Where Do They Start?
Streams begin when precipitation runs off the surface!
Runoff
Rill
Stream Formation
Stream
• Headwaters
– Region where water
first accumulates to
supply a stream.
Unit Essential Questions:
How does the Earth cycle its water through its major reservoirs?
How does society’s use of resources affect water quality?
Presentation Objectives:
§ Describe how stream develops from source to mouth.
§ Identify and describe the main features of a young and mature river.
§ Describe how a meander evolves into an oxbow lake.
§ Explain what happens to a river when it reaches its base level.
§ Briefly discuss estuaries and alluvial fans.
Headwaters
Gully
Typically in the Mountains!
Young Streams
• Since the occur in the mountains, young
streams have:
– Fast moving water
– V-shaped valleys
Headwaters of the Mississippi River
Itasaca State Park, Minnesota
Headwaters of the Connecticut River
NH’s Connecticut Lakes Region
– Rapids
– Waterfalls
Young Stage Features - Rapids
Young Stage Features - Water Falls
Housatonic River Rapids
Lower Niagara River Rapids
Niagara Falls Up Close and Personal
Niagara Falls
Angel Falls, Venezuela
World’s Tallest Waterfall - 979 m
Mature Streams
• Mature streams occur where the land is more
gradual.
– Meanders
– U-shaped valleys
– Oxbow Lakes
Meandering Rivers
Oxbow Lakes
• Eventually the meanders become too big.
• Sides connect to into each other, cutting off the
meander forming an oxbow lake.
• Faster water causes erosion, while slower water
deposits sediment.
– Erosion occurs on the outside of the meander.
– Deposition occurs on the inside of the meander.
• This relationship causes the meander to get
larger.
Curves Become Straight!
Final Destination
• When rivers reach a quiet sea, their velocity
decreases and deposition occurs.
– Fan-shaped deposit formed is called a delta.
Mississippi Delta
The Nile Delta
Estuaries
• An estuary is where freshwater from a river mixes
with the saltwater from the ocean.
– They provide habitat for many plants and animals.
– Act as a nursery for the young of aquatic organisms.
Long Island Sound is an estuary!
Alluvial Fans
• Streams can also change velocity drastically
when there is an abrupt change in slope.