Rivers: Study Guide Notes

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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.
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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)

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• 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.

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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

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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.

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Changes to a River

• Young Rivers Flow fast, often over rapids and
  waterfalls. They are usually narrow with steep
  sides.
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• 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.