Environmental Earth Science Field Study Lab

Name: _______________________________ Period ____

1.0 PROBLEM:  According to 1970 figures, every American directly and
    indirectly uses 56,000,000 gallons of water in their lifetime!
    Adjacent to the school, two small streams combine to form a larger
    stream. Our task is to determine how many peoples' water needs can
    be met by these streams.

2.0 RESEARCH: Volume of flow is determined by measuring the cross section of water in a stream (square feet, square meters etc), and multiplying that figure by the speed of the water (feet per second, meters per second etc) to get the volume of water (cubic feet, cubic meters) that flows by every second.

    The formula for this is F = bwdl/t, where F is discharge volume, b is a factor to compensate for friction (.9 for a smooth bed, .8 for a rough bed), w is average width of the stream, d is average depth of the stream, l is the length of the stream measured, and t is the time it takes for a float to go distance l.

    1 gallon equals 231 cubic inches, 1 cubic foot equals 7.481
    gallons. 1 cubic meter equals 1.308 cubic yards.

    (extra credit) What are the latest figures available for water
    consumption?  What is a lifetime?   What is meant by 'indirect'
    water consumption?

3.0 HYPOTHESIS:  Based on your observation of the streams we feel that
    each of the small feeder streams is capable of supplying the water
    needs of ________ people.

4.0 TESTING THE HYPOTHESIS: prove that your hypothesis is right, or prove that it is wrong.

    4.1 Resources:  watch, tennis ball, string, meter sticks, ruler, boots, data team of four people (recorder, boot person, stick/string  holders)

4.2 Procedure and Data:

	4.21 THE MAP. Observe and map your assigned stream area:















	4.22 THE WIDTH. Measure the distance across the stream through the water at three depths: the top of the water, the middle of the water at the deepest point in the stream, and 1 cm above the bottom of the deepest point. Record widths and depths.

Stream cross section


Depths below surface: _________  __________  __________

      Widths of stream:     _________  __________  __________

Average width (add the three distances across the stream and divide by 3):


4.23 THE DEPTH. Stretch the string across the stream.  Every 25cm or less across the stream, measure the depth of the water.  Make at least 5 measurements, evenly spaced across the stream, no more than 25cm apart.  Record the distances from shore and depths.


Depths every 25 cm or less across stream

        Distances from shore at which you measured depths:

               _______  ________  ________  _______  _______ ________

	Depths:  _______  ________  ________  _______  _______ ________

	Average Depth:





4.24 THE SPEED.  Measure a distance along the middle of the stream that is at least 2 meters long and free of obstructions. Time how long it takes a float to travel the distance you measured.  Repeat five times.

  	Distance float traveled:

	Times: _______  ________  ________  _______  _______

	Average Time:         Speed of water (distance/time):


  4.30 Control of variables.

    4.31 Why do you measure the width of the stream at three depths?






    4.32 Why do you find the depth of the stream so many times?





    4.33 What effect does friction have on the speed of the flow?  What effect will this have on the accuracy of these calculations?







    4.34 Why are these measurements being done at three locations on different parts of the stream?







    4.35. What can affect how much water is flowing in this stream at other times?  How will this affect the accuracy of our predictions?









5.0 DATA / CALCULATIONS / ANALYSIS:

5.1 Use graph paper or a computer graphing program to plot the above data to show the stream's cross section. Label the graph with a title and axis labels, and attach to this report.
    
5.2 Compute the volume of flow by using the formula bwdl/t. Show your calculations here. Label each number.







 

     5.3 Use the graph of the stream profile to find the cross section
       area of the stream by counting squares. Use this figure to
       check your work by multiplying the cross section area by the
       speed of the water. Show your calculations here. Label each
       number.






5.4 Convert your volume of flow calculation into gallons per second, then calculate how many people the stream could provide for.  Show your calculations here. Label each number.











6.0 CONCLUSION: 
   6.1 Was your hypothesis correct or not? Describe how the data shows this.






    6.2 If your hypothesis was incorrect, how far off were you?  Why do you think your guess was this far off?




7.0 PUBLICATION and VERIFICATION: During the week before this report is due, you should: 
  7.1 Compare your results with those of your data gathering team.      

  7.2 Once you have verified your calculations with your team, compare with the results of teams that studied a different stream.  List the results below and describe how they compare.  For example, does the volume of flow of the feeder streams add up to that of the main stream?  











  7.3 Calculate the percentage of error: (expected result-actual result)/(expected result)*(100)