Accurate, meaningful and practical to implement
Northern Wairoa Flood Model - Northland Regional Council
The complexity of the Northern Wairoa River system has made flood management and forecasting extremely difficult for Northland Regional Council. Following the impacts of Cyclone Gabrielle in 2023, the council turned to Submergent to develop a robust rainfall, tidal and storm-surge model for the Northern Wairoa catchment – a first of its kind for the region.
Flood Scheme Peer Review and oversight - Hawke's Bay Regional Council
Following Cyclone Gabrielle, the Hawke’s Bay Regional Council (HBRC) was condensing ten years of work into one, with reviews of all flood control schemes, stop banks and pump stations. With the extensive workloads split among four consultancies, HBRC needed expert oversight and peer review to provide confidence in the results.
Submergent created a common template for review and meticulously documented and ranked all identified issues by priority. Weighing the benefits of schematisation choices, we made models significantly faster to run and better suited to the council’s needs. We then worked with Council staff to give them the confidence to run the models themselves in the future.
Ad-hoc model development and flood risk assessments
Our specialist advice and high-resolution flood modelling for small-scale applications supplement the engineering work of Weir, a specialist water-infrastructure company. Our recent projects include a flood hazard assessment for the Inga Road Bridge replacement in Milford and speed-table impact modelling for Auckland Transport. We also provided hydraulic analysis for the proposed Kakanui River bridge in partnership with Andy O’Sullivan and Associates Ltd and Concrete Structures Limited. Each model was tailored to support design criteria, quantify flow impacts, and inform scour and safety assessments.
“They’ll optimise your designs – pay them $20,000 and save $20 million. They’re just the best at what they do.”
Navin Weeraratne, Director, Weir Consulting Engineers Ltd
Hauraki Plains Flood Hazard Modelling – Waikato Regional Council
As part of the Hauraki Plains Adaptation Planning project, Waikato Regional Council (WRC) and Submergent refined and expanded the regional flood model to cover nearly 3,950 km². Calibrated against the impacts of Cyclones Debbie, Cook and Gabrielle, the model was used to test eight climate scenarios and horizons representing 10year-ARI and 100 year-ARI storm events. Technical innovations, such as a two-layer soil representation and variable antecedent moisture conditions, improved accuracy and adaptability, with this data now underpinning WRC’s community engagement and long-term adaptation planning.
Māngere WWTP Splitter CFD Modelling – Apex Water
With a new wastewater splitter channel proposed for Māngere Wastewater Treatment Plant, Apex Water needed to assess the flow split performance. Submergent developed a detailed CFD model in OpenFOAM to simulate free-surface and rapidly varying flow under seven gate configurations. This verified compliance with flow split requirements, giving Apex Water confidence in the design and valuable insight for future flow optimisation.
Who we have worked with
