Formation of Floodplains

Refers to AQA AS Geography (Chapter 1 -Rivers, floods and management)

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  • Created by: Bethany
  • Created on: 10-05-13 15:09
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  • Formation of Floodplains
    • How are they created?
      • Accumulation of river deposits suggests that they are probably depositional
      • Features a result of both erosion and deposition
        • Accumulation of river deposits suggests that they are probably depositional
      • Composed of alluvium - river-deposited silts and clays.
        • Over time, becomes wider and depth of sediment accretions  increases
        • Width determined by amount of meander migration and lateral erosion that has taken place.
          • Lateral erosion most powerful just downstream of the apex of the meander bend. Results in migration of meanders. Scars left visible.
          • Interlocking spurs eventually moved by lateral erosion in middle course.
            • Leaves behind a bluff line and widens the valley.
        • Depth of alluvial deposits depends on amount of flooding in the past, so floodplain linked to extreme events.
          • Over time point bars and meander scars become incorporated into floodplain and add to alluvial deposits.
            • Become stabilised by vegetation as meanders migrate and abandon former courses.
    • What is their appearance?
      • Relitevely flat areas of land either side of a river.
      • Form on valley floor in middle and lower courses.

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