Wetlands

1. Meaning, formation and classification

A wetland is an area where inundation or saturation by water strongly influences ecosystem development. Its hydroperiod—the timing, duration and frequency of flooding—is often more important than whether open water is visible throughout the year. Many wetlands have hydric soils, formed under prolonged saturation, and hydrophytic vegetation adapted to waterlogged conditions. Wetlands can occupy transitions between terrestrial and aquatic environments, but the term also covers extensive lakes and shallow coastal waters.

The Ramsar Convention defines wetlands broadly as marsh, fen, peatland or water areas, whether natural or artificial, permanent or temporary, with static or flowing water that is fresh, brackish or saline. It includes marine waters whose depth at low tide does not exceed six metres. Consequently, rivers, reservoirs, rice paddies and some aquaculture areas can fall within the Convention's scope; wetlands are not synonymous with freshwater lakes.

Inland wetlands include riverine systems, floodplain marshes, oxbow lakes, lakes, peatlands and saline depressions. Coastal wetlands include estuaries, lagoons, mangroves, salt marshes and tidal flats. Marshes are generally dominated by herbaceous plants, whereas swamps support woody vegetation. Peatlands accumulate partly decomposed organic matter under waterlogged conditions. An estuary receives river water and exchanges water with the sea; a lagoon is separated from the sea by a barrier but may retain tidal connections.

2. Distribution and important Indian examples

India's wetland diversity reflects its monsoon climate, long coastline, Himalayan relief and extensive alluvial plains. The National Wetland Atlas, 2011, prepared by the Space Applications Centre, ISRO, estimated about 15.26 million hectares of wetlands. This is a dated inventory estimate, not a measure of present ecological health. Gujarat had the largest wetland area among states in that assessment, substantially influenced by extensive coastal and intertidal systems.

Himalayan wetlands include high-altitude Tso Moriri in Ladakh and Wular Lake in the Kashmir Valley. Wular is linked to the Jhelum drainage and helps accommodate floodwater. Across the Ganga–Brahmaputra plains, river migration, channel abandonment and seasonal inundation create oxbow lakes, marshes and beels. Deepor Beel, southwest of Guwahati, is an important freshwater wetland in Assam.

Coastal examples include Chilika in Odisha, a brackish-water lagoon; the Sundarbans mangrove wetlands in the Ganga–Brahmaputra–Meghna delta; and the Vembanad–Kol system in Kerala. Sambhar in Rajasthan illustrates an inland saline wetland in an arid environment. Loktak in Manipur is associated with floating phumdis—masses of vegetation, organic matter and soil. Keibul Lamjao National Park, located on Loktak, protects habitat of the endangered sangai deer.

• Map practice: locate Wular, Harike, Sambhar, Keoladeo, Deepor Beel, Loktak, Chilika, Kolleru, Pulicat and Vembanad.
• Distinguish neighbouring coastal sites: Kolleru is a freshwater lake between the Krishna and Godavari deltas; Pulicat is a brackish lagoon along the Andhra Pradesh–Tamil Nadu coast.

3. Ecological and economic importance

Wetlands temporarily store runoff and can reduce downstream flood peaks when their storage space and natural connections remain intact. Some recharge groundwater, while others are sustained by groundwater discharge; recharge is therefore not a universal property. Vegetation slows flowing water and traps sediments. Microbial processes and plant uptake can retain or transform nutrients, but wetlands cannot absorb unlimited untreated sewage without degradation.

Wetlands provide breeding, feeding and refuge habitats for fish, amphibians, reptiles and waterbirds. Indian wetlands form important nodes along the Central Asian Flyway. Seasonal shallow waters and exposed mudflats offer feeding opportunities different from those of permanently deep lakes. Maintaining a mosaic of water depths and habitats is therefore often more valuable than keeping every wetland permanently full.

Fisheries, grazing, reeds, edible plants, tourism and culturally significant landscapes support local economies. Mangroves and tidal wetlands can reduce coastal erosion and wave energy, although protection varies with vegetation, topography and storm intensity. Peatlands and vegetated coastal wetlands store substantial carbon. Some wetlands also emit methane, so their climate role must be evaluated through the full greenhouse-gas balance rather than a simple claim that all wetlands are uniformly carbon sinks.

4. Threats and ecological change

Major pressures include reclamation, encroachment, catchment deforestation, sedimentation, untreated sewage, industrial effluents and excessive extraction. Roads, embankments and dams can sever wetland–river connections or alter natural flood pulses. Upstream diversions reduce inflow, while blocked sea mouths can alter a lagoon's salinity and fish recruitment. Climate change adds pressures through altered rainfall, drought, sea-level rise and changing Himalayan snowmelt.

Nutrient enrichment can cause eutrophication: excessive algal or plant growth followed by decomposition that consumes dissolved oxygen. Fish deaths may result from oxygen depletion rather than direct poisoning. Invasive alien plants such as water hyacinth can obstruct navigation, reduce light penetration and alter habitat conditions. Their removal without controlling nutrient inputs usually treats a symptom rather than the underlying cause.

Wetland degradation is not limited to a reduction in mapped area. A lake can remain visible while losing native species, seasonal variability, water quality or connections with its catchment. Restoration must therefore recover ecological character and hydrological processes. Routine deepening, concrete embankments, ornamental plantations and conversion of seasonal marshes into permanent ponds may damage rather than restore wetland functions.

5. Ramsar Convention and Indian governance

The Ramsar Convention promotes conservation and wise use of wetlands. Wise use means maintaining ecological character through ecosystem approaches within sustainable development; it does not mean excluding every human activity. Sites enter the List of Wetlands of International Importance by meeting at least one of nine criteria. These concern representative wetland types, threatened species, biodiversity and populations of waterbirds, fish or other wetland-dependent animals. Regular support for 20,000 or more waterbirds is one criterion, not a mandatory condition for every site.

The Montreux Record identifies listed Ramsar wetlands where ecological character has changed, is changing or is likely to change because of technological developments, pollution or other human interference. It is a mechanism for attention and assistance, not a separate protected-area category. Chilika was placed on the Record in 1993 and removed in 2002 after restoration. Keoladeo National Park and Loktak Lake are Indian sites associated with the Record.

India's Wetlands (Conservation and Management) Rules, 2017, were issued under the Environment (Protection) Act, 1986, replacing the 2010 Rules. They apply to Ramsar wetlands and wetlands notified under the Rules, with exclusions for specified areas already covered by other legal regimes. Their wetland definition excludes river channels, paddy fields, certain purpose-built human-made water bodies and tanks, and structures specifically constructed for drinking water, aquaculture, salt production, recreation or irrigation.

State and Union Territory Wetlands Authorities identify wetlands, recommend notification and guide management. Prohibited activities in covered wetlands include conversion to non-wetland uses or encroachment, establishment or expansion of industries, solid-waste dumping and discharge of untreated waste or effluents. The Rules also restrict permanent construction within 50 metres of the mean high flood level observed over the preceding ten years, with an exception for boat jetties. They should not be reduced to a blanket claim that every activity is prohibited near every water body.

6. Conservation priorities and examination approach

Effective conservation starts with delineating the wetland, its catchment and zone of influence. Management should maintain environmental flows, protect natural drainage, control pollution at source and integrate fisheries, biodiversity and livelihood needs. The National Plan for Conservation of Aquatic Ecosystems supports conservation and management of wetlands and lakes. Mission Sahbhagita emphasises participatory conservation, while the Amrit Dharohar initiative announced in the Union Budget 2023–24 promotes conservation values and local livelihood opportunities associated with Ramsar sites.

For Prelims, separate three questions: whether an ecosystem is scientifically a wetland, whether it falls within the 2017 Rules, and whether it has Ramsar status. These categories overlap but are not identical. Learn site–state–river associations and distinctive features rather than only changing designation totals. Monitoring should assess water quality, hydroperiod, habitat connectivity and indicator species alongside wetland extent.

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