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Since 1972

Flood Forecasting with WATFLOOD®/CHARM® 

WATFLOOD and CHARM are a registered trademarks  

NEW WATFLOOD is Open Source Software under GNU LGPL License ProgrammersManual.pdf


FEWS - CHARM example

CWRA 2015 Workshop Example

2017 FloodNet AGM poster

Operational Users:

  • Environment and Climate Change Canada - CMC - Great Lakes Basin flow forecasts using coupled Numerical Weather Models and WATROUTE (WATFLOOD routing algorithm)
  • Environment and Climate Change Canada - Burlington: Great lakes Water balance
  • Manitoba Hydro - Nelson River System (Red, Winnipeg, Saskatchewan, Interlake and Churchill Rivers) Climate Change Impacts and Flow Forecasting
  • Lake of the Woods Control Board - Winnipeg River Flow Forecasting - eg.:                     RL-LOW_FlowBulletin_20140619.pdf
  • Ontario Power Generation - Mattagami and Madawaska Rivers - Flow Forecasting FloodNet_4DM_poster.pdf
  • Manitoba Infrastructure - Flow Forecasting
  • Parks Canada - flow forecasting


WATFLOOD is a set of computer programs for automatic  hydrological forecasting and modelling:



  • Run_daily.exe - Write Windows .bat files for downloading WSC provisional flows & CMC numerical weather forecasts

  • WSC_rt.exe - convert and assemble WSC real-time provisional flows to WATFLOOD readable tb0 files.

  • read_grib2.exe - decode and assemble CMC  GRIB2 files to WATFLOOD readable r2c files.

  • regl_conv.exe - extract data from the CMC domain for the WATFLOOD doamin

  • glb_conv.exe - extract data from the CMC domain for the WATFLOOD doamin

  • read_geps.exe - decode and assemble CMC GRIB2 ensemble files to WATFLOOD readable r2c files

  • geps_conv.exe - extract data from the CMC domain for the WATFLOOD doamin

  • DA.exe - disaggregate CMC forcing precipitation interval to one hour time step for CHARM

  • DIFF64.exe - extract 24 hour max -min tmp difference for Hargreaves ET

  • CHARM.exe - Canadian Hydrological And Routing Model  CHARM®

Setup & Modelling

  • BSN.exe - converting measured watershed data (DEM & Landcover) to hydrologically relevant watershed data for modelling

  • RAGMET.exe - point to gridded precipitation

  • TMP.exe - point to gridded temperatures

  • SNW.exe - snow course data to gridded Snow Water Equivalent

  • MOIST.exe - point to gridded soil moisture

Modelling Objectives for WATFLOOD®

  • Flow forecasting    Flow_Forecasting_Manual
  • Flood studies
  • Climate change impact studies
  • Environmental impact studies
  • Continuous modelling
  • Efficiently model very large as well as small domains
  • Optimal use of gridded data sources e.g.. Land cover, DEM’s, weather model output, Radar data
  • Universally applicable parameter set
  • Quick turn around
  • Model a wide variety of landscapes

WATFLOOD® Features

  • Green Kenue (ENSIM) pre & post processor  (free)  Log in with user name "Public.User" and password "anonymous"
  • Grouped response units (GRU’s): leads to universal parameter set because parameters are associated with land cover and NOT watersheds
  • Embedded 18O and 2H isotope model isoWATFLOOD Manual
  • Gridded model:
    1. Optimal use of remotely sensed data
    2. Optimal use of numerical weather data
    3. Optimal use of RADAR precipitation data
    4. Optimal use of 1,2 and 3D display facilities (e.g. GreenKenue - see below for link)
  • The combination of GRU’s and grids make the effective resolution much greater than the grid size used.
  • Source tracing
  • Grids < 1 km
  • Meta-data on all files

WATFLOOD is the first hydrological model to compare isotope flow separation measurements to computed flows from source areas in a watershed. This feature is of the utmost importance for water quality modelling by ensuring that contributions to streamflow are properly assigned to their sources.

About the developers:

Dr. Nick Kouwen is a Distinguished Professor Emeritus and Adjunct Professor at the University of Waterloo, a registered Professional Engineer in Ontario and a Fellow of the American Society of Civil Engineers.

He currently provides support to the WATFLOOD user community which currently includes Manitoba Hydro, Ontario Ministry of Natural Resources, Lake of the Woods Control Board, Manitoba Ministry of Infrastructure and Technology, 4DM Consulting (Toronto), Conestoga Rovers (Waterloo), NRC and the University of Manitoba.

Dr. Kouwen acknowledges the work of Ric Soulis, Todd Neff, Frank Seglenieks, Luis Leon, John Donald, Wayne Jenkinson and Trish Stadnyk who have contributed substantially to to the development of WATFLOOD.

Dr. Kouwen is known for the development of the WATFLOOD hydrological model and for the development of flow resistance relationships for vegetation in channels and on flood plains. WATFLOOD was the first non-urban hydrological model to use the Grouped Response Unit (GRU). Dr. Kouwen’s unique experience in dealing with vegetated channels and other hydraulic problems, as well as several years working on highway construction projects, conducting hydrological field work and life on a farm, has resulted in a hydrological model that robustly represents the hydrological processes of watersheds from a few km2 to watersheds as large as the Great Lakes and the Mackenzie River.

Click on picture for full size.

For more information about Dr. Kouwen's work on resistance in vegetated channels, please click here.

For Dr. Kouwen's full resume, please click here

Dr. Trish Stadnyk is an Associate Professor with the Department of Geography at the University of Calgary and holds a Chair in Hydrological Modelling. She is a registered Professional Engineer with the Engineers and Geoscientists Manitoba. She is also a National Director and Manitoba Board member for the Canadian water Resources Association, Chair of the Manitoba Chapter of the Canadian Society for Civil Engineering and Chair of the Canadian Geophysical Union’s Isotope Tracer Committee. She is a specialist in hydrologic modelling and the use of stable water isotope tracers to segregate runoff flow paths.

Dr. Stadnyk has been a developer and user of WATFLOOD for nearly 20 years, starting as a researcher for Dr. Kouwen with major contributions to code efficiency, wetland hydrology and routing, hydrograph separation modules, and most recently, isotope tracers (isoWATFLOOD). Her research aspires to help fill the gap in our understanding of large river basins and mesoscale hydrological processes by providing tools to assist researchers, governments and regulatory bodies in evaluating mesoscale hydrologic processes for such river basins. Her research development focus is on identifying and validating flow paths and sources within mesoscale hydrologic models by applying stable water isotope tracers. Dr. Stadnyk also has considerable experience applying WATFLOOD for long-term water supply studies under climatic change and for short-term forecasting studies, with particular focus on large Canadian river basins and arctic-freshwater linkages. She collaborates directly with industry and government in regards to using and setting up the WATFLOOD model for various applications, and offers training workshops to assist potential new users.


Key words: WATFLOOD; CHARM (Canadian Hydrological And Routing Model); Grouped Response Units GRU's; Hydrologically Similar Units HSU's; Aggregated Simulation Areas ASA's; Hydrotops; Pixel Grouping; Tiles. These are some of the names used by other modellers for the GRU method. The GRU method originates (!!!!)  with WATFLOOD - first published by Tao & Kouwen in 1989.

For more details, please check out the Features page.

Other stuff:

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WATFLOOD™  manual  with WORKSHOP chapter   (4Mb)

WATFLOOD & WATROUTE Executables can be downloaded free at:  Watflood Downloads

GreenKenue  Reference Manual    Included in the download

WATFLOOD     Publications   &   Presentations

Note  for prospective graduate students

Introduction to WATFLOOD  
Find out about how WATFLOOD works, the data requirements of the program, and see a list of publications involving WATFLOOD. You can try the software with the demo data

History of WATFLOO:  History


If you have any questions about WATFLOOD that haven't been answered at this site please do not hesitate to contact:

Please note that we do not look at any mail unless the mail is a text file AND

  1. We know the sender     OR

  2. the subject line is marked with "WATFLOOD QUESTION"

** WATFLOOD is a registered trademark: Enter WATFLOOD at

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© copyright 1999-2020 N. Kouwen.