Channels and Spillways

Diversion channels are made to direct or redirect flowing water. They can be constructed across a slope with a supporting ridge on the lower side. Land treatment practices or structural measures designed to prevent damaging accumulations of sediment in the channels should be installed with or before the diversions.

During flooding, spillways release flows at a controlled rate from a dam or levee into a downstream area, so as not to overtop and damage the dam. A spillway can also refer to bypasses of dams or outlets of a channels used during high water. Flood waters can cause catastrophic damage through erosion, and in areas where flooding is expected, protection measures should be installed.

Drop structures are low-elevation structures that span the entire width of the channel, creating an abrupt drop in channel bed and water surface elevation in a downstream direction. They can be used to stabilize channel grades, redistribute or dissipate energy, improve fish passage, and reduce erosion, and create structural and hydraulic diversity in uniform channels. (Above: Bryant Pond Dam, Richmond, VA)