Those Darn Dams
People have built dams for thousands of years. Modern dams are designed to be multi-purpose. They provide irrigation, flood control, water supply, electric power and recreation. Hydroelectric dams use the energy of falling water from reservoirs to produce electricity through the use of turbines.
There are several types of dams which
include rock, timber, embankment, masonry, earthen and concrete. Construct
an earthen dam and find out whether you can make it hold water! You
will need:
- 1/2 gallon milk carton (cut one side and the top off of the carton)
- 6 – 8 craft sticks, cut in half
- Pottery clay
- Sticks, gravel, dirt, pebbles
Glue the craft sticks together, side by side until the form a wall. Glue the wall to the middle of the "floor" of the milk carton. After the glue dries, form a triangle shape over the wall with the clay. Add sticks, gravel or dirt over the clay layer, ending with a top layer of close fitting pebbles (in a real dam, these are known are riprap). Note: You may want to mix you "loose" materials with clay to help them be more cohesive. Press all of the layers firmly down so that it forms very tight layers.
After you've constructed your dam, let it dry for 5 – 7 days. Then slowly pour water behind the dam. Does your dam hold water? Could wildlife survive in your type of dam?