This classroom activity will give students a hands-on experience of the differences between a karst and non-karst watershed. Individuals should come away with an understanding of how and why a karst topography is more vulnerable to pollution.
Divide students into teams of 3 or 4. Their task is to recreate a watershed found in both a karst and non-karst area, according to the directions below:
Constructing the Non-karst Watershed
Once groups have completed the two watersheds, establish the different features represented in their models. They should recognize bedrock, soil, and sinkhole. After geographical features have been established ask students to predict what would happen when it rained.
Next have each group simulate "rain" by pouring about 1/4 cup of water over each of their models. Once it has rained on each group's karst and non-karst watersheds, discuss what students saw in their models. After everyone understands the relationship between the surface and sub-surface, have students brainstorm what other substances can get into the groundwater from the surface.
To represent pollutants, sprinkle the drink mix across the top layer of each model. Brainstorm what will happen when it rains next. After all input, students should simulate the next rainstorm. Once the rain has ended ask students what they saw in each of their models. Leading questions such as "Which watershed had a polluted water table first?" should be enough to wrap everything together for individuals.
Follow up with a discussion about how to prevent groundwater pollution. Topics like better education of the public and groundwater monitoring should be part of the discussion.