Introduction to Watersheds and Erosion
A Yakima WATERS 5E Lesson
This lesson will further student understanding about watersheds, the forces that act within watersheds, specifically erosion, and how these forces form the watershed, such as the Yakima Basin, that students live in. Students will be provided guidelines on how to develop and complete their own experiments. Using stream tables and other props, students will hypothesize and test how to design particular river shapes.
Targeted grade: 9th
Suitable grades: 9-12th
Expected length: 50 minutes
Standards
· 9-12 SYSCIn complexsystems, entirely new and unpredictablepropertiesmay emerge. Consequently, modeling a complexsystemin sufficient detail to makereliable predictionsmay not be possible.
· 9-12 INQA QuestionScientistsgenerateandevaluatequestionstoinvestigatethenatural world.
· 9-12 INQB InvestigateScientific progress requires the use of various methods appropriate for answering different kinds of researchquestions, a thoughtful plan for gathering data needed to answer thequestion, and care in collecting,analyzing, and displaying the data.
· 9-12 APPBThetechnologicaldesignprocessbegins by defining a problem in terms ofcriteriaandconstraints, conducting research, and generating several differentsolutions.
Outcomes
Knowledge: Students will be able to:
– Define what a watershed is and identify the basin and sub-basin in which they live.
– Explain what erosion is and how landscapes are influenced by the phenomenon.
– Identify a model, in this case, stream tables, and explain the pros and cons of using models to recreate scientific processes.
Skill: Students will:
– Create models of different rivers within watersheds.
– Improve modeling skills by recreating river-types from images.
– Improve problem-solving skills by working as members of teams to direct the flow of their watersheds into certain patterns.
– Practice developing their own experiments and carrying out these experiments using models.
Materials, Equipment and Preparation
· Observation Notebook (for each student)
· Pencils
· Water bottle for each team (such as Nalgene bottles or recycled juice bottles)
· Stream table for each team
· Sand
· Rocks of varied sizes (a handful for each team)
· Vegetation (such as leaves or twigs)
· Aluminum foil for mountain for each team
· Catch basin for excess water from stream table(such as five-gallon buckets)
· Blocks to increase slope of stream tables
· Paper towels
· “Erosion” PowerPoint presentation and computer (including images of different river types). An overhead projector would work as well if the images were printed
· All materials should be distributed between tables. If not done already, students should be assigned evenly into groups at each table (approximately 5 students per stream table)
Prior Knowledge
Prior to this lesson, students will have a basic understanding of the components that make up a watershed from the previous “What is a Watershed” lesson and stream table activity. Students will have prior knowledge about the mountains, tributaries, lakes, rivers and other basic watershed components from using stream tables to conduct prior experiments. They learned about the flow of water through a watershed and how the water cycle contributes to this process.
They will have become familiar with the boundaries and collection points within a watershed. This lesson will further their understanding about what a watershed is and its functions.
Minimally, students should be able to describe what a watershed is and what direction the water flows through its features. This lesson will also assess the students’ knowledge about erosion and further their understanding of this topic.
Safety
There are no safety considerations for this activity. This lesson, however, does involved large amounts of water and sand. Additional setup and cleanup time may be required before and after the lesson.
Engage (10 min)
This lesson will begin with the question, “What is a Watershed.” This question can be posed to the students verbally, but I used a PowerPoint slide (number 1) with a fun picture of a shed flooded with water to pique student interest. Allow students a few minutes to jot down some ideas. Gain the students attention and discuss their answers. What is a watershed? What are some words you think of when you hear the term “watershed?” Students should come up with words such as, water, river, mountain, collection points, water cycle and lakes. Encourage students to think about other components of a watershed. What’s in a watershed? What are some smaller things? Are you in a watershed? Are we in a watershed right now? Help students understand that a watershed is not a far off, distant landscape; they live and go to school in a watershed every day. Use a PowerPoint slide (number 2) with a watershed graphic to illustrate what a watershed looks like and the different components of the watershed (divide, tributaries, valley). This slide can be accompanied by an additional map of local watersheds. Do you know which watershed you live in? Show a slide (number 3) that outlines the basin or sub-basins students live in? Explain how water traveling over the landscape wears the landscape down (erosion). Show a slide to help illustrate this point (number 4).
Explore (15 min)
Announce that students will be shaping their own watersheds with the stream tables and materials in front of them. The main question students will be trying to answer with their model watersheds is: How does water erode the landscape into different shapes? Students should already be familiar with stream tables and their materials. Tell students that you will be giving them a couple challenges during class. The challenge is to create the shape of the river in a photo on the stream table (meandering and braided river). Transition to a slide that lists instructions for the experiment (number 5). The instructions are as follows:
• Do:
• Change rate of water flow
• Change slope of the watershed
• Place rocks and trees strategically
• Record your observations in you notebook
• Do Not:
– Dig out your river
– Completely line your river with rocks or trees
Make sure students understand that the objective of the experiment is to create a river naturally, not by digging out the river path with their hands. Also, reiterate that students should record their observations in their notebooks (Was the water flow fast or slow? Was the flow steep? What happened to the sediment? Were you able to create the river shape in the photo?) Transition to the slide with the first challenge (braided stream) (number 6). Circulate around the room to ask and answer questions. Ask students to take their seats and to share their group’s observations.
Explain (5 min)
Explain to the class that the new shapes they created in their watersheds were the result of erosion. Ask students to discuss what they think erosion is. Transition to PowerPoint slides that follow the flow of water and, ultimately, the sediment that results in erosion and change in landscape features. Ask the students what factors affect the rate of erosion. What makes the landscape erode at a faster rate? Based on their observations, students should be able to identify slope and water flow rate as contributors to erosion. Discuss examples of erosion in local landscapes. Discuss how erosion is both a naturally occurring process and a process affected by humans. Show the PowerPoint slide of erosion images (number 7). Can you think of any examples of erosion influenced by people? (Cemeteries after Hurricane Katrina, erosion control with vegetation).
Extend/Elaborate (15 min)
In this section, students will be challenged to create a more complex river shape using the stream tables. Transition to the slide with the photo of a meandering river (number 8). Tell students that their next challenge is to create this more difficult river shape. Ask students to discuss in their groups what the flow and slope of their watershed should be in order to achieve a meandering stream. Ask them to write their ideas in their notebooks. Also, ask them to draw a picture where they think the rocks and vegetation should be placed. Next, make sure to reiterate the previous Do’s and Do Not’s for the experiment. Make sure to tell students to record their observations in their notebooks. Ask students to begin their experiment. Circulate around the room to address questions. Ask for the students’ attention and discuss if they successfully created a meandering stream and why or why not.
Evaluate (5 min)
After the Extend section, ask students to take a minute to discuss within their group what they could have done differently to create a meandering stream. What other materials could you use to model a meandering stream? Students should write their ideas in their notebooks. Also, ask students to brainstorm other factors that influence erosion (vegetation, sediment size/composition). Ask students to elect a speaker from their group to share one thing they could have done differently in their experiment and one other factor influencing erosion. Allow enough time for clean-up and show the slide with specific clean-up instructions (number 9).
Follow-up: As the year progresses, students will learn about more factors that affect erosion and the shaping of watersheds, which they can add to their notebook. This experiment can be repeated later in the year with materials students request based on their observations and what they decided they needed in order to shape their watersheds into the landscape the want.
Performance Rubric
The rubric here is an example. Replace with your actual assessment piece or rubric relevant to your lesson.
Element / Excellent(5pts.) / Good
(4pts.) / In Development (3pts.) / Needs Rethinking (2pts.) / Not Scorable
(1pt.)
Knowledge (1, 50%) / Student is able to explain how a watershed is shaped through erosion. As water travels over the landscape, the water wears away the sediment to form rivers and other watershed features. The flow of water and slope of the landscape influence the shape of the river’s path. / Student is mostly able to explain how a watershed is shaped through erosion.
A watershed’s shape depends on water moving the sediment downstream. / Student is somewhat able to explain how a watershed is shaped through erosion.
Erosion occurs when water moves sediments throughout the landscape. / Student has trouble explaining how a watershed is shaped through erosion. Water flows through the watershed. / Student is unable to provide any kind of to explanation about how a watershed is shaped through erosion. No answer.
Skill (1, 50%) / Student is able to create a specific river type using a stream table model. / For the most part, student is able to create a specific river type using a stream table model. / Student is somewhat able to create a specific river type using a stream table model. / Student has trouble creating a specific river type using a stream table model. / Student is does not create any stream table model
Teacher Background Information
A watershed is an area that is bordered by ridges. These ridges, known as divides, determine the flow of water into one watershed or its neighboring watershed. Forced by gravity, water rolls downhill into the watershed through runoff. This runoff can travel through tributaries, rivers and lakes. The larger watersheds we are used to seeing are actually a collection of smaller watersheds. Catchments form sub-basins. Sub-basins combine to form large watershed basins. The water traveling through the basins will eventually reach the ocean and begin the water cycle all over again.
The Yakima Basin is made up of three sub-basins: The Upper Yakima, Lower Yakima and the Naches Sub-basins. This watershed extends north into Wenatchee and west to the Cascade Mountains. To the south, the basin extends to the Simcoa Hills and east to the Vantage plateau.
Erosion is a critical element to the formation and shaping of watersheds. Many factors contribute to the erosion of the land. Humans, animals, vegetation, wind, gravity and ice all cause erosion. Water, however, has the most impact on the erosion of the landscape. Erosion occurs as water travels over the landscape and degrades sediment to form the surface features we see every day. These features include streams, canyons and lakes. The severity of erosion is influenced by the speed and amount of water eating away at the soil.
Resources
Yakima County
Yakima basin watershed assessment
www.yakimacounty.us/ybwra/assessment/Section2_4.pdf
Bryant Watershed Education Project
http://www.watersheds.org/earth/erosion.htm
Jamie Sheahan
Introduction to Watersheds Presentation
By: Kelsey Johnson, Fall 2011, for Selah Jr. High School