Geotextiles as Filters in Erosion Control

Geotextiles are often used in place of conventional mineral filters in erosion control applications along lake or ocean shorelines, canals, stream channels, and other hydraulic structures. The basic concepts of a geotextile filter system are explained, and basic applications are described. The functional design considerations for mechanically needle-punched nonwoven geotextiles are discussed with reference to current filter criteria, and filter design based on known values of soil particle size and uniformity coefficients is presented in relatively simple graphical form. In particular, filter design criteria for laminar monodirectional flow and granular soil and turbulent, alternating water flow and granular soil are presented.