What is the Difference Between Delta and Estuary?

By BYJU'S Exam Prep

Updated on: November 9th, 2023

The difference between a delta and an estuary is that Delta is a wetland created due to rivers depositing silt; and an estuary is a location where fresh river water and seawater combine. A tidal bore creates it. The Godavari, Cauvery, Krishna, Ganga, Brahmaputra, Mahanadi, and other rivers in India combine to form the delta. The estuary in India is formed by the rivers Tapti and Narmada.

Difference between Delta and Estuary

The primary differences between Delta and Estuary have been elaborated in the table given below:

Delta Estuary
In alluvial deposits, a delta is a low and triangular area where a river splits before draining into a bigger body of water. Tides come in and go out at the river’s mouth, shaped like a funnel.
The majority of fishing activities involve deltas. Agriculture is practiced in estuarine environments.
Deltas developed at the mouths of rivers that transported enough sediment to expand outward. Estuaries are found where lake or ocean waters overflow into a river valley.
Deltas form when rivers discharge their water and sediment into another body of water, such as an ocean, lake, or Rivers of India. An estuary is a partially enclosed coastal body of water where freshwater from rivers and streams mixes with saltwater from the ocean.
Deltas can also empty into the land, though this is uncommon. Estuaries and their surrounding lands serve as transition points from land to sea.
As a river approaches its mouth or end, it moves more slowly. Estuaries and the wetlands surrounding them are bodies of water typically found where rivers meet the sea.

Delta vs Estuary

The primary distinction between the two is where the sediment carried by the river is collected. It gathers in the river basin for an estuary and lakeward or seaward of the typical shoreline for deltas.

  • The equilibrium between the flow of sediment and variations in sea/lake level determines whether a particular river-sea/lake interaction is an estuary or a delta.
  • Deltas require a significant buildup of sediment at the river mouth, which can occur when the river contributes a large amount of material, the sea or lake’s transport operations are slow, and/or the sea or Lakes level is gradually declining.
  • In each scenario, the river gradually extends into the body of still water.
  • When the sediment supply is limited, large amounts of sediment are carried away from the shore by waves and storms, and/or the sea level or lake level rises faster than silt accumulates, causing river valleys to flood and form estuaries.
  • Similar sedimentary rocks made up of fluvial, shallow marine facies and shorelines are deposited in deltas and estuaries.

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