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Definition
A wetland is any area with soil and plant life that has adapted to life in especially wet conditions. These can be along coastlines, riverbanks or any low-lying area where water pools at or near the surface. Saltwater and fresh water wetlands are distinct systems, each with life especially adapted to either salty or fresh water. Many wetlands are seasonal in nature, with saturation of the soil only occurring for part of the year. Next to coral reefs and tropical rain forests, wetlands are home to the greatest diversity of life on the planet.
History
In the United States, wetlands were not always seen as valuable natural resources. During the colonial years, wetlands were drained through brute force so as to make way for agriculture. The westward expansion of the 19th century saw further destruction of natural wetlands. Industrial machinery made an accelerated pace of destruction possible. In the country's midsection, as much as 85 percent of native wetland habitat was lost. Again, the primary motivation in draining the land was for agriculture.
Functions
Wetlands perform a multitude of beneficial functions. As a flood control measure, wetlands absorb and slow down surges of water from heavy rain. They are also natural filters, with their plant life and sediments helping to remove pollutants from the water. Climatologists are now realizing that wetlands have a role to play in regulating global temperatures. Wetlands store carbon in their plants and soils, reducing the amount of greenhouse gas in the atmosphere. Besides all of these useful functions, wetlands are aesthetically pleasing and allow for a variety of recreational pursuits.
Drainage Techniques
The simplest method of filling in wetlands is to transport rock and dirt to the site and begin piling it up. Eventually the wetland is smothered with foreign material. An alternative method involves channelizing nearby waterways and facilitating faster removal of surface water. A wetland can also be drained by building a levee around it and then manually pumping water out of the enclosure. Modern techniques involve underground piping to pull away rainwater before the soil can saturate.
Drainage Consequences
Wetlands are delicate ecosystems. Draining them has immediate and long-term consequences for plants, animals and humans. Obviously all the organisms that had adapted to the wetland environment will not survive the transition. A lucky few may migrate to new habitats, but overall an enormous amount of biodiversity is lost when wetlands are drained. The flood control and filtration benefits of wetlands will be negated, impacting safety and water quality for people living in the region.
Restoration Efforts
According to the Natural Resources Conservation Service, in 2001 there were over 6,500 wetland restoration projects under way across the United States.(5) Many parks and natural preserves have been established to protect original wetlands from further encroachment. Some wetland restoration projects are relatively simple and only require the removal of man-made barriers to water. In other cases, the wetland must literally be rebuilt from the bottom up. In the Chesapeake Bay near Maryland, there is an ongoing effort to restore coastal marshland through soil and plant importation.