The process of straightening or redirecting natural streams in an artificially modified or constructed stream bed. Channelization has been carried out for numerous reasons, most often to drain wetlands, direct water flow for agricultural use, and control flooding. While this process makes a stream more useful for human activities, it tends to interfere with natural river habitats and to destabilize stream banks by destroying riparian vegetation. When annual flood patterns are disrupted, fertilizing sediment is no longer deposited on river banks and excessive sediment accumulation can occur downstream. Perhaps most importantly, wetland drainage and the removal of instream obstacles such as rocks, fallen trees, shallow backwaters, and sand bars eliminate feeding and reproductive habitats for fish, aquatic insects, and birds.