Crumple Your Own Watershed
by Erica Ritter
Make your own three-dimensional map, and use it to explore how flowing water defines the areas of land we call “watersheds.” This activity provides opportunities for creativity and for meaningful discussion, a great combination for engaging students.
You can have each student make their own, or have groups collaborate.
Loosely crumple a piece of graph paper, unfold it but don’t smooth it out, and tape it onto a stiff backing so that the remaining wrinkles and creases resemble mountain ridges and valleys.
Use brown, purple, or black ink to identify and mark the ridgelines — “where water would ‘choose’ whether to go on one side or another.” These are the lines that define a watershed: on one side, the water will go one direction, and on the other side, the other. (The Rocky Mountains are the classic example of a defining ridgeline: raindrops that fall to earth on either side of the main ridgeline may end up flowing downhill to oceans thousands of miles apart.)
Use blue ink to trace where you think water will gather into rivers, lakes, streams, etc. These are the water-bodies that the water is shed into. Water connects areas of land — discuss various ways water connects landscapes, local bodies of water that define students’ home watersheds, etc.
Use other colors to add farms, houses, factories, roads, cities, etc. If students are planning out an island or city, this process can be quite elaborate. The grid-lines on the graph paper can be used to designate personal land areas in group projects, or to estimate the relative sizes of farms, cities, etc.
When “all done,” bring the landscapes over to a suitable table, and “make it rain” with the squirt bottle. (Squirt water onto the map until it runs down the creases.) See if student’s drawn-in blue rivers correctly anticipated the flow of water; did any cities drown? If landscapes sag, this may be a good opportunity to discuss how forces of nature (including water) can cause similar effects in real life.
In addition to watching the water, watch the colors it carries with it. Colors from uphill things will smear downhill, and water bodies below populated areas will show the effects. If you let the paper dry, the end result is often quite beautiful, with streaks of color from the ridges and valleys.
While watching the colors run, you can discuss connections to local watershed issues, such as dams, agricultural or urban runoff, water-rights negotiations, etc. One of my favorite all-purpose factoids is the “Fido Hypothesis:” in California, Florida, Idaho, and Virginia, researchers have found that dog “doo” runoff from parks and yards contributes dangerous bacteria to lakes and coastal waters, sometimes to the point where it’s unsafe to swim at local beaches. (Dog doo can be responsible for 10%-30% of the fecal coliform bacteria in coastal waters, including the now-infamous E. Coli.)
You can also discuss other kinds of land features, and what their analogies would be: sponges for wetlands, tiny clay dams, permanent-marker forests or other structures that resist runoff.
Some teachers extend this basic activity to teach students to read contour lines. (To make this work smoothly, it’s helpful to crumple the paper around something so that there’s one mountain peak and all the slopes can be reached from outside by the fixed-height pen. This isn’t as useful for showing watersheds, as it tends to eliminate meandering valleys, but it’s way easier to show contour lines around a single mountain.)
Prop a waterproof pen or pencil at a fixed height (tape it securely across a ruler, or stick it horizontally through a paper cup or piece of cardboard, so that the point stays the same height). Slide the pen around against the crumpled ridges, marking an equal-height line. Mark other lines at other heights the same way; 3 or more heights is appropriate. At the end of the activity, unfold the papers. The now-flat paper approximates a topo-map of the origonal surface. (There will be a few discrepancies, and steep slopes will not show up as dramatically as on a real topographical map. A photocopy or photograph of the intact crumpled paper would be more accurate, but not as beautiful.)
This activity has been documented several times, so you may be able to find it online. Credit goes to Chris Maun for the version in “The Living River: An educator’s guide to the Nisqually River Basin,” and to Greg Dardis who originally adopted that activity for use at OMSI (the Oregon Museum of Science and Industry).
The “Fido hypothesis” was reported in USA Today (06/06/2002, “Dog waste poses threat to water” by Traci Watson, USA TODAY), and in other sources.
Erica Ritter is an educator formerly with the Oregon Museum of Science and Industry (OMSI).