MAPPING YOUR STREAM. TIME REQUIRED 50 minutes in Field 50 minutes in Classroom 50 minutes Homework

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1 OUR MAPPING YOUR STREAM STREAM ACTIVITY SUMMARY Students will draft a cross-sectional profile of the stream and measure the velocity of the current. They will use both of these to calculate the discharge (flow) of the stream in cubic feet per second. If you have extra time, consider having the students make a plan-view map of the stream as well (see Extensions). OBJECTIVES Students will: make a map of a cross-sectional profile of the stream, calculate the velocity of the stream, calculate the discharge of the stream. MEASURING VELOCITY Pencils Field notebooks Yardstick or tape measure (one per group) Floatable objects such as oranges, rubber duckies, or twigs (one per group) Note: Don t use tall objects on a windy day because they can be blown about. Stakes Stopwatch or watch with second hand (one per group) String (optional) TIME REQUIRED 50 minutes in Field 50 minutes in Classroom 50 minutes Homework MATERIALS METHOD 1 - Tape Measure 50 ft. Tape measure (one per group; long enough to go across stream) Stakes Flagging material yard sticks or pole with measurements marked on it (one per group) Pencils Field notebooks or copies of Method 1 Profile Data Sheet Graph paper or copies of Student Page #1 Copies of Student Page #2 -Classwork Instructions (optional) METHOD 2 - Stick & String Two sticks: one 2 x 2 x 5 and one 2 x 2 x 8 Large ball of string Marker Measuring tape Hanging string level (masonry line level) or a sight level Pencils Field notebooks or copies of Method 2 Profile Data Sheet Graph paper or copies of Student Page #1 Copies of Student Page #2 -Classwork Instructions (optional) 1 MAKING CONNECTIONS In Module 1, the class became familiar with the stream by observing and sketching it. Most of the observations were qualitative. In Module 2, students will get to know the stream in a more quantitative way by mapping and measuring several key characteristics. The work the students will do will draw on skills and techniques they use in math class and other science classes. Ask students to make comparisons between what they do in this activity and problems they have solved in other classes.

2 BACKGROUND In order to study a stream scientifically, students will need to have an accurate, quantitative picture of the stream. This picture will be composed of maps and measurements. The maps and measurements will provide baseline information against which to measure any changes that occur during the study. For example, after a rainstorm, students might observe that the current appears faster than usual and the bank looks more eroded. These observations can become scientific conclusions if the students have baseline measurements against which to compare. Students will draw a cross-sectional profile of the stream bed by using one of two methods: (1) a tape measure across the stream bank or (2) stick and string. Using one of these methods, they will measure change in elevation at regular intervals across the stream banks and stream. Sample stream profiles for each method are shown at the end of this activity guide. In order to calculate the velocity of the stream, students will time how long it takes a rubber ducky (for shallow streams) or an orange (for deeper water) to float a set distance. Students will calculate the discharge of the stream in cubic feet per second by multiplying the velocity by the area under water on the profile they drew. In the field, students will need to work quickly and efficiently to gather all the data they need. If you feel time will be short, it may be worthwhile to set up some things in the field ahead of time. For example, you could string up the tape measure across the stream and decide on an appropriate interval for students to take depth measurements. Choose an interval that will capture an appropriate level of detail, and allow the students to measure all the way across the stream in one class period. Narrow streams need smaller intervals than wide streams. Also, think through the instructions with your stream in mind and make any necessary adjustments. Will a yardstick be long enough for the depth measurements for the profile? Is the stream too deep or wide to safely take measurements for a profile? Is there enough water in the stream to support an orange for velocity measurements? PROCEDURE A short video with tips on how to implement this activity is available at WARMUP First, review the safety rules in the Overview to It s Our Water and any others that you may have come up with when you scouted out the stream. Ask students to explain the difference between quantitative and qualitative. Ask them to brainstorm instances where quantitative data would be more useful than qualitative. Assign working groups of three or four students each. Impress upon students the importance of taking complete, legible notes in the field, and including a unit with every number. THEACTIVITY PART I: FIELD WORK METHOD 1 Tape Measure 1. String up a tape measure from bank to bank across the stream between two stakes. Put the 0 end of the tape measure on the left side as you look downstream. The profile will include everything between the two stakes, so let that guide where you place the stakes (you will want to include some of the banks in the profile, but not too much). 2. At regular intervals across the tape, measure the distance from the tape to the ground or the bottom of the stream bed. For each measurement, write two numbers (with units!) in your notebook: the horizontal distance on the tape measure, and the vertical distance to the ground. Each person will help make observations for the recorder to write down at each interval. Observations can include whether the reading was taken on the bank or in the water, the changes in vegetation on the bank, erosion evidence, and whether the streambed is rocky or sandy. These comments will help you when you are drawing the profile. 3. Make a measurement at water s edge on each side of the stream, even if it s not at the regular interval. Make sure to write down the distance on the tape measure accurately, and write water s edge by these numbers in your notebook. 4. Measure the distance from the tape measure to the water level in several places and record in your notebook. This data will help you draw the surface of the water on your profile of the stream. 5. Take a careful look around and make any notes to yourself that will help you when you re drawing the profile back in the classroom. You might want to sketch an approximate version of the profile (looking downstream) and label noteworthy spots on it (water s edge, steep banks, rapids). 2

3 METHOD 2 Stick & String PREPARATION 1. Cut a groove into the shorter, 5 stick exactly 4 feet from the bottom in order to keep the string in place. This will be your Fixed- String Stick. 2. Using the marker and the measuring tape, place a zero mark at the four foot spot on the longer, 8 stick. This will be your Measurement Stick. Above that measurement, label the inches starting from zero to the height of the pole using negative numbers due to the fact that if the string is moving up the pole, then you must be going downhill. Below the four foot zero mark count down the pole in positive inches since you must be going uphill if the string needs to slide down. 3. Measure a length of string to be tied between the two sticks, such that the distance between the two posts will be exactly 1 foot (if your study stream is wide, you may wish to make this 2 or 3 feet, depending on how many data points you d like to collect). One end of the string will be tied into the groove on the Fixed-String Stick, and the other end should be able to slide up and down the Measurement Stick. When both sticks are held upright on level ground, with the string stretched taut and placed at the four foot zero mark on the Measurement Stick, the string should be perfectly level. PROCEDURE 1.Divide the class into groups of three or four: two to hold the sticks upright, one to use the string level, and one to record the data and make observations at each interval. 2. Place each group and their equipment a set distance apart from each other (ex. Every five feet). Have the groups take measurements from one bank to the other. 3. Place the Fixed-String Stick at the starting position at a high point on the stream bank and the Measurement Stick closer to the stream (you will want to include some of the banks in the profile, but not too much). Separate the sticks until the string is taut. (Record the horizontal distance on the profile data sheet as 1 foot, or whatever horizontal distance you are using between the posts.) 4. Slide the string along the Measurement Stick until the string is level. The recorder will then write down the number of inches the string moved from the zero mark in the column labeled Change in Elevation. If the string moved up the pole, then record the measurement as a negative number (as previously marked on the pole). Record as a positive number if the string moved down. Add this number to the previous number in the Total Elevation column (The first number in the Total Elevation column, which represents the starting point, should be 0.). 5. Each person will help make observations for the recorder to write down at each interval. Observations can include whether the reading was taken on the bank or in the water, the changes in vegetation on the bank, erosion evidence, and whether the streambed is rocky or sandy. These comments will help you when you are drawing the profile. 6. Move the Fixed-String Stick off of the starting point and place it in the exact same spot the Measurement Stick was standing and then separate the sticks for the second measurement. Once again, move the string up or down along the Measurement Stick until it is level, and record this change in elevation. Add each change in elevation to the previous Total Elevation number and record this in the Total Elevation column on the data sheet. 7. Make a measurement at water s edge on each side of the stream, even if it s not at the regular interval, and write water s edge by these numbers in your notebook. 8. Take a careful look around and make any notes to yourself that will help you when you re drawing the profile back in the classroom. You might want to sketch an approximate version of the profile (looking downstream) and label noteworthy spots on it (water s edge, steep banks, rapids). Suggestion: Place a long piece of string across each group s first ten foot mark, then another along each of the twenty foot marks, etc., to see how the contour lines get closer together as the hills get steeper! It is a striking visual aid to help your students get a better understanding of topographic maps. MEASURING VELOCITY 1. Choose a good location for measuring the velocity of the current someplace where there are not a lot of rocks or sticks in the water and where there is a relatively clear space on the shore to work. 2. Choose a floatable object: a rubber ducky for shallow streams or an orange for deeper water. If the stream is too deep or wide to retrieve the floatable object by hand, attach a string to it to retrieve it. 3

4 3. Set up four stakes on the shore, two on each side of the stream, which form a rectangle. The long axis of the rectangle should be parallel to the stream and roughly twice as long as the stream is wide. The two stakes that are upstream form Sightline 1. The two stakes that are downstream form Sightline 2. curving line. If you sketched the profile in the field, use this sketch to help you. Do not simply connect the dots. (Why wouldn t that be accurate?) 5. Connect the two dots that represent the water s edge. This is the surface of the water. Measure down from the line on your paper and make sure this measurement corresponds correctly to the measurements you took in the field of the distance between the tape and the surface of the water. 6. Put a title on your profile, and include a scale. 4. Using a stopwatch or a watch with a second hand, time how long it takes the floatable object to float the measured distance. Place the floatable object in the current a little bit upstream of the stakes. Start the stopwatch when the floatable object is in line with Sightline 1. Stop the stopwatch when the floatable object is in line with Sightline 2. This will be most accurate if you have one student at each sightline, rather than having one person run back and forth. 5. Time the floatable object at least five times. Record the times in your notebook. Re-do any trials that are clearly unrepresentative for example, if the floatable object got hung up in an eddy or stuck on a stick. PART II: CLASS WORK Sample stream profiles for each method are shown at the end of this activity guide. You may want to display the appropriate one as a guide for your students as they create theirs. METHOD 1 - Tape Measure 1. Using an appropriate scale, draw a straight horizontal line near the top of a piece of graph paper. This line represents the tape measure across the stream. Mark off the intervals on this line at which you took depth measurements. 2. Using the data in your notebook, at each interval measure down the correct scaled distance from the tape to the ground. Draw a point or small circle to represent the ground. 3. Remember to include any measurements you took that were not at the regular intervals. For example, if your regular interval was one foot, and you measured the water s edge at 1.75 feet, draw that point halfway between 1.5 feet and 2.0 feet. 4. Once all your points are drawn, connect them with a gently 4 METHOD 2 - Stick & String 1. To begin drawing the cross section of the stream on graph paper, choose an appropriate scale that will allow you to fit the distance and the total elevation on the paper. 2. Place your starting point on the far left of the graph paper. Mark it as Elevation 0. From this point, draw a horizontal dotted line and mark it off in intervals representing each distance at which you made measurements in the field. 3. At each distance, make a point representing the number in the Total Elevation column from your data sheet. If the number is negative, measure down from the dotted line representing Elevation 0. If it is positive, measure up from the dotted line. 4. Once all your points are drawn, connect them with a gently curving line. Using your data and observations, draw a straight line representing the water surface. Add any other observations you made in the field. MEASURING VELOCITY Average the times you recorded. Write down the velocity as a ratio of distance traveled over the average number of seconds. Now divide the number of seconds into the distance so that your answer is expressed in a certain number of feet per 1 second. That is the velocity of the current. EXAMPLE: Average time = 30 seconds. Distance = 10 feet. 10 feet/30 seconds = 0.33 feet per 1 second. CALCULATING DISCHARGE 1. Calculate the area of water in your stream profile in the following manner: using your scale, figure out the area of one square of graph paper. Count out how many squares are under water, then multiply the number of squares by the area of one square. EXAMPLE: 1 square = 1 square foot. Total squares under water = X 1 = 25 square feet. 2. Multiply this area of water (in square feet) by the velocity (in feet per second) to get discharge (in cubic feet per second). EXAMPLE: 25 square feet X 0.33 feet per second = 8.25 cubic feet per second.

5 3. Compare your results to the results of the U.S. Geological Survey on your stream or a nearby stream ( usgs.gov/nc/nwis/ or WRAP UP AND ACTION Have a class discussion so students can share what they have learned about the stream through these activities. Did gathering and displaying quantitative data add to their previous understanding of the stream? Also record any questions the students may have come up with about the stream while working on these projects. Discuss ways of designing scientific studies to answer these questions. ASSESSMENT Have students: Explain in writing or orally how to complete each of the tasks in this activity. Complete one or all of the tasks using new data from a hypothetical stream. Make group presentations to the class reviewing what they learned about the stream. RESOURCES Compton, Robert R Manual of Field Geology. New York: John Wiley & Sons, Inc North Carolina Essential Standards for 8TH GRADE SCIENCE GOALS & OBJECTIVES The stream activities in each module are intricately tied. Although this activity may not be correlated to your standards, it is needed for the complete picture of the stream and to achieve the objectives listed below. 8.E.1: Understand the hydrosphere and the impact of humans on the local systems and the effects of the hydrosphere on humans. 8.E.1.3: Predict the safety and potability of water supplies in North Carolina based on physical and biological factors, including: Temperature Dissolved Oxygen ph Nitrates and phosphates Turbidity Bio-indicators 8.E.1.4: Conclude that the good health of humans requires: Monitoring of the hydrosphere Water quality standards Maintaining safe water quality Stewardship for EARTH/ENVIRONMENTAL SCIENCE GOALS & OBJECTIVES EEn.2.4: Evaluate how humans use water. Explain various water uses by humans and evaluate for benefits and consequences of use (ex. wells, aquifer depletion, dams and dam removal, agriculture, recreation). Evaluate the effects of population growth on potable water resources. Infer future effects. Explain how pollutants might flow through a watershed and affect inhabitants that share the same watershed. EEn.2.4.2: Evaluate human influences on water quality in North Carolina s river basins, wetlands, and tidal environments. Evaluate issues of ground water and surface water pollution, wetland and estuary degradation, and salt water intrusion. Evaluate water quality of NC streams (chemical, physical properties, biotic index). Analyze non-point source pollution and effects on water quality (sedimentation, stormwater runoff, naturally and human induced occurrences of arsenic in groundwater). Evaluate conservation measures to maximize quality and quantity of available freshwater resources. 5

6 CLASSWORK Student Page #1 Distance Traveled (in feet) Total Squares of Water Area of Water (in square feet) MEASURING VELOCITY = Average Time (in seconds) x = VELOCITY CALCULATING DISCHARGE Area of Square (in square feet) x = VELOCITY (in feet per second) DISCHARGE feet per 1 second square feet of water cubic feet per 1 second

7 SAMPLE SAMPLE METHOD 1 - Tape Measure PROFILE DATA SHEET Horizontal Vertical Distance Distance Observations (in feet) (in feet) 0 2 Tall grasses, scrubs 1 2 Tall grasses Short weeds and grasses Short weeds and grasses 4 3 Sandy creek bed Sandy creek bed 6 4 Sandy creek bed, *Water s 5.75H, 3.75V Sandy creek bed 8 6 Sandy creek bed 9 7 Rocky creek bed 10 7 Rocky creek bed, Thalweg (lowest 9.25H, 7.25V Rocky creek bed 12 6 Rocky creek bed 13 6 Rocky creek bed Rocky creek bed Rocky creek bed 16 5 Rocky creek bed Rocky creek bed 18 2 Eroded bank, *Water s 17.25H, 3.75V 19 1 Eroded bank 20.5 Short weeds and grasses, small trees Horizontal Distance (in feet) Tape Measure 0 0 Vertical Distance (in feet) Water Level Thalweg square = 1 square foot under water squares = 23 square feet 9

8 METHOD 1 - Tape Measure Student Page Method 1 PROFILE DATA SHEET Name: Date: Group Members: Period: CURRENT WEATHER OBSERVATIONS HORIZONTAL VERTICAL DISTANCE DISTANCE OBSERVATIONS

9 CLASSROOM INSTRUCTIONS Student Page Method 1 Instructions METHOD 1 - Tape Measure 1. Using an appropriate scale, draw a straight horizontal line near the top of a piece of graph paper. This line represents the tape measure across the stream. Mark off the intervals on this line at which you took depth measurements. 2. Using the data in your notebook, at each interval measure down the correct scaled distance from the tape to the ground. Draw a point or small circle to represent the ground. 3. Remember to include any measurements you took that were not at the regular intervals. For example, if your regular interval was one foot, and you measured the water s edge at 1.75 feet, draw that point halfway between 1.5 feet and 2.0 feet. 4. Once all your points are drawn, connect them with a gently curving line. If you sketched the profile in the field, use this sketch to help you. Do not simply connect the dots. (Why wouldn t that be accurate?) 5. Connect the two dots that represent the water s edge. This is the surface of the water. Measure down from the line on your paper and make sure this measurement corresponds correctly to the measurements you took in the field of the distance between the tape and the surface of the water. 6. Put a title on your profile, and include a scale. MEASURING VELOCITY Average the times you recorded. Write down the velocity as a ratio of distance traveled over the average number of seconds. Now divide the number of seconds into the distance so that your answer is expressed in a certain number of feet per 1 second. That is the velocity of the current. Average time = 30 seconds. Distance = 10 feet. 10 feet/30 seconds = 0.33 feet per 1 second. CALCULATING DISCHARGE 1. Calculate the area of water in your stream profile in the following manner: using your scale, figure out the area of one square of graph paper. Count out how many squares are under water, then multiply the number of squares by the area of one square. EXAMPLE: 1 square = 1 square foot. Total squares under water = X 1 = 25 square feet. 2. Multiply this area of water (in square feet) by the velocity (in feet per second) to get discharge (in cubic feet per second). EXAMPLE: 25 square feet X 0.33 feet per second = 8.25 cubic feet per second. 3. Compare your results to the results of the U.S. Geological Survey on your stream or a nearby stream ( or

10 SAMPLE SAMPLE METHOD 2 - Stick & String PROFILE DATA SHEET Horizontal Change Total Distance in Elevation Elevation Observations (in feet) (in feet) (in feet) Tall grasses, scrubs Tall grasses Short weeds and grasses Short weeds and grasses Sandy creek bed Sandy creek bed Sandy creek bed, *Water s 5.75H, -1.75V Sandy creek bed Sandy creek bed Rocky creek bed Rocky creek bed, 9.25H, 7.25V Rocky creek bed Rocky creek bed Rocky creek bed Rocky creek bed Rocky creek bed Rocky creek bed Rocky creek bed Eroded bank, *Water s 17.25H, -1.75V Eroded bank Short weeds and grasses, small trees Horizontal Distance (in feet) Vertical Distance (in feet) Thalweg Water Level 1 square = 1 square foot under water squares = 23 square feet

11 METHOD 2 - Stick & String Student Page Method 2 PROFILE DATA SHEET Name: Date: Group Members: Period: CURRENT WEATHER OBSERVATIONS CHANGE TOTAL DISTANCE IN ELEVATION ELEVATION OBSERVATIONS

12 CLASSROOM INSTRUCTIONS Student Page Method 2 Instructions METHOD 2 - Stick & String 1. To begin drawing the cross section of the stream on graph paper, choose an appropriate scale that will allow you to fit the distance and the total elevation on the paper. 2. Place your starting point on the far left of the graph paper. Mark it as Elevation 0. From this point, draw a horizontal dotted line and mark it off in intervals representing each distance at which you made measurements in the field. 3. At each distance, make a point representing the number in the Total Elevation column from your data sheet. If the number is negative, measure down from the dotted line representing Elevation 0. If it is positive, measure up from the dotted line. 4. Once all your points are drawn, connect them with a gently curving line. Using your data and observations, draw a straight line representing the water surface. Add any other observations you made in the field. MEASURING VELOCITY Average the times you recorded. Write down the velocity as a ratio of distance traveled over the average number of seconds. Now divide the number of seconds into the distance so that your answer is expressed in a certain number of feet per 1 second. That is the velocity of the current. EXAMPLE: Average time = 30 seconds. Distance = 10 feet. 10 feet/30 seconds = 0.33 feet per 1 second. CALCULATING DISCHARGE 1. Calculate the area of water in your stream profile in the following manner: using your scale, figure out the area of one square of graph paper. Count out how many squares are under water, then multiply the number of squares by the area of one square. Average time = 30 seconds. Distance = 10 feet. 10 feet/30 seconds = 0.33 feet per 1 second. 2. Multiply this area of water (in square feet) by the velocity (in feet per second) to get discharge (in cubic feet per second). EXAMPLE: 25 square feet X 0.33 feet per second = 8.25 cubic feet per second. 3. Compare your results to the results of the U.S. Geological Survey on your stream or a nearby stream ( or