hydro-smash on Pypi

smash (Spatially distributed Modeling and ASsimilation for Hydrology) is a Python library, interfaced with an efficient Fortran computational engine, that provides user-friendly routines for both hydrological research and operational applications.

The platform enables the combination of vertical and lateral flow operators through either process-based conceptual models or hybrid physics-AI approaches incorporating Artificial Neural Networks (ANNs). It is designed to simulate discharge hydrographs and hydrological states at any spatial location within a basin, and to reproduce the hydrological responses of contrasting catchments by leveraging spatially distributed meteorological forcings, physiographic data, and hydrometric observations.

Documentation: https://smash.recover.inrae.fr
Source code: https://github.com/DassHydro/smash
Contributing: https://smash.recover.inrae.fr/contributor_guide
Citations and related papers: https://smash.recover.inrae.fr/citations
Scientific references: https://smash.recover.inrae.fr/bibliography
Bug reports: https://github.com/DassHydro/smash/issues

smash offers a range of advanced calibration techniques, including Variational Data Assimilation (VDA), Bayesian estimation for uncertainty quantification, and machine learning methods, all within a spatialized and differentiable modeling framework. This is enabled by a numerical adjoint model automatically generated using the Tapenade differentiation tool, which provides accurate gradients for high-dimensional, non-linear optimization and efficient model learning.

Tapenade website: https://team.inria.fr/ecuador/en/tapenade
Tapenade article: https://doi.org/10.1145/2450153.2450158
Tapenade source code: https://gitlab.inria.fr/tapenade/tapenade.git

Whether you are managing water resources or conducting research in hydrological modeling, smash can provide an easy-to-use yet powerful solution to support your work. Refer to the Getting Started guide for installation instructions and an introduction to its features.

How to cite smash

For smash software use, please cite:

Colleoni, F., Huynh, N. N. T., Garambois, P.-A., Jay-Allemand, M., Organde, D., Renard, B., De Fournas, T., El Baz, A., Demargne, J., and Javelle, P. (2025). SMASH v1.0: A Differentiable and Regionalizable High-Resolution Hydrological Modeling and Data Assimilation Framework. EGUsphere, 2025, 1–36. https://doi.org/10.5194/egusphere-2025-690.

BibTeX entry:

@article{Colleoni2025smash,
    author  = {Colleoni, François and Huynh, Ngo Nghi Truyen and Garambois, Pierre-André and Jay-Allemand, Maxime and Organde, Didier and Renard, Benjamin and De Fournas, Thomas and El Baz, Apolline and Demargne, Julie and Javelle, Pierre},
    title   = {SMASH v1.0: A Differentiable and Regionalizable High-Resolution Hydrological Modeling and Data Assimilation Framework},
    journal = {EGUsphere},
    volume  = {2025},
    year    = {2025},
    pages   = {1--36},
    doi     = {10.5194/egusphere-2025-690}
}

Please also cite the relevant references corresponding to the algorithms and methods used:

Hybrid process-parameterization for water flux corrections:

Huynh, N. N. T., Garambois, P.-A., Renard, B., Colleoni, F., Monnier, J., and Roux, H. (2025). A Distributed Hybrid Physics-AI Framework for Learning Corrections of Internal Hydrological Fluxes and Enhancing High-Resolution Regionalized Flood Modeling. EGUsphere, 2025, 1–34. https://doi.org/10.5194/egusphere-2024-3665.
Hybrid regionalization, HDA-PR algorithm:

Huynh, N. N. T., Garambois, P.-A., Colleoni, F., Renard, B., Roux, H., Demargne, J., Jay-Allemand, M., and Javelle, P. (2024). Learning Regionalization Using Accurate Spatial Cost Gradients Within a Differentiable High-Resolution Hydrological Model: Application to the French Mediterranean Region. Water Resources Research, 60, e2024WR037544. https://doi.org/10.1029/2024WR037544.
Signatures, multi-criteria calibration, hydrograph segmentation algorithm:

Huynh, N. N. T., Garambois, P.-A., Colleoni, F., and Javelle, P. (2023). Signatures-and-sensitivity-based multi-criteria variational calibration for distributed hydrological modeling applied to Mediterranean floods. Journal of Hydrology, 625, 129992. https://doi.org/10.1016/j.jhydrol.2023.129992.
Fully distributed variational calibration:

Jay-Allemand, M., Javelle, P., Gejadze, I., Arnaud, P., Malaterre, P.-O., Fine, J.-A., and Organde, D. (2020). On the potential of variational calibration for a fully distributed hydrological model: application on a Mediterranean catchment. Hydrology and Earth System Sciences, 24, 5519–5538. https://doi.org/10.5194/hess-24-5519-2020.