Table of Contents
- Wetlands are areas of marsh or peatland with water that is static or flowing, fresh, brackish or saline, including areas of marine water the depth of which at low tide does not exceed 6 m.
- Wetlands are transition zones between terrestrial and aquatic ecosystems. E.g. Mangroves, lake littorals (marginal areas between highest and lowest water level of the lakes), floodplains (areas lying adjacent to the river channels beyond the natural levees and periodically flooded during high discharge in the river) and other marshy or swampy areas.
- These habitats experience periodic flooding from adjacent deep water habitats and therefore supports plants and animals specifically adapted to such shallow flooding or water logging.
- Waterlogged soil, adapted plant life (hydrophytes) and hydric soils (not enough O2) are the chief characteristics of wetlands.
- India has totally 27,403 wetlands, of which 23,444 are inland wetlands and 3,959 are coastal wetlands.
- Wetlands occupy 18.4% of the country’s area of which 70% are under paddy cultivation.
- Natural wetlands in India range from high altitude wetlands in Himalayas; flood plains of the major river systems; saline and temporary wetlands of the arid and semi-arid regions; coastal wetlands such as lagoons, backwaters, estuaries, mangroves, swamps and coral reefs, and so on.
Distinction from Lakes
- Lakes are generally less important when compared to wetland from the viewpoint of ecosystem and biodiversity conservation.
- There is no clear distinction between lakes and wetlands. Wetlands are shallow water bodies whereas lakes can be deep or shallow.
- National Lake Conservation Programme (NLCP) considers lakes as standing water bodies which have a minimum water depth of 3 m, generally cover a water spread of more than ten hectares, and have no or very little aquatic vegetation.
- Wetlands (generally less than 3 m deep over most of their area) are usually rich in nutrients (derived from surroundings and their sediments) and have abundant growth of aquatic macrophytes.
- They support high densities and diverse fauna, particularly birds, fish and macro invertebrates, and therefore, have high value for biodiversity conservation.
- Excessive growth of macrophytes (both submerged and free-floating; macrophytes –aquatic plant large enough to be seen by the naked eye) in wetlands affects the water quality adversely and interfere with the utilization of the water body.
- However, marginal aquatic vegetation is desirable as it checks erosion, serves habitat for wildlife and helps improve water quality.
Wetland (shallow lake)
|Origin||Largest are due to tectonic forces: Fluvial, Geomorphic, increase in water table, etc.||Mostly Fluvial, Residual lakes|
|Water turnover||Permanent||Permanent or Temporary|
|Water level changes||Relatively small||Relatively Large|
|Vertical mixing||Thermally regulated||Wind regulated|
|Food chain||Grazing Pathway||Detritus Pathway|
|Trophic status||Oligotrophic||Mostly Eutrophic|
|Functions-Flood control||Less Significant||Significant|
Importance of Wetlands
- Wetlands are indispensable for the countless benefits or “ecosystem services” that they provide humanity, ranging from freshwater supply, food and building materials, and biodiversity, to flood control, groundwater recharge, and climate change mitigation.
- Wetlands are habitat to aquatic flora and fauna, numerous species of native and migratory birds.
- Wetlands are an important resource for sustainable tourism.
- They carry out water purification, filtration of sediments and nutrients from surface water.
- They help in nutrients recycling, ground water recharging and stabilization of local climate.
- Play an important role in flood mitigation by controlling rate of runoff.
- Buffer (act as riparian buffer) shorelines against erosion and pollutants.
- They act as genetic reservoir for various species of plants (especially rice).
Reasons for depletion
- Excessive pollutants (Industrial effluents, domestic waste, agricultural runoff etc.) are dumped into wetlands beyond the recycling capacity.
- Habitat destruction and deforestation creates ecological imbalance by altering the population of wetland species.
- Conversion of wetlands for agriculture and encroachment by public and mafia.
- Over fishing and fish farming (Aqua culture).
- Overgrazing in marshy soils.
- Removal of sand from beds near seas makes the wetland vulnerable to wave action and tidal bore.
- Demarcation of wetlands using latest technology, proper enforcement of laws and stringent punishments for violators.
- Preventing unsustainable aquaculture and cultivation of shellfish.
- Treating industrial effluents and water from farm lands before discharging into wetlands.
- Utilizing wetlands on a sustainable basis by giving enough time for natural regeneration. Artificial regeneration for quick recovery.
- Afforestation, weed control, preventing invasive species is the key to wetland conservation.
- Preventive measures to stop the introduction of exotic invasive species like water hyacinth.
- Soil conservation measures & afforestation. Preventing grazing in peripherals of wetlands.
- Wildlife conservation, sustainable tourism, eco-tourism and sensitizing local populace.
- Eutrophication abatement by processing nutrient rich discharge into the water body.
- Involving local population in the conservation of wetlands.