Lesson 4: Splash Zone: Erosion in Action

Erosion Erosion is the wearing away of land by natural forces. Erosion is a natural process. Erosion can be increased or decreased by human activity.

Erosion Natural Bridge- created by water erosion Mammoth Cave- created by water erosion Tell students that these are examples of some of the positive effects due to erosion.

Erosion Erosion can be increased or decreased by human activity. Water mixed with the soil from the ground run down hills and into our water bodies, which can be harmful to the environment.

Weathering Weathering is the breaking down of rocks Different types of weather can push and wedge spaces between rocks that cause it to break down over time. Weathering can occur due to: Freezing Thawing Plants Wind Pressure Physical weathering is the breaking down of rocks due to water, wind and ice.

Erosion and Ecosystems Some erosion is needed for healthy ecosystems. An ecosystem is a complex set of relationships among living resources, habitats or residents of a region. Small amounts of sediment can act as soil and help grow healthier crops. Large amounts of sediment from erosion can be very hard on our stream ecosystems because it can block sunlight for plants and suffocate animals.

Protecting the Environment To help keep plants and animals safe when hill sides start to erode, vegetation can be planted. Vegetation includes various plants and vegetables that grow in a certain area. Vegetation allows soil to stay in place so sediment does not enter the waterways in large quantities. Sediment is the material, soil and debris deposited by water and the number one cause of pollution in the waterways.

Scavenger Hunt Activity Today, we will go outside to find evidence of erosion at our school. You will have 15-20 minutes to find the given items. *Bonus: List any potential point source and non-point sources of pollution. Review definitions of point source and non-point source pollution: Point source: one can identify the point where pollution is entering into the water. Most point source pollution comes through a pipe. A simple way to remember this is you can “point” out where point source pollution is coming from. Non-point source pollution: one cannot identify the source of the pollution. The pollution enters the bodies from various areas. You cannot detect or point out where it is coming from.

Runoff Runoff is the portion of precipitation that does not get absorbed into the ground and reaches streams, often with dissolved or suspended material like dirt and sediment. The process of runoff

Scavenger Hunt Activity What evidence of erosion did you find? Were the cracks in the sidewalks and potholes always there? What caused them? How do humans increase erosion? How can we decrease erosion? What items from our scavenger hunt help direct storm water away from buildings and roads? Discuss how water moving over these surfaces during storms picks up sediment and rocks in weakened pavement and carries it along. During the winter, water freezes in these small cracks, expands and then melts. This processing breaks off pieces a little bit at a time, but eventually these small pieces lead to bigger consequences. Ask the students. “How do humans increase erosion and how do we try to decrease erosion?” Surfaces that don’t allow water to filter through like concrete and blacktop increase storm water runoff and increase erosion. The faster the storm water flows the more sediment, rocks and pollution it can pick up. We can slow the water down from storms by adding more vegetation. It helps to break a raindrops impact on soil and reduces runoff by soaking up water. Wetlands and ponds help to store water from storms which reduces erosion. This also reduces pollution from damaging our complex ecosystems. Ask the students, “What items in the scavenger hunt help to direct storm water away from our buildings and roads?” Answer should be: gutters, drainpipes and storm drains. Ask, “Why do we try to control storm water?” We try to redirect storm water to protect our communities from flooding, landslides and pollution in our streams.

Splash Zone Each group will have: “Rain dropper” Recorder Observers Explain the instructions for the Splash Zone activity that is located in your Teacher Guide . Allow the students to make a hypothesis on their worksheet. Discuss the graphs once they are complete Make the connection that one drop of water can cause soil to travel, so imagine what happens when it rains and many drops of water move soil.

Extended Response Questions Examine the line graph you made carefully and think about what the trend of the graph is. What does this graph show about your experiment? How do you think a rain storm would affect a bare patch of soil at a construction site? What about cut grass? A forest? Have students answer questions in workbook.