Influence of permeability on sediment trapping efficiency in an Elj groyne field.

Abstract

In woody areas where traditional construction materials are not available engineered log jams (ELJ) may constitute a potential solution for controlling riverbank erosion. Two ELJ groyne fields formed by four structures were placed in a 12 m long rectangular flume. In the first setup, groynes had a 46% permeability whereas in the second setup, groynes had a 26% permeability. Sediment in suspension was incorporated at a constant rate after flow was stabilized. Tests showed that when groyne permeability has higher, maximum scour depth at the inner end of the groyne diminished while sediment deposition between groynes increased. This result indicates that use of the main resource for building ELJ groynes can be optimized. As the configuration of the groynes was basically idealized as a frame of cylindrical elements, results of this experimental program may also be used to design groynes made up of artificial materials resembling ELJs. This type of solution could be used where traditional construction materials are not readily available.