WBNM

WBNM (Watershed Bounded Network Model) is one of Australia's established runoff-routing flood models, in the same family as RORB and URBS: subareas bounded by watershed divides, nonlinear storage routing, and ensemble design-event simulation in the Australian Rainfall & Runoff tradition. Originating with Michael Boyd's work in the 1970s and long maintained with Ted Rigby and collaborators, it has decades of calibration literature behind it.

Unlike its commercial siblings it is free to download and use, which has kept it popular with councils and smaller consultancies. It pairs naturally with ARR 2019 Data Hub inputs, and the open pyromb library can now build its catchment files straight from GIS.