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Activity (Hands-On)Grades 6 - 8

Natural and Urban "Stormwater" Water Cycle Models

A two-part cutaway landscape diagram compares the water cycle before and after human development. Before, almost all rainfall is taken up by plants, evaporates or infiltrates through the ground. After conventional development (fewer plants and trees, more hard surfaces), surface runoff increases significantly while evaporation and infiltration into the ground decrease.What is the affect that humans and urban development have on the natural water cycle?

Students apply their understanding of the natural water cycle and the urban "stormwater" water cycle, as well as the processes involved in both cycles to hypothesize how the flow of water is affected by altering precipitation. Student groups consider different precipitation scenarios based on both intensity and duration. Once hypotheses and specific experimental steps are developed, students use both a natural water cycle model and an urban water cycle model to test their hypotheses. To conclude, students explain their results, tapping their knowledge of both cycles and the importance of using models to predict water flow in civil and environmental engineering designs. The natural water cycle model is made in advance by the teacher, using simple supplies; a minor adjustment to the model easily turns it into the urban water cycle model.

Civil and environmental engineers design and construct critical infrastructure for human communities—everything from roads and buildings to sewers and drainage ditches to dams and water and wastewater treatment facilities. Varying rates and occurrences of precipitation events affects both groundwater flow and surface runoff, which in turn, affects the volume of water that these designed infrastructures experience. Modeling the natural and urban "stormwater" water cycles is critical in predicting future surface and groundwater flow rates, as well as surface runoff rates. These predictions enable engineers to design infrastructure to survive and handle anticipated extremes. In this activity, students gain experience in developing and testing hypotheses to acquire a deeper understanding of the relationship between precipitation and resulting groundwater and surface runoff flows.

After this activity, students should be able to:

  • Develop hypotheses about how the intensity and duration of precipitation affects the runoff and groundwater flow in the natural water cycle model.
  • Develop hypotheses about how the intensity and duration of precipitation affects the runoff and groundwater flow in an urban "stormwater" water cycle and how it compares with the natural water cycle model.
  • Explain how humans have affected the natural water cycle and thus created an urban "stormwater" water cycle.
  • Test hypothesis using water cycle models and analyze results, using knowledge of the water cycle and its associated processes to explain the results.

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