Rivers are generally much wider at their mouths and this means the water speed is much less than further upstream. The result is that sediment is maintained in suspension less and therefore settles out.
The river flows into a lake
A river deposits sediment when it loses energy and its transporting capacity decreases. This can happen when the river slows down as it enters a larger body of water, like a lake or ocean, or when the volume of water decreases. Additionally, changes in the river's gradient, such as a decrease in slope, can also lead to sediment deposition.
The primary agent of erosion that creates a delta is a river. As the river flows towards a body of water, it carries sediment, which is deposited at the mouth of the river in a fan-shaped pattern. Over time, this accumulation of sediment forms a delta.
Most rivers have eroded and Deposited sediment.
Most sediment washes or falls into the river as a result of mass movement and runoff. Other sediment erodes from the bottom or sides of the river
Rain.
River valleys tend to have the most fertile soil due to the regular deposit of nutrient-rich sediment from flooding. This process creates a nutrient-dense layer of topsoil that is highly conducive to agriculture.
Most river sediments are deposited at the mouth of the river, where it meets a body of water such as a lake or ocean. The sediment settles due to the decrease in water velocity as the river enters a larger body of water, causing it to drop the sediments it was carrying.
triangle
The Amazon River.
The mouth of the river is where it flows into a larger body of water such as a lake, ocean, sea. However, deltas usually form at the mouths of rivers from sediment being deposited over time. Don't get these two things confused. +++ The lowest, tidal reach of a river as it reaches the sea is called its 'estuary'.
A delta is when a stream or river reaches a large body of water, such as a lake or ocean or stream, it slows down. Most of the sediment drops out, forming a triangular- shaped deposit called delta.- 6th- grade :)