My thesis topic focuses on the operationalization of the Independent Subsection Method (ISM), a 1D+ numerical method simulating overbank flows. This method, based on 1D bed modeling, allows for the calculation of water height in a river, as well as average flow rates in the main riverbed and both floodplains of the river. ISM differs from traditional 1D and 1D+ methods by providing a better representation of the physical phenomena related to overbank flows. It considers the interactions between the beds through mass and momentum exchanges while accounting for independent head losses in each bed. This method holds promise for estimating flow rates and water heights during flood events. However, several aspects must be improved to make it fully operational.
Initially, it is necessary to resolve certain numerical issues, such as problems with dry fronts. The next goal is to integrate complex geometries, such as confluences, diffluences, and hydraulic structures, into the ISM framework. Finally, a sediment transport module will be added to the ISM.
After these three steps, the performance of ISM will be evaluated through more complex simulations applied to a stretch of the Rhône River, with geometry provided by Compagnie Nationale du Rhône (CNR). A comparison between the INRAE ISM model and the CNR’s 1D Flood model is planned. If ISM proves to be functional on any stretch of the Rhône River, this method, which is more faithful to the physical phenomena of overbank flows and relatively low in computational cost, could be adopted by CNR for flood management.

Funding

CNR