What is a River Delta?

A river delta is a landform that is formed at the mouth of a river, where the river meets the ocean, lake, or another body of water. Deltas are formed when sediment, such as sand and mud, is deposited at the river’s mouth. This sediment is carried by the river from upstream, and when it reaches the mouth of the river, it is slowed down and begins to settle out. Over time, this sediment builds up and forms a delta.

Deltas are typically fan-shaped, and they can be very large. The Mississippi River Delta in the United States is one of the largest in the world, covering an area of approximately 12,000 square miles.

river delta

There are three main types of river deltas:

Arcuate Deltas:

  • Fan-shaped deltas with a convex (outward-curving) front
  • Formed by rivers with a high sediment load and a relatively low discharge
  • Examples: Mississippi River Delta, Nile River Delta

river delta

Birdfoot Deltas:

  • Deltas that are shaped like a bird’s foot
  • Formed by rivers with a low sediment load and a relatively high discharge
  • Examples: Mississippi River Delta, Ganges River Delta

birdfoot delta

Estuarine Deltas:

  • Deltas that are formed in estuaries, which are partially enclosed bodies of water where a river meets the ocean
  • Formed by rivers with a moderate sediment load and a moderate discharge
  • Examples: Chesapeake Bay, Delaware Bay

 

Estuarine Deltas