Section 13.1 streams and rivers - Link 308

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Transcript Section 13.1 streams and rivers - Link 308

Is a stream that flows into a larger stream or
River system is a river
and all of its tributaries.
- Also referred to as the watershed, is all of the
land that drains into a river system
A divide is a large landmass that separates two
drainage basins.
Ex. Rocky mountains.
3 factors that determine a streams velocity.
Velocity is the distance water travels in a
given amount of time.
channel shape
Gradient how steep or flat a river is.
The steeper the gradient the faster the river
will flow.
Discharge is the amount of water that passes
by a certain point in a given amount of time.
Discharge varies depending on the time of
year and the weather conditions.
Channel is the path that makes up a river.
The velocity of a river depends on the depth of
the channel, and how winding it is.
 A shallow river with many boulders has a lot
of surface area contacting the river creating
friction and slowing the water down
Stream Erosion and Deposition
 Depositon
 The Process by which the material is
 Pothole
 Deep circular basin
developed when the
river develops small
 Load
 Downstream
 Eroded rock and soil
 By action of the river
 Suspension
 Muddy looking
 Clay, silt and fine sand
 In between the water molecules.
 Bed Load
 Rock transport
 Capacity
 Total amount of sediment the stream can carry
 Competency
 Maximum size of particle the stream can carry
 Increase velocity more
 Decrease velocity
more deposition
 Everything held by the
water will be
 Deposition
 Fine sediment
 River slows down to a body of water
 Describe how rivers wear down rock
 How does a river’s velocity affect its
competence and capacity?
 Under what circumstances do rivers and
streams deposit sediment?
 A river carrying sediments in suspension
curves back and forth sharply. Predict what
you might find if you studied deposits on the
stream bed. Explain your predictions.
River Valleys
 Land is worn away at the head of a
 The level at which the stream can go down
 Set by the body of water the stream enters
 Differential erosion.
 Hard top
 Soft under-strata
What is a flood?
When a river or stream overflows it’s banks
A floodplain is the area along a river that is
most susceptible to flooding.
 A river flowing through a floodplain typically
winds back and forth is broad curves called
 Created because erosion is most rapid on the
outside of a river bend and channel is usually
deepened there
 As the water swings wider it could break
through a meander and result in an oxbow
lake: a curved body of water when deposited
sediments separate a meander from it’s river
 Natural levees form when thick deposits of
sediments form ridges on the side of the river
after a flood.
 Restoring natural plant life in areas along
 Dams can help to control the amount of
water moving downstream.
 Artificial levees such as sandbags can be put
into place as a temporary solution.
 Maintain safe floodplains by not allowing
people to develop the land in a floodplain.