20 March Science 8 River/watershed simulation–gather data

HAVE A PLAN that each participant in the group knows about. Each member of the group should have a role and responsibilities. Each member of the group should have access to all group data. Each member of the group should be familiar with all aspects of the simulation (everyone should have read the blog an instructions carefully–several times).

  • What observation will you make?
  • How will you observe–describe? count? measure?
  • How will you record your observations?
  • How will you investigate variables? (How will you control for starting conditions? Inclination of table, saturation of material in tray, rate of water flow, etc.)
  • What about things that are dynamic, that change during the simulation(for example, as the level in the water reservoir lowers, the flow out of the siphon lessens)?

See these notes from the initial days of the activity:

  1. Learn how to operate the siphon.
  2. Learn how to make observations:
  • Depth at head, middle, mouth of stream
  • Width at head, middle, mouth of stream
  • Ratio of Depth to Width at head, middle, mouth of stream
  • Velocity (distance/time—small floating object moving with the current)
  • GradientValley side angle—cross section
  • Stream type / Stream age
  • Keep full and complete records/notes/data/reasoning/lists of questions (including images, sketches, and short video clips) on how you set-up and run each trial and what you observe happening in your streams. Your group will make a multimedia presentation on your investigation of streams. (See below)
  • Pay attention to how the water and sand move at both smaller and larger scales.
  • Identify any landforms/riverforms and note what leads to their appearance, modification, and disappearance (alluvial fan, canyon, waterfall, meander, etc.)
  • Link patterns of development as well as particular features you observe in your streams with real streams.

Try to get rich results for Activity 1 and Activity 2. It is not necessary to try Activity 3 unless you have totally exhausted the possibilities for 1 and 2. Activity 3 is listed in a previous blogpost.

Activity 1 – Flat, Inclined Terrain Model

  1. Create a slightly inclined plane.
  2. Predict what will happen when the water is turned on. Turn on the water so that it pours in a steady, moderate stream.
  3. Record observations in 5-minute intervals for about 20 – 30 minutes. Include sketches and photos at each interval. You may try 30-second video segments, too. Try to make a time lapse record.
  4. Turn the water off after 20 – 30 minutes. Discuss the similarities or differences between the two models. What were their observations? Did each model have the same result? How did the landscape influence the course of the river?
  5. Refill the water jug to prepare for the next experiment.

Activity 2 – Hills and Valleys Landscape Model

  1. Remold the sand in the tray to create a surface with several hills and valleys.
  2. Predict what you think will happen in this scenario. Will the same river formation happen? Turn on the water so that it pours in a steady, moderate stream. Table is at same inclination as model 1.
  3. Record observations in 5-minute intervals for about 20 – 30 minutes. Include sketches and photos at each interval. You may try 30-second video segments, too. Try to make a time lapse record.
  4. Turn the water off after 20 – 30 minutes. Discuss the similarities or differences between the two models. Did each model have the same result? How did each landscape influence the course of the river? How were the results different or the same, compared to the flat and inclined model?

What’s Happening?
If you’ve been in mountains and seen a spectacular waterfall, you probably were looking at the beginning of a river. Most rivers begin on top of mountains where water from rain or melting snow collects. Under the influence of gravity, this water flows downhill to form brooks, streams or rivers. As the stream or river flows downhill, it can change the landscape by eroding rocks and depositing sediments.

Some observations that can be made by comparing both models are:

  • The speed of the water flowing downhill will be affected by the degree of incline, and any structures or topographical features in its path.
  • The faster the water flows, the more erosion occurs.
  • Water flowing downhill moves and deposits sand at the bottom of the river. The faster the water flows, the more sand will be deposited at the bottom. A delta at the mouth of a river forms in the same way.

Although the formation of the “rivers” in this activity appeared very quickly, in reality rivers can take millions to billions of years to form a path from land to sea.

More Discussion

  • How would the river formation be affected if the water continued to flow for one hour, two hours or three hours?
  • How would the river formation or pattern be affected if the sand were replaced with soil?
  • How can the stream table be used to simulate a landslide? What variables could be changed to induce a landslide?
  • What are some kinds of man-made structures or human activities that can affect a river system? Name rivers in India and in home countries that are being affected in these ways.
  • Name an important Indian and and important home country river that does not originate in mountains.

On Friday–Prepare for Presentation to take place the week after break.

Presentation:

You and your group will need to decide how to illustrate, describe, and explain your stream simulation investigation in a multimedia presentation. Judicious use of photos, videos, diagrams, graphs, and data are an important part of the presentation. Be sure to attend to the following:

  • Experimental methods
  • Control of variables
  • Repeated trials
  • Observables (descriptive, quantitative—counts and measures)
  • Analysis and Interpretation
  • Explaining the observed simulated river landforms—their origin and development–principles and mechanisms of the effect of flowing water on the landscape and the effect of the landscape on the way water flows)
  • Links to actual river landforms
  • Tests of the explanations (evidence is gathered to support or challenge explanations)
  • Organization and display of data
  • Clarity, completeness, and accuracy of the presentation
  • Big ideas—significance of watershed to the water cycle; importance of people understanding watersheds with regard to human impact on the environment

About rfrazier

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