Understanding nature key part of solving stream erosion concerns
Without proper care and an understanding of how streams operate under the rules of Mother Nature, a landowner with a stream running through his or her property may have a serious problem without an affordable solution.
Along with water, streams also transport sediment, which can create a problem if the amount of sediment picked up and moved downstream is not the same amount of sediment being deposited into the stream.
In unhealthy streams, this balance is lacking, said Marley Beem, Oklahoma Cooperative Extension Service aquaculture specialist with Oklahoma State University's Division of Agricultural Sciences and Natural Resources.
"Either too much sediment is being deposited and mid-channel sediment bars form or too little is being deposited and the stream down-cuts its bed or widens its channel," he said.
The faster the water is rushing through, the greater the potential for erosion. However, nature has ways of defending itself. The first way is called the riparian zone, which is the "area adjacent to a stream channel that is occupied by water loving trees, shrubs or other plants."
Although erosion still exists in these areas, the deep and dense root networks hold the soil together. The second way in which streams try to accommodate the erosive energy of flowing water is by "meandering." By forming curves, the distance the water travels is increased and the slope is decreased. As a result, the water's velocity--and therefore its erosive energy--is decreased.
"It's normal for stream and river channels to slowly move over time. If one could watch a stream from the air over a period of several lifetimes, it would appear as if it were a writhing snake," Beem said. "This is one reason why construction of homes and other structures close to streams should be discouraged."
As the stream moves over time, any structure in its path can be significantly damaged. Beem also said not to build a home in a floodplain. Not only will the house be in danger, but flooding may increase when many people build homes downstream.
"As long as people have been wise enough to avoid building houses and other structures in the floodplain, flooding is a beneficial process," Beem said.
During a flood, the water rises above the bank and spreads out, depositing sediment as the water slows. This is the third way in which nature defends itself from erosion.
"The new sediment helps form and maintain productive soils," Beem said. "Flooding is a natural occurrence that is part of normal stream functioning."
Larger streams also can benefit from the presence of live trees, plants, rocks or woody debris within the channel. These obstructions will slow the velocity of the water and create scour holes for fish populations.
Smaller streams, on the other hand, may be negatively affected by debris in the stream. A fallen tree in a small channel has the potential of creating a meander where one might not be desired. However, the clearing of logjams or beaver dams can be dangerous. Beem recommends landowners to seek advice before taking action.
"While it's true that there are engineering methods for solving any stream erosion problem, the costs are quite high and almost always beyond the reach of the private landowner," Beem said. "It's far better to understand and respect the ways in which nature regulates stream erosion and avoid such problems in the first place."