Channelization

The straightening of a river by removing meanders, ostensibly for the purpose of flood control. Usually, bulldozers and other heavy equipment are used. Channelization destroys the benthos and hyporheic zones, as well as the riparian ecotone. Disconnecting the communities of life forms of the river by short-circuiting the flow of energy through each trophic level is the end result. Recovery is protracted, depending upon the extent to which the banks were altered. The Kissimee River in Florida, for example, remained straightened for many years after extensive channelization by the Corp of Army Engineers. Today, that river is scheduled to be routed back to its original riverbed, because studies have shown that the altered river had too great an effect on natural processes in the everglades. Many other smaller rivers throughout the world suffer from channelization each year.

Links
  http://www.amrivers.org/fishwildlife/fwthreats.htm