A river delta is a land form that forms at the mouth of a river, where the river flows into an ocean, sea, estuary, lake, or reservoir.Deltas form from deposition of sediment carried by a river as the flow leaves its mouth. Over long periods, this deposition builds the characteristic geographic pattern of a river delta.
A river delta is a land form that forms from deposition of sediment carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment.
The following are conditions necessary for formation of river delta:
- The river must have large load. This will be possible if there is active erosion in the upper and middle stages.
- There should not be extensive deposition in the middle stage e.g. presence of lake in between or high evaporation rate (first).
- The river’s load must be deposited faster than it can be removed by the action of currents and tides.
- Presence of shallow adjoining sea or continental shelf.