Channelization: A More Controversial Way to Reduce Erosion Near Streams and RiversEnvironmental Training Resource
September 2, 2013 — 3,923 views
Several decades ago, the channelization of streams and rivers was actually encouraged by a number of environmental groups and state agencies. It was viewed as an effective way to control the flow of major rivers and streams, all while containing them and controlling their path through developments, agricultural lands, and wetlands. Since channelization went mainstream, though, studies have been conducted into its effects on those wetlands, as well as the net positive impact that it has on stream erosion and the protection of the streambed. The results of those studies are decidedly mixed, and channelization has become a far more controversial development method as a result.
Typically, channelization involves "straightening" a stream or river in an effort to reduce erosion on one side of the shore or the other. As most environmental engineers know, the nature of a winding stream is that it tends to build up sand and sediment on side of a curve while significantly reducing the amount of sand and sediment on the opposing side. In addition to making the stream "portable" and shifting its path on a regular basis, such uneven erosion can cause the stream to overflow its banks on one side or the other quite frequently, threatening commercial developments and residential areas.
Channelization seeks to "fix" such uneven erosion by straightening out the stream and reducing the curves that are causing the issue. In theory, this actually solves a problem without sending the stream underground or using one of many other highly disruptive methods. The problem, though, is that channelization has had a tendency to reduce the presence of nearby wetlands. A prime example of this damage can be seen in the channelization of Florida's Kissimmee River, which to this day still suffers from a dramatically reduced wetland area compared to the era prior to channelization.
Even so, there are a number of positive benefits that keep channelization in active conversations about how to control a stream and prevent its overflows or erosive processes. Among those advantages:
- Channelization gives developers the opportunity to create a channel deep enough to contain flood waters, reducing the risk to nearby developments or agricultural lands that might otherwise experience significant loss.
- The depth of a channel enforced on a larger body of water can be deepened and widened to be far more suitable for navigational purposes and even shipping.
- Rich topsoil is preserved due to the straighter nature of the stream, and this also results in less erosion on one side of the water or the other.