Areas of Science Geology
Difficulty
Time Required Very Short (≤ 1 day)
Prerequisites None
Material Availability Readily available
Cost Very Low (under $20)
Safety No issues

Abstract

Have you ever seen a river from far above? It is fascinating how they carve their way through the landscape. But what makes the water in a river flow? Where does a river start and end? And why is it that rivers usually have lots of turns or bends and almost never flow straight? In this science project, you will make river models using aluminum foil and water to explore how water flow inside a river changes based on its shape.

Objective

To make river models and find out how water flow changes with different river shapes.

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Credits

Svenja Lohner, PhD, Science Buddies

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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Lohner, Svenja. "Model Water Flow in Rivers." Science Buddies, 23 June 2020, https://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p049.shtml. Accessed 21 Sep. 2020.

APA Style

Lohner, S. (2020, June 23). Model Water Flow in Rivers. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p049.shtml


Last edit date: 2020-06-23

Introduction

There is lots of water on our planet! About 71% of the Earth's surface is covered by water. This water can be found in huge oceans, tiny ponds, large rivers, or small streams. Water can shape landscapes gradually over long periods of time. Many rivers such as the Colorado River, for example, have carved huge canyons into the landscape along their path (Figure 1).

 Picture showing the Colorado River flowing through the Grand Canyon.
Figure 1. The Colorado River has carved a huge canyon out of the rocks over millions of years, demonstrating how water can shape and reshape land over time.

But how is water able to shape and reshape landscapes? Water comes from rainfall, snowmelt, groundwater, or springs. Some of this water soaks into the ground. The rest flows across the land as runoff into rivers, streams, and lakes. On its way, water drags sediments such as soil and sand with it. Once these sediments end up in a river they are carried along with the flowing water and grind the rocks at the bottom of the river slowly creating a deeper and deeper riverbed.

Rivers are usually confined to a riverbed that looks like a long channel. They can shape the landscape in different ways as their channel can be meandering (very curvy), braided, or straight, as shown in Figure 2. The shape of a river is a result of the constant movement of the water inside the riverbed. This water movement is due to gravity as a river always travels downhill from a higher area to a lower area. Many rivers for example start high up in the mountains and then flow all the way down into the ocean.

 Three images showing aerial views of different river channel patterns. The left images shows a braided river channel, the middle image shows a straight river channel, the right image shows a meandering river channel.
Figure 2. A river channel pattern can be braided (left), straight (middle), or meandering (right).

How fast the water flows inside a river is also very important. The speed at which water moves through its channel can change along the course of a river. For example, it might speed up where the river gets narrower and slow down where the river gets wider. It can also change with time. For example, a river might move faster on a rainy day when there is more water flowing. The river could also flow faster in areas where it is steeper (it has a steeper slope).

Hydrologists are scientists that study water bodies and their water flow. They often use models in addition to outdoor observations to gather information. Some of these models exist on the computer whereas others are physical replicas of real rivers. Both are great tools to study rivers. This video shows you how scientists at the UC Berkeley use a river model for their research.

In this project, you will become a hydrologist and make several river models to find out how the shape of a river affects its water flow. Ready to get your hands wet?

Terms and Concepts

  • Runoff
  • Sediment
  • Riverbed
  • Meander
  • Braided
  • Speed
  • Slope
  • Hydrologist
  • Model

Questions

  • How do rivers shape the land?
  • Where does the water in rivers come from?
  • Where do rivers start or end?
  • What do hydrologists do?

Bibliography

For help creating graphs, try this website:

  • National Center for Education Statistics, (n.d.). Create a Graph. Retrieved June 25, 2020.

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Materials and Equipment

  • Outside space
  • Aluminum pan, 19.5" x 11.5" x 3.5"
  • Aluminum foil
  • Tap water
  • Marker
  • Paper or plastic cup, 16 oz (2)
  • Tape
  • Timer or stopwatch
  • String
  • Scissors
  • Nail or screw
  • Ruler
  • Adult helper
  • Boxes or books
  • Paper towels
  • Pencil
  • Lab notebook
  • Optional: Food coloring

Experimental Procedure

Preparing Your River Model

  1. With a permanent marker draw a line on the bottom of the pan about 2 inches into the pan from one of the short ends.
  2. With the help of an adult, use the nail to poke a couple of small holes into the bottom of the pan behind the marked line (Figure 3).
 End section of the aluminum pan showing the marked line as well as the poked holes in the bottom of the pan behind the line.
Figure 3. Holes at the bottom of the aluminum pan will help drain the water.
  1. Add 400 mL of water to one of the plastic cups and mark the water level with a permanent marker inside the cup.
  2. Remove the water from the cup. Then, with the help of an adult, use the nail to poke a small hole into the side of the plastic cup, about one inch from the bottom as shown in Figure 4.
 A cup with a small hole at the bottom of its side wall.
Figure 4. Water will flow out through a hole in the cup.
  1. Fold three different river channels out of the aluminum foil. Each river should be about 2 inches wide. Make one river channel straight, one a bit curvy, and one very curvy. Some examples are shown in Figure 5.
 Three aluminum pans with a straight, a curved and a slightly bent aluminum foil river model.
Figure 5. Examples of several river models.
  1. Make sure that all the river models fit inside the aluminum pan. They should start at the far end of the pan and end at the line that you marked inside the aluminum pan.

Measuring Water Flow Depending on the River Shape

  1. Find a space outside where you can set up your river experiment. It should be a place where the water from the pan can drain directly onto the floor or the grass, etc. Note: If you cannot go outside place a water collection container such as a small bowl or a tray underneath the end of the aluminum pan that has the holes in it.
  2. In your lab notebook, make a table similar to Table 1. Write the names of the three river shapes that you made into the first column. You could, for example, name them "straight", "slightly curved" and "very curvy".
      River shape       Time #1 Time #2 Time #3
    
    
    
Table 1. Data table to write down how long it took for the water to flow from the start of the river to its end dependent on the river shape.
  1. Put the first river model into the aluminum pan, so that it ends at the marked line and starts at the opposite side as shown in Figure 6. Secure the river model in place with tape.
 Aluminum pan with a lightly curved aluminum foil river model inside.
Figure 6. The river model ends at the marked line starts on the opposite side of the aluminum pan.
  1. Once the river model is placed into the pan, smooth out the aluminum riverbed, so that it is as flat as possible. This is very important as you want to avoid that water pooling behind a foil wrinkle instead of flowing down the river.
  2. Before you start with the water flow, measure the length of the aluminum channel with a piece of string. Do this by placing a string in the middle of the riverbed as shown in Figure 7. Cut the string where the aluminum channel ends. Mark the string, so you know which river shape it belongs to.
 Aluminum pan with a lightly curved aluminum foil river model inside. The length of the river model is measured by laying a string inside the riverbed.
Figure 7. A string is used to measure the length of the river.
  1. Place the top end of the aluminum pan on a book that is about 1 inch high to create a slope for the river. The end with holes should be at the bottom. Note: If you use a collection container, make sure that the top end of the aluminum pan is 1 inch higher than the bottom end with the water collection container.
  2. Fill the cup with water up to the mark. Cover the little hole with one of your fingers, so the water does not flow out. Optionally, you can add food dye to the water, to see the water better.
  3. Position the cup at the top of the aluminum pan, so that the hole lines up with the river channel. The final experiment setup is shown in Figure 8. If necessary, place your cup on the second cup or a box to make it the right height.
 Inclined aluminum pan with the river model inside. A plastic cup is placed on top of boxes next to the aluminum pan, so that the water can flow from the cup into the aluminum river.
Figure 8. Experimental setup for testing the water flow in the different river models. Note: This setup does not show a water collection container.
  1. Have your stopwatch ready. Then remove your finger from the hole. As soon as the water starts flowing into your river channel, start your stopwatch. Note: If the water from the cup does not flow into the river channel, reposition the cup until it does. Then fill it up to the mark with water again and let the water drain from the aluminum river before starting again.
  2. Observe how the water flows along the river and stop the stopwatch as soon as it reaches the marked line at the end of the river channel. Write down the time it took for the water to travel down the river into your data table. Round your time to the nearest second.
  3. Remove any remaining water from your river model by turning the pan upside down and tapping it gently. You can also use a paper towel to carefully dry the inside of the aluminum channel. Then reposition the pan on the 1-inch book as you did before.
  4. Refill the cup to the marked level with water and cover the hole with your finger.
  5. Repeat steps 8–12 two more times. Each time write your measured time in the data table. Dry out the aluminum pan in between each trial, but make sure not to change the position of your river model inside the pan. Scientists repeat every measurement several times to confirm their results.
  6. Once you are done with your first river model, remove it from the pan, dry the pan out with paper towels and repeat steps 3–13 with the other two river models. Make sure to write each of your measured times into the data table. Make sure to smooth out the aluminum riverbed for all river models before you start your measurements.

Analyzing your Data

  1. Look at your data in Table 1. Did you get the same measurements for each trial? How different or similar are your measurements for each trial? If the measurements are all very similar, you know that your data is correct. If they are very different from each other, then something must be wrong with your measurements or your test setup.
  2. Making graphs may help you visualize your data. If you need help creating graphs, try the Create a Graph website.
  3. Based on your results in Table 1, make a single bar graph for each river shape. Graph the three measurements (or trials) you did for one river shape on the horizontal axis and the time it took for the water to flow down then river for each trial on the vertical axis. You can also write the measured values above the bar for each trial. Do not forget to label the axes and add a title. An example showing how to graph your data is shown in Figure 9. Here is a a graph template to use.
 Bar graph showing the results for a curved river with the three trials on the horizontal axis and the water flow time in seconds on the vertical axis.
Figure 9. An example bar graph showing all three water flow measurements for the river model that was slightly curved.
  1. Take all three strings that you cut for each river shape and place them next to each other. Which river is the longest? Which one the shortest? Can you explain why?
  2. Look at the graphs and the strings for all three river shapes. Can you observe a trend? How does the shape of the river affect its water flow? Can you explain your results?
  3. Based on your results can you make a general statement about how the water flow in a river is affected by its shape? Such a statement could be:
    • In a very curvy/slightly curved/straight river, water takes ____________________ [fill in blank] to travel down the river because _________________________________________ [fill in blank].
.

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Variations

  • Test more river shapes in addition to the ones that you have chosen for this project. How do your results change for each one?
  • Measure how the slope changes the water flow in the river. Instead of placing the aluminum pan on a 1-inch high book, use a 2-inch, or 3-inch high book. How does the water flow change if you change the slope of the river?
  • Model how water flow changes the shape of a river channel. You can find instructions on how to do this experiment in Science Buddies' project Go with the Flow: Model Rivers with Cornmeal, Sand, & Water.
  • Find out how much sediment is carried along the river depending on the speed of its water. Choose one of your river models and put it in the aluminum pan. Tape a coffee filter at the end of the river between the marked line and the end of the aluminum pan. The coffee filter should cover the holes that you poked into the bottom of the aluminum pan as well. This time cover the bottom of your river channel with a layer of sand. Fill the cup to its mark and let the water flow until the cup is empty. Any sand that is washed away with the river should be collected on the coffee filter. You can measure the amount of washed away sand by removing the coffee filter and weighing it on a scale. Repeat the experiment with different water speeds. You can vary the speed of the water flow by letting the water flow out of different sized holes from the cup. The larger the hole is, the faster the water will flow out.
  • Try to find out more about how rivers are formed. Read about different rivers on our planet. Which river is the longest, which one the widest? Which one has the fastest water flow?

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