Semi-analytical model for temporal clear-water scour at prototype piers

The temporal pier scour process was studied extensively for laboratory scale but remains poorly understood for prototype piers. This research presents a novel semi-analytical solution for temporal clear-water scour at prototype piers with arbitrary initial scour conditions, by integrating the fundamental mass conservation law and the empiricism from previous studies. The proposed solution includes the conventional power-, log-and exponential laws for the initial, growth and decay phases, respectively, in a single model agreeing with recent high-quality data for long durations and prototype scour with a determination coefficient higher than 0.98. The results show that (i) temporal pier scour process is described by two basic parameters: characteristic time t_c and equilibrium scour depth η_∞; and (ii) the proposed solution may be useful for data correction in relation to η_∞ and for real-time bridge scour monitoring during floods. Yet, its predictive power depends on the predictability of t_c and η_∞, indicating a future research need.