Grade Levels

K - 9

Objectives

    Students investigate interrelationshps among precipitation, runoff and wetlands by:

• modeling  and observing  flood buffering and filtering effects of wetlands in class.

Standards of Learning

Science:

• Kindergarten: K.1, K.5, K.9
• Grade One: 1.1, 1.3
• Grade Two: 2.1, 2.5, 2.6
• Grade Three: 3.1, 3.6, 3.7, 3.10
• Grade Four: 4.1, 4.8
• Grade Five: 5.1, 5.7
• Grade Six: 6.1, 6.2, 6.11
• Life Science: LS.1, LS.12
• Earth Science: ES.1, ES.2, ES.9

    A wetland model demonstrates some of the critical functions of wetlands, and illustrates how wetlands effectively buffer the impact of flooding and filter runoff from land.

Background

    It's hard to tell just by looking at wetlands that they help filter silt and pollutants from runoff (water coming from land) as well as tidal waters, and often reduce flood damage. By building a simplified wetland model, some of these important wetland functions can be demonstrated.

    For more background information on wetland values, see "Marsh March" on this site.

Materials

• modeling clay
• aluminum roasting pan
• carpet scraps
• 4 jars of clean water
• 2 jars of soil

  For in-class extension:
  

• small aluminum pans
• modeling clay
• florist foam
• an assortment of paints, papers, toothpicks, twist ties, cotton swabs
• an assortment of natural materials such as twigs, pine needles, soil, pebbles, feathers, etc.

Resources

Buck, L.

1974. Wetlands: Bogs, Marshes and Swamps. 
Parent's Magazine Press.

Educational Images, Inc.

Ecology of a Swamp; Freshwater and Salt Marshes  (slide sets).
P.O. Box 3456, West Side, Elmira, NY 14905.

Niering, W.A.

1975. Audubon Society Naure Guides: Wetlands. 
Alfred A. Knopf, NY.

Teal, J. and M. .

1969 Life and Death of the Salt Marsh.
Ballantine Books, NY

Procedure

1. Along the bottom of one side of an aluminum roasting pan, spread a layer of modeling clay to represent land. Leave the other half of the pan empty to represent a Bay tributary or other body of water.

2. Form the clay into a gradual slope toward the center of the pan.

3. Smooth the clay along the sides of the pan to seal the edges. If desired, form meandering streams in the clay.

4. Cut a carpet scrap or sponge two to three inches wide, and long enough to stretch across the bottom 0of the pan along the entire edge of the clay (see diagram). The carpet or sponge will represent the wetland buffer between dry land and open water.

1. Show the class pictures of different types of wetlands, including swamps, fresh and saltwater marshes, and discuss the different types of plants and animals found in these wetlands.

2. Lead a class discussion by asking the students what they consider to be the characteristics of wetlands. List these characteristics on the board.

3. Explain that the wetland model will be used to demonstrate, in a simplified way, two important functions of wetlands.

1. Explain that water will be poured slowly on the upland portion of the model twice to represent rain. The first time, the wetland strip will be in place. The second time, the strip will be removed.

2. Ask the students which time they think the water will accumulate fastest in the open side of the pan, or if they think there will be no difference. Take a count of hands for each option.

3. With the marsh in place, pour water slowly on the upland as shown. The students observe and describe what happens. (The water should move across the pan and accumulate slowly.)

4. Remove the carpet strip, pour the water out of the model and repeat the demonstration. Again the students observe and describe what happens. (The water should reach the other side of the pan and accumulate more quickly without the barrier.)

5. Explain that wetlands function like the carpet or sponge, by slowing and retaining rain water running off the land and thus help prevent flooding.

6. Discuss:
   • If a wetland is destroyed and houses are built there, what might happen to the houses during a severe rain storm? Why? 
     (They might be flooded because the wetlands will not be there to absorb and slow the rush of water off of the higher ground.)
   • If many wetlands are destroyed along a river and many houses are built near the river, which houses will probably experience the worst flooding -- the ones upstream or downstream? Why? 
     (The ones downstream because the water will be accumulating in the river from a larger area. The more wetlands that are destroyed in a watershed,  the greater the flooding problems.)

1. Explain that the second demonstration will be just like the first, except that soil will cover the clay. The rain should pick up and carry some of the sediment as it travels over the land.

2. Ask the students if they think the water accumulating in the open part of the pan will be cleaner with the marsh in place or with it removed, or if they expect no difference. Take a tally of hands.

3. Pour the water from the previous demonstration out of the pan and replace the carpet or sponge. Spread soil over the clay and slowly pour water on the upland as before. The students observe and describe the water that accumulates in the pan. (The water in the pan should be fairly clear since the carpet or sponge should trap most of the sediment.)

4. Repeat the demonstration with the carpet or sponge removed. The students describe the results.

5. Explain that the thick mat of roots and plant stems in a real wetland helps trap sediments that wash off of the land, much as the carpet or sponge did, and thus helps keep waterways free of silt and some other pollutants.

6. Conclude with a discussion:
   
   • What might a river look like after a heavy rain if much of its wetlands have been destroyed?  (Muddy)
   • How might muddy water affect fish in a river?  (It makes it hard for them to see and clogs their gills.)
   • How might muddy water affect oysters in an estuary?  (The mud settles out and smothers the oysters.)
   • How might muddy water affect boats and ships?  (The mud settles out and fills channels important for navigation.)

Extensions

1. Students, individually or as small groups, make their own, more detailed, wetland models, using small aluminum pans and, instead of carpet, use florist foam. Provide reference books with pictures of different types of wetlands. Students can use their imaginations to make plants and animals from an assortment of materials and stick them in the foam and clay. Some ideas:
   • For cattails, use cotton swabs painted brown or toothpicks painted green with bits of brown clay stuck to the tops.
   • Use pine needles for reeds.
   • Shape wetland creatures from clay or cut them from paper and glue them onto toothpicks.
   • Make trees by gluing pieces of green sponge onto twigs.

   
   

2. Follow-up by doing "Marsh March," a wetlands field observation activity on this site.

Where

When

Time of Year:

Any time. Try to tie in with field trip for "Marsh March" also on this site.

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