The present report is devoted to the topic of river bank erosion and
its prevention. Emphasis is placed on a physically-based model of bank
erosion, into which various kinds of bank protection can be imbedded. For
simplicity, the study is restricted to straight channels. The methods
developed here can, however, be applied to the broader context of
The report consists of two parts. The first part is devoted to an
experimental study of the problem. The process of bank erosion of coarse
material is first studied. The channel is allowed to erode until such point
as a stable equilibrium is attained. Such experiments provide a baseline
against which to test the effectiveness of various means of bank protection.
The type of bank protection studied falls under the category of distributed
drag. Such methods use timber-pile permeable dikes, jacks, jetties, or trees
in conjunction with the Palmiter method to slow the flow down in the
vicinity of the bank. In the present study, screens similar to permeable
dikes were used to accomplish this. It was shown that a sufficient density
of distributed drag elements can substantially slow or stop bank erosion.
When fine, suspendable material was added to the water, this material
tended to settle out preferentially in the near-bank field of retarded velocity
due to distributed drag. As a result, not only could bank erosion be
prevented, but eroded banks could be reconstructed by means of deposition
The second part of the study was devoted to a theoretical and
numerical model of bank erosion and its prevention, in parallel with the
experiments. The theory is based on a description of bedload transport on
side slopes up to the angle of repose. The Finite Element Method was used
to model the flow and sediment transport field, as well as describe the time
evolution of the channel. At present, the model has proved successful in
describing the process of bank erosion documented in the experiments.
Numerical work continues on the subject of bank protection by means of
Izumi, Norihiro; Kovacs, Agnes; Parker, Gary; Leuthew, David P..
Experimental and Theoretical Studies of Bank Erosion in Rivers and its Prevention by Low-Cost Means.
St. Anthony Falls Hydraulic Laboratory.
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