The history

The Watershed Bounded Network Model WBNM arose out of a Master of Engineering Science project by Michael Boyd, supervised by David Pilgrim in 1973. This was further developed into a PhD project, under the supervision of David Pilgrim and Ian Cordery.  

The original study was concerned with correct allocation of lag times to the various subareas of a larger catchment, using established relations between catchment geomorphology and hydrology.

This resulted in a simple yet realistic model of the flood rainfall-runoff process, and one which required a minimum of model parameters.  

This has remained the emphasis, but with continuing interchange of ideas with users leading to the addition of significant enhancements, to produce a very flexible yet easy to use tool for engineering flood studies. 

The original investigations were reported in University of New South Wales Water Research Laboratory Report 154 (1979). It is interesting to note that the original computer program consisted of just 145 lines of Fortran code !  WBNM now has more than 40,000 lines of code.

Further developments were carried out in 1987, by Michael Boyd, Bryson Bates, David Pilgrim and Ian Cordery, adding storage reservoir routing and urbanisation (University of New South Wales Water Research Laboratory Report 170 (1987)).

Then in 1994, Michael Boyd, Ted Rigby and Rudy VanDrie, with assistance from Mike Sharpin, moved WBNM from what was essentially a model for calculating flood hydrographs, to one in which the emphasis was on a useful tool for engineering flood studies.

This included built-in design storms and culvert/weir hydraulics, graphics, and saving of results for QA purposes.  The model was further refined in 2002, developed by Michael Boyd and Ted Rigby, with the addition of a results viewer developed by Rudy VanDrie and Irene Schymitzek.

In 2007, iWBNM was first released.  iWBNM is a more sophisticated pre and post processor model than the original fixed dimension wbnmGUI, permitting easier runfile creation and calling of the WBNM components.

It was developed by Andrew Wiersma and Steve Roso.  A further version was finalized for release in 2012, and is essentially the last version of WBNM prior to the revisions to the design flood estimation procedure in Australian Rainfall & Runoff (ARR). 

This version of WBNM including ‘adjustable arrays’ which allowed users to run extremely large and complex models containing 1000’s and 1000’s of subareas.

The most current version of WBNM is WBNM2021-v003.  It was developed by Ted Rigby, with assistance from Michael Boyd, Anthony Barthelmess, Steve Roso, Andrew Wiersma, Rudy VanDrie and Bronson McPherson. 

WBNM is able to cater for the estimation of design floods using the ARR 87 and ARR 16 design flood estimation procedures and is a comprehensive update to 2012.  More information on the current capabilities of the model can be found elsewhere on this site.

Who uses WBNM products?

When you are used by over 30,000 people, you become recognised by industry.

WBNM is proud to be used by many academic institutions, government and semi-government organizations and some of the finest private flood consulting firms in Australia.


Now that you are up to speed with all the history around the product ...

Find out about the most recent version of WBNM, and changes to the software over time.

Watershed Bounded Network Model

Whilst we aim to provide as professional support as we can, we are all volunteers and have full time jobs. We have always provided our users with timely and efficient levels of support, and will continue to do so, however there will be times where day-to-day responsibilities will prevent an immediate response. We thank you for your understanding.

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