Environmental Geology Spring 2010 – Text Notes

Wetlands:
Poorly drained
Low relief areas
Soil is seasonally or perennially saturated
Support hydrophitic plants (water loving)

Include: Swamps (tree dominated), marshes (often inundated by water), bogs (soggy but not deep standing water), prairie potholes.

Function and Benefit:
Waterfowl breeding (over 12 million ducks nest and breed in northern U.S. wetlands).  This is 60% to 70% of the continents breeding duck population.

Provide habitat for waterfowl and other birds:
2.5 to 3 million mallards in the Mississippi Flyway and nearly 100% of the wood ducks winter in flooded bottomland forests.

Wildlife Habitat:
Provide food and shelter for many other forms of wildlife including fur bearing critters (as example Loiusiana’s nutria), snakes, turtles, alligators, frogs, etc.

Habitat for at least 1/3 of threatened and endangered species

Marine fish and shellfish production rely on coastal marshes for spawning and nursery grounds.

Timber production

Flood Control

Water Quality
•    Natural purification system
•    Remove silt
•    Remove nutrients
•    Remove trace metals
•    Help prevent salt water intrusion

Shoreline stabilization
Absorb wave energy reducing damage to the coast

Recreational opportunities

In mid 1970’s there was about 99 million acres of wetland left in 48 states which represented about 5% of the nations land area.

This included about 93.7 million acres of inland freshwater wetlands and about 5.2 million acres of coastal saltwater marshes.

Net average loss in the period 1950-1970 was 458,000 acres/year

Expanding agriculture accounted for about 87% of this loss.

What was done to reverse the trend?

EPA requires permits for dredge, fill and drainage under the Clean Water Act

Swampbuster legislation passed as part of 1985 food security act.  Protection of wetlands by limiting access to federal funds if wetlands are drained, filled or destroyed.

Wetlands reserve program provides incentives to restore and maintain wetlands by providing funds for not using previously developed wetlands and allowing them to return to the normal wetland condition.

Riparian Buffers:
Buffer of wetland plants, shrubs, trees and grasses between the active channel and the upland area adjacent to surface water bodies (lakes, streams, and wetlands).

Benefits:
•    Filter sediments
•    Filter nutrients and contaminants
•    Provide shade, shelter and food for aquatic organisms
•    Provide wildlife habitat
•    Aesthetically pleasing