The Next Evolution of DRAINS is coming. Take a Peek!
WATERCOM RELEASES NEW TOOL
Climate Change Rainfall Modifier
Allows easy application of various climate change scenarios to rainfall depths and losses, in line with the latest ARR update.
ARR v4.2 Update
The Australian Rainfall & Runoff (ARR) guidelines have been updated with improved guidance on how to consider climate change when planning for future floods.
Climate Change Considerations
In 2024, ARR announced new guidance on how to consider climate change when estimating future flood risk.
Because our climate is changing, unadjusted historical observations are no longer a suitable basis for design flood estimation: they must be adjusted to reflect the impacts of rising global temperatures.
To consider the impact of climate change, the updated guidance requires adjusting rainfall depths and losses by applying a matrix of climate change factors. These factors include climate scenarios (also known as ‘Shared Socio-economic Pathways’ or SSPs) and the time horizon of interest.
To streamline this process and support best-practice modelling, Watercom has released the Climate Change Rainfall Modifier.
CLIMATE CHANGE RAINFALL MODIFIER
Automatically apply climate change scenarios to rainfall
In response to the recent updates to ARR (version 4.2), the Watercom Climate Change Rainfall Modifier was developed to streamline climate change modelling.
The Modifier automatically adjusts rainfall depths and losses based on a matrix of climate change factors defined in the ARR, including climate change scenarios (also known as SSPs) and time design horizons.
Who is it for?
The Climate Change Rainfall Modifier is for water engineers and practitioners who wish to utilise the latest ARR guidance and apply best-practice modelling techniques to their hydrological and hydraulic modelling.
How does it work?
Simply upload your rainfall data in two files (ARR Datahub & BOM IFD depth files) and select a climate scenario and time horizon. The Modifier will return updated data files, ready for import back into DRAINS or other software.

Catch up on this webinar
Watch the full recording and download all slides here.
Date: Tues 18 March 2025
PAST TECHNICAL WEBINAR
ARR 4.2 Climate Change in Stormwater Modelling
The ARR v4.2 release marks a pivotal shift in modelling climate change impacts, particularly in rainfall and loss calculations. Watch now for essential insights and practical guidance on applying the new methodologies in real-world scenarios.
What to Expect
- Presentation + live Q&A session
- Impacts on stormwater modelling and infrastructure, such as detention basins
- Essential insights and practical guidance for applying the new methodologies in real-world scenarios
- Demonstration of the Watercom Climate Change Rainfall Modifier.
Key Topics
- Climate Change Projections: Shared Socioeconomic Pathways (SSPs) in rainfall intensity predictions
- Case Study: Residential development evaluation
- Stormwater Design Impacts: Detention basin requirements, failure risks & impacts
- Design Guidelines: Practical recommendations & sensitivity analyses
Presented live on Tuesday 18 March from 1-2pm AEDT by Hossein Ansari (Technical Manager at Watercom) and followed by a Q&A session.