Big Ideas
Velocity and volume of stormwater in heavy rain events causes erosion and alters the characteristics of the stream in negative ways.
To restore urban streams, PWD “re-engineers” stream beds and daylight streams that have been buried.
This, along with planting trees and other plants along the river and in surrounding areas, helps the health of the river to improve.
Summary
Streams and rivers in urban areas have often been compromised due to urban development and paving of large swaths of land. Planting trees and other plants along the river and in surrounding areas helps the health of the river to improve
Engage
Introduce the idea of Ecological Restoration. Generate a list of the different areas of impact in the city that students have been exploring so far.
Visit the PWD website for Ecological Restoration. This page has excellent descriptions of the areas of focus for Philadelphia.
The webpage describes a VISION for a healthy ecosystem in Philadelphia.
Have students select an item of interest from the Tools or Projects menu on the left menu. They can share their reactions and summarize the information with the class.
Explore and Explain
EROSION IMAGES
View Erosion Powerpoint: 2017.04.27 erosion powerpoint.pptx
COMPARE GRAPH TO OBSERVATIONS OF STREAM TABLE OR PHOTOS
Discuss implications of the Stream Flow Graph (Attachment D).
Discuss erosion that occurred during Stream Table simulations. What factors affected erosion? (Velocity and amount of water.)
Examine photographs of creeks (Attachment F) at peak flow and normal flow and look for evidence of eroded stream banks.
HURRICANE IRENE
SLOW THE FLOW
Give students a photograph of an eroded stream. Include some physical features and some information about the surrounding watershed.
Write a reflection addressing the following prompts:
Should we restore streams? Why or why not? Explain
Elaborate
EXAMINE PHOTOGRAPHS OF ERODED STREAMS
Re-examine photographs of streams (Attachment 5.3-F) under normal flow conditions and under peak flow conditions. Discuss what causes erosion.
Has erosion changed the stream? Often historic photos of bridges will show where the water used to run.
Look at some of the photographs for clues. Take a trip to a complete mitigation site and/or site under design for mitigation and/or research mitigation projects. Click Philadelphia Water Department Ecological Restoration as a resource for why streams need to be restored and for PWD restoration projects.
Click through PROJECTS to see explore in more detail projects near your school or across the city.
Teacher Support
Essential Question:
How can we create a healthy, beautiful, and sustainable Philadelphia for everyone?
Guiding Questions:
Explore and Explain
What causes erosion?
Why is erosion a problem?
Why should we restore streams?
What will happen if the streams are not restored?
Elaborate
What other work is being done to restore the health of the rivers and streams in Philadelphia?
Students will be able to:Calculate Stream Flow to predict the risk of erosion.
Describe what caused the erosion; Back up ideas with evidence from the stream table simulation. Flow rate calculations should be included in the description.
Explain what could be done to slow down the flow, to reduce the volume of the water and to restore the stream.
Engage
- Watershed Journal or Foldables
- Stream Types and Features for Labeling Stream Table (Attachment A)
- Rosgen Chart of Stream Classification (Attachment B)
- Stream Table Worksheet (Attachment C)
Explore & Explain
- Why Do We Restore Streams? (Attachment D)
- Common Flow Rates (Attachment E)
- Photographs of streams in normal and peak flow and Historic Photos of Streams and Bridges showing erosion (more photos needed) (Attachment F)
- Stream Flow Calculation Sheet (Attachment G)
BASIC TERMS
Bankfull adjective
The water level, or stage, at which a stream, river or lake is at the top of its banks and any further rise would result in water moving into the flood plain.
Braided Channel noun
A channel (body of water) that consists of a network of small channels separated by small and often temporary islands. Braided channels occur in rivers with high slope and/or large sediment load.
Delta noun
An area of low, flat land, often shaped like a triangle where a river divides into several smaller rivers before flowing into a larger body of water.
Degrade verb
Break down
Deposition noun
The sediment that the stream leaves behind.
Erode verb
To wear away by the action of water, wind or glacial ice.
Fork noun
A place where a river or stream divides into two parts.
Gravel Bar noun
An elevated region of gravel that has been deposited by the flow.
Headwaters noun
The beginnings of a stream
Flood Plain noun
Flat land next to a river or stream.
Meander noun
A winding curve or bend of a river
Mouth noun
The point at which the stream discharges into a larger body of water.
Sediment noun
Solid material that is moved and deposited in a new location. Sediment moves from one place to another through the process of erosion.
Stream Restoration noun
Set of activities that help improve the environmental health of a river or a stream.
Peak Flow noun
Highest flow in the stream as a result of a rain event.
Substrate noun
A substance or layer that underlies something.
Slope noun
A surface of which one end is at a higher level than another. A number describing how steep the straight line is.
Tributary noun
A river or stream flowing into a larger river or lake.
Velocity noun
Speed
Wetland noun
Land area that is saturated with water—often along the edges of streams and rivers.
ADVANCED TERMS
Flow Discharge Calculations noun
Calculations based on volume and velocity and permeability
Rosgen Stream Classification noun
Widely used method for classifying streams based on common patterns of channel shape
Sinuosity noun
A bend in the stream. Term that describes how curvy a stream is.
Students will use their Watershed Journal and/or Foldables to record observations, discoveries, reflections, etc.
Calculate Stream Flow to predict the risk of erosion.
Describe what caused the erosion; back up these ideas with evidence from the stream table simulation. Flow rate calculations should be included in the description. Explain what could be done to slow down the flow, to reduce the volume of the water and to restore the stream.
Write a reflection addressing the following prompts: Why should we restore streams? What will happen if the streams are not restored?
PA STEELS Standards
Environmental Literacy and Sustainability
3.4.6-8.H Sustainability and Stewardship: Design a solution to an environmental issue in which individuals and societies can engage as stewards of the environment.
Related Standards
EfS F.7b Natural Laws and Ecological Principles – Make a case for why global citizens should understand the basic natural laws and principles including the basic principles of ecology
Student Materials
Student Worksheet