Data Assimilation for Parameter Estimation of a Distributed Hydrological Flash Flood Model

The challenge in hydrological distributed modelling is to make the best use of the available data and capture the dominant response of the catchment, by reducing uncertainties linked to the system characterisation. For this purpose, a parameter estimation process based on the adjoint method is used in this study. The principle is to consider parameters as control variables and optimise them in order to minimise the discrepancy between the observations and solutions of the model. An example using the flash flood MARINE model on the Gardon d'Anduze catchment, is presented. This example illustrates that the methodology may be used to parameterise and calibrate fully distributed physics based models, and is capable of making reliable forecasts. Furthermore, the methodology contributes to improve flash flood generation understanding and to validate physical hypothesis used in the model.