For Developers

Know where to look before the engineering starts.

Many council flood maps stop at major rivers. If you are looking at land for subdivision or multi-unit residential, a quick look at overland flow shows early whether a site warrants a closer look from an engineer, rather than that surfacing at design stage. It is a screening prompt, not a basis for a purchase decision — that needs a site-specific assessment. The map is free.

When to use it

Three points in the deal where the OFP layer matters.

Pre-purchase DD

Early in due diligence

Open the map, search the address, see whether overland flow paths cross the site. Identify problem sites in your shortlist before you commit to the formal due-diligence spend.

Feasibility

Lot yield modelling

Flow paths constrain building platforms and reserve setbacks. Knowing where they run shapes the realistic lot yield before you commission concept layouts.

Design hand-off

Brief your civil engineer

Send the engineer a screenshot or share the FloodMap link with the address. They have a free check on overland flow before they start the consent design — fewer clarifying-question loops.

A worked example

Why a 30-second check is the cheapest line item in your DD.

Scenario

4-lot rural-residential subdivision, pre-settlement DD

Site looks clean on the council viewer — no mapped flood overlay. Vendor and agent both confirm "no flooding". You're 7 days from going unconditional on a $1.4M rural block.

Open FloodMap. The map shows a Tier 4 flow path crossing the proposed building envelope, with a 6.2 ha upstream catchment. Council mapping missed it because their layer was built from 2016 LiDAR; the current survey shows the gully has scoured deeper.

Outcome: you commission a site-specific assessment early, with time to understand the constraint properly rather than meeting it as a surprise at design stage. The map costs nothing to check; the assessment is what the decision should rest on.

Illustrative — actual outcomes depend on the site and council requirements. For a formal site-specific flood assessment with HEC-RAS depth and velocity outputs, that's an engineering job: see what a site-specific assessment covers, and we can scope and quote.