Land that is saturated or covered by shallow water for long enough to develop waterlogged soils and plants adapted to wet conditions, such as marshes, swamps, peatlands, floodplains, lagoons and mangroves.
A wetland sits on the boundary between dry land and open water, and that in-between position explains almost everything about it. Water arrives from rain, rivers, tides or springs and stays long enough to starve the soil of oxygen. Ordinary plants cannot cope with such soil, so the community that develops is made of reeds, sedges, floating leaves, mangroves or peat mosses that tolerate waterlogging. Ecologists therefore recognise a wetland by three clues taken together: how often and how long it is wet, the grey or dark "hydric" soil that forms without oxygen, and the presence of water-loving vegetation.
For centuries wetlands were treated as wasteland. Colonial and post-independence revenue records often listed them as unproductive land fit for drainage, reclamation or dumping. The scientific view changed in the second half of the twentieth century, when studies of migratory waterbirds, fisheries and floods showed that these "marginal" lands do disproportionate work for people. India has a very wide range of them, from high-altitude lakes in Ladakh and the floodplain lakes (beels) of Assam to the salt pans of the Rann of Kachchh, the backwaters of Kerala and the mangrove deltas of the east coast.
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