We analysed 1.47 million South East Queensland lots. Here's where the ground is wet, steep, and low.

We maintain a lot-level risk database covering residential property across South East Queensland: every addressable lot in Brisbane, Gold Coast, Moreton Bay, Logan, and Redland council areas, each one intersected against its council's flood mapping, LiDAR-derived elevation, and terrain slope. That's 1.47 million lots across 452 suburbs.

Datasets like this usually stay inside council GIS departments and insurer models. We think the headline numbers are worth publishing. Here's what the maps say about where South East Queensland's ground is wet, steep, and low, and what that means if you're buying, building, or developing.

The headline numbers

Across the 1,468,551 residential lots we analysed:

A note on what "intersects flood mapping" means: council flood layers include everything from mapped river flooding to minor overland-flow paths, the route stormwater takes across a lot in heavy rain. A lot touched by an overland-flow path is not "going to flood" in any ordinary sense. But it is a development constraint: it can affect site cover, floor levels, and drainage design. That's why the numbers below are bigger than most people expect.

Flood exposure by council

Each council maintains its own flood studies and publishes its own mapping, so figures are best compared within a council rather than across them.

Each bar shows the share of lots touched by any flood layer; the dark segment is the share rated High.

Logan stands out: it has the lowest share of lots touched by any flood layer among the big three non-Brisbane councils, but the highest share rated High: the Logan and Albert River floodplains are large, well-mapped, and heavily developed around their edges.

SEQ-wide, the most flood-mapped places are exactly where you'd expect: low-lying coastal settlements like Toorbul (98.5% of lots) and Beachmere (98.2%) on Pumicestone Passage, plus master-planned estates like North Lakes, where a 90% figure is driven almost entirely by overland-flow mapping through an engineered drainage network. But Brisbane is where most of the lots (and most of the buyers) are, so that's where we'll look more closely.

Brisbane's most flood-mapped suburbs

Share of lots intersecting any Brisbane City Council flood layer, among suburbs with at least 2,000 lots. The last column shows lots that intersect the mapped extent of the actual January 2011 or February 2022 flood events:

Rocklea is Brisbane's best-known floodplain suburb and the data shows why: nearly every lot is flood-mapped, almost half are rated High, and 89% sit inside the mapped extent of the 2011 or 2022 floods. The more interesting pattern is the split between the two kinds of suburb on this list. River-bend suburbs like Graceville, Jindalee, and Yeronga are heavily flood-mapped but mostly in lower categories: broad mapping, comparatively few High ratings. Bayside suburbs like Sandgate, Brighton, and Deagon flip that: a smaller mapped footprint, but a third or more of lots rated High, because storm-tide mapping near the bay tends to come with higher categorisations.

The expensive suburbs: what the data says about blue-chip Brisbane

Brisbane's premium suburbs cluster along the river, and the river is precisely what the flood mapping follows. Some of the city's most tightly held streets carry the most mapping; others, a few hundred metres away on a rise, carry almost none.

Three patterns sit inside these numbers.

The western riverbend trades prestige against the river. Chelmer, Graceville, Tennyson (69.2% flood-mapped), and Fig Tree Pocket (58.6%) hold some of Brisbane's most expensive riverfront land, and they are among the most flood-mapped suburbs in the city. Crucially, most of that mapping is in lower categories (Graceville's High share is just 4.3%), but the 2011 and 2022 events are written plainly into the data: more than half of Chelmer's lots intersect a mapped historical flood extent. On these streets, the difference between a lot at 8 m AHD and one at 12 m AHD is the difference between a flood story and a view.

The hill suburbs swap flood risk for slope. Paddington, Red Hill, Bardon, and Highgate Hill carry almost no flood mapping (Paddington has not a single High-rated lot), but their median slopes run 14–16%, and in Highgate Hill nearly 1 in 7 lots is steeper than 25%. That's the terrain where AS 2870 classification, retaining design, and tight character-housing access combine to produce expensive surprises at footing stage. The constraint didn't disappear; it changed shape.

Elevation is doing quiet work in the newest precincts. Bulimba's café strip sits on a peninsula with a median lot elevation under 4 m AHD, and Newstead's apartment towers stand on reclaimed riverbank at 2.6 m; storm-tide and river-flood planning levels are a routine part of development approval in both. Meanwhile Ascot, one ridge over from the Hamilton riverfront, records zero flood-mapped lots out of more than 4,000. In Brisbane, a few metres of elevation is often the entire difference.

The steepest suburbs

Median lot slope, suburbs with at least 500 lots:

The Gold Coast hinterland owns this list: six of the top ten, all on the flanks of the Tamborine–Springbrook volcanic terrain. In Brisbane, Red Hill is the notable city entry: a dense, old inner suburb where a median lot slope of 16% meets character-housing controls and tight access, which is exactly the combination that produces expensive surprises at footing stage.

Slope matters because AS 2870 site classification, retaining design, and earthworks costs all scale with it. On a 25% slope, a flat 600 m² building platform implies metres of cut or fill, and on the volcanic soils of the hinterland, that often means engaging with both reactive clays and slope stability in the same design.

The lowest suburbs

Median lot elevation, suburbs with at least 500 lots:

The Gold Coast's canal estates (Paradise Point, Biggera Waters, Hollywell, Runaway Bay) were dredged and filled to sit just above the tide, and the data shows it. Newstead's appearance is a reminder that some of Brisbane's most expensive new apartment precincts sit on reclaimed riverbank at under 3 m AHD; storm-tide and river-flood planning levels are a routine part of development approval there.

At the other end of the scale: Springbrook's median lot sits at 624 m AHD, more than 200 times higher than Toorbul's.

What this means in practice

None of these numbers, on their own, say a lot is good or bad. Flood mapping categories, slope, elevation, and the underlying geology interact: a High flood rating on a lot with an existing high-set house is a different proposition from the same rating on a vacant lot you intend to build on, and a steep lot on sandstone behaves differently from a steep lot on basalt-derived clay.

What the data does show is how common these constraints are. One in four lots in SEQ carries some form of flood mapping. If you're doing site due diligence or a pre-purchase review, the question isn't whether to check; it's to check early, before contract terms are set rather than after.

The lot-level data behind this article is what powers our tools: Scout surfaces flood category, elevation, and slope on every realestate.com.au listing as you browse, our planning overlay maps show the underlying flood, bushfire, and zoning layers for any address, and a geotechnical desktop study adds the geology, soils, and groundwater picture underneath it all.

Methodology: figures derived from LayeredGeo's lot risk database of 1,468,551 residential lots across Brisbane, Gold Coast, Moreton Bay, Logan, and Redland local government areas, current as at June 2026. Flood categories reflect each council's published combined flood mapping (river, creek, storm-tide, and overland-flow layers); categorisation methodologies differ between councils. Historical flood extent figures reflect Brisbane City Council's published mapping of the January 2011 and February 2022 flood events. Elevation and slope are derived from state LiDAR digital elevation models sampled at the lot point. Suburb statistics are limited to suburbs with sufficient analysed lots (500 SEQ-wide; 2,000 for the Brisbane table). This article describes mapped constraints, not predictions of flooding at any individual property.

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