Wetlands valuable areas
Jan 27, 2012 at 9:22 PM
What is a wetland? We all hear the term “wetland” and likely conjure up our own images of what exactly is a wetland.
You might imagine a swamp, with eerie trees hanging over dark waters, with snakes swimming in the water. Or you might imagine a large open body of water, with waterweeds growing on its surface and waterfowl grouped together. Or you may imagine somewhere like the Florida Everglades, a vast expanse of sawgrass, under which flows an inches-deep sheet of water. Even our mountains have wetlands, maybe where a stream has rerouted itself, or an area along the Nolichucky that periodically floods, or the cranberry bogs in Shady Valley.
Any one of these images is not entirely incorrect. According to the United States Environmental Protection Agency wetlands are “lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface.” To translate the government garble, it means an ecosystem of which water is the key ingredient. One more part of the definition also states, “Wetlands generally include swamps, marshes, bogs and similar areas.” So wetlands can take varied forms.
Wetlands don’t have to be under water or even wet year-round to be wetlands. Some plant communities in wetlands in fact depend on a cyclical flooding and drying out of their terrain. The Everglades is a prime example.
Wetlands can be the bane of farmers who like to till rich stream bottoms. In West Tennessee, many of the rivers and creeks have been channelized. On your average tract, farmers cleared the trees from the creek bottoms, making land arable. To maximize the yield in the valley, the farmer straightened out the adjoining stream, allowing more land to be farmed. Less land was flooded, too. Over time, the soils were exhausted, especially without being replenished by nutrients during high water events. The straightened out stream also cut a deep channel. Floods scoured the stream more and more when big rains came. Over time, the life in the channelized streams degraded, since the stream was altered from a watery wetland to a straight, deep bed that rapidly rose and fell with precipitation, rather than rising and lowering gradually.
Now, we are all learning that wetlands are essential to slow runoff and cut down on erosion. They absorb excess water during floods. They harbor unique flora and fauna. Wetlands are being restored. On a channelized streambed, the old streambed is first re-dug, replicating its original shallow, meandering curves instead of the altered straight and deep channel. This way, high waters would slow down, cruising around the curves instead of surging straight downstream. The banks are stabilized with rocks, logs and root balls. Burlap is laid over the banks to keep soils from washing away. Small rocks are spread on the stream bottom, creating riffles, which adds oxygen to the stream and more evenly deposits sediment during floods. “V” shaped spillovers are built to deepen the channel in spots, for a variety of stream widths and depths adds to the variety of life within.
And natural flood control is a good thing for humans and the world in which we live. It saves the land, the water, the life within, and taxpayer dollars used in flood recovery.
Johnny Molloy is the author of several outdoors guidebooks. Visit www.johnnymolloy.com.