KWRRI Research Reports


Vegetative filters serve the purpose of retarding flow. As a result the sediment carrying power of flowing water in a vegetated channel is greatly reduced and silting takes place along the section where the vegetation is planted.

The mechanism of the filtering action of real or artificial vegetation can be described by a simplified principle, in that a gross reduction of turbulent fluctuation of the fluid is involved. This in turn allows the sediment particles to settle under the force of gravity more readily. In the case of nonsubrnerged flow, solid particles may settle out even faster due to the lengthening of the path the particles travel as they move with the fluid around the vegetation blades and the creation of zero velocity regions in front and behind the vegetation sterns.

In order to determine the actual sediment trapping efficiency, a series of experimental tests were conducted under various flow conditions in a channel with continuous and discrete vegetative covers. The research results will be presented in three parts: (1) sediment filtration efficiency of continuous grass media; (2) bedload behavior in continuous and discrete vegetative filters; and (3) trapping of suspended solids by discrete vegetative filters. This research report addressed the effectiveness of the vegetative filter in trapping suspended solids when the filter is arranged in a continuous manner.

Publication Date


Report Number


Digital Object Identifier (DOI)

Funding Information

The work upon which this report is based was supported in part by funds provided by the Office of Water Research and Technology, United States Department of the Interior, Washington, D.C., as authorized by the Water Research and Development Act of 1978. Public Law 95-467.