11 Mar 2022
11 Mar 2022

Multi-dimensional hydrological-hydraulic model with variational data assimilation for river networks and floodplains

Léo Pujol1, Pierre-André Garambois2, and Jérôme Monnier3,4 Léo Pujol et al.
  • 1Laboratoire des sciences de l’ingenieur, de l’informatique et de l’imagerie (ICUBE), Fluid Mechanics Team, CNRS, Universite de Strasbourg, France
  • 2INRAE (Irstea), Aix Marseille Univ, RECOVER, Aix-en-Provence, France
  • 3Institut de Mathematiques de Toulouse (IMT), France
  • 4INSA Toulouse, France

Abstract. This contribution presents a novel multi-dimensional (multi-D) hydraulic-hydrological numerical model with variational data assimilation capabilities. It allows multi-scale modeling over large domains, combining in situ observations with high-resolution hydro-meteorology and satellite data. The multi-D hydraulic model relies on the 2D shallow water equations solved with a 1D2D adapted single finite volume solver. 1Dlike reaches are built through meshing methods that cause the 2D solver to degenerate into 1D. They are connected to 2D portions that act as local zooms, for modeling complex flow zones such as floodplains and confluences, via 1Dlike-2D interfaces. An existing parsimonious hydrological model, GR4H, is implemented and coupled to the hydraulic model. The forward-inverse multi-D computational model is successfully validated on academic and real cases of increasing complexity, including using the second order scheme version. Assimilating multiple observations of flow signatures leads to accurate inferences of multi-variate and spatially distributed parameters among bathymetry-friction, upstream/lateral hydrographs, and hydrological model parameters. This notably demonstrates the possibility for information feedback towards upstream hydrological catchments, that is backward hydrology. A 1Dlike model of part of the Garonne river is built and accurately reproduces flow lines and propagations of a 2D reference model. A multi-D model of the complex Adour basin network, inflowed by the semi-distributed hydrological model, is built. High resolution flow simulations are obtained on a large domain, including fine zooms on floodplains, with a relatively low computational cost since the network contains mostly 1Dlike reaches. The current work constitutes an upgrade of the Dassflow computational platform. The adjoint of the whole tool chain is obtained by automatic code differentiation.

Léo Pujol et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-10', Anonymous Referee #1, 18 Apr 2022
  • RC2: 'Comment on egusphere-2022-10', Anonymous Referee #2, 19 Apr 2022

Léo Pujol et al.

Léo Pujol et al.


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Short summary
This contribution presents a new numerical model for representing hydraulic-hydrological quantities at the basin scale. It allows modeling large areas at a low computational cost, with fine zooms where needed. It allows the integration of local and satellite measurements, via data assimilation methods, to improve the model's match to observations. Using this capability, good matches to in situ observations are obtained on a model of the complex Adour river network with fine zooms on floodplains.