Numerical–Experimental Study of Scour in the Discharge of a Channel: Case of the Carrizal River Hydraulic Control Structure, Tabasco, Mexico

Abstract

Scour processes occur, among other causes, by the interaction of flow and sediment transport around structures built within a river. It is important to identify the location and quantify the magnitude of scour to avoid under or overestimation since the former puts the structure at risk and the latter demands an excessive economic cost. The data obtained from a physical model with a scale of 1:60 (without distortion) was used to assess the accuracy of a 2D free-surface numerical model (2DH) in predicting maximum scour. The physical model corresponds to the hydraulic-regulating structure located at the entrance of the Carrizal River, tributary to the Mezcalapa River bifurcation, located in Tabasco, Mexico. The scour is produced by the effect of a jet generated by a discharge channel. The maximum experimental scour was compared to the results of a numerical model and the estimation of four empirical equations: Breusers, Farhoudi and Smith, Negm, and Dietz. Setting an acceptance threshold of 75% accuracy, only the Breusers method provided values close to the measured values, and the numerical model failed to reproduce the location and magnitude of maximum scour, yet when the 2DH model was calibrated for secondary flow effects in the hydraulics. This indicates that the application of 2D models for the estimation of scour caused by jets may not provide good results when secondary currents are developed.