Riparian buffers and wetlands control erosion, absorb runoff and mitigate natural pollutants.

These natural transitions between land and water capture, store, and release water and secure the quality of our waterways.

Students will discover that, in addition to gravity and topography, soil geology, vegetation, weather, and human development are factors in how the natural water cycle interacts with the watershed.

Students create a model that will demonstrate how water infiltrates a natural surface (soil) and how water percolates through the soil and is filtered (cleaned) in the process.

The unit slide deck has step-by-step instructions to create the filtration model.
You can create one model to observe as a class or have small groups create models to test different combinations of soils.

For an additional challenge students may research different types of soils (See The Dirt on Soil linked in the Materials list).
They can compare the different soils and combinations in terms of filtration, absorption, and runoff prone and draw conclusions about the efficacy of certain combinations on filtration, absorption and runoff.

INTRODUCE TERM “RIPARIAN BUFFER”

As students note the differences between a paved surface and a forested surface, use the term, “Riparian Buffer.” A riparian buffer is a zone of vegetation located along the bank of a waterway that serves to protect the water from harmful runoff. The roots of plants and trees in the riparian buffer stabilize the soil and control erosion. Without these plants, the soil will wash away leaving a less pervious surface! The plants slow water flow, reducing the threat of downstream flooding after heavy precipitation. By slowing water flow, riparian buffers allow more water to infiltrate the soil. As a result, more water enters the groundwater system where it is filtered as it slowly passes through the soil.

VIEW THE VIDEO

View this video: Riparian video (20 minute video but the first 7 minutes are recommended or this other shorter Riparian Buffer video (a 3-minute video based on the Lower Chippewa River) .

Compare images in video to modeling activity (do this if you show the video first or last).

READ ABOUT RIPARIAN BUFFERS

Encourage students to read articles about Riparian buffers. Some suggested articles are listed here:

Riparian Forest Buffers (Pennsylvania Department of Conservation and  Natural Resources)
Riparian Buffers for Wildlife (Penn State Extension)

Students will investigate how soils and vegetation affect how the water cycle interacts with the watershed.

Students may use this Riparian Model Observation Sheet  to assist with documenting their observations.

Choose one of the  demonstration models—the set up you choose may be determined by whether you have access to the Foss Landforms kit or the STC Land and Water kit. If you have access to either kit, use the stream table set up and you may choose to follow up with the paint tray demonstration. If you do not have access to a stream table, use the paint tray model.

If you have a stream table, use it for a class demonstration and then have students break into smaller groups using the paint trays, aluminum foil roasting pans or clear plastic sweater boxes

Stream tables can also be made from paint trays, aluminum foil roasting pans or from clear plastic sweater boxes. A drainage hole can be drilled or cut in the corner and covered with duct tape.

Stream tables can be filled with soil, sand, gravel and/or diatomaceous earth (if allowed) first as a demonstration.

The stream table model can be followed by a group activity using paint tray model , which does not require soil.  You can use  different types of sponges and/or some soil to model soils found under different types of vegetation.

Allow the students to explore the model themselves.

Encourage students to examine what happens in both models when the slope of the hill is varied; and how does vegetation protect those steep slopes?

If the students started this project in Learning Experience 1.2, the project may be updated to demonstrate an understanding of how soil composition and vegetation affect the interaction between the water cycle and the watershed.

Draw and label a model explaining how riparian buffers and wetlands benefit the health of a watershed.

Engineering – Engineer a drainage system
Flooded roads and flooded basements are a problem for an urban community. Students will design and build a drainage system to carry away excess water. Materials for drainage could include black oak tag and straws of different sizes.

Ecology: Plan a riparian buffer

Plant stream table with plants and experiment with rain on the riparian buffer.  As students observe that plants lessen the erosion. The teacher can also un-pot a root bound plant to demonstrate that roots hold the soil in place.