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River Delta

Last updated date: 27th Feb 2024
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About River Delta

When the river meanders its way to the lake or the sea, the water slows down gradually, and the river flow loses the power in carrying the sediment along the way. The sediment gets dropped at the river mouth, and this is the first step of forming a River Delta. There are some rivers to drop a greater amount of sediment, which the tides and the waves cannot carry all through the way. In consequence, layers are built in forming the River Delta. Some deltas are extremely large that you can find human existence on them. In Egypt Nile delta is the most vital farming region or agricultural zone. 

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Understanding River Delta Diagram

If you look at the River Delta Diagram, you can well understand the structure and the shape of the delta in real life. There is the flat part of the delta, and the same is referred to as the delta plain, and it remains above the level of the water. From here, the river gets divided into many small channels, and these are known as distributaries. You also have the portion of the delta under the water. There is also the steep and the sloping delta, and it is the front that can easily face the ocean or the lake. There is the prodelta portion, and it rests away from the deeper mouth, and it is extremely under the water. 

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Not all deltas have similar shapes. Much depends on the amount of sediment that gets deposited by the actual river. This can be compared to the amount of sediment that faces erosion, and it is redeposited by the waves and also by the tides. Things are understandable from the River Delta Diagram, and once you follow the map, it is easy to have the best understanding of the delta influenced by the river. There are many river deltas present. For example, the Danube delta, Fly delta, Indus river delta, Amazon delta etc. 

Types of River Delta

Arcuate Delta – Here is the delta with the curve and the bow shape and it has the convex margin which faces the water body. The same is also called the fan-shaped delta with examples of the River Nile Delta in Egypt and the Ganges Delta in India. 

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Estuarine Delta – This delta is formed at the mouth of the submerging river. It forms due to continuous deposition at the sides of the estuary and the examples of the same are the Seine River Delta of France. 

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Birds foot Delta – The delta forms because of the deposition of the finer materials carried by the river water. The alluvial material that is being deposited is divided into smaller and finer distributaries. It is also called the finger delta and the example of the same is the Mississippi river delta, in the USA.

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Lacustrine Delta – The delta is formed when the river is flowing into the lake. The example of the same is Lough Leanne river delta in Ireland. 

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Truncated Delta – The Ocean and the sea wave currents can help in modifying and can even cause destruction of the deltas that are being deposited and delivered by the river by means of the continuous erosion action. The dissected and the eroded delta is called the truncated deltas.  

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Abandoned Delta – When the river is standing at the mouth and you have the formation of the delta at the left side. The accumulation of the abandoned material helps in forming the delta. This is the Abandoned Delta and the examples are Yellow River Delta, The China Delta and the Western part of the Ganges Delta formed due to the deposition of the Hooghly River. 

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Cuspate Delta – It is a tooth shaped delta and it is formed due to the flowing of the single distributary which flows and deposits the silt on either side forming the delta bed. An example of this is the Tiber River Delta in Italy.  

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How is the River Delta formed & It’s Delta Diagram Specification ?

By means of the delta formation diagram, it is understandable that in the uncommon sense, delta at times can even open into the land. So how is the delta formed? Once the river reaches the mouth, it becomes slow in motion. It slows down at the end when it is time for it to empty itself. In motion, the solid material and the sediment are carried downwards by means of the current, and it is made to fall at the bottom of the river. The velocity of the river becomes slow, and the sediment build-up of the same will make it possible for the river to break down into a single channel, and it is made to happen once the river reaches the mouth. 

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To define the delta in geography, there is the long and the narrow sediment mounding, and it is called the sleeve. The sleeve is there on the sides of the narrow and the thin distributary channels. A delta can be described as a wetland, and it is formed when the river empties the water and the sediment into one more water body like the lake or the ocean, and it can even empty the same into another river.

Owing to the river delta formation, when the conditions are right, the river is sure to form the deltaic lobe. There is the matured deltaic lobe to include the network of the distributaries, the range of the shallower and the smaller channels. These are called the distributaries, and they can easily depart from the river mainstream. At the deltaic lobe, the coarser and heavier components are made to settle down at first. However, the finer and the smaller sediments are carried far along with the downstream. This ultimately forms into the delta.

Based on the details of the delta geology, the finest material that is carried down to the mouth of the river is known as silt or alluvium. Silt is made of rich and fertile nutrients that are sure to help the plants and the microbes in the production and the growth of the food web. With the building up of the silt, there is the formation of new land. The specific land is called the delta.


There are various river delta examples, and these are the Danube Delta, Amazon Delta, Euphrates Delta, Ebro Delta, Ganges–Brahmaputra Delta, Fly Delta, Indus River Delta and the Godavari Delta. These are classic delta formations giving the earth its distinct shapes.

FAQs on River Delta

1. What are the three delta types?

A delta comes in the three major parts. There is the upper delta plain and the lower delta plain, and there is also the subaqueous Delta.

2.  Why do deltas form?

Deltas are like the wetlands that are formed when the river will empty the water and the sediment to another water body, like the lake, ocean or another river. When the river comes near the mouth, it flows in slow motion. Towards the end, there is a change in the course and motion of the river. This will cause the sediment and the solid materials to be carried downstream by the main current, and it is made to fall at the river bottom. In the end, it gives form to the delta-like land, which is used for both agriculture and human habitation. The soil of the delta is extremely fertile, and it is ideal for both human and green existence.

3.  What is delta in geography?

The delta is a flat and low triangle-shaped land, and it is formed due to the sudden splitting and the spreading of the river into several branches before it enters into the sea. The formation of a delta is a natural phenomenon, and it is a gift of land that acts as a boon for human existence. The quality of delta ids is highly fertile, and the farmers find it a good place to grow crops. Judging the nature and the quality of the delta, it is referred to as a magical gift of nature.