W hat The health happened of Missouri streams depends on the landowner Remember only you can help prevent the effects of to the stream urbanization from occurring and Urban streams can be preserved by limiting impervious eroding your streams in my surfaces and leaving a forested corridor adjacent to the stream backyard? TERMS TO KNOW Watershed: land area that drains into a stream Channelization: straightening of a stream which shortens the stream channel, increases the slope and erosive power of the stream Headcut: (downcutting) vertical drop in the stream bottom due to erosion from increased water velocities Streamside management zone: (riparian zone) strip of trees and other woody vegetation along both sides of a stream that protect a streambank from erosion and provide additional benefits If you need more information, contact your nearest Missouri Department of Conservation Impervious surface: surface which cannot be penetrated by water and increases potential Regional Office or: surface runoff Stream Unit Detention basins: small ponds used to detain Missouri Department of Conservation PO Box 180 runoff so water can be released at a slower, more Jefferson City, MO 65102-0180 natural rate (573)751-4115 Grade control structure: graded rock or other wwwmdcmogov structure placed perpendicular across a stream Mismanaged urban streams can become a liability from bank to bank to provide grade control and to the landowner and the community 4/13/04 stabilize the stream STR 238 Its my backyard! Its eroding away! It never did that before! Yeah, I know what you mean, we moved to this subdivision because of its natural beauty, and now its washing downstream! You know, things were okay until they built that mall up the hill I wonder if that has anything to do with it ?
his situation is a familiar one for many How can streams be protected Missouri urbanites With new con- from urbanization? Tstruction in urban areas, streamside roper watershed planning before properties are being negatively impacted from development can help reduce stream development upstream, downstream, or both Pproblems Maintaining a wooded Most stream problems in urban areas streamside management zone will: are caused by two factors: S help make banks more resistant to erosion 1 channelization S filter out chemicals harmful to the stream 2 increased stormwater runoff S provide habitat and greenways for wildlife hannelization, or stream straightening, he most effective way to protect streams Channelized and armored streams with heavy stormwater Cstresses the stream system When a stream Tis to object to channelization in your area and runoff are unstable and transfer problems downstream is channelized, it results in a shorter channel to try to minimize moving, clearing, and other Channelization and armoring will lead to eroding with an increased slope This leads to an streambanks above and below the channelized reach developments near the stream Most importantly, increase in water velocity in the channelized work with city planning and zoning boards to limit reach Faster moving water has more power to ncreased stormwater runoff is the second the amount of land covered by impervious surfaces erode the stream bottom and banks Imajor factor affecting urban streams and to require the use of detention basins, wet- Headcuts (streambed downcutting) are by- Watershed development and paving causes lands, and green space to slow water runoff from products of channelization and develop in and erosion and flooding Vegetated land is impervious surfaces If your watershed is already developed, there still may be room for stormwater upstream of channelized reaches Headcuts capable of soaking up a great deal of rainfall management structures like detention basins erode deep into streambeds and banks, creating which is then slowly released into streams via streambanks that are bare of vegetation and too groundwater However, in developed areas, Streambank erosion, an indicator of a stream tall to be stable rain falls on and flows over impervious adjusting to changing watershed conditions, can be In order to recover from effects of surfaces (eg concrete, asphalt, rooftops) and addressed in several ways If the erosion can be channelization, a stream will begin to widen and drains almost instantly into a stream channel tolerated, do nothing and let the stream adjust If tend to return to a natural meandering pattern With increased amounts of stormwater caused the erosion must be controlled, most of the As a result, the widening, meandering stream by accelerated runoff, streams flood more and solutions will involve rock rip-rap may undermine lawns, trees, roads, and bridges flow faster Furthermore, faster water erodes Streambed erosion is the most serious This eroded soil settles out and fills the channel more streamside land, also causing streams to problem This kind of erosion is also a sign that downstream, greatly reducing the channels widen and deepen the stream is trying to adjust to a change, but capacity to carry water This process also leads These two watershed alterations, unlike streambank erosion, vertical erosion should to further streambank erosion and increased channelization and increased stormwater be stopped as soon as possible The design and flooding In channelized streams, trees alone runoff, are why many small backyard creeks installation of a grade control structure will be may not be enough to stabilize the eroding turn into deep, wide canyons with steep, required, which necessitates the services of a streambanks eroding banks qualified engineer