Types of wetlands and wetland formation

TYPES AND FORMATION OF WETLAND

MIDHUN M NAIRTHIRD SEMESTER ES&M SESMG UNIVERSITYKOTTAYAM

Wetlands???

• “Wetlands are 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."

• Distinguishes between two major wetland types – mineral and organic

1) Mineral Soil Wetlands Marsh: poorly drained mineral soils dominated by grasses common at the mouths of river Tidal marshes, Tidal salt marshes,

Tidal Freshwater Marshes

Wetland Types

Salt marsh in Scotland

Swamp:• mineral soils with poor drainage• dominated by trees• Swamps are found throughout

the world, most often in low-lying regions (with poor drainage) • Some swamps develop from

marshes

Swamp in southern Louisiana

Organic Soil Wetlands• Generally these referred to as "peatlands“• Ability to form peat (organic soil produced by the

accumulation of plant material). • There are two major types– bogs and fens Bog –• wet, spongy, poorly drained peaty soil, • dominated by the growth of bog mosses,

Sphagnum, and heaths, particularly Chamaedaphne

• Bogs are usually acid areas,• frequently surrounding a body of open water.• Bogs receive water from rainfall.

Mer Bleue Bog, a typical peat bog, in Ontario Precipitation accumulates in

many bogs forming bog pools.

• Fen –peaty soil, dominated by grass like plants, grasses, sedges, and reeds • Fens are alkaline rather than acid

areas, receiving water mostly from surface and groundwater sources.• usually dominated by grasses

and sedges, and typically have brown mosses

Wicken Fen showing vegetation typical of a fen in the foreground and carr vegetation featuring trees and bushes in the background

Avaste Fen, Estonia

• The two major types of organic soil wetlands are, therefore, distinguished by their hydrological regime

• bogs receive water mainly from precipitation,

• fens are supplied with water mostly from surface and groundwater sources

Wetland Types

• Ecologically similar types of wetlands are referred to by different names through out the world

• Swamps in North America refers-wetland with trees or shrub

• In Europe-Carrs• Pocosin(Indian word for swamp on

hill) is south-eastern costal plain of US

• The "traditional terminology" has the significant disadvantage

• Two main scientifically-based and in a way comprehensive wetlands classification systems,

• Developed for the purpose of wetlands inventory and management

• The first of them has been developed by Cowardin and co-workers for the needs of the US government

• Second has been adopted by the Convention on Wetlands

Cowardin classification system• In tribute to the "traditional terminology",• In their system they distinguish between

"wetlands" and "deepwater habitats", • Because "traditionally the term wetland has not

included deep permanent water" (Cowardin et al, 1979).

• Nevertheless,the scientists recognize the importance of the holistic approach to classification of wetlands

• Therefore in their classification they have included both types.

• Defines five main Systems (Marine, Estuarine, Riverine, Lacustrine, and Palustrine),

• Which are further divided into smaller Subsystems, Classes, Subclasses, and Dominance Types

• Cowardin and co-workers (1979) did not include many wetland types that have resulted from human activities. 

• To avoid the weak point of Cowardin et all’s classification system, the Convention on Wetlands developed a new and more comprehensive wetland classification system (adopted in 1990 and modified in 1996)

Ramsar Classification System for Wetland Type

1) Marine/Coastal Wetlands• A – Permanent shallow marine waters in most cases

less than six metres deep at low tide; includes sea bays and straits.

• B – Marine subtidal aquatic beds; includes kelp beds, sea-grass beds, tropical marine meadows.

• C – Coral reefs.• D – Rocky marine shores; includes rocky offshore

islands, sea cliffs.• E – Sand, shingle or pebble shores; includes sand bars,

spits and sandy islets; includes dune systems and humid dune slacks.

• F – Estuarine waters; permanent water of estuaries and estuarine systems of deltas.

• G – Intertidal mud, sand or salt flats.• H – Intertidal marshes; includes salt marshes,

salt meadows, saltings, raised salt marshes; includes tidal brackish and freshwater marshes.

• I – Intertidal forested wetlands; includes mangrove swamps, nipah swamps and tidal freshwater swamp forests.

• J – Coastal brackish/saline lagoons; brackish to saline lagoons with at least one relatively narrow connection to the sea.

• K – Coastal freshwater lagoons; includes freshwater delta lagoons.

• Zk(a) – Karst and other subterranean hydrological systems, marine/coastal

Inland Wetlands• L – Permanent inland deltas.• M – Permanent rivers/streams/creeks; includes waterfalls.• N – Seasonal/intermittent/irregular rivers/streams/creeks.• O – Permanent freshwater lakes (over 8 ha); includes large

oxbow lakes.• P – Seasonal/intermittent freshwater lakes (over 8 ha);

includes floodplain lakes.• Q – Permanent saline/brackish/alkaline lakes.• R – Seasonal/intermittent saline/brackish/alkaline lakes

and flats.• Sp – Permanent saline/brackish/alkaline marshes/pools.• Ss – Seasonal/intermittent saline/brackish/alkaline

marshes/pools. • Tp – Permanent freshwater marshes/pools; ponds (below 8

ha), marshes and swamps on inorganic soils; with emergent vegetation water-logged for at least most of the growing season

• Ts – Seasonal/intermittent freshwater marshes/pools on inorganic soils; includes sloughs, potholes, seasonally flooded meadows, sedge marshes.

• U – Non-forested peatlands; includes shrub or open bogs, swamps, fens.

• Va – Alpine wetlands; includes alpine meadows, temporary waters from snowmelt.

• Vt – Tundra wetlands; includes tundra pools, temporary waters from snowmelt.

• W – Shrub-dominated wetlands; shrub swamps, shrub-dominated freshwater marshes, shrub carr, alder thicket on inorganic soils.

• Xf – Freshwater, tree-dominated wetlands; includes freshwater swamp forests, seasonally flooded forests, wooded swamps on inorganic soils.

• Xp – Forested peatlands; peatswamp forests.• Y – Freshwater springs; oases. • Zg – Geothermal wetlands• Zk(b) – Karst and other subterranean hydrological systems,

inland

• Human-made wetlands• 1 – Aquaculture (e.g., fish/shrimp) ponds• 2 – Ponds; includes farm ponds, stock ponds, small tanks;

(generally below 8 ha).• 3 – Irrigated land; includes irrigation channels and rice fields:• 4 – Seasonally flooded agricultural land (including

intensively managed or grazed wet meadow or pasture).• 5 – Salt exploitation sites; salt pans, salines, etc.• 6 – Water storage areas;

reservoirs/barrages/dams/impoundments (generally over 8 ha).• 7 – Excavations; gravel/brick/clay pits; borrow pits, mining

pools.• 8 – Wastewater treatment areas; sewage farms, settling

ponds, oxidation basins, etc.• 9 – Canals and drainage channels, ditches.• Zk(c) – Karst and other subterranean hydrological

systems, human-made

Classification characters

• Source of water• Ecological similarities• Topographic positions

Based on Source of Water

• Precipitation• Ground water discharge• Surface and near-surface in flow

Based on source of water

Peat Bogs and pocosin peatland

Fringe Marshes Riverine swamps

Mangroove swamps

Tidel marshes

Interior (nontidel) marshes

Forest graminoid fens

Surface flow

PrecipitationGro

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• Bogs and Pocosins receive their water almost from rainfall-such as are nutrient poor

• Fen and some marsh type are controlled by ground water-nutrient rich

• The surface flow dominated wetland types are very diverse and would include swamps,marshes,and wetland found along the fringe of lakes and streams

Wetland Formation

• Any process that produce a hollow or depression in the landscapes and holds sufficient water may result in wetland formation

• Climatic process and water condition which formed the swampy environment of the carboniferous period

• Most of current peat land form the past 12000 years(pleistocene ice ages)

• Wetland found in desert springs & high rain fall or runoff area of mountain

• Many of Northern bogs of Western US were formed in depression left by buried ice block(Kettle hole)

• Along rivers and streams, periodic flooding lays down alluvial deposits along the banks and flood plain creating swamp forests

• A major flood in Mississippi created new wetland along the Atchafalaya delta (1973)

• Anthropogenic activities also contribute wetland formation

• Cutting of forest in Europe and Britain caused water table rise form peat lands

• Peat extraction for fuel in Netherland and building fish pond in Bohemia created wetlands

Factors Related to Wetland formation

• Geomorphology• Hydrology• Climate• Precipitation

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