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Pre-Visit
Activities : River Erosion
Procedures
MAIN
| OBJECTIVES | STANDARDS
| BACKGROUND | PROCEDURES | ASSESSMENT
| RESOURCES
Top
Procedure
- 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.
- 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.
Top
Follow-up questions
(Students may want to create experiments to answer these
questions.)
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How do dams affect the water velocity and sediment transporting
capacity of rivers?
- How
does flowing into large bodies of water such as reservoirs
or the ocean affect the water velocity and sediment
transporting capacity of rivers?
- How
do rivers bring salt to the ocean?
- How
do rivers replenish the surrounding area with nutrients?
- If
rivers can carry sediment, can they also carry trash
and pollutants?
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