(Last Updated on : 10/11/2014)
Indian Wetland is referred to an area having sufficient water long enough to support the growth of hydrophytic (i.e. dependent on water) vegetation. It may be permanent or temporary. Marshes, swamps, jheels, lagoons, mangroves, backwaters, estuaries, ponds, lakes, and reservoirs are some of the names given to wetlands. Depending on their salinity, location and origin wetlands can be broadly classified as fresh water wetlands, maritime wetlands, inland saline wetlands and agricultural wetlands. Indian wetlands are a part of its ecosystem and are widely distributed from the cold and arid region located in the Ladakh region of Jammu & Kashmir
, and those with the wet and humid climate of peninsular India. Most of the Indian wetlands are directly or indirectly linked to river networks. The Indian government has identified a total of seventy one Indian wetlands for conservation and is part of sanctuaries and national parks.
Mangrove forests are present all along the Indian coastline in sheltered estuaries, creeks, backwaters, salt marshes and mudflats that are specifically the areas of Indian wetlands. The mangrove area covers a total of 4 461 Sq km (1,722 mileAy), which comprises around seven percent of the world's total mangrove cover. Prominent mangrove covers are located in the Andaman & Nicobar Islands
, the Sundarbans delta, the Gulf of Kutch
and the deltas of the Mahanadi River
, Godavari River
and Krishna River
. Certain regions of the state of Maharashtra
also have large mangrove covers and Indian wetlands.
The Sundarbans delta, one of the world-renowned Indian wetlands is home to the largest mangrove forest in the world. It lies at the mouth of the Ganga River
and spreads across areas of Bangladesh and West Bengal
. The Sundarbans is a UNESCO World Heritage Site, but is recognized separately as the Sundarbans (Bangladesh) and the Sundarbans National Park (India). A complex network of tidal waterways, mudflats and small islands of salt-tolerant mangrove forests, dissects the Sundarbans. The area is known for its varied fauna, being home to a large variety of species of birds, spotted deer, crocodiles and snakes. Its most famous inhabitant is the Royal Bengal Tiger
. It is estimated that there are now 400 Bengal tigers and about 30,000 spotted deer in these Indian wetlands.
The Rann of Kutch is a marshy Indian wetland located in north-western Gujarat
and the bordering Sind province of Pakistan. It occupies a total area of 27 900 Sq km (10,800 mileAý). The region was originally a part of the Arabian Sea
. Geologic forces such as earthquakes resulted in the damming up of this Indian wetland, turning it into a large saltwater lagoon. This area gradually filled with silt and turned it into a seasonal salt marsh. During the monsoons, the area turns into a shallow marsh, often flooding to knee-depth. After the monsoons, this Indian wetland turns dry and becomes parched.
Man plays an important role in the creation, transformation and deterioration of wetlands. Wetlands are created by making reservoirs, canals, ditches, ponds and gravel pits. Seasonally flooded crop fields, especially of paddy often cover a large area. Drainage and reclamation of wetlands, excessive fishing, and use of pesticides and discharge of waste material are some activities which affect wetlands.
Wetlands support a variety of invertebrates and vertebrates. Some are wholly aquatic while others are dependent on wetlands only for completing their life cycle; for example insects such as dragonflies and mosquitoes. Some animals depend on wetland only for their food. The most spectacular of all the wetland species are, perhaps, the birds - mainly ducks and geese, storks and egrets, pelicans and flamingos. About twenty percent of the bird species of India can be found in the wetlands.
Wetland plant communities are serial - transitional from aquatic to terrestrial community. In a new pond the plants to colonize first will be floating, rooted floating or submerged species. As the pond starts to fill with organic detritus and sediments, new emergent plants are attracted. With the addition of organic debris the pond fails to maintain a high water level and amphibian plants invade and establish themselves. These are followed by terrestrial plants and finally a terrestrial community is formed. This process is affected by many environmental factors. In a natural situation herbivores arrest the speed of succession.
Common wetland plant species are Nymphaea spp., Nymphoides spp. (rooted floating); Lemna spp., Azolla sp., Eichhornia spp., Pistia sp. (free floating); Hydrilla sp., Ceratophyllum sp., Chara sp. (submerged); and Cyperus spp., Eleocharis sp., Paspalum sp., Typha sp., (emergent).
The wetland is ecologically and economically valuable. It is useful in waste treatment as it can clean off agricultural sewage and filter pollutants. For example, water hyacinth can remove seventy five percent of the lead from contaminated water within twenty four hours and also absorb cadmium, nickel, chromium, zinc, copper, iron and toxic substances such as pesticides. It is recorded that the average animal protein production of an estuary is seven times more than that of a natural terrestrial ecosystem.