Making the Linkage: From Laboratory Testing to Design and Installation Guidelines for Channel Linings and Scour Countermeasures

The development of analysis, design, and installation guidance for selected channel linings and scour countermeasures must consider four important factors: (1) the nature of the mode of failure exhibited by each particular system. Typical failure modes associated with channel linings and scour countermeasures include (a) substrate winnowing; (b) overturning; or (c) flanking and/or undermining; (2) the threshold hydraulic conditions at which the mode of failure is initiated. Performance thresholds are often characterized by the local hydraulic conditions of shear stress, velocity, or a combination of both; (3) the need for ancillary system components or design features such as filter and/or bedding layers, structural connections, and system terminations such as turndowns. These are related to hydraulic conditions, bed material characteristics and, for pier scour countermeasures, pier type and geometry; and (4) the integration of the physical characteristics of the system to the field site. Typically, this consists of generic layout guidelines (plan, profile, and cross-section) based on structure geometry and the local, contraction, and degradation components of scour at the site. Additionally, system characteristics may result in constraints when placing under water versus in the dry.