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A Python wrapper to setup and run the hydrologic modelling framework Raven.

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A Python wrapper to setup and run the hydrologic modelling framework Raven.

RavenPy is a Python wrapper for Raven, accompanied by utility functions that facilitate model configuration, calibration, and evaluation.

Raven is an hydrological modeling framework that lets hydrologists build hydrological models by combining different hydrological processes together. It can also be used to emulate a variety of existing lumped and distributed models. Model structure, parameters, initial conditions and forcing files are configured in text files, which Raven parses to build and run hydrological simulations. A detailed description about modeling capability of Raven can be found in the docs.

RavenPy provides a Python interface to Raven, automating the creation of configuration files and allowing the model to be launched from Python. Results, or errors, are automatically parsed and exposed within the programming environment. This facilitates the launch of parallel simulations, multi-model prediction ensembles, sensitivity analyses and other experiments involving a large number of model runs.

The code is currently undergoing a number of changes to support semi-distributed watersheds, so expect some API changes over the next versions.


  • Download and compile Raven with pip

  • Configure, run and parse Raven outputs from Python

  • Parallel simulations over parameters, models or watersheds

  • Utility command to create grid weight files

  • Extract physiographic information about watersheds

  • Algorithms to estimate model parameters from ungauged watersheds

  • Exposes outputs (flow, storage) as xarray.DataArray objects


Please see the detailed installation docs.


RavenPy’s development has been funded by CANARIE and Ouranos and would be not be possible without the help of Juliane Mai and James Craig.

This package was created with Cookiecutter and the Ouranosinc/cookiecutter-pypackage project template.


0.9.0 (2022-11-16)

Breaking changes

  • HRUState’s signature has changed. Instead of passing variables as keyword arguments (e.g. soil0=10.), it now expects a state dictionary keyed by variables’ Raven name (e.g. {“SOIL[0]”: 10}). This change makes `rvc files easier to read, and avoids Raven warnings regarding ‘initial conditions for state variables not in model’.

  • nc_index renamed to meteo_idx to enable the specification of distinct indices for observed streamflow using hydro_idx. nc_index remains supported for backward compatibility.

  • The distributed python testing library, pytest-xdist is now a testing and development requirement.

  • xarray has been pinned below “2022.11.0” due to incompatibility with climpred==”2.2.0”.

New features

  • Add support for hydrometric gauge data distinct from meteorological input data. Configuration parameter hydro_idx identifies the gauge station index, while meteo_idx (previously nc_index) stands for the meteo station index.

  • Add support for multiple gauge observations. If a list of hydro_idx is provided, it must be accompanied with a list of corresponding subbasin identifiers (gauged_sb_ids) of the same length.

  • Automatically infer scale and offset :LinearTransform parameters from netCDF file metadata, so that input data units are automatically converted to Raven-compliant units whenever possible.

  • Add support for the command :RedirectToFile. Tested for grid weights only.

  • Add support for the command :WriteForcingFunctions.

  • Add support for the command :CustomOutput.

  • Multiple other new RavenCommand objects added, but not integrated in the configuration, including :SoilParameterList, :VegetationParameterList and :LandUseParameterList.

  • Multichoice options (e.g. calendars) moved from RV classes to config.options, but aliases created for backward compatibility.

  • Patch directory traversal vulnerability (CVE-2007-4559).

  • A local copy of the raven-testdata with environment variable (RAVENPY_TESTDATA_PATH) set to that location is now no longer needed in order to run the testing suite. Test data is fetched automatically and now stored at ~/.raven_testing_data.

  • RavenPy now leverages pytest-xdist to distribute tests among Python workers and significantly speed up the testing suite, depending on number of available CPUs. File access within the testing suite has also been completely rewritten for thread safety.
    • On pytest launch with “–numprocesses > 0”, testing data will be fetched automatically from Ouranosinc/raven-testdata by one worker, blocking others until this step is complete. Spawned pytest workers will then copy the testing data to their respective temporary directories before beginning testing.

  • To aid with development and debugging purposes, two new environment variables and pytest fixtures are now available:
    • In order to skip the data collection step: export SKIP_TEST_DATA=true

    • In order to target a specific branch of Ouranosinc/raven-testdata for data retrieval: export MAIN_TESTDATA_BRANCH=”my_branch”

    • In order to fetch testing data using the user-set raven-testdata branch, pytest fixtures for get_file and get_local_testdata are now available for convenience

0.8.1 (2022-10-26)

  • Undo change related to suppress_output, as it breaks multiple tests in raven. New Raven._execute method runs models but does not parse results.


Breaking changes

  • Parallel parameters must be provided explicitly using the parallel argument when calling emulators.

  • Multiple nc_index values generate multiple gauges, instead of being parallelized.

  • Python3.7 is no longer supported.

  • Documentation now uses sphinx-apidoc at build-time to generate API pages.

  • Add generate-hrus-from-routing-product script.

  • Do not write RV zip file and merge outputs when suppress_output is True. Zipping rv files during multiple calibration runs leads to a non-linear performance slow-down.

  • Fixed issues with coverage reporting via tox and GitHub Actions

  • Add partial support for :RedirectToFile command, tested with GridWeights only.


  • Added functionalities in Data Assimilation utils and simplified tests.

  • Removed pin on setuptools.

  • Fixed issues related to symlinks, working directory, and output filenames.

  • Fixed issues related to GDAL version handling in conda-forge.

  • Updated jupyter notebooks.


  • Updated internal shapely calls to remove deprecated .to_wkt() methods.


  • Automate release pipeline to PyPI using GitHub CI actions.

  • Added coverage monitoring GitHub CI action.

  • Various documentation adjustments.

  • Various metadata adjustments.

  • Pinned owslib to 0.24.1 and above.

  • Circumvented a bug in GitHub CI that was causing tests to fail at collection stage.


  • Update test so that it works with xclim 0.29.


  • Pinned climpred below v2.1.6.


  • Pinned xclim below v0.29.


  • Update cruft.

  • Subclass derived_parameters in Ostrich emulators to avoid having to pass params.


  • Add support for V2.1 of the Routing Product in ravenpy.extractors.routing_product.

  • Add collect-subbasins-upstream-of-gauge CLI script.

  • Modify WFS request functions to use spatial filtering (Intersects) supplied by OWSLib.


  • Add support for EvaluationPeriod commands. Note that as a result of this, the model’s diagnostics property contains one list per key, instead of a single scalar. Also note that for calibration, Ostrich will use the first period and the first evaluation metric.

  • Add SACSMA, CANADIANSHIELD and HYPR model emulators.


  • Simplify RVC configuration logic.

  • Add ravenpy.utilities.testdata.file_md5_checksum (previously in xarray.tutorial).


  • Some adjustments and bugfixes needed for RavenWPS.

  • Refactoring of some internal logic in ravenpy.config.rvs.RVT.

  • Improvements to typing with the help of mypy.


  • Refactoring of the RV config subsystem:

    • The config is fully encapsulated into its own class: ravenpy.config.rvs.Config.

    • The emulator RV templates are inline in their emulator classes.

  • The emulators have their own submodule: ravenpy.models.emulators.

  • The “importers” have been renamed to “extractors” and they have their own submodule: ravenpy.extractors.


  • Update to RavenC revision 318 to fix OPeNDAP access for StationForcing commands.

  • Fix grid_weights set to None by default.

  • Pass nc_index to ObservationData command.

  • Expose more cleanly RavenC errors and warnings.


  • Add notebook about hindcast verification skill.

  • Add notebook about routing capability.

  • Modify geoserver functions to have them return GeoJSON instead of GML.

  • Collect upstream watershed aggregation logic.

  • Fix RVC bug.


This is an interim version making one step toward semi-distributed modeling support. Model configuration is still in flux and will be significantly modified with 0.5. The major change in this version is that model configuration supports passing multiple HRU objects, instead of simply passing area, latitude, longitude and elevation for a single HRU.

  • GR4JCN emulator now supports routing mode.

  • Add BLENDED model emulator.

  • DAP links for forcing files are now supported.

  • Added support for tox-based localized installation and testing with python-pip.

  • Now supporting Python 3.7, 3.8, and 3.9.

  • Build testing for pip and conda-based builds with GitHub CI.


  • Update external dependencies (Raven, OSTRICH) to facilitate Conda packaging.


  • Migration and refactoring of GIS and IO utilities (, utilities/ from RavenWPS to RavenPy.

  • RavenPy can now be installed from PyPI without GIS dependencies (limited functionality).

  • Hydro routing product is now supported from (a notebook has been added to demonstrate the new functions).

  • New script ravenpy aggregate-forcings-to-hrus to aggregate NetCDF files and compute updated grid weights.

  • Add the basis for a new routing emulator option (WIP).

  • Add climpred verification capabilities.


  • Regionalisation data is now part of the package.

  • Fix tests that were not using testdata properly.

  • Add tests for external dataset access.

  • utilities.testdata.get_local_testdata now raises an exception when it finds no dataset corresponding to the user pattern.


  • Set wcs.getCoverage timeout to 120 seconds.

  • Fix Raven.parse_results logic when no flow observations are present and no diagnostic file is created.

  • Fix ECCC test where input was cached and shadowed forecast input data.


  • Fix xarray caching bug in regionalization.


  • Refactoring of ravenpy.utilities.testdata functions.

  • Bump xclim to 0.23.


  • Fix xarray caching bug affecting climatological ESP forecasts (#33).

  • Fix deprecation issue with Fiona.

0.1.6 (2021-01-15)

  • Correct installer bugs.

0.1.5 (2021-01-14)

  • Release with docs.

0.1.0 (2020-12-20)

  • First release on PyPI.

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