Sand dunes and beaches change with the weather. Wind and water can blow or wash dunes and beaches away over time. In this invesitigation you build sand dunes and test the effect wind and water has on their shape and size.

 

What you need:

  • A wind source (e.g., a blow dryer or air mattress inflator)
  • 3 different colors of sand from a craft store (red, blue and white work well), 1 large container of red and blue and 2 large containers of white.
  • Tops from copier paper boxes
  • Sun or saftey glasses to keep the blowing sand out of your eyes.
  • What you do:

    This could get messy so do this outdoors on the porch, in the driveway or the garage.

    Place the copier paper box top upside down on a flat surface.

    1. Cut or tear 2 corners of the box top lip at one end of the box top. Press the loose section of the lip down flat. The other 3 sections of the lip should remain standing.
    2. Create a "dune" by pouring 1/2 of the red sand in a straight line across the open end of the box top.
    3. Using 1/2 of the blue sand, create another dune of the same size just behind the red one.
    4. Using the white sand, create 2 more dunes, each the same size as the previous ones, behind the blue one.
    5. Predict how the sand will be affected by a wind blowing directly into the dunes from the open end of the box. 
    6. Standing facing the open end of the box, use the wind source to create a wind blowing directly into the dunes. Start with a fairly low wind speed and then increase it. Continue until about half the red sand has been blown away. Note any changes in the behavior of the dunes and the particles of sand at different wind speeds.
    7. Observe the distribution of the colored sand particles. Are there any differences in the where the red and blue particles landed or how much of each of the dunes was blown away?
    Now pick one of these dune investigations to do with the rest of your sand:
    1. How does the shape of the dunes affect their erosion? Investigate by building semicircular or serpentine model dunes and applying wind to them.
    2. How do changing wind directions affect dune erosion? Find out by blowing wind across the dunes from different directions.
    3. How does water influence wind erosion of the dunes? Spray the dunes with varying amounts of water before applying wind to them. Note: The food dyes are water-soluble and may separate from the colored sands. Take precautions to avoid stains.
    4. How do plants influence dune erosion? Use dried lichens to model shrubs on your dunes. Apply wind to the dunes and see what effect the shrubs have on erosion.
    5. Do plants act only as barriers at the surface, or do their roots also affect dune erosion? Look into this question by partially burying a shrub in a dune and setting another shrub on the surface. Apply wind to the dune and then compare the erosion around the 2 shrubs to see if there is a difference.

    What else do you want to know about sand dunes or beach erosion? Do some research and see what you can find out.