Floodplains are flat areas of land adjacent to rivers that experience occasional flooding when river discharge exceeds channel capacity. Floodplains hold excess water, allowing it to be slowly released and infiltrate while also providing time for sediment to settle. They support important wildlife habitats and are used for agriculture, recreation, and settlement due to fertile soil and access to transportation, though flooding must be controlled in urban areas through measures like levees. Floodplains form through erosion as rivers cut into channels and banks or through aggradation when sediment supply exceeds transport capacity, raising land elevation and water levels.

1. Floodplains
BY
PARVA SHAH

2. What are Floodplains?
• A floodplain, or alluvial plain, is a piece of flat land on either side
of a stream or river, that will experience occasional flooding. It
holds the excess water, allowing it to be slowly released into the
river system and/or to infiltrate.
•Flooding is when river discharge exceeds the capacity of the
channel, water rises over the channel banks and floods the
surrounding low-lying lands.
• Floodplains also give time for sediment to settle out of
floodwaters.
•Floodplains often support important wildlife habitats and are
frequently used by humans as recreation areas.

3. What are Floodplains?
Floodplains generally contain
sediments, often accumulations of
sand, gravel, loam, silt, and/or clay.
Sections of the Missouri River
floodplain show layers or areas of
varying material. Sometimes the
deposits are of coarse gravel, fine sand
or silt.

4. EROSIONAL
FLOODPLAIN
An erosional floodplain
is created as a stream
cuts vertically and
laterally into its
channel and banks.
Such as the Colorado
River, Arizona.
Floodplains are formed in two ways: by erosion and by aggradation
Floodplain Formation

5. Floodplain Formation
AGGRADATIONAL FLOODPLAIN
•Aggradation is the term used
in geology for the increase in land
elevation due to the deposition of
sediment. Aggradation occurs in areas in
which the supply of sediment is greater
than the amount of material that the
system is able to transport. So when
aggradation occurs the land elevation
increases and thus the water level
increases and causes floodplain.

6. Floodplain Uses
•The main use of floodplains is for agriculture, however the use of the land
for settlement has become more popular.
Settlement on floodplains, despite occasional flooding, is attractive because:
- Water is most available.
- The land is more fertile.
- Rivers correspond to cheap modes of transport.
- Flat or gently sloping land is more suitable for development.
Here is an example of how floodplains have been used for settlement
and how the river flooding has had to be controlled.

7. Human influences on floodplains
•In areas where floodplains have been used for
settlement, flooding can be a hazard, and
therefore it has had to be controlled.
•Levees are built or strengthened to prevent
flooding, which would help to benefit and protect
the urbanised area surrounding the floodplain.
•Here is an
example of a
levee in an
urban area.

8. THANK YOU