To model and observe stream processes, including factors that affect erosion and deposition

Time Approximately 45 minutes

Question What factors affect the power of a stream or river to cause erosion?

Summary In this lab, you will use a virtual model to observe stream behavior. You will model five scenarios involving a stream, and investigate the effect of water velocity, water volume, the stream slope, and the size of sediment on sand, pebbles, and various-sized rocks in a stream.

Lab Procedure

2. Prepare for the project.
   2. Read through this guide before you begin, so you know the expectations for this lab.
   4. If anything is not clear to you, be sure to ask your teacher.
5. Open the virtual lab.
7. Model a low-gradient, low-velocity stream.
   1. Read the scenario.

You are on a research trip to observe pronghorn in the prairie grasslands of Colorado. As you observe a herd grazing next to a nearby stream, you notice storm clouds moving in overhead and feel rain beginning to fall. How does the stream act right now upon the objects in it?

2. Analyze the scenario and characterize the slope of the stream, the amount of rainfall, and the terrain of the area.
4. Press the "Go to the model." button to open the modeling tool. You can always return to the scenario by clicking the "?" button in the top-right corner.
6. On the left panel, choose the description for each parameter that would correctly model the scenario.
8. Press the "Check" button.
   2. If all your descriptions are correct, proceed to step f.
   4. If your descriptions are not all correct, analyze the scenario again and correct your descriptions. Click on the "Check" button. o this step until all descriptions are correct. Then proceed to step f.
   6. Observe what happens to the sand and pebbles in the stream.
   8. When ready, press the "Pause" button and rite your observations in the space below Low-Gradient, Low-Velocity Stream in the Data section of this guide.
   10. Draw what you see in Table A.
   12. Proceed to the next activity.
11. Model a low-gradient, high-velocity stream.
    1. Read the scenario.

As you continue to observe the pronghorn herd, the rainfall gradually increases until it is falling at a steady pace, causing the stream to flow more quickly. How does the stream act right now upon the objects in it?

2. Analyze the scenario and characterize the slope of the stream, the amount of rainfall, and the terrain of the area.
4. Press the "Go to the model." button to open the modeling tool. You can always return to the scenario by clicking the "?" button in the top-right corner.
6. On the left panel, choose the description for each parameter that would correctly model the scenario.
8. Press the "Check" button.
   2. If all your descriptions are correct, proceed to step f.
   4. If your descriptions are not all correct, analyze the scenario again and correct your descriptions. Press the "Check" button. o this step until all descriptions are correct. Then proceed to step f.
   6. Observe what happens to the sand and pebbles in the stream. Compare the erosion of sediment in this scenario and the erosion of sediment in the Low-Gradient, Low-Velocity Streamscenario.
   8. When ready, press the "Pause" button and rite your observations in the space below Low-Gradient, High-Velocity Stream in the Data section of this guide.
   10. Draw what you see in Table Bin the Data section of this guide.
   12. Proceed to the next activity.
11. Model a high-gradient, low-velocity stream.
    1. Read the scenario.

You make a second research trip to observe pronghorn in the Colorado Rockies. You are next to a steadily flowing river, observing a local herd, when you start to feel raindrops fall from overhead. How does the river act right now upon the objects in it?

2. Analyze the scenario and characterize the slope of the stream, the amount of rainfall, and the terrain of the area.
4. Press the "Go to the model." button to open the modeling tool. You can always return to the scenario by clicking the "?" button in the top-right corner.
6. On the left panel, choose the description for each parameter that would correctly model the scenario.
8. Press the "Check" button.
   2. If all your descriptions are correct, proceed to step f.
   4. If your descriptions are not all correct, analyze the scenario again and correct your descriptions. Press the "Check" button. o this step until all descriptions are correct. Then proceed to step f.
   6. Observe what happens to the sand, pebbles, and rocksin the stream. Compare the erosion of sediment in this scenario and the erosion of sediment in the Low-Gradient, Low-Velocity Streamscenario.
   8. When ready, press the "Pause" button and rite your observations in the space below High-Gradient, Low-Velocity Stream in the Data section of this guide.
   10. Draw what you see in Table in the Data section of this guide.
   12. Proceed to the next activity.
11. Model a high-gradient, high-velocity stream.
    1. Read the scenario.

As you continue to observe the pronghorn herd, the storm overhead gradually grows and the rainfall becomes a steady flow, increasing the speed of the river. How does the river act right now upon the objects in it?

2. Analyze the scenario and characterize the slope of the stream, the amount of rainfall, and the terrain of the area.
4. Press the "Go to the model." button to open the modeling tool. You can always return to the scenario by clicking the "?" button in the top-right corner.
6. On the left panel, choose the description for each parameter that would correctly model the scenario.
8. Press the "Check" button.
   2. If all your descriptions are correct, proceed to step f.
   4. If your descriptions are not all correct, analyze the scenario again and correct your descriptions. Press the "Check" button. o this step until all descriptions are correct. Then proceed to step f.
   6. Observe what happens to the sand, pebbles, and rocks in the stream. Compare the erosion of sediment in this scenario and the erosion of sediment in the High-Gradient, Low-VelocityStream scenario.
   8. When ready, press the "Pause" button and write your observations in the space below High-Gradient, High-Velocity Stream in the Data section of this guide.
   10. Draw what you see in Table Din the Data section of this guide.
   12. Proceed to the final activity in this lab.
11. Model a low-gradient, high-volume stream.
    1. Read the scenario.

You make a third and final research trip to observe pronghorn in the flatlands. While making your observations, you are caught in a downpour. You hurry away from the nearby river to seek shelter. What will happen to the flow of water in the river, and how will the river act upon the objects in it?

2. Analyze the scenario and characterize the slope of the stream, the amount of rainfall, and the terrain of the area.
4. Press the "Go to the model." button to open the modeling tool. You can always return to the scenario by clicking the "?" button in the top-right corner.
6. On the left panel, choose the description for each parameter that would correctly model the scenario.
8. When you are ready, press the "Check" button.
   2. If all your descriptions are correct, proceed to step f.
   4. If your descriptions are not all correct, analyze the scenario again and correct your descriptions. Click on the "Check" button. o this step until all descriptions are correct. Then proceed to step f.
   6. Observe what happens to the sand, pebbles, and rocks in the stream. Compare the erosion of sediment in this scenario and the erosion of sediment in the Low-Gradient, Low-Velocity Stream scenario.
   8. When ready, press the "Pause" button and write your observations in the space below Low-Gradient, High-Volume Stream in the Data section of this guide.
   10. Draw what you see in Table Ein the Data section of this guide.
   12. When you have completed the lab, move to the next activity in the Virtual Classroom.

Directions 

Now that the lab is complete, it is time to write your lab report. The purpose of this guide is to help you write a clear and concise report that summarizes the lab you have just completed.

The lab report is composed of two sections:

Section I: Overview of Investigation

• Provide background information.
• Summarize the procedure.

Section II: Observations and Conclusions

• Include any charts, tables, or drawings required by your teacher.
• Include answers to follow-up questions.
• Explain how the investigation could be improved.

To help you write your lab report, you will first answer the four questions listed below based on the lab that you have just completed. Then you will use the answers to these questions to write the lab report that you will turn in to your teacher.

You can upload your completed report with the upload tool in formats such as OpenOffice.org, Microsoft Word, or PDF. Alternatively, your teacher may ask you to turn in a paper copy of your report or use a web-based writing tool.

Questions

Section I: Overview of Lab

1. What is the purpose of the lab?

1. What procedure did you use to complete the lab?

Outline the steps of the procedure in full sentences.

Section II: Observations and Conclusions

1. What charts, tables, or drawings would clearly show what you have learned in this lab?
   1. An appropriate title

Each chart, table, or drawing should have the following items:

1. Appropriate labels

1. If you could repeat the lab and make it better, what would you do differently and why?

There are always ways that labs can be improved. Now that you are a veteran of this lab and have experience with the procedure, offer some advice to the next scientist about what you suggest and why. Your answer should be at least two to three sentences in length.

Writing the Lab Report

Now you will use your answers from the four questions above to write your lab report. Follow the directions below.

Section I: Overview of Lab

Use your answers from questions 1 and 2 (above) as the basis for the first section of your lab report. This section provides your reader with background information about why you conducted this lab and how it was completed. It should be one to two paragraphs in length.

Section II: Observations and Conclusions

Use your answers from questions 3 and 4 (above) as the basis for the second section of your lab report. This section provides your reader with charts, tables, or drawings from the lab. You also need to incorporate your answers to the follow-up questions (from the Student Guide) in your conclusions.

Overall

When complete, the lab report should be read as a coherent whole. Make sure you connect different pieces with relevant transitions. Review for proper grammar, spelling, punctuation, formatting, and other conventions of organization and good writing.