Wetlands in Swamps, Floodplains, and Estuaries

Wetland definitionEPA - Clean Water Act

• Areas inundated or saturated by surface or groundwater at a frequency and duration sufficient to support a prevalence of vegetation typically adapted for life in saturated soil conditions.

Habitable Planet textbook series

Wetlands International

• Areas on which water covers the soil or if water is present either at or near the surface of that soil. Water can also be present within the root zone, all year or just during various periods of time of the year.

• Even wetlands that appear dry at times for significant parts of the year -- such as vernal pools-- often provide critical habitat for wildlife adapted to breeding exclusively in these areas.

• 6% of the planet’s surface designated as wetlands.

Ramsar Convention on Wetlands definition

• 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.

Variety inside the US• bogs and fens of the northeastern and north-central states

and Alaska• wet meadows or wet prairies in the Midwest• inland saline and alkaline marshes and riparian wetlands of

the arid and semiarid west• prairie potholes of Iowa, Minnesota and the Dakotas• alpine meadows of the west• playa lakes of the southwest and Great Plains• bottomland hardwood swamps of the south pocosins and

Carolina Bays of the southeast coastal states• tundra wetlands of Alaska.

What makes the wetland wet?

• Groundwater table intersects ground surface

• Occasional inundation of landscape “concavities” underlain by material with low hydraulic conductivity

• Tidal inundation

Groundwater outcropping versus flooding

Groundwater outcropping

Wetland supplied by flooding --- Okavango delta

Riparian wetland (floodplain)

• Earlier examples presented --- – Mesopotamian

Marshlands– Donana Marshlands– Lecture on floodplain

formation

Coastal wetland -- inundation by groundwater emerging over saline wedge and tidal oscillation

• Estuarine• Deltaic• Review ESM203 on

controls on distribution of these two landform types and on changing land-sea levels

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Where aquifers meet a coast (or other margin of a saltwater body)

More complex view of the groundwater body

Note the influence of topography, the encounter with the saline ocean, and the fact that the water table outcrops at the surface in streams, marshes, lakes,

and the ocean.

The slopes of flow lines (blue) are overestimated here by the vertical exaggeration of the diagram. In reality, they are almost horizontal (hence the

approximations in the preceding text)

Coastal wetland -- inundation by groundwater emerging over saline wedge and tidal oscillation

• Estuarine• Deltaic• Review ESM203 on

controls on distribution of these two landform types and on changing land-sea levels and wetland loss in the world’s deltas

They provide everything

http://beachwoodhistoricalalliance.files.wordpress.com/2009/03/wetlands-diagram.jpg

Caution

• “Success of new replacement wetlands depends on extent to which the new wetland is hydrologically similar to original.” Meaning?

• The replacement of a wetland that is dependent on ground water for its water and chemical input needs to be located in a similar ground-water discharge area if the new wetland is to replicate the original.

• Replacement wetland may have a water depth similar to the original, but the communities that populate the replacement wetland may be completely different from communities that were present in the original wetland because of differences in hydrogeologic setting.

• Is it “hydrology” or chemistry? That is important to replicate?

“Pond and plug” meadow restoration