Natural and Urban "Stormwater" Water Cycles
How does the natural water cycle (top) differ from what you would find in your neighborhood?Copyright Commonwealth of Massachusetts http://www.mass.gov/envir/smart_growth_toolkit/pages/mod-lid.html
Through an overview of the components of the hydrologic cycle and the important roles they play in the design of engineered systems, students' awareness of the world's limited fresh water resources is heightened. The hydrologic cycle affects everyone and is the single most critical component to life on Earth. Students examine in detail the water cycle components and phase transitions, and then learn how water moves through the human-made urban environment. This urban "stormwater" water cycle is influenced by the pervasive existence of impervious surfaces that limit the amount of infiltration, resulting in high levels of stormwater runoff, limited groundwater replenishment and reduced groundwater flow. Students show their understanding of the process by writing a description of the path of a water droplet through the urban water cycle, from the droplet's point of view. The lesson lays the groundwork for rest of the unit, so students can begin to think about what they might do to modify the urban "stormwater" water cycle so that it functions more like the natural water cycle. A PowerPoint® presentation and handout are provided.
The hydrologic cycle is the central focus of hydrology. In fluid mechanics, the application of the basic principles of mass, momentum and energy to a fluid flow system is accomplished with a control volume. A comprehensive understanding of the hydrologic cycle is important for civil and environmental engineers who design critical infrastructure systems such as stormwater ponds, control structures, earthen dams, levees, treatment facility influent and effluent; sheet, overland and channelized flows; and stream flow and base flow. They are responsible to account for stormwater runoff, infiltration rates and treatment processes that occur as a result of the stochastic nature of storm events.
After this lesson, students should be able to:
- Discuss the planet's limited freshwater resources.
- Explain how water transforms from one phase to another within the natural water cycle.
- Describe how humans affect the movement of water within the urban water cycle.
- Explain how reaction rates and transformation processes are critical to engineering design.