December 2001
Dams have been built to regulate the flow of rivers since ancient times. Today, they are used to supply water to agriculture and prevent flooding, to create lakes and modify rivers for transporation and recreation, and to produce electricity cleanly and efficiently. For these reasons, state and federal governments have invested in dams as multi-purpose civil engineering projects. Although dams have many benefits, critics have raised a number of concerns about dams and their impact. For example, dams alter natural flow patterns, flooding areas behind them and changing sediment distribution throughout the river system; they disrupt ecosystems and make it difficult for fish and other wildlife to travel freely; they can fail if poorly engineered, causing catastrophic flooding; and dams may even induce small-to-moderate earthquakes. All of these issues are contentious, and much research is being done on ways to improve the safety, the ecological soundness, and the efficiency of existing and future dams.
Two articles this month - one from the rainforest of Belize, the other from the Tigris River in Turkey - present some of the many environmental, economic, and social complexities inherent in deciding whether or not and where to build a dam. The stories could be tied in to lessons on the water cycle, natural resources, watersheds and river systems, sediment transport, flooding, and human-mediated environmental change. Both articles come from the Environment News Service, via Lycos.
British Engineering Company Withdraws from Ilisu Dam Project
Chalillo Dam Project Cleared by Belize Government
Related Web Sites
Water Power - Use and Regulation of a Renewable Resource: The Federal Energy Regulation Commission maintains this webpage, which gives background information on hydroelectric power, as part of its Hydropower website.
Friends of the River: This organization concerns itself with the protection of California's river ecosystems, and has a very different perspective from FERC. The site features some news articles and alerts of interest:
- Auburn Dam Fans Try, Try Again
- The Energy Crisis: New hydroelectric dams are not the answer
- Removing Dams in California
Los Trancos Creek Fishway Steelhead Restoration Project: This web page details the efforts of a group at Stanford to engineer a fish ladder at an existing dam to help preserve the creek's steelhead trout population. Gives very readable background on the project and some photographs.
Review of seismic-hazard issues associated with the Auburn Dam project, Sierra Nevada foothills, California: The US Geological Survey (USGS) produced this report in 1996, dealing with the earthquake hazards related to a dam project that had been scrapped in the late 1970s but was revived in the early 1990s and is still in the news today (see Friends of the River alert, above). The paper uses technical vocabulary and concepts, but the maps and tables, the introduction, and the summary are fairly readable.
Dam Failure Inundation Hazard: Information and scenarios related to dams in the Bay Area. The site, from the Association of Bay Area Governments (ABAG) deals with earthquake-related dam failure and the flooding that could result. Good maps and references.
Related Classroom Activities and Discussion Topics
Large Dams: Benefits and Issues: This is a nice graphical summary of issues related to dams, from the World Commission on Dams. Ask each student to pick an issue and assume the role of a stakeholder, becoming an "expert" about that topic. Hold a mock public forum about a new dam project and then vote on whether or not it should be built and under what conditions.
Discovery.com's DiscoverySchool has several good lesson plans and activities, all of which include a glossary with pronunciation sound clips, further reading, links, and other teacher-oriented classroom suggestions:
- Water: To the Last Drop: From Joy Brewster, this lesson plan geared towards students in grades 6-8 presents a wide range of discussion topics related to water, including dams. It focuses on humans' needs for water and how water has affected United States history. It also includes regional examples from around the world.
EPA Office of Water - Kids' Stuff - Experiments: The EPA has a collection of water- resource-related activities for all grade levels, in printable PDF format. Examples include:
- Build your own watershed for grades 8-12
- The case of the disappearing water for grades 4-7
- Where does your water come from? for grades K-3
Testing the Waters: An applied, real-life example from the Peace Corps in Paraguay, this activity for grades 6-9 focuses on the many sources of pollutants and the interaction of multiple factors in determining the health of a waterway. Activity requires students to research different aspects of the problem in groups. A pollution information sheet is attached.
To Dam or Not to Dam: From the Montana Environmental Education Association. This activity's target grade range is 4-12. Provides a scenario and requires students to work in groups to recommend solutions to problems posed by the scenario and report their recommendations to FERC in a mock hearing. Also encourages students to find out about any actual dams or proposed dam projects in their area and to get involved.
How Much Water Do We Have?: This activity is intended for middle school and high school students, and comes from the Colorado River District's teacher guides. It deals with watersheds, the water cycle, and how reservoirs are used to counter drought conditions. The authors suggest that it will take about 50 minutes to complete, and involves a hands-on simulation of river flow and water diversion.
Science News Write-Up: Write a report on one of these articles for your class! Here is a suggested outline to help you organize the report.
News Archive
Earth Science News Archive: We are building an archive of these news features. Feel free to browse earlier articles and resources!