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Definition of Wetlands ..

Wetlands are the ecotones or transitional zones between permanently aquatic and dry terrestrial ecosystems. Ramsar Convention has defined wetlands as "areas of marsh, fen , peatland or water, whether natural or artifical, permanent or temporary with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low t ide does not exceed six meters". A wides variet y of wetlands like marshes, swamps, open wat er bodies, mangroves and tidal flats and salt marshes etc. exists in our country.

Why save Wetlands ?

Wetlands are integral to a healthy environment. They help to retain water during dry periods, thus keeping the water table high and relatively stable. During periods of flooding, they act to reduce flood levels and to trap suspended solids and nutrients to the lakes than if they flow directly into the lakes. The removal of such wetland systems because of urbanization or other factors typically causes lake water quality to worsen. In addition, wetlands are important feeding, breeding, and drinking areas for wildlife and provide a stopping place and refuge for waterfowl. As with any natural habitat, wetlands are important in supporting species diversity and have a complex and important food web. The recent millenium assessment of ecosystems puts freshwater biodiversity as the most threatened of all types of biodiversity.

How are they threatened..?

These wetland values are increasingly facing several anthropogenic pressures. The rapidly expanding human population, large scale changes in land use/landcover and burgeoning development projects and improper use of watersheds have all caused a substantial decline of wetland resources of the country. Absence of reliable and updated information and data on extent of wetlands, their conservation values and socioeconomic importance has greatly hampered development of policy, legislation and administrative interventions by the state.

Why do we need to map wetlands...?

For the long-term conservation planning of wetlands, spatial data and information is required for any intervention. Wetland eco-system constitute an integral part of cultural and biodiversity landscape of India. It is estimated that 3.5 millions ha exists in the country according to the 1992-1993 study by the Space Application Centre. However, this information pertains to wetlands above 56ha in size. Past research on wetland conservation in the country has shown conclusively that micro wetlands or satellite wetlands around a bigger wetland act as a constellation of habitat mosaic for resident and migratory waterfowl. This is of special importance for inland wetland habitats in the flyways of migratory birds in the Indo-Gangetic plains and in Deccan peninsula. Often, the size of these micro wetlands is much smaller than 50ha Therefore, there is a great need to map wetlands of size smaller than 50ha. Spatial information on wetlands resources is a critical and an urgently needed for an effective conservation of these important eco-system.

Use of advanced spatial technology tools

For a country like India, with its vast biological and cultural diversity, a comprehensive use of remote sensing, GIS and other related technologies will be of great use in conservation. Classifying and mapping wetlands based on geomorphology, water quality and other biological attribute can lead to qualitative assessment. Results obtained could be used in planning, inventorying and monitoring wetlands in the country.


Wetlands Classification Scheme

Inland Wetlands
1. Natural
  • Lakes/Ponds
  • Ox-bow lakes/ Cut-off meanders
  • Waterlogged (Seasonal)
  • Playas
  • Swamp/marsh

2. Man-made
  • Reservoirs
  • Tanks
  • Waterlogged
  • Abandoned quarries
  • Ash pond/cooling pond

Coastal Wetlands
1. Natural
  • Estuary
  • Lagoon
  • Creek
  • Backwater (Kayal)
  • Bay
  • Tidal flat/Split/Bar
  • Coral reef
  • Rocky coast
  • Mangroove forest
  • Salt marsh/marsh vegetation
  • Other vegetation

2. Man-made
  • Salt pans
  • Aquaculture

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  • Sálim Ali Centre for Ornithology and Natural History
    Anaikatty Post
    Coimbatore - 641108
    Tel : +91-422-2203100,128,130
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