2. Watersheds and Wetlands
Wetlands book First page of a 6th grade student's book on wetlands, written and shared with the 4th grade class. Cardstock paper, water spray bottles, markers and sponges are turned ...
Wetlands book: First page of a 6th grade student's book on wetlands, written and shared with the 4th grade class. Cardstock paper, water spray bottles, markers and sponges are turned into models of wetlands and watersheds in this simple activity. Students follow the path of the water (and urban runoff) to a bay and develop an initial understanding of what watersheds are. Then some students add sponges to the borders of their bay to simulate wetlands and compare watersheds with wetlands to those without. Students extrapolate the role of watersheds as reservoirs in times of drought, as sponges in times of flood, and as filters for pollution. Finally, students compare watersheds with wetlands to those without after a “toxic chemical spill” (Koolaid drink mix) to see the effects of pollution throughout the watershed as well as to discover the role of wetlands in reducing the harm of severe pollutants to a bay. This series of activities is an excellent prelude for a wetlands restoration field trip (see the Save the Bay field trip planning guide) so that after learning what wetlands are, they can explore and restore a wetland area firsthand. Another extension and application of these ideas might be an exploration of the students’ own watershed, the effects of urban runoff and watershed protection.
Can define wetlands and watersheds.
Can look at a 3-dimensional model and identify different watersheds.
Can explain how runoff carries water, sediments (from natural areas), and pollution (from urban areas) to rivers, bays and oceans.
Can understand that an event in a watershed affects all downstream areas.
Can describe some of the many important roles wetlands serve in an ecosystem.
2. Watersheds and Wetlands - Logistics
70-90 minutes - approximately 20-30 minutes per wetland for construction, the activity, discussion and clean up. I recommend doing the first activity to introduce the idea of a watershed on one day then do both wetland activities on the following day. If you are short on time or if students are already familiar with the concept of a watershed, then you can add wetlands right away.
Teams of 3 students that later pair up into groups of 6
Each team of 3 students needs:
- 1 plastic shoebox-sized container (great for organizing supply closets later on!)
- 1 kitchen sponge cut into 4 rectangular pieces (the yellow sponges with the green scrubbing material are cool because kids can observe a color change in the yellow “soil” portion of the sponge while the green material simulates plants living in the wetlands)
- 1 water spray bottle (available at most hardware stores near the cleaning supplies or at plant nurseries for watering and misting plants)
- a multi-color assortment of water-based markers
The teacher needs:
- a stack of white cardstock paper (each team will use 3 sheets)
- 1 packet of colored drink mix like Koolaid or Hawaiian Punch
- 1 spoon
- optional - map or satellite image of the school and neighboring areas showing the watershed
- a copy of the Watershed and Wetlands Questions
- a sink to clean sponges and dump dirty water
- a trash can
2. Watersheds and Wetlands - Background
The concept of the watershed forms the foundation of much environmental science. Formally, a “watershed” is the area of land that water flows over and through on its way to a larger body of water like a creek, river, lake, or bay. Practically, this means that a watershed is all the land that drains into a specific body of water. Every house, school, and neighborhood is part of a watershed. Studying ones own watershed allows students to apply scientific knowledge to their neighborhood and community and are easy ways for students to make connections between their actions (pollution, water conservation, habitat restoration, etc.) and the quality of the environment they live in.
Watersheds may be as large as several states (the Mississippi River watershed for example) or as small as a few city blocks. For instance, the San Francisco Bay watershed covers the entire western slope of the Sierra Nevada Mountains, the Central Valley of California, the Sacramento River Delta, and the many smaller creek systems that surround the San Francisco Bay itself. This area of land is approximately 40% of the entire state of California! One could also refer to the Codornices Creek watershed in Berkeley that my school is near. It’s area encompasses a narrow strip of land 5 blocks wide and 3 miles long between the San Francisco Bay and the Berkeley hills. Both are equally valid watersheds to discuss since students can see their personal connection both to the Bay and to the neighborhood they live and go to school in.
A watershed begins in the tallest mountain areas where water falls as rain or snow. This water then trickles into rivulets, rivulets merge into creeks, and creeks merge into rivers on the water’s way downhill. Eventually, these streams of water reach the larger body of water under study – a bay, a river, a lake, a creek. Much of this water will also seep into the ground as groundwater and may travel much more slowly through the soil and rock and perhaps underground aquifers to reach a body of water. Any land a water drop has traveled over or through to get to the body of water being studied belongs to that watershed. All this movement of water is part of the larger water cycle (see the Water Cycle Stories Lesson).
I found that my students had a difficult time understanding that a watershed meant land and did not just include the creeks, rivers, lakes and bays. Pointing out that a watershed is usually bordered by ridges helps. Using a 3-D map to illustrate separate valleys that have separate watersheds also helps.
At the edges of a watershed, particularly those with little human development, one will find wetlands. Broadly defined, “wetlands” are transitional areas between land and water habitats. More specifically, the wetlands are characterized by:
- lots of water - the water table is at the surface or close to it most of the time
- soil that is wet much of the time (although some wetlands are actually dry for more of the year than they are wet)
- specialized plants that are adapted to live in wet soils with lots of groundwater
The many types of wetlands include marshes, swamps, bogs, meadows, mud flats, and other habitats where land and water meet.
In the not so distant past, up until even the 1970’s, wetlands were often considered to be wasted space. The marshy land at the edges of bays seemed wasted on the weedy plants that grew there and seemed like perfect, flat strips of land that could be filled in with soil and concrete to build desirable waterfront housing, office, and industrial space. In a span of 150 years, the San Francisco Bay watershed lost 90% of its wetlands. And only now are we realizing their worth and importance to a healthy ecosystem.
Wetlands serve many essential roles in the environment. They are critical habitat for many specialized plants and animals that survive nowhere else. The plants that live in a wetland act as a filter to soak up pollution that runs off upstream. In fact, several communities such as Arcata, CA and Phoenix, AZ use wetlands as part of their urban water treatment facilities instead of the harsh chemical treatments that must otherwise occur. Wetlands also serve as a reservoir to even out fluctuating water levels, soaking up excess water during a wet times and releasing stored water during dry times. Finally, as the nation learned in the Hurricane Katrina disaster, wetlands can serve as a buffer against natural disasters such as hurricanes (for more on this, see Katrina Case Study lesson).
An understanding of the water cycle (see Water Cycle Stories lesson).
2. Watersheds and Wetlands - Getting Ready
- Set out cardstock paper.
- Fill water bottles (or kids can do this).
- Collect the remaining materials needed for each group of 3 students (4 pieces of kitchen sponge, 1 water spray bottle, a multi-color assortment of water-based markers) into their plastic bin and set out near cardstock paper.
- Open the packet of drink mix and set aside with the spoon in a place students won’t readily access (or they’ll try to eat it!).
2. Watersheds and Wetlands - Lesson Plan
Part 1 – Building a watershed
- Tell students to imagine that it is raining. Ask the students: “Where does raindrop go after it hits the school building? Where does it go from there? Where does it end up?” They should be able to trace it to a gutter. You may need to prompt them towards naming a nearby creek and onwards to a river, bay or ocean. You may want to draw a diagram of this path on the board.
- Discuss the idea of a watershed. It includes all the land that water flows over and through to get to a larger body of water. Help students imagine what this means in terms of a raindrop that falls in different places in your watershed. Use a map if you want. It is not important that all the kids completely understand the idea right now. The activity that follows should help consolidate the idea for kids that aren’t getting it right away.
- Tell the students that they will be building models of watersheds and observing what happens to their models when it “rains”. Briefly demonstrate what they will be doing to make their watershed (see steps 5-8 below) so they can see a nearly finished product before setting the kids loose.
- Split the class into groups of 3 and have 1 member of each group collect 3 sheets of cardstock and 1 watershed tub. The rest of the group should clear everything off the tables except for a pencil for each student (they may get wet).
- Crumple the sheet of cardstock into a ball then slowly flatten it out again. You should have a piece of paper with many valleys and ridges. Pick one end to be the top; this end will have tall mountains. The other end will be near a bay.
- First, add water to your watershed – creeks that run into rivers, lakes, ponds. Make students think about where to put these rivers. Will they be at the tops of ridges or in the valleys? Where might lakes form?
- Next add natural areas – animals, trees, plants, rocks, sandy banks. Add urban and agricultural areas – houses, cars, schools, farms, gardens, factories, roads, cars. Make students think about where to put various things. Where would you find forests? Where would you find meadows? Where would animals want to live? Where might it be very rocky? Where would people want to build houses? How would they get to their houses? Where would they work and go to school? Where would their food come from? Would you want to build a farm at the top of a mountain? Allow 5-10 minutes for students to finish their watersheds. They should be very colorful at this point.
- Carefully fit the watershed into the plastic bin so that the mountainside is propped up on the narrow end of the bin (the mountain end) and the land slopes gradually towards the far end of the bin (the bay end), leaving a 2-3 inch gap between the end of the paper and the bay end. Wedge the paper snugly in place leaving as little gap as possible between the sides of the bin and the paper.
- Take one of the markers and prop the mountain end of the bin up a little. This is to make sure that a bay forms on the bay end and does not run back under the land.
- The 3 students should take turns spraying the paper using the fine mist setting. Spray for 3-5 minutes until there is a decent sized puddle in the bay end.
- Give students the Watershed and Wetlands Questions handout and give students a few minutes to answer the first set of questions. The questions do not have to be used during class. You could use the questions to being a class discussion or use them as a homework assessment. I found that the discussions following each activity were more directed and targeted after students had thought about the activity individually first. I still collected the questions as an assessment.
- When students have finished writing their answers, begin a discussion of how this model represents a watershed and how different things affect the watershed. If you still have the diagram of your watershed on the board, you could add these ideas to your diagram. Now is the time to really consolidate the idea of a watershed. Some questions you may want to consider include:
- What path did the rain take through your watershed?
- What effect do natural areas have on the watershed? Urban areas? Agricultural areas?
- What is “runoff”? Is runoff different in natural versus urban versus agricultural areas? It is important to distinguish erosion from urban runoff. Also, it may be interesting to think about differences in urban versus agricultural runoff.
- What affect does runoff have on the bay?
- What is a watershed? How is this model similar to a real watershed? How is it different?
Part 2 – Adding Wetlands
- Tell students that they will now build another watershed. This time, we will compare watersheds with wetlands to those without. Open a discussion of what students think wetlands are. Have they ever seen one? What does it look like? What kinds of plants and animals live there? If they don’t know the term wetland, they will likely have heard of a marsh and can bring up a good mental picture.
- Pair teams up with one another. One team will have a wetland represented by sponges at the border between the land and the bay; the other will do the activity exactly as before (in the third rendition, they will switch roles so that everyone has a wetland once).
- Clean up the materials and allow groups to create a new watershed with a new sheet of cardstock paper. It should not take as much time this time nor is it necessary for the watersheds to be as elaborate.
- Set up the bins as before, however, one team should add a tightly packed row of damp sponges to the border between the land and the bay. THE SPONGES MUST BE DAMP. They should not be sopping wet, nor should they be wrung out as much as possible. They should be somewhere in between so that some water could still be wrung out if you tried.
- Place the watershed with wetlands directly beside the watershed without wetlands and prop up the mountain end with a marker.
- Allow it to rain an equal amount on each watershed. The students should make an effort to squirt the 2 watersheds an equal number of times. As it rains, encourage them to notice any differences between the 2 watersheds.Stop when a decent sized bay had built up – about 3 minutes.
- Give students a few minutes to answer the second set of questions. When students have finished writing their answers, begin a discussion of what the role of watersheds might be. Some questions you may want to consider include:
- Were there any differences in how quickly each bay filled? What does that mean about what wetlands do in times of heavy rain? Introduce the idea of wetlands as sponges during wet times and reservoirs during dry times to even out the flow of water.
- What happened to the color of the bottoms of the sponges? What does this represent? Introduce the idea of wetlands as filters for pollution.
Part 3 – Toxic Waste!
- Have students hypothesize what might happen to a watershed if a truck carrying pesticides crashed along a highway near a creek. What parts of the watershed might be affected?
- Students will now have a chance to test their ideas on their models. As before, there will be one team with a wetland and one without, however they should switch roles. A spoonful of pesticide will be added to each watershed before it rains.
- Clean up the materials and allow groups to create a new watershed with a new sheet of cardstock paper. Set up the bins as before, placing the watershed with wetlands directly beside the watershed without wetlands and prop up the mountain end with a marker.
- At this point, the teacher should go around and add a teaspoonful of drink mix to the middle of each watershed.
- Allow it to rain an equal amount on each watershed. Notice any differences between the 2 watersheds. Stop when a decent sized bay had built up – about 3 minutes.
- Give students a few minutes to answer the final set of questions. When students have finished writing their answers, begin a discussion about the differences between non-point source pollution (runoff) and a pesticide spill. This activity should clearly illustrate how a single event in one location can affect a very large area and affects all downstream water users including wildlife in the marsh and the bay. Students will observe that while a wetland can soak up some pollution, some will also leak through into the bay. Can it be cleaned up once it gets into the water? Emphasize that although a waste spill is far more dramatic, urban non-point source pollution accounts for the vast majority of the pollution in most watersheds.
- Given what we’ve discovered about watersheds and wetlands, what can we do to help them thrive? Have students brainstorm ideas.
- Clean up.
2. Watersheds and Wetlands - Assessments
- The Watershed and Wetlands Questions can be used as an assessment tool.
- Have students create a flyer that encourages other students to do something to help their watershed. Post them around the classroom or around school.
- Have students research the use of constructed wetlands as an alternative wastewater treatment option and present their findings on posters. The Water Resources Research Center at the University of Arizona offers some excellent information as does the Arcata Marsh and Wildlife Sanctuary.
- Go on a field trip to a wetland! Even better, do some restoration work there. For one idea, see the Save the Bay Field trip.
- Delve into a case study of how wetlands form, how they are destroyed, and what the effects of wetland destruction are. Research your local area or investigate the wetlands of Louisiana and their role in the Hurricane Katrina disaster. See the Katrina Case Study lesson.
2. Watersheds and Wetlands - Sources and Standards
The idea for this lesson came from the “Watershed in your hand” lesson from the Watershed Project’s Kids in Creeks curriculum and from the “Wetlands in a pan” lesson from Save the Bay’s Watershed curriculum. Save the Bay’s versions of these lessons are available below as pdf documents.
The following sites provide excellent scientific background information about wetlands and watersheds.
- The National Wetlands Research Center by USGS
- Science in your Watershed also by USGS
- An article on Wetland Environments by James Aber
- Save the Bay recently launched its fantastic new Bay Classroom
Although out of print, the USGS Water Resources Outreach Program has produced 9 fabulous posters with beautiful, colorful depictions of watersheds, wetlands, waste water treatment, water quality and more. Each poster has activities on the back with you can view online.
2. Topography is reshaped by the weathering of rock and soil and by the transportation and deposition of sediment. As a basis for understanding this concept:
a. Students know water running downhill is the dominant process in shaping the landscape, including California’s landscape.
b. Students know rivers and streams are dynamic systems that erode, transport sediment, change course, and flood their banks in natural and recurring patterns.
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
a. Develop a hypothesis.
f. Read a topographic map and a geologic map for evidence provided on the maps and construct and interpret a simple scale map.