Pre-Visit Activities : River Erosion : Procedures
Sixth - Eighth Grade Online Curriculum : Watersheds

Materials 

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Procedure

  1. Students will observe infrared aerial photographs of the mouths of the Santee, Pee Dee and Edisto Rivers as well as the joining of the Saluda and Broad Rivers to form the Congaree River to examine the sediment load of each. (Sediment in the rivers will look white in the aerial photos. The whiter it is, the more sediment that is present. Clear water will be very dark blue). The teacher will pose the questions: how does sediment get into these rivers and how is it transported by the rivers? Why do some rivers have more sediment than others? The class will discuss their thoughts and write their ideas on the board.  

  2. Students will be broken up into small groups, with at least three members. Each group will come up with a hypothesis as to why they think sediment gets into water. Each group will be shown the materials available to them and will be told to use these to try to determine whether their hypothesis is correct or not. Each group should write their hypothesis down, list the materials they used, describe the experiments they conducted, record the data and observations they collected and write a conclusion describing whether their experiments supported their hypothesis or not.  

Helping to Facilitate the Students
If students are floundering while attempting to come up with an experiment, here are some suggestions as to where the activity might go. Sediment is carried by moving water. The faster the water moves the more and larger sediment it can carry. To look into this, students can lay sediment in the middle of a tray and then continuously raise the elevation of one end of the tray. At each elevation, students can pour water on the tray and observe how increased velocity affects the amount of sediment transported. Students can conduct similar experiments with water volume. As water volume in a stream increases, the water velocity increases. Students can conduct experiments to show how increasing the volume of water in the tray will increase the amount of sediment that is carried. Different sediment sizes require different rates of water velocity to be transported. Students can be informed that most of the soils in South Carolina are made of clays and sands and can experiment by pouring water on both of these sediment sizes as well as gravel to see which is transported the easiest.

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Follow-up questions
(Students may want to create experiments to answer these questions.)