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November 25th--Mapping the watershed on our playground
#1. Mapping the playground watershed.
Purpose
- Develop powers of observation and experimentation
- Find out where a rain garden can be effective
- Children can apply these same methods to their neighborhoods
- The playground will serve as a small model for the entire Wingra watershed.
By pouring water at various places in the garden, children can observe which way the water runs. By repeating the process in many places, they will be able to find the "divides" between basins on the playground.
When children find a divide, they will mark it with small flags held by blocks of wood. Then the flags will be connected by some kind of line made by chalk, rope, or tape (to be decided). The lines will surround and define each basin.
Finally, children draw a map of the playground showing it's several watersheds, bare and paved ground, drains, and possible locations for rain gardens.
Optional: Older children can measure the square feet of each basin. This helps determine how large a rain garden should be.
Optional: Student goes out in rain, and makes video to show if basins have been correctly marked.
#2. How soil and plants in a rain garden help to filter stormwater
Materials:
- Hose as a source for water.
- Numerous water cans with spouts
- Flags anchored on blocks of wood. N=40???
- Line markers--rope, surveyor's tape, and chalk (for pavement)??
- Large sheets of graph paper, for maps.
- Tape measures (students can use the tape to determine their pace length, then pace the playground as a rapid way to measure it).
- Colored markers to mark various areas of maps.
#2. How well do rain garden plants filter the runoff?
Identical plastic pots will be filled with different materials or plants...
- Rubber tire chips.
- Sand
- Bare soil
- Silt fence cloth
- Silt sock cloth (and mulch stuffing)
- Growing lawn grass (turf)
- A larger plant (hopefully a native prairie plant)
- A clear plastic saucer is placed under each pot.
- Muddy water is prepared in a large storage container, then poured into 6 watering cans.
- At the same time, 7 students pour muddy water into each pot.
- Students observe the water coming through. They measure how fast, how much, and is it clear or still muddy?
- Some of the filtered water from each pot is poured into a jar, and all 7 jars are photographed against a white background. This shows, comparatively, how clear each sample is.
It's expected that some muddy water will pass through 1-3. The contents of pots 4-5 may reduce the mud somewhat. Pots 6-7 are expected to pass the clearest water. Pots 5-7 will also soak up a good deal of water, so less water will come through. This shows how rain gardens can help reduce flooding.
It's possible that only #1 will pass muddy water, and all the rest will be clear. However, mud is relatively easy to filter. Other pollutants are harder to filter, so we'd still expect 7 to do the best job, even if the student's can't see the difference.
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