Flood Modelling in a Changing South Australia: Why Governance Matters

27/02/2026

High quality flood modelling is not delivered by chance - it is the result of deliberate effort, consistent governance and technical leadership that protects the integrity of decisions made on the back of model outcomes. Flood models influence land‑use planning, infrastructure investment, development approvals, and risk mitigation for communities. When those decisions carry high consequence, the quality of the modelling supporting them matters more than ever.

As Tonkin’s technical lead for flood modelling, I’ve spent the past 12 years establishing, extending, and governing the flood modelling capability our clients rely on. This includes defining the modelling framework, validation approaches, and quality assurance standards that underpin every flood modelling project ensure consistency in delivery for all of our clients. 

This sustained technical leadership has enabled modelling outcomes that now inform decisions protecting a significant portion of South Australia’s population from flood risk.

It has also led to key contributions to South Australia’s forthcoming flood modelling guidelines and committee membership within Stormwater SA, where I help translate practical project experience into guidance used across the broader industry. Achieving this scale of impact requires consistent, sound technical judgement and long-term stewardship. Clients may not always see this oversight directly, but it consistently underpins the reliability and defensibility of our strong technical work. 

Urban environments are evolving rapidly. Cities are expanding, infill development is changing the hydrologic response of catchments, and climate variability is increasing pressure on existing drainage systems and risk planning.

As complexity increases, the tolerance for uncertainty reduces. Local and state governments, utilities, and developers need models that clearly articulate risk, quantify uncertainty, and deliver outputs that can be integrated into multi‑disciplinary planning.

In South Australia, substantial residential expansion is underway to respond to population growth, housing demand and broader state government strategic development objectives. PlanSA’s Flood Hazard Mapping and Assessment Project (which Tonkin supported with modelling services) is now tightly integrated into South Australia’s Planning and Design Code, and is an important recognition of how the use of advanced flood modelling in housing expansion planning is critical to minimise risk to people, property and infrastructure.

Accordingly, as South Australia accelerates large-scale housing expansion amid increasing climate variability and urban densification, the quality, transparency, and robustness of flood modelling are as important now as they ever have been.

Flood modelling often becomes most important when clients are facing uncertainty: difficult topography, incomplete datasets, fast‑moving project timelines, or rising stakeholder scrutiny. In these situations, technical expertise provides clarity. I lead our flood modelling team by defining the framework the team works to, and remain closely involved where technical complexity or risk is higher, ensuring clients benefit from my guidance even when it isn’t immediately visible. For clients, this means clarity, consistency, and confidence regardless of project scale.

Whether clients need:

I’m available to support these conversations! I encourage clients seeking deeper technical discussion, reassurance on assumptions, or advice on complex flood risk challenges to reach out to me directly.