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Difference between estuary and delta

febrero 11, 2020

When the river enters the sea or any other stream, where the flow of water slow and can no longer carry the sediment brought by the river, the sediment is dropped at the mouth of the river and the result is the formation of a delta . Not exactly the same as a estuary, than a coastal body of water, where the river meets the sea or any other stream, with brackish water.

In short, the fundamental difference between estuary and delta is that the former is a tidal mouth of the river, where it meets the sea, while the latter is nothing more than the wetland, formed as a result of the accumulation of sediments transported by the river when it joins a permanent water body. So, let's take a reading of this article to know more differences about these two.

Comparative chart

Basis for the EstuarioDelta comparison
SenseThe estuary refers to the body of water, along the coast, which is formed when the fresh water of the river meets the salt water of the ocean.Delta connotes a form of land formed by river sediments deposited at the mouth of the river when it joins the sea.
riversEstuary of Narmada and Tapi form.Mahanadi, Godavari, Krishna, Cauvery, Ganga and Brahmaputra form deltas.
TideHigh tidesLow tides
RegionThe region near the non-fertile estuary.Delta are fertile lands.
Useful toFishing activityAgricultural activities

Definition of estuary

The estuary can be understood as the coastal water body of one or more rivers that connects to the sea or ocean. partially enclosed by the earth and contains brackish water, that is the mix of fresh and salt water. In short, an area where tides flow in and out, and the river widens and slowly converges towards the sea. It winds to meet the sea. It can also be called a bay, lagoon and slough.

Depending on the location and climate, the size and shape of the estuary may differ. In addition to this, the water level and salinity vary with the tides.

Definition of Delta

The delta defined as the shape of the soil, created by the deposition of sand, clay and crack, brought by the river, while the river enters another river, sea, ocean, lake, etc. It occurs where the river joins a larger waterway whose flow of water is slow and unable to transport the sediment supplied and leaves it at the mouth of the river which causes the delta to form.

The delta accumulates with the continuous deposition of sediments, which makes the water shallow, causing the conformation of the soil to rise above the sea level. A delta divided into four parts, ie subaqueous, subaerial, lower delta plain, upper delta plain.

Key differences between estuary and delta

The difference between estuary and delta discussed in the following points:

  1. By estuary we mean a semi-closed body of water, including brackish water. a place where the river meets the sea. On the other hand, the delta defined as the wetlands, which are formed when a fast moving river joins a slowly moving water body, and thus empties the sediments to its mouth.
  2. In India, rivers like Narmada and Tapi form an estuary, while Delta formed by the rivers Mahanadi, Godavari, Krishna, Cauvery, Ganga and Brahmaputra.
  3. The funnel-like estuary, the mouth of a river from where the tides move in and out. Vice versa, Delta is a triangular land at the mouth of the river crossed by its distributors.
  4. Rivers that encounter high tides are more likely to estuary. On the contrary, the delta is formed when rivers testify to low tides.
  5. The land of the fertile delta in nature. By contrast, the area close to the non-fertile estuary in nature.
  6. Delta is good for agricultural activities, while fishing activities are suitable in the estuary regions.


While an estuary is a semi-enclosed body of water, where the river meets the ocean, the delta is a low plain, formed by the accumulation of floods. There are four main types of estuaries which are drowned river valley estuary, bar built estuary, fjord estuary and tectonic estuary. In contrast, various types of deltas include wave-dominated delta, tidal-dominated delta, Gilbert delta, freshwater tidal delta, inland delta, and mega-delta.

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