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Rivers: Study Guide Notes
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River Formation
Rivers start from precipitation that begins
to flow downhill and forms surface runoff.
Runoff joins together to make small
creeks and streams that flow into larger
rivers.
All rivers flow downhill, eventually leading
to the ocean.
Parts of a River
Tributary – a small stream or river that flows
into a larger main river.
Source - the start of a river
Mouth -the end of a river
Gradient – the change in elevation of a river.
(steepness of a river) The gradient always
decreases from the source to the mouth.
(Downhill)
Meander - the bend of a river
Inside bend – (Point Bar) water slows down,
load (sediment) is deposited
Outside bend – (Cut Bank) water speeds up,
bend gets “curvier”, rock is cut away
Floodplain - the area that floods when a river
overflows its banks.
River Erosion
Discharge - amount of water flowing in a river.
Load – minerals, silt, weathered rocks, and
sand mixed into the water and flowing
down the river. Sometimes dissolved in
(clear appearance) other times a muddy
appearance.
More Discharge = More Erosion = More Load
Where does the water go?
Drainage Basins (Watersheds) – The land
drained by a river system, which includes
the main river and all its tributaries.
All the water in a drainage basin drains to
one location.
Divide – Separates drainage basins. It is an
area of higher ground than the basins that
it separates, like mountain ranges.
Changes to a River
• Young Rivers: Flow fast, often over rapids and waterfalls.
They are usually narrow with steep sides.
• Old Rivers: Wide with strong meanders and flow smoothly
and slowly through a flat area of land. They are found in
floodplains and often deposit sediment along their banks or
into deltas.
• Why Rivers “age”: Over time, the rocks that cause rapids
are eroded away. As rivers mature, they reach level ground,
the discharge slows, and they begin to form meanders and
even oxbow lakes.