Difference Between Delta and Estuary (With Table)

Delta vs Estuary

If you have studied geography carefully during your school days, you must remember coming across terms like delta and estuary.

Both the terms are associated with rivers and large water bodies such as oceans and seas.

Although for a layman, deltas and estuaries would appear to be similar, there are certain important points of differences between the two.

Rivers commence from the mountain ranges and end up at the seas or oceans. The point where it meets the ocean the speed of the river diminishes, which restricts the ability of a river to carry various sediments any further.

At the point where a river is about to meet a sea or an ocean, it drops all the sediments which form a low triangular area of alluvial deposits. This is known as delta.

Estuary, on the other hand, is somewhat similar to some extent. It is also associated with rivers and oceans or seas.

However, an estuary is a coastal water body or rivers that meet a sea or an ocean and form a transition zone between the two water bodies.

In other words, an estuary is formed in regions that experience rift valleys and high tides.

Parameter of ComparisonDeltaEstuary
DefinitionIt is a low triangular-shaped fertile area consisting of alluvial deposits brought in by a river before meeting a large water body.It is just an area where the fresh water from a river meets the saltwater of seas and oceans.
FormationFormed when rivers fail to carry along the sediments any further due to reduced current before meeting an ocean or a sea.It is formed by a tidal bore that gradually erodes the riverbed and also carries the fertile soil or silt to the sea.
FertilityIt is extremely fertile.It is not very fertile.
TypesBird’s foot, cuspate, and fan-shaped or arcuate.Tectonic estuaries, fjord estuaries, and coastal plain estuaries.
Where it is formedForms in regions that experience coastal plants and low tides.Forms in regions that experience rift valleys and high tides.
Suitability for habitation and agricultureAlthough it is a flood-prone zone, it is extremely suitable for agriculture due to the fertile sediments.Not suitable for agriculture but good for wildlife habitats.
ExamplesGanges Delta and Mahanadi Delta.Baga Creek and Kayamkulam Kayal.


What is Delta?

Rivers carry loads of soil and other sediments during their long and tiring journey from the mountain ranges to an ocean or a sea.

A delta or most popularly referred to as a river delta is a landform that is created when sediments, carried by rivers, are deposited at the junction of the river and a larger water body such as a sea or an ocean.

Deltas are normally formed at the meeting points of rivers with seas, oceans, lakes, reservoirs, estuaries, and another river, which is a rather rare situation.

The shape and size of the delta formed are entirely dependent upon by the mere balance between the receiving water body that may either export or redistribute the sediments and the watershed process that acts as the supplier of the sediments.

Different types of deltas are formed. These include wave-dominated deltas, tide-dominated deltas, gilbert deltas, tidal freshwater deltas, mega deltas, and inland deltas.

Some common examples of deltas include Amazon delta, Godavari Delta, Indus River Delta, Rhine Delta, and the Yangtze.

Deltas are extremely fertile, which is why most of the age-old habitats could be found in some of the major delta regions of the world.

Delta Farming in Practice
Delta Farming in Practice

What is Estuary?

If you think that deltas and estuaries are the same, you need to think again! When you talk about an estuary, it is a limited area of an encircled coastal body of saline water with a minimum of one river flowing into it. It also has a free connection to a sea or an ocean.

It is usually seen that estuaries tend to form a type of transition zone between maritime environments and river environments.

You also need to know that estuaries are easily influenced by various marine influences that include waves, tides, and inundation of salty water to flows of freshwater.

Due to the mixture of freshwater and seawater, a high level of nutrients is formed both in the sediments and water column. Several estuaries suffer from degeneration due to several factors.

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These include deforestation, soil erosion, overfishing, filling up of the wetlands, and overgrazing.

Unlike deltas, estuaries are not that fertile and it also has several types that are based on geomorphologies, such as drowned river valleys, fjord type, bar-built or lagoon-type, and tectonically produced.

Estuary joining a sea
Estuary joining a sea

Main Differences Between Delta and Estuary

  1. Deltas are practically wetlands that are normally formed when a fast-moving river empties its sediments before joining a slow-moving water body such as a sea or an ocean or a lake. On the other hand, estuaries are semi-enclosed water bodies that constitute of salty water. It is normally an area where a river merges with a sea.
  2. Deltas are normally shaped like a bird’s foot or fan-shaped, whereas, estuaries are fjord estuaries or tectonic estuaries.
  3. Deltas are extremely fertile by nature that makes it suitable for agriculture and estuaries are not at all fertile and thus, not suitable for agriculture.
  4. Deltas are formed in regions that experience coastal plants and low tides, whereas, estuaries are formed in regions that experience rift valleys and high tides.
  5. Examples of deltas include Krishna Delta and Brahmaputra Delta. Examples of estuaries include Thekkumbhagam estuary and Baga Creek.


Frequently Asked Questions (FAQ) About Delta and Estuary

How is an estuary formed?

Estuaries are formed when the sea level Rises and the river valleys are drowned with water.

Once they are formed they trap the sediments which are present in that area like sand and mud and also form a layer of gravels which again runs down the hill during the time of rainfall and runoff.

What is the synonym of the estuary?

There are many synonyms for the estuary. Some of them are as follows: branch, inlet sound, tributary, subdivision, Creek, channel, firth, Strait, stream.

The estuary is also referred to as a simple river or sometimes Delta by the people who do not know about the technicality of geography and river tributaries.

What is a synonym for Delta?

Delta is a flat, low level and a triangle-shaped area where the river comes, splits and finally spreads out into several numbers of branches before finally entering the sea.

The most common synonyms of the delta are formation, Alluvial deposit, Alluvion, alluvium, Alluvial sediment, and geological formation.

👨 ‍ 👨 ‍ 👦 ‍ 👦 What are the three types of deltas?

The Delta is mainly of three types. They are as follows: the first is the bird & foot delta, the second Delta is the cuspate and the third Delta is arcuate delta.

The arcuate Delta is usually in the shape of a fan where the wider portion of the fan is mostly facing the water.

What is the most famous Delta?

The deltas are most common to be found in the region of India and Bangladesh as they are one of the most fertile regions in the world.

But the most famous Delta is the Nile delta. The other most famous Delta is the Mississippi delta.

💸 What are the four types of estuaries?

The estuaries are basically of four kinds.

They are as follows: the first is the coastal plain estuary, second is the tectonic estuary, the third is the bar built estuary and the fourth estuary is the Fjord estuary.

What is the largest estuary in the world?

There are many large estuaries present all around the globe but the world’s largest estuary in the Gulf of Saint Lawrence River estuary.

The major portion of this estuary lies in Canada and the length of the river is around 1900 square miles and the water span of this particular estuary is about 390000 square miles.



Delta vs Estuary



Unlike popular beliefs, deltas and estuaries are not the same things at all. Although both are geographical happenings, there are several points of differences between the two terms.

One of the primary differences between the two is the fact that deltas are very fertile and one of the best regions for agriculture.

On the other hand, estuaries are not at all fertile and any type of agricultural attempt at the region will fail miserably.

There are 4 types of estuaries, bar-built, drowned river valley, tectonic, and fjord. However, deltas are of several types such as tide-dominated and wave-dominated.


Word Cloud for Difference Between Delta and Estuary

The following is a collection of the most used terms in this article on Delta and Estuary. This should help in recalling related terms as used in this article at a later stage for you.

Difference Between Delta and Estuary
Word Cloud for Delta and Estuary



  1. https://www.sciencedirect.com/science/article/pii/S0025322705003063
  2. https://link.springer.com/article/10.1007/s11625-016-0355-7
  3. https://www.jstor.org/stable/208680

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