. Discharge is computed as the volume of water in the stream passing by in one second.
DISCHARGE = DEPTH
times WIDTH times AVERAGE VELOCITY.
(Keep in mind that for this very simplistic stream the velocity at a fixed depth is constant from side to side. Water velocity in a real stream varies not only with depth, but from side to side.)
What is the discharge of this stream? (Calculate to TWO decimal places in cubic meters per second)

_____cu m / sec

 

You should now be at:  http://vcourseware3.calstatela.edu/VirtualRiver/Files/page09a.html

 

22a.  Why is it difficult to measure the discharge in real streams?

 

 

 

 

 

22b. Make up a way you think would work to measure them and write it here:

 

 

 

 

 

23.  Draw a meandering stream below:

 

 

 

 


 

24.  This picture isn’t the best: #1 riffle should be letter D, #2 should be F, the rest seem correct:

1. riffle
A B C D E F G

5. cutbank on left bank
A B C D E F G

2. upstream pool
A B C D E F G

6. point bar on right bank
A B C D E F G

3. downstream pool
A B C D E F G

7. point bar on left bank
A B C D E F G

4. cutbank on right bank
A B C D E F G

 

 

 

25.  Draw a stream cross section divided into verticals below:

 

 

 

 

 

 

 

 

26.  If a stream is 30 meters wide, and we want to compute discharge in a stream using 20 verticals, how many meters wide would each vertical be? _____meters

27.  On the next 2 pages you don‘t need to write anything here, the computer will record the info for you and you can move on.

 

28.  You should be on page: http://vcourseware3.calstatela.edu/VirtualRiver/Files/page21_SS_VM.html

You don’t need to write you chart numbers here, but please describe HOW you find the “area of vertical” and draw a picture of what this means. 

 

 

 

 

 

 

 

 

 

29.  What was the total discharge on the above page? ____________ m3/sec

 


 

30.  How many cubic meters are there in one cubic foot? 

(.3048 to the third power, or .3048 x .3048 x .3048 = ?) ­­­______

31.  How many cubic feet are in one cubic meter?(1/.0283 = ?) ______

32.  Now, convert 4.925 cubic meters per second to cfs (4.925 x 35.33 = ?) ______

 Congratulations, you are done!

Enter your completion info on the computer and print the next page and turn it in with this assignment.  If you have problems printing, finish writing the end of the URL here:

http://vcourseware3.calstatela.edu/VirtualRiver/Files/_____________________________