Flood plains, levees and estuaries

• What are floodplains?

  Wide valley floors on either side of a river
• What happens when rivers flood?

  The water slows down, loses energy, and deposits material
• How do floodplains build up over time?

  By the deposition of material during floods
• What are levees?

  Raised banks formed by repeated flooding
• How are levees formed?

  By the deposition of coarse material during floods
• What is an estuary?

  Where the river meets the sea
• What happens to the river in an estuary?

  The river becomes tidal
• What occurs when the sea retreats in an estuary?

  The volume of water in the estuary is reduced
• What happens when there is less water in the estuary?

  The river deposits silt to form mud flats
• Why are mud flats important?

  They provide habitat for wildlife
• What are the key features of floodplains, levees, and estuaries?

  • Floodplains: Wide valley floors beside rivers
  • Levees: Raised banks from repeated flooding
  • Estuaries: Where rivers meet the sea, tidal areas
• How do floodplains and levees interact during flooding events?

  • Flooding slows water, deposits material
  • Coarse material builds levees near riverbanks
  • Floodplains expand as sediment accumulates