Activity 2: Disappearing Drainage - the Incredible Shrinking Everglades Watershed

Materials

• original and present Everglades watershed maps (see Student Packet),
• string,
• rulers,
• graph paper,
• tag board or cardboard for mounting,
• cutouts of historic and present day Everglades watershed, and
• balance.

Procedure

1. Ask students to examine the two watershed maps provided in the Student Packet. Ask them to compare the maps, then list changes in the Everglades watershed from the original to the present day. Changes include the decline in watershed area, the addition of agriculture, the loss of wetlands, and the introduction of Water Conservation Areas.
2. Open a discussion of the changes in the watershed configuration and how these changes might be results of the impact of human settlement on the Everglades. Have the students brainstorm reasons why the watershed configuration has been changed.

   Note: Hold this discussion before students read the Student Packet text about the history of the Everglades.

   Tell students that their next task will be to determine the change in area of the Everglades watershed. Have students brainstorm about ways they can calculate the difference in the areas of the original and present watershed. Once they have generated a list of methods for calculating the areas, have students work in pairs or small groups to determine the change in watershed area. Have each group try a different technique from the list.

   Possible methods for determining the change in the area of the watershed include the following:

   • Use string to create shapes within the watershed that students will be able to calculate the area for.
   • Put the graph paper on top of the watershed map. Trace the outlines of the current and historic watersheds. Count the squares within the traced outlines. Compare the numbers of squares.
   • Cut out each of the historic and current day maps. Mount each of these on cardboard. Weigh the two pieces of cardboard. Compare the weights.
   • By using two copies of the map, overlay the present watershed on the original watershed. Find the area of the difference in the two watersheds, then weigh the difference (as suggested above) or use graph paper to count the squares within the difference.
3. Once the students have completed their measurements, have each group report their results. (The difference is less than 25 percent) Have the students suggest why different techniques might yield different results. Ask students which techniques they believe yield the best results.

Extension
In addition to changes in the watershed caused by the extensive water-management system, other land-use changes have affected the movement of water in south Florida. Draining and filling in wetlands for agricultural use and paving for extensive urbanization have increased runoff and the risk of flood.