Floodplain (Fluvial Deposition) Flashcards
What are floodplains?
Relatively flat areas of land either side of the river, which form the valley floor in the middle and lower courses of the river.
What are floodplains made of?
Alluvium- river deposited silts and clays
What happens to floodplains over time?
It becomes wider and the depth of the sediment accretions increases.
What is the width if a floodplain determined by?
The amount of meander migration and lateral erosion that has taken place.
Where is lateral most powerful?
Just downstream from the apex of the meander bend.
What happens to meanders over time?
The migration of meanders- leaving scars clearly visible on the floodplain.
Interlocking spurs are eventually removed by lateral erosion in the middle course, leaving behind a bluff line and widening the valley.
What does the depth of the alluvial deposits depend on?
The amount of flooding in the past
What features are created over time?
Point bars and old meander scars become incorporated into the floodplain, adding to the alluvial deposits. These become stabilised by vegetation as the meanders migrate and abandon their former courses.
What are floodplains a creation of?
Erosion and deposition, although the accumulation of river deposits suggests that they are predominantly depositional features.
