Last updated: January 7, 2020
Lesson Plan
Freeing the Elwha (Sediment Deposition and River Structures)
- Grade Level:
- Middle School: Sixth Grade through Eighth Grade
- Subject:
- Science,Social Studies
- Lesson Duration:
- 60 Minutes
- State Standards:
- Science EALR4 6-8, ES3A, EALR 4 6-8, ES2G
Reading EALR 1, Component 1.2
Social Studies EALR 5, Component 5.2
Writing EALR 2, Component 2.1 - Thinking Skills:
- Remembering: Recalling or recognizing information ideas, and principles. Understanding: Understand the main idea of material heard, viewed, or read. Interpret or summarize the ideas in own words. Applying: Apply an abstract idea in a concrete situation to solve a problem or relate it to a prior experience.
Essential Question
What combination of factors both natural and man-made is necessary for healthy river restoration and how does this enhance the sustainability of natural and human communities?
Objective
As rivers age and slow they deposit sediment and form sediment structures. How are sediments and sediment structures important to the river ecosystem?
Background
The focus of this lesson is the deposition and erosional effects of slow-moving water in low gradient areas. These "mature rivers" with decreasing gradient result in the settling and deposition of sediments and the formation sediment structures. The river's fast-flowing zone, the thalweg, causes erosion of the river banks forming cliffs called cut-banks. On slower inside turns, sediment is deposited as point-bars. Where the gradient is particularly level, the river will branch into many separate channels that weave in and out, leaving gravel bar islands. Where two meanders meet, the river will straighten, leaving oxbow lakes in the former meander bends.
Preparation
- Lesson 4 - River Flows and Sediment Movement Lesson Plan.doc
- Sediment Deposition and River Structures PowerPoint
- StreamTable (Freeing the Elwah) PowerPoint
- Mass Wasting and Flash Floods PowerPoint
- Vocabulary notes (printable handouts)
- Reflection Journal Pages (printable handouts)
- Stream Table
- Sand
Materials
Sediment Deposition and River Structures PowerPoint
Download Sediment Deposition and River Structures PowerPoint
Mass Wasting and Flash Floods Powerpoint
Download Mass Wasting and Flash Floods PowerPoint
Stream Table PowerPoint (Freeing the Elwah)
Download Stream Table PowerPoint (Freeing the Elwah)
Lesson 4 - Sediment Deposition and River Structures Lesson Plan
Download Lesson 4 - Sediment Deposition and River Structures Lesson Plan
Vocabulary Notes and Reflection Journals
Download Sediment Deposition and River Structure Worksheets
Procedure
1. Review the Essential Question and introduce the Guiding Question.
2. Hand out the First Reflection Journal page and have students take a minute to consider and respond to the questions, then discuss responses and questions they've generated.
3. Hand out and go over the Vocabulary Notes. Students will define the vocabulary words as they watch the Sediment Deposition and River Structures PowerPoint Lesson.
4. Present Sediment Deposition and River Structures PowerPoint Lesson.
5. Run Demonstration on Stream Table of a low-gradient mature river. Use the Stream Table (Freeing the Elwah) PowerPoint for a demonstration/instruction.
6. Run Demonstration of Mass Wasting and Flash Floods.
7. Show features such as the thalweg, meanders, cut-banks, point-bars, and braiding.
8. Finally have students respond to the Second Reflection Journal page.
Vocabulary
- Meander: When the floodplain is becomes sufficiently level rivers meander. As the river strikes an area of slightly more resistant material, it is deflected. This causes the thalweg of the river to strike the banks at angles and at higher velocity, cutting into the outside turn, while depositing material on the inside turn.
- Thalweg: Line of fastest water velocity in a river. Thalwegs strike the cut-bank in a river meander.
- Cut-bank: The outside curve of a river meander, where erosion is greatest due to the higher stream velocities, causing cutting on the bank and sometimes forming a small cliff.
- Point-bar: The inside-curve of a river meander, where stream velocity is slow and deposition of sediment is greater.
- Braided Stream: When a fast flowing river from high gradient encounters a broad, flat valley that is overloaded in erodible sediment, it will begin to spread out into multiple channels that are interconnected. These channels constantly migrate across the flood of the valley, as they meander through the sediment.
- Oxbow Lake:When two meander curves meet, they circumvent the meander, and straighten the flow of the river. The abandoned channel can become disconnected from the river by sediment to form a lake. These lakes eventually fill in with sediment.
Additional Resources
http://chamisa.freeshell.org/flow.htm
WASHINGTON STATE STANDARDS:
SCIENCE:
1. EALR4: 6-8 ES3A: Our understanding of Earth history is based on the assumption that processes we see today are similar to those that occurred in the past.
- a. Describe Earth processes that we can observe and measure today (e.g., rate of sedimentation, movement of crustal plates, and changes in composition of the atmosphere) that provide clues to Earth’s past.
- a. Explain how a given landform has been shaped by processes that build up structures and by processes that break down and carry away material.
1. EALR 1: The student understands and uses different skills and strategies to read.
- a. Component 1.2 Use vocabulary (word meaning) strategies to comprehend text.
1. EALR 5: The student understands and applies reasoning skills to conduct research, deliberate, form, and evaluate positions through the processes of reading, writing, and communicating.
- a. Component 5.2: Uses inquiry-based research.
1. EALR 2: The student writes in a variety of forms for different audiences and purposes.
- a. Component 2.1: Adapts writing for a variety of audiences.