Transcript Running Water - Jefferson Township Public Schools

Running Water
Running water
Water as an agent of
erosion; water in
streams, tributaries
(larger streams) and
rivers that flow down
hill therefore
changing the
landscape (erosion)
Running water
• Abrasion –
wearing away
of rock by
grinding
action
3 ways rock is carried by water
• Solution – mineral matter dissolved from
bedrock is carried in a river (25%)
3 ways rock is carried by water
• Suspension – small rock materials, silt and clay,
carried by a river are stirred up & kept from
sinking by the turbulence of stream flow (50%)
3 ways rock is carried by water
• Bed Load – sand,
gravel, pebbles, and
boulders that are
moved along the bed
of a stream & that are
too heavy to be
carried in suspension
(25%)
• Carrying Power – how much total
sediments a stream can carry and the size
of the particles being carried by the
stream at given time and stream velocity
• Discharge – volume of water flowing
past a given point in a stream at a given
time
Stream features depend on 3 major things
1. The type of rock being eroded.
2. The amount of water & sediment
3. The climate of the area
• Base Level – the level of the body of
water into which a stream flows
• Gully – a miniature
valley formed by
erosion from heavy
rains
• Headward Erosion – wearing away of
land at the head of a gully or a stream
valley
More Headward
Erosion
Divide – the higher land separating two
adjacent drainage basins
•
Continental Divide
made of Rocky Mountains and Sierra Madre
Occidental Mountains
– Streams on the East drain into the Atlantic
Ocean or Gulf of Mexico
– Streams to the West drain into the Pacific
• Stream Velocity – the speed of water at
a given point at a given time
• Drainage system - Streams flow into
larger streams (tributaries), which flow
into rivers, which flow into oceans …
cumulative denotes a “drainage system”
• Drainage Basin (watershed) – an area
of land who’s runoff supplies water to the
stream of a drainage system - area
drained by a river system
• Stream Piracy –
the diversion of
the upper part of
one stream by the
headward growth
of another stream
• Water Gap – a pass
in a mountain
ridge through
which a
stream flows,
created by
resistant rock
layers
Life of a River
A Youthful Stream
• Narrow V-shaped
valley
• Down cutting
• Swift water
• Steep gradient
• Erosion is dominant
Mature Stream
• Lateral Erosion
begins
• Meanders develop
• Floodplains
develop
• Gradient lowers
Old Age
• Wide meanders and
oxbow lakes
• Wide floodplain
• Low velocity
• Low gradient
• Dynamic equilibrium
between erosion and
deposition
Flow speed
High velocity (erosion):
• Outside of curve
• Middle of surface
• Well below the surface
• Increase in discharge
• Increases with increase
in gradient
Flow speed
Low velocity
(deposition):
• Inside of curve
• Edges of river
surface
• Decrease in
discharge
• Decreases with
decrease in gradient
Flash Flood – a
sudden rush of water,
usually caused by a
single cloudburst over
the narrow valley of a
young mountain
stream
3 Common types of natural dams
A. landslides
B. ice jams 
C. volcanoes
3 Common types of artificial flood
control
A. build up levees
B. pump rising water into back swamp
reservoirs
C. build a series of dams and control the
overall flow of the river
Features…
Meander – a curve in a mature or old stream
Mississippi River
Features…
• Oxbow Lake – crescent- shaped lake
formed when a river meander gets cut off
from the river and the ends of the original
bend have ‘silted up’
– Erosion on the outside bend of a river
– Deposition of the inside bend of a river
Features…
• Floodplain – the broad flat valley floor
carved by a meandering stream and often
covered with water when a stream floods
• Levee – a natural or artificial bank
confining a stream or river channel
• Pothole – deep
oval or circular
holes cut into a
stream bed by
abrasion from
swirling sand &
pebbles. Very
large ones are
called plunge
pools
• Delta – a fan-shaped deposit of sediment formed
at the mouth of a stream or river when it flows
into a quiet body of water, such as a lake, gulf, or
inland sea (ex. Mississippi & Nile river deltas)
Laizhou Bay (Laizhou Wan) is the southern arm of the
Bohai Sea (also Known as the Bohai Bay, or just Bo Hai),
which is a large relatively shallow extension of the Korea Bay
Nile River Delta
Alluvial Fan –
sloping triangular
deposits of
sediment located
where a mountain
stream reaches
level land (ex. At
the foot of the
Rocky Mountains
and the Sierra
Nevada’s)
Online quiz…
• http://www.uh.edu/~jbutler/physical/chap
13mult.html