a Delta
The triangular-shaped landforms caused by deposited sediment are called deltas. Deltas typically form at the mouth of rivers where the flowing water slows down and deposits sediment, creating a triangular shape as it spreads out into a larger body of water like a lake or ocean.
Alluvium is a deposit of sediment or soil carried and deposited by flowing water, often found near rivers, streams, and floodplains. It is used in agriculture to enrich soil fertility, in construction to make concrete, and in landscaping for creating natural-looking water features.
When it is flowing slowly
Water is typically the most powerful agent of deposition due to its ability to transport and deposit large amounts of sediment. This is especially true for rivers and streams, where flowing water can pick up and carry a variety of sediment sizes.
Tributaries can both erode and deposit sediment. In the upper reaches of a tributary, erosion may occur as the flowing water picks up and moves sediment. Closer to the main river, deposition may happen as the velocity of the water slows down and sediment is dropped.
Sediment deposited by flowing water
Deltas are created when a thick river with slowing meanders deposit the sediment and rocks build up and create new land. This new land causes the river or stream to break apart and creates branches. A delta is now created.
Alluvial fans are formed when a fast-flowing stream or river suddenly encounters a flat or gently sloping plain, causing the water to slow down and deposit sediment. This sediment builds up over time, creating a fan-shaped deposit. Factors such as the gradient of the slope, the volume of water, and the size of the sediment particles all play a role in the formation of alluvial fans.
runoff
Stream deposition occurs when a flowing stream loses energy, causing it to slow down and deposit sediment that it was previously carrying. This commonly occurs when the stream enters a flatter area, like a floodplain or a lake. As the stream's velocity decreases, it can no longer transport sediment, leading to deposition.
a bedload
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