Pollutants & Ground Permeability: The Other Water Cycle
Runoff from a storm water drain.Copyright U.S. Geological Survey
For students who have already been introduced to the water cycle, this lesson is intended as a logical follow-up. Students learn about human impacts on the water cycle that create a pathway for pollutants beginning with urban development and joining the natural water cycle as surface runoff. The extent of surface runoff in an area depends on the permeability of the materials in the ground. Permeability is the degree to which water or other liquids are able to flow through a material. Different substances such as soil, gravel, sand and asphalt have varying levels of permeability. In this lesson, along with the associated activity, students learn about permeability and compare the permeability of several different materials for the purpose of engineering landscape drainage systems.
Landscape engineers, environmental engineers and civil engineers consider the permeability of the ground around major construction projects when designing drainage systems and altering terrain. Human infrastructure has historically reduced permeable materials in exchange for non-permeable materials, resulting in increased stormwater runoff and pollution concentration. Carefully planned systems can reduce pollution due to runoff as well as prevent flooding.
After this lesson, students should be able to:
- Identify different materials based on their level of permeability.
- Identify which materials (permeable vs. impermeable) would be better for development of agriculture in various (urban vs. rural, coastal vs. inland) settings and why.
- Describe how pollutants concentrate and runoff over non-permeable surfaces.
- Describe some human impacts on the natural environment.
- Learn how to link anthropogenic pollutants and contaminants to local environmental issues such as water quality and estuary health.
- Describe how non-permeable surfaces cause runoff and affect the health of local watersheds.