What We Do

WRF-Hydro Modeling System

WRF-Hydro Modeling System

Project Tabs - WRF Hydro


Schematic of the modularized multiscale, multi-physics WRF-Hydro modeling framework.
Schematic of the modularized multiscale, multi-physics WRF-Hydro modeling framework.

Welcome to the users page for the WRF-Hydro modeling system.  The WRF-Hydro modeling system has been developed by the National Center for Atmospheric Research and its research partners through the generous support of the U.S. National Science Foundation and through research projects supported by the U.S. National Aeronautics and Space Adminsitration (NASA) and the U.S. National Oceanic and Atmospheric Administration (NOAA).

The WRF-Hydro system was originally designed as a model coupling framework designed to facilitate easier coupling between the Weather Research and Forecasting model and components of terrestrial hydrological models.  WRF-Hydro is both a stand-alone hydrological modeling architecture as well as a coupling architecture for coupling of hydrological models with atmospheric models.  WRF-Hydro is fully-parallelized to enable its usage on clusters and high performance computing systems alike.  Like the WRF model it does not attempt to prescribe a particular or singular suite of physics but, instead, is designed to be extensible to new hydrological parameterizations.  Although it was originally designed to be used within the WRF model, it has evolved over time to possess many additional attributes as follows:

Conceptual diagram of WRF-Hydro components
Conceptual diagram of WRF-Hydro components
  • Multi-scale functionality to permit modeling of atmospheric, land surface and hydrological processes on different spatial grids
  • Modularized component model coupling interfaces for many typical terrestrial hydrological processes such as surface runoff, channel flow, lake/reservoir flow, sub-surface flow, land-atmosphere exchanges
  • Parallel code development for application on commodity cluster and higher performance computing systems
  • Stand-alone capabilities for hydrological prediction and research uncoupled to atmospheric models
  • Efficient coupling architecture so that it can be embedded within (or coupled to) other types of Earth system models such as the NCAR Community Earth System Model (CESM) or the NASA Land Information System (LIS)
  • Utilization of many standard data formats for efficient job construction and evaluation


The NCAR 'WRF-Hydro' System

The Weather Research and Forecasting Model Hydrological modeling extension package (WRF-Hydro) is a new community-based model coupling framework designed to link multi-scale process models of the atmosphere and terrestrial hydrology.  The underlying goal of WRF-Hydro development is to improve prediction skill of hydrometeorological forecasts using science-based numerical prediction tools.  To support this goal, hydrometeorological scientists at NCAR, in collaboration with university researchers and federal agencies, have built an extensible, multi-scale coupling architecture to link weather and climate models with hydrological component models (figure below).  The system provides the capability to perform coupled and uncoupled multi-physics simulations and predictions of terrestrial water cycle processes on a wide range of spatial and temporal scales.

Simulated streamflow for a flash flood event in Denver, Colorado during the summer of 2008. Red colored numbers indicate high streamflow values, blue indicates low flow values.
Simulated streamflow for a flash flood event in Denver, Colorado during the summer of 2008. Red colored numbers indicate high streamflow values, blue indicates low flow values.

Designed to operate on the National Science Foundation’s (NSF) high performance computing platforms, the WRF-Hydro system leverages many existing and emerging standards in data formats, pre-/post-processing workflows and parallel computing libraries.  The architecture is intended to significantly simplify the often laborious task of integrating, or coupling, existing and emerging hydrological models into the WRF modeling framework.  In doing so, an extensible, portable and scalable environment for hypothesis testing, sensitivity analysis, data assimilation and environmental prediction has emerged.  The WRF-Hydro system is also adopting a ‘community-based’ development processes with an open and participatory working group environment.  NCAR in collaboration with other NSF and university entities are developing a support structure for WRF-Hydro in the way of model documentation, public, online code repositories, a library of user cases and many pre- and post-processing utilities.

The WRF-Hydro system has been applied for a wide range of research and operational prediction problems both in the U.S. and abroad.  Specific past projects include flash flood prediction, regional hydroclimate impacts assessment, seasonal forecasting of water resources and land-atmosphere coupling studies. An important aspect of WRF-Hydro system has been serving as the core model for the new National Water Model.

WRF-Hydro Downloads


Source Code

WRF-Hydro 3.0

This is the formal release WRF-Hydro source code version 3.0. The tarfile contains the code necessary for both fully-coupled runs with the WRF model version 3.7 and offline or 'uncoupled' runs where meteorological forcing is provided externally by the user. To perform coupled runs, users need to "untar" the tarfile under the WRF 3.7 root directory, which is the same directory level as the "main/" directory in the WRF model. Doing so will overwrite any existing "hydro/" directory if there is one. For users not running WRF_Hydro coupled to WRF they may untar and build the code where they wish.

WRF-Hydro v3.0 Change Log
This pdf file contains a list of major changes to the WRF-Hydro modeling system contained within version 3.0.

Until further notice, please cite the WRF-Hydro system as follows:
Gochis, D.J., W. Yu, D.N. Yates, 2013: The WRF-Hydro model technical description and user's guide, version 1.0. NCAR Technical Document. 120 pages. Available at: WRF-Hydro 1.0 User Guide

Gochis, D.J., W. Yu, D.N. Yates, 2014: The WRF-Hydro model technical description and user's guide, version 2.0. NCAR Technical Document. 120 pages. Available at: WRF-Hydro 2.0 User Guide

Older versions


Catalog of WRF-Hydro Test Cases

Below we provide a set of example test cases users can use to familiarize themselves with the configuration and execution of the WRF-Hydro system. The cases are separated by fully-coupled (with WRF) versus stand-alone (uncoupled) model configurations. Different cases also use different forcing data sets to users can have examples of what some of the forcing data options are.

V.I.P.:  Users need to build the code (i.e. executable files) on their own machines. Please refer to the User Documentaion for support on how to build the stand-alone WRF-Hydro and fully-coupled WRF/WRF-Hydro executables.

Test Case 1: Simple small watershed with idealized forcing
Example test case for a single small watershed (Boulder Creek, Colorado) using idealized forcing.  This test case shows examples of the Noah and NoahMP LSMs driven by idealized forcing (FORC_TYP = 4). No external forcing datasets are provided or required for this test case. This test case is a good case for testing if the WRF-Hydro compilation is successful.

Test Case 2: Regional WRF-Hydro test case with 2 different forcing types
Example test case for stand-alone/uncoupled WRF-Hydro run with either the Noah or NoahMP land surface models. This test case covers the Colorado Front Range region. The Noah and NoahMP LSMs are configured on a dx=1km grid and the routing grid is configured with dx=100m. Input forcing data for this WRF-Hydro run is provided in both standard, preprocessed input format (i.e. 'LDASIN' files - FORC_TYP = 1) or in native (unmanipulated) wrf model output (i.e. 'wrfout' files - FORC_TYP = 3) in netcdf format. [Note that the time window of the different forcing data is different so users need to edit the namelists to reflect those different run times.]  Users should consult the User Document for more specific descriptions on the namelist settings and data formats.

NoahMP Test Case
Alternative forcing data for Noah and Noah-MP example test cases over the Front Range domain. The data contained in the following zip file contains gridded meteorological forcing data derived from the NASA NLDAS2 data base and the NOAA/NWS MPE precipitation product. Users will need to put this data into a directory and edit their namelists to point to this data. This data meets the format requirements for FORC_TYP = 1 or FORC_TYP = 6 in the namelist.input files. See User Documentation for a more complete description of forcing data formats. Gridded Forcing Data

Fully-coupled WRF/WRF-Hydro Test Case

This tarfile contains an example test case for WRF-Hydro run in a fully-coupled mode with the WRF model v3.7. All data necessary to run this test case and a simple README instruction file is provided. Testing data with WRF3.7 fully coupled

Catalog of WRF-Hydro Pre- and Post-Processing Utility Scripts

Arc-GIS Tools for Preparing WRF-Hydro Routing Grids:

To help WRF-Hydro users create surface input data for WRF-Hydro we have created a couple sets of tools. Presently these tools consist of scripts for use with the ArcGIS Geographical Information System. This is a stand-alone set of scripts which ArcGIS users can install and run locally on their own systems.  ArcGIS is a licencsed and proprietary piece of software and we recognize that not all WRF-Hydro users will have access to it. Instructions on how to install and use the stand-alone tool are provided in the .pdf file contained within the download zip files. We have also included here some example test data which contains a sample geogrid domain file and topographic dataset which which users can gain experience in using the stand alone tool. Final result data is also contained in the sample data zipfile so users can compare their results against those created at NCAR. User-generate results should match the packaged results data closely. Lastly, it requires noting that the input file created by these tools should not be deemed as definitive and accurate for every application. Preparation of hydrologic network data (such as channel networks and station data) is inherently an iterative process fraught with geospatial data uncertainties. Therefore we encourage users to closely examine the outputs from the tools provided here and make their own necessary adjustments.


General Pre-processing Utility Scripts

Below are several utility scripts that are useful in pre-processing data for input into WRF-Hydro.

  • ncks_file_concatenaor.sh: Shell script with embedded 'nco' commands to append individual netcdf files together into a single file using the netcdf command operator (nco) command 'ncks'. This tool is useful for concatenating the individual netcdf data layers together into the WRF-Hydro routing input file that are generated by the ArcGIS pre-processing tools.
  • ESMF_NLDAS2_2_WRF_Hydro_Regrid.tar.gz: This tar package contains NLDAS2 data acquisition scripts and ncl-based regridding scripts that will regrid NASA-NLDAS2 meteorological forcing data onto a WRF/WRF-Hydro 'geogrid' domain. The scripts require a current version of the 'ncl' scripting langauge and the ESMF regridding libraries for ncl to be installed locally on a users workstation. Sample NLDAS2 input data, converted to netcdf format from its native grib format and a sample geogrid file are provided.
  • nco_script_to_create_wrfinput_from_geogrid_with_nco_initilization.sh:  Shell script to create a very basic WRF-Hydro initialization file from a WRF geogrid file and a set of user-specified conditions. The script produces fields of spatially uniform initial model states of soil moisture, soil temperature, soil liquid water content and skin temperature among a few other variables necessary for model execution. The script uses nco commands to create this file. Users can use this file as a 'cold start' for long term model spin or they can overwrite the fields in the file created.  Please refer to the script header for specific use information.

Please see the Support page for additional information regarding the WRF-Hydro and links to various support tools.

Rwrfhydro: An R Package for working with WRF-Hydro

community-contributed tool box for managing, analyzing, and visualizing WRF Hydro input and output files in R.

Intentionally, "rwrfhydro" can be read as "our wrf hydro". The purpose of this R package is to focus community development of tools for working with and analyzing data related to the WRF Hydro model. These tools are both free and open-source, just like R, which should help make them accessible and popular.

R is freely available from CRAN (the Comprehensive R Archive Network) along with over 6500 add-on packages for special purposes. While rwrfhydro is not available on CRAN (and may never be), it is available on github and can easily be installed as described in the README file.

For users new to R, several introductory resources are listed at the bottom of the README.

For users who wish to contribute to the code base, there are also explicit details in the README.

The rwfhydro NEWS details the latest changes to rwrhydro.

Further details are listed below in a CRAN-like package overview.

Please browse the rwrfhydro vignettes which provide working examples with output and illustrate application of rwrfhydro to WRF-Hydro modeling. Two example images are shown below for the Fourmile test domain.

Until further notice, please cite rwrfhydro as follows:
McCreight, J.L., Dugger, A., Gochis, D.J., 2015: The rwrfhydro R package.
Available at http://www.ral.ucar.edu/projects/wrf_hydro

CRAN-like overview of rwrfhydro

rwrfhydro: R tools for the WRF Hydro Model

A community-contributed tool box for managing, analyzing, and visualizing WRF Hydro input and output files in R. See the github repository README file for more information.



The WRF-Hydro HydroInspector is a state-of-the-art Web Mapping Service (WMS) that allows users to manipulate and interact with a host of hydrologic observation and hydrologic model output data.    The HydroInspector software is an internet-based toolset for visualizing and analyzing output from the WRF-Hydro modeling system, and other hydrologic models, as well as for comparing model output against other real-time observational data. It allows users to directly interact with the data and create compelling visualizations of surface hydrologic data such as snowpack, soil moisture, evaporation, precipitation and streamflow that are tailored specific time periods, spatial domains or station locations.  Below are a set of links to example implementations of the HydroInspector WMS.

Project Links

Coming Soon.

Support, Documentation and Terms of Use

WRF-Hydro Technical Description and User's Guide

This User's Guide describes the WRF-Hydro model coupling architecture and physics options, released in April 2013. As the WRF-Hydro system is developed further, this document will be continuously enhanced and updated. Please send feedback to wrfhydro@rap.ucar.edu

This document is complementary to the main Weather Research and Forecasting (WRF) model User's Guide and technical document http://www.mmm.ucar.edu/wrf/users/docs/arw_v3.pdf, which describes the equations, numerics, boundary conditions, and nesting etc. of the WRF model in greater detail. To the degree practicable, this document parallels the structure of the WRF model documents.

Until further notice, please cite the WRF-Hydro system as follows:
Gochis, D.J., W. Yu, D.N. Yates, 2013: The WRF-Hydro model technical description and user's guide, version 1.0. NCAR Technical Document. 120 pages. Available online at: http://www.ral.ucar.edu/projects/wrf_hydro/

Training Materials


WRF-Hydro Coupling with Other Systems

Noah and NoahMP LSM/HRLDAS

WRF-Hydro users who use the Noah land surface model will find information specific to the Noah and NoahMP LSM and the accompanying 'High Resolution Land Data Assimilation System (HRLDAS)' at http://www.ral.ucar.edu/research/land/technology/lsm.php

NASA Land Information System (LIS)

WRF-Hydro users who are interested in using the NASA Land Information System (LIS) with WRF-Hydro will find information specific to LIS athttp://lis.gsfc.nasa.gov/. Note: The coupling to LIS is presently at a prototype stage and no user support for this is presently available.

NCAR Community Earth System Model/Community Land Model (CESM/CLM)

WRF-Hydro users who are interested in using the NCAR Community Earth System Model/Community Land Model (CESM/CLM) with WRF-Hydro will find information specific to those models at http://www.cgd.ucar.edu/tss/clm/. Note: The coupling to CESM/CLM is presently at a prototype stage and no user support for this is presently available.

Terms Of Use

  1. License. Subject to these terms and conditions, University Corporation for Atmospheric Research (UCAR) grants you a non-exclusive, royalty-free license to use, create derivative works, publish, distribute, disseminate, transfer, modify, revise and copy the WRF-Hydro software, in both object and source code (the "Software"). You shall not sell, license or transfer for a fee the Software, or any work that in any manner contains the Software.
  1. Disclaimer of Warranty on Software. Use of the Software is at your sole risk. The Software is provided "AS IS" and without warranty of any kind and UCAR EXPRESSLY DISCLAIMS ALL WARRANTIES AND/OR CONDITIONS OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTIES OR CONDITIONS OF TITLE, NON-INFRINGEMENT OF A THIRD PARTY?S INTELLECTUAL PROPERTY, MERCHANTABILITY OR SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. THE PARTIES EXPRESSLY DISCLAIM THAT THE UNIFORM COMPUTER INFORMATION TRANSACTIONS ACT (UCITA) APPLIES TO OR GOVERNS THIS AGREEMENT. No oral or written information or advice given by UCAR or a UCAR authorized representative shall create a warranty or in any way increase the scope of this warranty. Should the Software prove defective, you (and neither UCAR nor any UCAR representative) assume the cost of all necessary correction.
  1. Compliance with Law. All Software and any technical data delivered under this Agreement are subject to U.S. export control laws and may be subject to export or import regulations in other countries. You agree to comply strictly with all applicable laws and regulations in connection with use and distribution of the Software, including export control laws, and you acknowledge that you have responsibility to obtain any required license to export, re-export, or import as may be required.
  1. No Endorsement/No Support. The names UCAR/NCAR, National Center for Atmospheric Research and the University Corporation for Atmospheric Research may not be used in any advertising or publicity to endorse or promote any products or commercial entity unless specific written permission is obtained from UCAR. The Software is provided without any support or maintenance, and without any obligation to provide you with modifications, improvements, enhancements, or updates of the Software.
  1. Controlling Law and Severability. This Agreement shall be governed by the laws of the United States and the State of Colorado. If for any reason a court of competent jurisdiction finds any provision, or portion thereof, to be unenforceable, the remainder of this Agreement shall continue in full force and effect. This Agreement shall not be governed by the United Nations Convention on Contracts for the International Sale of Goods, the application of which is hereby expressly excluded.
  1. Termination. Your rights under this Agreement will terminate automatically without notice from UCAR if you fail to comply with any term(s) of this Agreement. You may terminate this Agreement at any time by destroying the Software and any related documentation and any complete or partial copies thereof. Upon termination, all rights granted under this Agreement shall terminate. The following provisions shall survive termination: Sections 2, 3, 6 and 9.
  1. Complete Agreement. This Agreement constitutes the entire agreement between the parties with respect to the use of the Software and supersedes all prior or contemporaneous understandings regarding such subject matter. No amendment to or modification of this Agreement will be binding unless in a writing and signed by UCAR.
  1. Notices and Additional Terms. Copyright in Software is held by UCAR. You must include, with each copy of the Software and associated documentation, a copy of this Agreement and the following notice: 

    "The source of this material is the Research Applications Laboratory at the National Center for Atmospheric Research, a program of the University Corporation for Atmospheric Research (UCAR) pursuant to a Cooperative Agreement with the National Science Foundation; 2007 University Corporation for Atmospheric Research. All Rights Reserved." 

    The following notice shall be displayed on any scholarly works associated with, related to or derived from the Software: 

    "The WRF-Hydro modeling system was developed at the National Center for Atmospheric Research (NCAR) through grants from the National Aeronautics and Space Administration (NASA) and the National Oceanic and Atmospheric Administration (NOAA). NCAR is sponsored by the United States National Science Foundation."


On this page is an archive of resources that may be useful for working with the WRF-Hydro system.

Modeling Links

Weather Research and Forecasting model:http://www.mmm.ucar.edu/wrf/users/
Community Earth System Model: http://www.cesm.ucar.edu/
NASA-Land Information System: http://lis.gsfc.nasa.gov/

Organizational Links

CUAHSI: http://www.cuahsi.org/

Pre-processing Links

ESRI-ArcGIS: http://www.esri.com/software/arcgis
MapInfo: http://www.pb.com/software/Location-Intelligence/MapInfo-Suite/MapInfo-Professional.shtml
netcdf command operators (nco): http://nco.sourceforge.net/
netcdf command langauge (ncl): http://www.ncl.ucar.edu/

Post-processing and Visualization Links

UniData-IDV: http://www.unidata.ucar.edu/software/idv/
netcdf command operators (nco): http://nco.sourceforge.net/
netcdf command langauge (ncl): http://www.ncl.ucar.edu/
R: http://www.r-project.org/

Calibration Tool Links

PEST: http://www.pesthomepage.org/

Meteorological Data Links

TRMM: http://trmm.gsfc.nasa.gov/
PERSIANN: http://chrs.web.uci.edu/persiann/
NLDAS/GLDAS: http://ldas.gsfc.nasa.gov/nldas/ http://ldas.gsfc.nasa.gov/gldas/
NARR: http://www.emc.ncep.noaa.gov/mmb/rreanl/

Terrain Data Links

HydroSheds: http://hydrosheds.cr.usgs.gov/index.php
NHDPlus: http://www.horizon-systems.com/nhdplus/
STATSGO: http://dbwww.essc.psu.edu/dbtop/doc/statsgo/statsgo_info.html

WRF-Hydro Modeling System