Hydraulic modelling of rivers and river structures

The modeling of watercourses and hydraulic structures is a mandatory and systematic step in the study of new developments or in the diagnosis of existing structures. It is an essential decision-making aid, enabling us to guarantee the correct dimensioning of structures, even in extreme situations, to optimize their design and to diagnose faults with great flexibility. Models are also excellent communication tools for decision-makers and the general public.

While a few decades ago, physical modeling and experimentation were the only techniques available for diagnostic and design studies, today's engineers have many digital tools at their disposal to replace or complement physical models. In fact, hybrid modeling, which combines physical and digital models, is an extremely powerful and comprehensive study tool.

This article presents the processes involved in hydraulic and hydrosedimentary modeling of rivers and river structures, from modeling strategy to interpretation of results. It describes the principles of modeling and presents a non-exhaustive overview of the different types of models, as well as highlighting modeling limitations and biases.

Modelling work of any kind must follow the same steps, which are essential to the relevance of the proposed models and the accuracy of the results obtained. This article describes the various stages involved in each model. In particular, it details the physical analysis of the phenomena to be modeled and the synthesis of the available input data required to define the tools best suited to the problem to be addressed. It also presents the choice of modeling strategy and the type of model (physical, numerical or hybrid) to be used, as well as the steps involved in model design and construction.

It covers the process of calibrating the model or, failing that, defining the sensitivity of the results to the modeling assumptions (using a parametric approach), which guarantees the quality of the conclusions, and finally the steps involved in implementing the model and interpreting the results, taking into account the biases and limitations inherent in all modeling.

This article aims to provide a broad overview of hydraulic modeling of rivers and river structures, but is not intended as a practical guide to model use.