A water body where saltwater & freshwater mixes together.
Classic definition of Estuary
“ An estuary is a semi-enclosed coastal body of water having a free connection with the open sea and within which the sea-water is measurably diluted with fresh water deriving from land drainage”
Types of Estuaries
Classification based on geomorphology:
Classification based on water circulation:
Drowned river valleys:
In places where the sea level is rising relative to the land, seawater progressively penetrates into river valleys and the topography of the estuary remains similar to that of a river valley. Ex: Hudson River, Chesapeake Bay.
Bar-built estuaries are found in a place where the deposition of sediment has kept pace with rising sea level so that the estuaries are shallow and separated from the sea by sand spits or barrier islands. Ex: Pamlico Sound, North Carolina.
Tectonically produced :
Based on Water Circulation
Estuary type varies dramatically depending on freshwater input and is capable of changing from a wholly marine embayment to any of the other estuary types.
Major Estuaries of Asia
- Phang Nga Bay in Thailand.
- It is punctuated with islands.
- A variety of geological forces have fractured the underlying limestone beds and pushed up the 40 steep-sided islands that provide the exotic scenery.
Bay Of Bengal
- An arm of the Indian Ocean, the Bay of Bengal is 1,300 miles (2,090 km) long and 1,000 miles (1,610 km) wide.The Andaman and Nicobar Islands separate it from the Andaman Sea.
- The Bay of Bengal’s Sunderbans is the largest estuarine delta in the world.
The White Sea
- The White Sea is an arm of the Barents Sea.
- It is 580 km (360 mi) long and has an area of 90,000 sq km (30,000 sq mi).
- The flow of fresh water into the Sea is responsible for relatively low salinity.
- The southern part is home to the beluga whale.
- The adult individuals are completely white.
The Gulf of Ob
- The Gulf of Ob is a bay of the Arctic Ocean
- It is located in Northern Russia.
- It is the world’s longest estuary.
- Also known as Ob Bay
- It is about 1,000 km (600 mi) long and varies in width from about 50 to 80 km (30–50 mi)
- The Gabon River or Gabon Estuary is a short wide estuary in the west of Gabon.
- The estuary empties into the Gulf of Guinea.
- The estuary is locally known as the Estuaire du Gabon.
The Orange River
- The Orange River is the longest river in South Africa.
- The Orange River plays an important role in the South African economy by providing water for irrigation, as well as hydroelectric power.
The Severn Estuary
- The Severn Estuary is the estuary of the River Severn
- It is the longest river in Great Britain.
- The estuary has one of the highest tidal ranges in the world — about 50 feet (15 m)
The Thames Estuary
- The Thames Estuary is the estuary of River Thames .
- It constitutes a major shipping route
- More recently one of the largest wind farms in the UK has been developed in the estuary.
North America Continent
The Chesapeake Bay
- The Chesapeake Bay is an estuary in the U.S. states of Maryland and Virginia.
- It is the largest estuary in North America.
- The bay is approximately 200 miles (320 km) long & 2.8 miles (4.5 km) wide .
- It shows potential for growth of the native oyster population.
- Delaware Bay is the estuary outlet of the Delaware River of the United States.
- Approximately 782 square miles (2,030 km2) in area
- it serves as a breeding ground for many aquatic species, including horseshoe crabs.
The Great Bay
- The Great Bay is a tidal estuary located in United States.
- The bay occupies over 6,000 acres (24 km2)
- The water surface of Great Bay covers 8.9 square miles (23 km2) at high tide and 4.2 square miles (11 km2) at low tide.
- Pamlico Sound in North Carolina in the US is the largest lagoon along the North American East Coast
- It extends 129 km (80 miles) long and 24 to 48 km (15 to 20 miles) wide.
- Once it was used as an atomic bomb test site during the late 1940s and early 1950s.
- Portions of Pamlico Sound are used as a bombing and training range for Camp Lejeune.
- The sound also supports local commercial fishing, crabbing, shrimping, clamming, and oystering.
The Spencer Gulf
- The Spencer Gulf is the westernmost of two large inlets on the southern coast of Australia
- The Gulf is 322 km (200 mi) long and 129 km (80 mi) wide at its mouth.
- The western shore of the Gulf is the Eyre Peninsula.
- Port Jackson is the ria or natural harbor of Sydney, Australia.
- Its located at the Sydney Opera House & Sydney Harbour Bridge.
- Many recreational events are based on or around the harbor.
The Amazon River
- The Amazon River in South America is the largest river by discharge of water in the world and longest in length.
- The Amazon represents 20% of the global riverine discharge to the ocean.
Lagoa dos Patos
- Lagoa dos Patos is the largest lagoon in Brazil and the largest barrier-lagoon in South America.
- It is located in the state of Rio Grande do Sul, southern Brazil.
Factors influencing an estuary
- Nutrients etc
Written By: Badsha Fahad