• What is wetland ?
• Facts about wetlands
• Wetlands very widely
• Importance of wetlands
• Classification of wetlands
• Uses of wetlands
• Threats to Wetlands
• Distribution and extent of wetlands in India
What is wetland ?
An area fully or partially
immersed in water for a
part or whole of the
Wetlands are... areas where a water table is at, near, or
just above the surface and where soils are water-saturated
for a sufficient length of time such that excess water and
resulting low soil oxygen levels are principal determinants
of vegetation and soil development. The vegetation in
wetlands and soils with a "hydric" characteristic will have
a relative abundance of hydrophytes.
Wetlands very widely :-
1. Regional and local differences
4. Water chemistry
6. Human disturbance
Importance of wetlands :-
• Wetlands such as tanks, ponds, lakes, and reservoirs have long been providing
multiple-use water services include water for irrigation, domestic needs, fisheries
and recreational uses, ground-water recharge, flood control and silt capture.
• Major services include: carbon sequestration, flood control, groundwater recharge,
nutrient removal, toxics retention and biodiversity maintenance.
• Swamps, mangroves, peat lands, mires and marshes play an important role in
• Wetland sediments are the long-term stores of carbon, short-term stores are in
wetland existing biomass (plants, animals, bacteria and fungi) and dissolved
components in the surface and groundwater.
• Wetlands act as a sink for contaminants in many agricultural and urban landscapes.
• Wetlands help to lessen the impacts of flooding by absorbing water and
reducing the speed at which flood water flows.
• Wetlands are important in supporting species diversity as some vertebrates and
invertebrates depend on wetlands for their entire life cycle while others only
associate with these areas during particular stages of their life.
• Integral to a healthy environment
• Socio-economic importance
• Flood Control→ peatlands and wet grasslands act as sponges, absorbing rainfall
and controlling its flow into streams
• Help to retain water during dry periods, water table stable
• Provide clean water→ they act as the earth’s filters
• Wetlands removes pollutants from water
• Add moisture to the atmosphere
• Wetlands capture and retain rainfall, it prevent sediments from being washed into
lakes and rivers
• Productive environment
• Maintain biological diversity, Important feeding, breeding
• A source of life for people and wildlife
• Shoreline and storm protection: Coastal wetlands act as frontline defences against
potential devastation Physical barriers that slows down storm surges and tidal
• Cultural value
• Materials and medicines
• Recreation areas
• Vital habitat: 40% species and 12% of animal species
• A refuge for migrating birds
2. Environment :-
Wetlands can be classified into five basic
systems on the basis of Environment, namely:
• Marine :- Open ocean overlaying continental shelf (coastal
wetlands including coastal lagoons, rocky shores, and coral reefs)
(i). Subtidal: Substrate continuously submerged.
(ii). Intertidal: Substrate exposed and flooded by tides.
• Estuarine :- Deep water tidal habitat with freshwater runoff
from land (including deltas, tidal marshes, and mangrove
(i). Subtidal: as under I (1)
(ii). Intertidal: as under I (2)
• Riverine :- Include all wetland and deep-water habitat contained
within a channel (wetlands along rivers and streams)
(i). Lower Perennial: gradient low, no tidal influence
(ii). Upper Perennial: gradient high, velocity of water fast
(iii). Intermittent: non-tidal flowing water for only part of the year
• Lacustrine :- Topographic depression, lacking tree, shrub and exceed
8 ha. (wetlands associated with lakes)
(i). Limnetic: all deep water above 2m depth
(ii). Littoral: all wetland below 2m depth or non-persistent
• Palustrine :- All wetland dominated by trees, shrubs and tidal
wetland with salinity below 0.5%. (meaning “marshy” - marshes,
swamps and bogs)
3. Ramsar Convention system :-
• Marine/coastal or Tidal wetlands • Inland or Non-Tidal wetlands
• "Man-made" Wetlands
• Marine/coastal or Tidal wetlands
(i). Sea water mixes with fresh water to form an environment
of varying salinities → Due to tidal action
(ii). Shallow coastal areas are unvegetated mudflats or sand
(iii). Grasses and grass like plants survive this condition
(iv). Mangroove swamps with salt loving shrubs or trees are
common in tropical climate
• Inland or Non-Tidal wetlands
(i). Common in floodplains along rivers and streams→ Riparian
(ii). Isolated depression surrounded by dry land → Playas, Basins
(iii). Along the Margins of lakes and ponds
(iv). Low-lying areas where the GW intercepts the soil surface or
where precipitation sufficiently saturates the soil → Vernal pools
(v). Marshes and wet meadows → Herbaceous plants
• "Man-made" Wetlands
(i). Aquaculture (e.g. fish/shrimp) ponds.
(ii). Ponds; includes farm ponds, stock ponds, small tanks; (generally below
(iii). Irrigated land; includes irrigation channels and rice fields.
(iv). Seasonally flooded agricultural land.
(v). Salt exploitation sites; salt pans, salines, etc.
(vi). Water storage areas; reservoirs/barrages/dams/impoundments;
(generally over 8 ha).
(vii). Excavations; gravel/brick/clay pits; borrow pits, mining pools.
(viii). Wastewater treatment areas; sewage farms, settling ponds, oxidation
(ix). Canals and drainage channels, ditches.
Wetlands plants and
soil store carbon
instead of releasing it
to the atmosphere as
carbon dioxide. Thus
they help moderate
THREATS TO WETLANDS :-
▪ Anthropogenic pressures
▪ Rapidly expanding human evolution
▪ Development projects
▪ Improper use of watershed
▪ Converting floodplains to aquaculture
▪ Planting trees on bogs
▪ Draining marshes for agriculture
▪ Forestry and urban development
▪ Mining them for peat
Wetlands are amongst the most productive ecosystems
on the earth. Historically, they have been at the center of
evolution of human civilization for millennia as they are
means of precious ecological goods and services. The
conservation of wetlands is very important by that the
ecosystem can be balanced. The decreasing number of
wetlands led to the evolution of various legal
conventions with major aim to conserve the wetlands.