Evaluation of Performance of Empirical Models for the Prediction of Local Scour at Bridge Piers (Case Study Chanchaga Bridge, Minna, Nigeria).

Abstract

Scour is the removal of sediment from streambeds and stream-banks and is caused by the erosive action of flowing water. It is more significant during high flow events under high velocity. Due to the complexity of stream dynamics, scour is often exacerbated at bridge piers and abutments, potentially undermining the structure and jeopardizing its stability. The accurate prediction of sediment scour depths near bridge piers under design storm conditions is very important in bridge design, especially when the bridge is located in an un-gauged catchment. The physical processes involved are very complex and difficult to analyze, and, thus, most design scour depth predictive equations are based on laboratory scale experimental results. Here, laboratory study was combined with onsite measurements to obtained relevant parameters. The parameters were fed into empirical models. Subsequently, the best empirical model is determined for estimation of local pier scour at downstream of the Tagwai intake weir among the numerous empirical models. This is achieved by using consistency-correlation analysis which compared the measured depth of scour and calculated depth of scour obtained using selected empirical models.