Cascading effects of erosion

This exercise is a part of Educator Guide: Shores Still Reeling from 2010 Oil Spill / View Guide

Directions for teachers:

Have students read the Science News article “The Deepwater Horizon oil spill ruined long-term shore stability” and answer the questions below. A version of the article “Shores still reeling from 2010 oil spill” appears in the March 25, 2023 issue of Science News.

If you’re introducing the concept of erosion, pair this discussion with How Erosion Alters the Landscape, a hands-on activity that allows students to explore factors that contribute to erosion.

Oily erosion

1. What disaster is referenced in the article? In one sentence, describe what happened.

The Deepwater Horizon oil spill of 2010 pumped nearly 800 million liters of oil into the Gulf of Mexico.

2. Discuss the impact of the Deepwater Horizon disaster on the local ecosystem and the surrounding region. Name both short-term and long-term effects on the ecosystem as a result of the disaster.

A short-term effect was the immediate deaths of humans and the deaths of animals and plants due to the oil spilled into the water. A long-term effect was the increase in shoreline erosion due to the oil seeping into the soil and killing the marsh plants, which weakened the soil.

3. How did the disaster drive erosion in the area? How long did it take scientists to understand the impact? Explain what the researchers measured and the timeline.

The oil seeped into the soil on the coast and killed the marsh plants, which weakened the soil’s strength, making it more susceptible to strong winds and rains caused by storms. The series of events increased erosion. Scientists used a sheer vane to test soil strength and examined satellite images of the coastline to measure erosion. The researchers began their field tests immediately after the oil spill and continued testing the soil for the next eight years. They also analyzed satellite images taken over 23 years.

Impacts of erosion on humans

4. Erosion is a natural phenomenon that occurs over time. Give an example of natural erosion that you have seen or read about. What do you think caused the erosion in your example?

Student answers will vary but could include the formation of riverbeds, canyons, mountains or cliffs along a shore. In the cliff example, students might say ocean forces altered the rocks, soil and sand.

5. Search the Science News or Science News Explores archives to find a specific example of a time when erosion impacted humans. Explain the impact. What were the short-term and long-term effects of your example? Provide a link to the story.

Student answers will vary. One example of erosion’s impact involves the development of civilizations. In places like ancient Mesopotamia, now modern-day Iraq, wind eroded sediment along the Tigris and Euphrates rivers. Fertile deltas formed where sediments accumulated. The fertile river deltas allowed agriculture to flourish, which contributed to thriving civilizations. The article “Drone photos reveal an early Mesopotamian city made of marsh islands” describes one ancient settlement.

How humans increase and decrease erosion

6. Name some ways humans increase or decrease erosion compared with what would happen naturally. Are those influences positive, negative or both?

Humans can have both positive and negative influences on erosion. Humans have increased erosion through deforestation, poor agricultural practices and construction. Human-driven climate change has influenced rainfall, which can drive erosion. Too much rain can lead to landslides and erosion; too little rain means the soil dries up and can be blown by the wind. Humans can help control erosion by planting or building roads and structures in ways that limit erosion.

7. Discuss an example of human-caused erosion that has happened near you. How did humans contribute to erosion in your example? 

Student answers will vary. One example could be the problem of soil erosion in the Midwest. Agricultural practices such as particular ways of tilling have increased soil erosion. (Tilling refers to the turning over and breaking up of soil for planting.)

8. What were some short-term and long-term effects of your example?

In the short-term, increased soil erosion in the Midwest leads to soil runoff into the region’s rivers. The accumulation of sediments lowers water quality. Long-term, the loss of topsoil reduces soil nutrients, which, in turn, can lower crop yields over time.

9. Discuss possible solutions to this human-caused erosion that has created a problem in your local area. How could you go about engineering a potential solution to control the erosion?

Student answers will vary. Midwestern farmers could practice conservation tillage to preserve soil and keep it from eroding. Conservation tillage combines a variety of tilling techniques along with the practice of leaving crop residue on a large portion of the soil surface to keep water from washing soil away.