350 RIVER ENGINEERING
Fig. 8.16 River training with groynes and training wall
Fig. 8.17 Use of deflectors for bank protection
8.7.3 Bank protection
Bank protection is carried out by planting, faggotting (faggots or fascines
are bundles of branches, usually willow), thatching, wattling, mattresses,
rubble, stone pitching, gabions, bagged concrete, concrete slabs, asphalt
slabs, prefabricated concrete interlocking units with or without vegetation,
articulated concrete mattresses, soil–cement blocks, asphalt and asphaltic
concrete, geotextiles (woven and non-woven fabrics, meshes, grids, strips,
sheets and composites of different shapes and constituents), used tyres,
etc., all used with or without membrane linings (e.g. nylon, rubber, poly-
thene, etc.). The choice of material is influenced by the extent of the area
to be protected, hydraulic conditions, material availability, material and
labour costs, access to the site, available mechanization, soil conditions,
design life, required impermeability, robustness, flexibility, roughness,
durability, environmental requirements, etc.
Geotextilesand related materials have found increasing use in civil
engineering projects since about the late 1950s (mainly in coastal engin-
eering) and have been widely used in bank protection since about 1970.
Non-wovens were initially used in Europe while the use of woven monofil-
aments originated in the USA; both are now used worldwide. When used
as turf reinforcement in bank erosion control, velocities up to about 4 m s^1
