Riverbank protection with groynes, numerical simulation 1D

Abstract

Riverbank protections are essential when carrying out river channeling or redirection works. Predicting its proper functioning is the responsibility of the designers and agencies in charge of safeguarding the safety of the population surrounding them. The numerical simulation is one of the tools that allow these forecasts to be made. In this work, we used HEC-RAS 1D to evaluate its capacity to reproduce adequately the hydraulic behavior of riverbank protection based on seven groynes. The numerical model was calibrated with experimental measurements made in a reduced physical model, 1:40 scale. Three ways to input the geometry of the groins were tested: i) as a barrier, with dimensions of height, width, and average length; ii) as a set of stepped obstructions and iii) as part of the natural terrain. The barrier was the optimal geometry. The numerical results reproduced satisfactorily the effects measured in the physical model. From this calibration, two alternatives were tested, finding that an arrangement of four groynes combined with a marginal revetment could have the same effect as the full arrangement of seven groynes but with a smaller volume of work. Although the phenomenon under study presents 2D characteristics, the key in numerical modeling 1D is in the quality of the data with which it is calibrated. Also, the 1D models are faster and have fewer instabilities than the 2D and 3D models, which allows analyzing different design conditions in less time.