What Happens When Sea Level Rises or Falls
A Topographic Model

The current concerns with global warming have made us wonder what will happen if there are changes in water levels of Lake Pontchartrain and the Gulf of Mexico. This activity is meant to increase our awareness of the effects of changing water levels on a coastal landscape.


  • Construct a model of a contour map

  • Use a contour map model to study changes in water levels and land elevations

  • Understand the impact of sea level rise on the Lake Pontchartrain Basin

per group

  • Clear Plastic Shoebox
  • Brown & Green Clay
  • Acetate Transparency Sheet


  1. Use the clay to form a coastal landscape in the bottom of the shoebox. Don't forget to leave room for water representing the Gulf of Mexico!

  2. Using the metric ruler, mark one-centimeter increments starting from the bottom to the top on the outside of the shoebox.

  3. With the marker or grease pencil, record the level of the coast/clay, according to the marks on the side.

    How many centimeters does your clay coastline rise from the bottom of the shoebox?

  4. Slowly pour water into the container and on to the clay coastline until it becomes level with the first centimeter mark from the bottom of the shoebox.

    How much of the clay coastline is covered with water?

  5. Continue adding water to the next centimeter mark.

  6. Place the clear transparency sheet over the top of the shoebox. Have members of your group hold the sheet as flat as possible. Look straight down into the shoebox. With the marker or grease pencil, draw a line where the water meets the clay as you look straight down upon the coastline.

  7. Continue steps 5 and 6 until you have several lines on your transparency, marking each line with the corresponding centimeter mark on the side of the shoebox. The lines formed are called contour lines, and they are used on topographic maps to indicate elevation of land and water.

Once your map is completed, answer the following questions:

  1. How can contour maps be used to determine impact of sea level rise on a coastline?

  2. If the water level decreased one centimeter in elevation on your model, how much more land would be exposed? How can you determine this by using your math skills? Explain your answer.

  3. What are problems associated with sea level rise in the Lake Pontchartrain Basin? What can we do about it?

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