Definition and Types of Wetlands in India
Definition of Wetlands
Wetlands are areas of land where water covers the soil or is present either at or near the surface of the land, permanently or seasonally. They form a transition zone between terrestrial and aquatic ecosystems and include marshes, swamps, bogs, lakes, floodplains, mangroves, and estuaries.
As per the Ramsar Convention (1971), wetlands are defined as:
“Areas of marsh, fen, peatland or water, whether natural or artificial, 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 tide does not exceed six metres.”
In simple terms, wetlands are ecosystems that are saturated with water and support aquatic vegetation and biodiversity.
Importance of Wetlands
Wetlands are often referred to as “kidneys of the ecosystem” due to their ability to filter pollutants. They provide numerous ecosystem services such as:
- Water purification
- Flood control
- Groundwater recharge
- Biodiversity support
- Carbon sequestration
- Livelihood to millions through fishing, farming, and tourism
Types of Wetlands in India
India has a rich diversity of wetlands due to its varied topography, climate, and hydrology. According to the National Wetland Atlas (2011) by ISRO, India has over 7.6 lakh wetlands, covering approximately 4.6% of the country’s geographical area.
Wetlands in India can be classified based on their origin, water regime, and salinity:
1. Inland Natural Wetlands
These are wetlands located inland (non-coastal) and occur naturally.
Types include:
- Lakes and Ponds: E.g., Wular Lake (Jammu & Kashmir), Loktak Lake (Manipur)
- Oxbow Lakes: Formed by meandering rivers; e.g., Kanwar Lake (Bihar)
- Swamps and Marshes: Low-lying water-logged areas; e.g., Haor wetlands (Assam)
- Riverine Wetlands: Found along riverbanks and floodplains; e.g., Yamuna floodplains (Delhi)
Characteristics:
- Mostly freshwater
- Support rich biodiversity
- Serve as breeding grounds for migratory birds
2. Inland Man-Made Wetlands
These are artificial water bodies created by human activities such as agriculture, industry, and urbanisation.
Types include:
- Reservoirs and Dams: E.g., Gobind Sagar (Himachal Pradesh), Hirakud (Odisha)
- Village Ponds and Tanks: Common in rural India for irrigation and drinking water
- Canals and Irrigation Channels: Often support aquatic vegetation
- Wastewater Treatment Ponds
Characteristics:
- May be temporary or permanent
- Serve human needs but also support biodiversity
3. Coastal Natural Wetlands
These are natural wetlands located along the coastline, influenced by tidal water and salinity.
Types include:
- Mangroves: Salt-tolerant trees found in coastal intertidal zones; e.g., Sundarbans (West Bengal), Bhitarkanika (Odisha)
- Coral Reefs: Though not classic wetlands, they are protected marine ecosystems often considered under wetland frameworks
- Mudflats and Salt Marshes: Found along estuaries and bays; e.g., Gulf of Kutch
- Lagoons and Backwaters: E.g., Chilika Lake (Odisha), Vembanad Lake (Kerala)
- Estuaries: Where rivers meet the sea, e.g., Godavari and Krishna estuaries
Characteristics:
- Brackish or saline water
- High productivity and biodiversity
- Crucial for fisheries, coastal protection, and tourism
4. Coastal Man-Made Wetlands
These are wetlands created by human intervention along the coastal regions.
Types include:
- Salt Pans: Shallow man-made ponds for salt extraction; e.g., Rann of Kutch (Gujarat)
- Aquaculture Ponds: Used for shrimp and fish farming, especially in Andhra Pradesh and Tamil Nadu
- Harbours and Jetties: Often create semi-natural wetland ecosystems
Characteristics:
- Economically significant
- Often prone to pollution and ecological degradation
Ramsar Wetlands in India
India is a signatory to the Ramsar Convention and has 80 Ramsar sites (as of 2023), which are wetlands of international importance.
Some prominent Ramsar sites include:
- Keoladeo National Park (Rajasthan)
- Chilika Lake (Odisha)
- Loktak Lake (Manipur)
- Sundarbans Wetland (West Bengal)
- Ashtamudi Lake (Kerala)
- Nalsarovar Bird Sanctuary (Gujarat)
- Deepor Beel (Assam)
Conclusion
Wetlands are vital ecosystems that act as natural buffers, water purifiers, climate regulators, and biodiversity hotspots. In India, their diverse types—ranging from the high-altitude lakes of Ladakh to the tropical mangroves of Sundarbans—play critical roles in ecological balance and human livelihoods.
However, wetlands face threats from urbanisation, pollution, encroachment, and climate change. Hence, conservation and wise use of wetlands are essential to ensure sustainable development, food security, and climate resilience.