Sophia Buchanan, ANZ Regional Product Lead for Flood Products at Jacobs
Introduction
Since stepping back into the Australian Flood Industry almost two months ago, I’ve been busy getting up to speed on industry changes and updates I might have missed while I was working in a global role. Attending the Hydrology and Water Resources Symposium, meeting new colleagues and catching up with old friends has led to interesting conversations on traditional hydrologic modelling tools and got me questioning their future. So, in an attempt to learn more and inevitably uncover more that I don’t know, I expanded my conversations and included those who currently own/maintain/author these tools.
Background
Australia has a long history of robust hydrologic modelling tools: RORB, URBS, XPRAFTS and WBNM. It has been the status quo for decades, with runoff models of choice prescribed in national, state and local council guidelines. Practitioners use the modelling tools developed close to home, and rivalry between states is fierce. It seems that using RORB in QLD or URBS in Victoria can get you into a lengthy debate with local practitioners on which is best, irrespective of whether it gives them the answers they need.
Each runoff model has seen multiple updates over the years as technology, methods and data advances. The 2016 changes to design rainfall and the introduction of ensembles forced software to update GUIs or analysis, support new datasets and enhance engine performance. A list of the recent or upcoming improvements are listed further down this blog – thanks to all that provided these!
Why is the future in question?
Early into my conversations on hydrologic modelling, several experts suggested the longevity of these traditional models was short – perhaps less than 5 years. In fact, some professionals have abandoned traditional methods altogether in favour of using the Direct Rainfall Method (DRM), even when it leads to longer simulation run times, larger data sets and potentially compromised results. Why is this? Traditional models are more time-consuming to develop, require parameter selection by a reasonably qualified engineer and have users running multiple programs, including GIS, Text editors and Excel. There is also a lack of public training, and due to varying state preferences, learnings (model-specific tricks) are rarely shared across state borders.
What are the alternatives?
Solutions such as CatchmentSIM and Storm Injector by Catchment Simulation Solutions and QMydro (Beta) by HydroRepo help unify and streamline hydrologic modelling in Australia and go a long way in reducing the steep learning curve that we have built ourselves. As, of course, does integrated modelling solutions such as DRAINS and InfoWorks ICM.
We have already overcome some of the earlier problems with using DRM, and hardware has come a very long way since the 1970s. Our ability to manage large datasets and simulate many scenarios is rapidly increasing – especially with tools such as Flood Platform. There are also new hydrologic solutions being developed, such as TUFLOW Catch by BMT.
Are we ready to ditch these traditional tools?
With the adoption of Monte Carlo and Continuous Simulation appearing to be on the rise and with many relying on traditional hydrologic models to reduce the number of hydraulic simulations rather than investing in higher simulation solutions, I think we will see these methods continue well into the future.
But if these tools are here to stay for the foreseeable future, is the industry ready for further streamlined and, dare I say, national approach?
Australia is not unique in the use of not so user friendly and disparate tools to undertake hydrologic and hydraulic modelling. Technical Director for Flood Modeller & Flood Platform, Adam Parkes, spent years undertaking flood analysis in the UK under similar conditions. He developed Hydrology+ specifically to address these issues, bringing consistency, repeatability, and easy adoption of the latest hydrological methods in a single platform. Could this be next for Australia?
Latest developments in hydrologic modelling tools
Knowing these tools aren’t going anywhere anytime soon, check out the latest updates below.
WBNM
In 2023, a workflow-oriented GUI was added together with a number of supporting tools covering construction, checking/formatting/sorting, editing, and running WBNM, as well as reviewing/plotting selected outputs. A set of training webinars is under development with a target release date of Easter 2025, together with a tool to quickly extract design hyetographs or hydrographs for input to hydrodynamic models like TUFLOW.
More information, plus the free downloads, are available on the WBNM website.
XPRAFTS
Although many are still grieving from the sunset of the original XPRAFTS product, the method lives on inside InfoWorks ICM – which has seen recent updates. The latest release of InfoWorks ICM (2025.4) includes a new routing option - the Muskingum channel routing model (for XPRAFTS in ICM). Users can now specify Muskingum K and X values as per XPRAFTS as inputs to represent the behaviour of flow routing between subcatchments along a notional reach. Users also have the option to input a Lag delay to the runoff routing between catchments.
For more information, see InfoWorks ICM help documentation.
URBS
Recent updates to the URBS model include support for the ARR 2024 Climate Change factors and the addition of a new option to apply the Laureson non-linear runoff routing procedure. A procedure which made XPRAFTS so well loved is where each individual subcatchment is divided into 10 equal sub-areas where each sub-area is treated as a cascading non-linear storage.
If you are after more information, we hear a new website is coming in early 2025 (phew!), but in the meanwhile, you might like to check out the latest paper by Terry Malone and Don Carroll, Guidelines For URBS Routing Parameters, which was presented at HWRS in late 2023 by Terry Malone.
RORB
There is a RORB Plugin for QGIS, which was made available late last year. See here for details.
Storm Injector & Catchment Sim
Recent updates to Catchment Sim include support for GSAM & GSTMR temporal patterns for full coverage of PMP/PMF modelling. A user-friendly method for running Monte Carlo analysis is in the pipeline for Storm Injector with the first iteration out for review with a dedicated working group.
For more information, visit the Storm Injector website.
Sophia Buchanan
Sophia is the ANZ Product Lead for Flood Products at Jacobs. Growing up surrounded by waterways on Australia’s coastline, Sophia is passionate about supporting peers in ANZ with technology that solves water problems.