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Sinking City of Venice

Classroom Activity

Objective
To help students understand the complexity of finding a solution to Venice's floodwater problems.

• copy of the "Water Logged" student handout (PDF or HTML)

1. Venice is confronted with the problem of how to control the flooding of its city, a problem that is predicted to increase over time. But experts cannot agree about how often flooding will occur or how high floodwaters will be. To help students understand this complex issue, have them keep a log of the various aspects of the issue as they watch the program.

2. Provide each student with a copy of the "Water Logged" student handout. Review the student handout with students, noting the locations of Venice, the lagoon, the barrier islands, the city's port, and the other features.

3. Organize students into four groups. As they watch, have one group take notes on the causes for Venice's flooding problems. Have the second group focus on the arguments for the installation of the mobile floodgates. Have a third group record the arguments against the gates. Have the final group note any alternate solutions that have been proposed.

4. Have students use the map to mark the areas affected by the problems and the areas where solutions or proposed solutions have or would occur.

5. After watching, discuss the causes for Venice's water problems, the arguments for and against the floodgates, and the alternate solutions that have been proposed, summarizing them on the chalkboard.

6. Discuss with students the advantages and disadvantages of the mobile floodgates and the alternate solutions that have been proposed.

7. To conclude, have students consider the following:

   • Of the problems Venice currently faces, which are most immediate?

   • Of the solutions given for Venice's current flooding problems, which do you think is the most sound? Why?

   • What scientific information do officials need to make decisions regarding saving Venice from flooding?

   • What role does science play in solving Venice's water problems? What role does the government play?

8. As an extension, have students research lagoon environments within the United States. Where are most of the lagoons located? What issues, if any, do they face?

The key issue surrounding the mobile floodgates is the question of how often the gates would need to be deployed. Opponents fear that without the cleansing effect of the tides, the lagoon's pollution problems will be exacerbated. (Pollution sources include industrial waste disposal, sewage outflow from the city's drainage system, and agricultural runoff of fertilizers. Additional risks include oil spills from tankers serving a major petrochemical center.)

Some of the causes of Venice's flooding
Severe storms are more frequent. A rise in mean sea level is predicted, although estimates vary from a rise of 1.57 inches to 19.69 inches (4 centimeters to 50 centimeters). The sediment under Venice is slowly compacting. In addition, for several decades local industry pumped millions of gallons of water out of the ground, resulting in added soil compaction. These factors threaten Venice with increasing high-water problems.

Some of the arguments for the mobile floodgates:

• The gates meet the guidelines set down by law.

• They provide a workable solution that can be implemented now before the problem gets too severe.

• The gates will be high enough to counter the high water expected by sea level rise.

• The number of closures will not be enough to harm the lagoon's ecosystem.

Some of the arguments against the mobile floodgates:

• The gates are expensive and are taking money away from a more workable solution.

• The gates will not solve the problem long-term. Much of the problem can be solved with alternative measures in the short run, providing additional time to plan a permanent solution.

• They won't be high enough to counter the high water expected by sea level change.

• The number of closures will harm the lagoon's already stressed ecosystem.

Some of the alternative measures proposed:
Less technological approaches include narrowing the shipping lanes or opening the fish farms to receive water to expand the lagoon's surface area. Other proposals include raising city sidewalks and canal walls by a foot or less. More drastic measures include: closing off Venice's industrial sector; decreasing the size of the lagoon; closing the lagoon off permanently from the sea and turning it into a freshwater lake; or building permanent structures at the inlets to control water exchange.

Some of the information officials need to make decisions regarding the lagoon includes: short- and long-term meteorological forecasts to help predict storms and future sea level rise; water quality reports to track pollution levels within the lagoon; ecological data to help understand lagoon and sand bank dynamics; and water quality models to predict potential outcomes of various proposed solutions.

Book

Keahey, John. Venice Against the Sea: A City Besieged. New York: T. Dunn Books/St. Martins Press, 2002.
Explains how the city and its 177 canals were built and what has led up to the current flooding crisis. Also explores the various options currently being considered for solving the problem and chronicles the ongoing debate among scientists, engineers, and politicians about the pros and cons of potential solutions.

Articles

Barker, Don. "Saving Venice." Architecture Week, August 15, 2001, page B1.
Provides an overview of Venice's flooding problems. Also online at: www.architectureweek.com/2001/0815/building_1-1.html

"Measuring Water Exchange between the Venetian Lagoon and the Open Sea." EOS, May 14, 2002, page 1.
Details preliminary results of current measurements in all three lagoon inlets; includes articles for and against the mobile floodgates.

Web Sites

NOVA Online—Sinking City of Venice
www.pbs.org/nova/venice/
Provides program-related articles, interviews, interactive activities, and resources.

Safeguarding of Venice
www.salve.it/uk/
Includes information on the problems and solutions for Venice's lagoon, extensive resources about the lagoon's ecosystem, and a glossary of lagoon terminology.

The "Water Logged" activity aligns with the following National Science Education Standards:

Grades 5-8

	Science Standard F: Science in Personal and Social Perspectives

Natural hazards

• Internal and external processes of the earth system cause natural hazards, events that change or destroy human and wildlife habitats, damage property, and harm or kill humans. Natural hazards include earthquakes, landslides, wildfires, volcanic eruptions, floods, storms, and even possible impact of asteroids.

• Natural hazards can present personal and societal challenges because misidentifying the change or incorrectly estimating the rate of scale of change may result in either too little attention and significant human costs or too much cost for unneeded preventive measures.

Grades 9-12

	Science Standard F: Science in Personal and Social Perspectives

Science and technology in local, national, and global challenges

• Progress in science and technology can be affected by social issues and challenges. Funding priorities for specific health problems serve as examples of ways that social issues influence science and technology.

• Individuals and society must decide on proposals involving new research and the introduction of new technologies into society. Decisions involve assessment of alternatives, risks, costs, and benefits and consideration of who benefits and who suffers, who pays and gains, and what the risks are and who bears them. Students should understand the appropriateness and value of basic questions—"What can happen?"—"What are the odds?"—and "How do scientists and engineers know what will happen?"