ABSTRACT

Abutments are part of the valley side against which dams are constructed or approach embankments in the case of bridges. Groynes in rivers are usually designed to protect the banks or to provide enough flow depth for navigation purposes. Generally, groynes appear as a series of transverse structures whereas abutments are single structures. Alternative names for these structures include spurs and transverse dikes. The geometry of abutments in rivers or estuaries can be schematised to define some basic types of geometries: wing-wall, spill-through abutments and vertical-wall abutments. Wing-wall abutments have several complicated shapes, including straight wing-wall abutments with a T-head or L-head (guide bunds), curved wing-wall abutments shaped like a hockey stick or an inverted hockey stick. Scour along the streambank and at the abutment tip is also influenced by the permeability of the abutment.