Understanding Watersheds

Earth is the blue planet, so one would expect to never worry about having enough water for human use. Unfortunately, most of that water is either salty or frozen in glaciers. Fresh surface water accounts for only 0.007 percent of all water on Earth. Yet, somehow, this provides water for the almost 7 billion humans on Earth. It is easy to see why protection of these water supplies is important.

A watershed is the area of land drained by a stream, river, or lake. The activities on the land contribute to the quality of water since surface runoff can make its way through the watershed to the river. Students do not always see the implications of a car leaking oil in the parking lot to the quality of their drinking water, so I like to demonstrate this with a model. Modeling a watershed is relatively easy. There are large-scale models you can purchase or even borrow, but I have found it just as effective to have students model a watershed in a pan with aluminum foil. I first teach students about contour lines and topographical maps. They practice translating the two-dimensional map into a three-dimensional landscape using modeling clay. Next, we discuss how the slope of the land determines the boundaries of the watershed. Once students understand the maps, they delineate a watershed on an actual topographic map. By determining the highest points of land that will flow into a river, they determine the location of the watershed.  

Using the map as a guide, students mold aluminum foil to model the slope of the watershed. They place the aluminum foil in a large shallow pan and prop it up if needed with rocks, cups, or other objects. They make it ‘rain’ on the watershed model with a spray bottle set on mist. Once they have observed the flow of water over the landscape, they experiment with adding dams and wetlands using sponges. They also introduce point and nonpoint pollution with food coloring. Students write down their observations and translate what they have learned to the real world. 

I hope that this activity can make my students think twice about dumping oil or other chemicals on the ground. I want my students to understand that their actions really can make a difference in the quality of the world we all live in. You can help your students understand their connection to their watershed with the lessons below.

Watershed Lessons and Activities:

What Makes Up a Healthy Watershed  

Students, after observing the elements of a local watershed, explore the need to protect watersheds as water resources for the future. They examine the factors involved in a watershed: geology, ecology, and the effect of man's influence. In addition, they record their observations in their science journals and write a short report about the watershed area visited.

Mapping Your Watershed  

Students investigate the importance of watersheds around the world. By visiting resource links, students can locate watersheds and their sources in the USA and Russia and analyze their effects on the surrounding topography. This lesson culminates with students examining how human activity may affect local watersheds.

Water: Where in the Watershed?  

Students become connected to their watershed by exploring a local water body and mapping its features. They focus on how the local watershed fits into the larger scheme of the watershed.

Watersheds, Land Use and Pollution  

Students compute the land-to-water ratios for two watersheds. They interpret land use maps and develop a scale model for land-to-water volume ratios. They interpret data and conduct independent research.

Conducting a Watershed Snapshot of Blockhouse Creek 

Students examine specific skills in assessing water quality from a holistic approach. They assess the health of a local watershed and identify problems in the local watershed and suggest remediation.