Vadamarachchi lagoon is a lagoon

Lagoon

A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...

 in Jaffna District

Jaffna District

Jaffna district is one of the 25 administrative districts of Sri Lanka. The district is administered by a District Secretariat headed by a District Secretary appointed by the central government of Sri Lanka. The headquarters is located in Jaffna city. Parts of the district were transferred to...

, northern Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

. The lagoon is sometimes referred to as Thondamannar lagoon. The lagoon separates the Vadamarachchi

Vadamarachi

Vadamarachchi is one of the three historic regions of Jaffna peninsula in northern Sri Lanka. The other two regions are Thenmarachchi and Valikamam. Vadamarachchi is sometimes spelt Vadamarachi, Vadamaraachi or Vadamaraadchi.-Etymology:...

 region from the Valikamam

Valigamam

Valikamam is one of the three historic regions of Jaffna peninsula in northern Sri Lanka. The other two regions are Thenmarachchi and Vadamarachchi. Valikamam is sometimes spelt Valikaamam or Valigamam.-Etymology:...

 and Thenmarachchi

Thenmarachi

Thenmarachchi is one of the three historic regions of Jaffna peninsula in northern Sri Lanka. The other two regions are Vadamarachchi and Valikamam. Thenmarachchi is sometimes spelt Thenmarachi, Thenmaraachi or Thenmaraadchi...

 regions.

The lagoon is connected to the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 by a narrow channel

Channel (geography)

In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks.A channel is also the natural or human-made deeper course through a reef, sand bar, bay, or any shallow body of water...

 to the north, near the town of Thondamannar. The lagoon's water is brackish to saline

Saline water

Saline water is a general term for water that contains a significant concentration of dissolved salts . The concentration is usually expressed in parts per million of salt....

. There is a sluice gate at Thondamannar to prevent sea water enetering the lagoon.

The lagoon is surrounded by a densely populated region containing palmyra palms

Borassus flabellifer

Borassus flabellifer, the Asian Palmyra palm, Toddy palm, Sugar palm, or Cambodian palm, is native to South and Southeast Asia, in the Indomalaya ecozone...

, coconut palm, grassland

Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

, rice paddies, arid

Arid

A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...

 scrubland and open forest

Forest

A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...

.

The lagoon has extensive mudflats, seagrass

Seagrass

Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...

 beds and mangrove

Mangrove

Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 swamps, particularly Avicennia

Avicennia

Avicennia is a genus of flowering plants currently placed in the bear's breeches family, Acanthaceae. It contains mangrove trees, which occur in the intertidal zones of estuarine areas and are characterized by aerial roots. Species of Avicennia occur worldwide south of the Tropic of Cancer.The...

. The lagoon attracts a wide variety of water bird

Water bird

The term water bird or waterbird is used to refer to birds that live on or around water. Some definitions apply the term especially to birds in freshwater habitats, though others make no distinction from birds that inhabit marine environments. In addition, some water birds are more terrestrial or...

s including American Flamingoes, duck

Duck

Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...

s, gulls, terns and other shorebirds.