Wetlands are a diverse group of ecosystems, defined by the type of vegetation native to them, which is in turn determined by the presence of water. They are found throughout the world, on every continent except Antarctica.
Saturated soil conditions prevail in wetland ecosystems. However, the presence of water can be seasonal as is the case with prairie potholes. Water-loving or hydric soils form the foundation of these habitats. Likewise, the vegetation shares these water-loving properties and can tolerate habitat inundated with water.
Like the species that inhabit them, wetlands are endangered ecosystems. The U.S. Geological Survey estimates that the lower 48 states have lost over 50 percent of their wetlands in the last 200 years due to agriculture, development, and other human disturbances. With the loss of wetlands comes the forfeiture of their benefits.
The most important benefit of wetlands for people is flood protection. Wetlands act as giant sponges, absorbing flood waters from extreme weather events.
According to the U.S. Environmental Protection Agency (EPA), a single acre of wetlands can hold up to 1.5 million gallons of floodwater. Coastal wetlands offer additional flood protection. These habitats absorb the brunt of storm surges from tropical storms and hurricanes, thus mitigating weather impact.
Wetlands located adjacent to areas prone to flooding or along shorelines also control soil erosion by anchoring the soil in place. Shoreline erosion is a serious problem in the United States. According to the Federal Emergency Management Agency (FEMA), ocean coasts are eroding 1 to 4 feet each year. The potential risk becomes clear when one considers that two-fifths of the world’s major cities of 1 to 10 million people are located on or near coastal areas.