Riparian buffers

Riparian buffers are the natural vegetation (plants) from the edge of the stream bank out through the riparian zone. The vegetative zone serves as a buffer to pollutants entering a stream from runoff, and provides habitat and nutrient input into the stream.

Perhaps one of the most important qualities of the riparian buffer zone is its ability to control erosion, and thus, to prevent sediment pollution. Movement of sediment and silt will affect the stream banks in the immediate area, as well as the water quality and ecology downstream.

Riparian Buffer Experiment

How do riparian buffers help to protect water? In this activity you will simulate a stream bank with vegetation and a stream bank that has eroded. Which habitat holds and filters water?

Materials

• Two empty, clean 2-liter drink bottles, one per experiment

• Two clear jars, one per experiment

• Coffee filters

• Several kinds of soil – sand, clay, gravel, etc. (cotton balls can be used as a substitute)

• Dead leaves

• Fresh leaves

• Grass

• Materials collected from nature – small rocks, twigs, pine cones, etc.

• Large rocks (must be able to fit into bottle)

• Permanent markers

• Muddy water (reuse water from Mud Shakes activity, add water to make 16 oz)

• Measuring cup

Preparation

Cut the bottom off the 2-liter bottles so that the top portion of the bottles can be placed upside down to drain into your clear jars.

Collect fresh leaves and grass, and dried leaves and grass from outside.

Procedure, Part 1

1. Hold the bottle with the spout pointing down and label it Riparian Zone.

2. Place the coffee filter in the bottle just over the spout.

3. Layer the gravel and sand (if you do not have gravel and sand you can substitute cotton balls).

4. Make a layer of leaves.

5. Make a layer of grass.

6. Continue layering using leaves, grass, and other items you found in nature until bottle is full.

7. Place the layered bottle into the glass jar with the spout pointing down.

8. Measure one cup (8 oz) of water from your mud shake jar.

9. Slowly pour the muddy water into the layered bottle.

Observe the movement of water.

Procedure, Part 2

1. Hold the bottle with the spout pointing down and label it Eroded Bank.

2. Place the bottle into the glass jar with the spout pointing down.

3. Carefully add the large rocks to the bottle.

4. Measure one cup (8 oz) of water from your mud shake jar.

5. Slowly pour the muddy water into the bottle.

Observe the movement of water. How quickly did the water move through the two systems? Which filtered and cleaned the water better; the riparian zone or the eroded bank? How does the amount of soil differ in the two clear jars?

This activity shows how the natural movement of water changes within built environments. Groundwater is filtered through Earth via soils and rock to supply clean water to streams and aquifers. How does this change when the land is altered?

You may be wondering why the Riparian Zone experiment had some levels of soil in the results. Soil erosion is also a natural process, and rivers and creeks naturally hold soil, deposit it in some places and pick it up in other places. Soil erosion is a problem when it is accelerated because of high water flow and human disturbance (i.e. farming, construction) of the land surrounding our streams. When the amount of soil in the creek exceeds the ability of the water to transport it downstream, the excess soil can clog rocks and gravel beds, which are important habitat for fish, insects, and other river life. When excess soil drops out of the water and remains in the stream, the process is known as sedimentation.

Riparian Buffers Vocabulary

Riparian Buffer Zone: The vegetated area near a stream, usually forested, which helps shade and partially protect the stream from the impact of adjacent land uses.

Pervious: Allowing water to pass through; permeable.

Impervious: Not allowing fluid to pass through.

Erosion: Water erosion is the detachment and removal of soil material by water. The process may be natural or accelerated by human activity. The rate of erosion may be very slow to very rapid, depending on the soil, the local landscape, and weather conditions.

Sedimentation: The process of soil particles settling to the bottom of a body of water.

Natural Ecosystems Keep Water Healthy!