Relevance of 2D hydraulic model to address fish behaviour in large rivers

The article presented herein seeks to demonstrate how a two-dimensional hydrodynamic model representing abiotic conditions can be used to study the behaviour of fish affected by large fluctuations of environmental conditions in the Rhone River. Despite the complexity of the Rhone's physical environment, the results presented in this article show that a 2D model is capable of correctly representing the hydraulic conditions, water temperature and habitats for the studied area at each time step. This represents a major advancement in the understanding of aquatic community structures and in particular, for the structure of fish communities that are rarely used in France. For the first time, the environmental conditions affecting fish and their spatial localization will be known simultaneously. The model can also simulate habitat conditions and temperatures over longer periods of time. For example, this methodology is compatible with the monitoring of fish communities of the Rhone initiated in 1979. In this regard, a 2D hydrodynamic model answered a major need of experts working on the Rhone therm - Phase III project in 2006. The interest in modeling precise habitat and temperature conditions in two-dimensions for a large array of flows allows one to speculate that it will be possible to know the role that these two key environmental factors play on the behavioural choices of fish.