River Delta

Up: Ural river delta (Bird-foot shape)

Down: Nile river delta (Delta shape)

A delta is a landform that is created at the river mouth where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as

the flow leaves the mouth of the river. Over long periods of time, this deposition builds the characteristic geographic pattern of a river delta.

(Wikipedia definition)

What is sediment?

Sediment is naturally-occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluid such as wind, water, or ice, and/or by the force of gravity acting on the particle itself.

(Wikipedia definition)

In this case, sediment that are deposited in a river delta is often very fertile, therefore most of the agricultural activities are on river delta.

How sediment is deposited?

When the river channel's flow enters a standing water (non-moving water), since the width of the channel is expanded, its flowing speed decreases. When it decreases, sediments starts to dropping out of the flow, and deposit.

Sediment could also deposit in the middle of the river, since the slope decreases. Deltas are formed.

Based on what erode the delta, which could be river flow itself, the waves, or tides, different type of delta which have different shape, will be formed.

Those types are

_ River-dominated delta: Bird-foot shape

_ Wave-dominated delta: Delta shape (Greek capital Delta)

_ Tide-dominated delta: Dendritic structure.

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Vu Xuan Kim Cuong