The recent norm ISO TR 18228-8 deals with the design of geosynthetics used for erosion control on slopes and in channels for water flow. In particular it applies to channels that are non-navigable by vessels and that sustain flow for intermittent periods and at relatively low velocities, for examples surface water and run-off control channels and spillways. The applications for erosion control geosynthetics are typically in channels with fluid velocity up to 3 m/s for sustained periods or up to 6 m/s for short periods. Allowable water velocities and sustainable periods of flow depend on the subsoil parameters and the geosynthetic product’s ability to prevent the soil particles moving. Once the hydraulic parameters of the flow have been evaluated, the stability of the channel bottom and side banks against erosion can be assessed using two limit criteria: the first one takes into consideration the allowable water velocity, and the second one the allowable shear stresses. The paper presents the detailed design procedure for geosynthetics for erosion control in channels.
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