Wetlands are complex ecosystems and encompass a wide range of inland, coastal and marine habitats.
They share the characteristics of both wet and dry environments and show immense diversity based on their genesis, geographical location, hydrological regimes and substrate factors. They include flood plains, swamps, marshes, tidal marshes etc.
Among the most productive life support, wetlands have immense socio-economic and ecological importance for mankind. They are crucial to the survival of natural biodiversity. They provide suitable habitats for endangered and rare species of birds and animals, endemic plants, insects besides sustaining migratory birds.
As an ecosystem, wetlands are useful for nutrient recovery and cycling, releasing excesses nitrogen, removing toxins, chemicals and heavy metals through absorption by plants and also in the treatment of waste water. Wetlands also help in mitigating floods, recharging aquifers and reducing surface run-off and erosion. The mangrove wetlands of India and Bangladesh act as buffers against the devastating storms of the Bay of Bengal.
India's wetlands are distributed in different geographical regions. They occur in the cold arid zone of Ladakh, the wet humid climate of Imphal, arid zone of Rajasthan, tropical monsoonic central India and the wet humid zone of the Southern peninsula. Most of the Indian wetlands are linked directly or indirectly with the major river systems such as Ganga, Brahmaputra, Narmada, Godavari, Krishana and Kaveri.