Cowan flood map & planning overlays
A planning-constraint profile of Cowan
(Hornsby, NSW) - 33.7 km², mapped from live council and
state overlay data. This suburb is highly constrained.
Profile updated 3 October 2026.
Suburb-wide figures; the free map shows which overlays touch your lot.
Constraint readout
33.7 km² - this suburb is highly constrained by planning overlays.
Elevation hillshade with street names, clipped to Cowan's boundary, with the flood, bushfire and environmental overlays drawn on top. Magenta is where aircraft were observed in the sampled period, brightest below 3,000 ft.
Nearby suburbs, nearest first
Aircraft noise and flight paths over Cowan
Two different things, kept apart on purpose. The ANEF contour is the planning instrument - a forecast published per airport that planning schemes use to control noise-sensitive development. Observed overflight is what a sampled aircraft-tracking feed actually recorded over the suburb - where aircraft flew, how low and how often.
Observed overflight - sampled 4 Sep to 2 Oct 2026
typical observed square 2 a day
Night movements: observed, lowest 2,000 ft - night is sampled as often as day, but night traffic is light, so this is a floor and no rate can be put on it.
Traffic is sampled rather than watched continuously, so every figure is a floor: aircraft not captured between samples are not represented. Rates are per 500 m square - the busiest square in the suburb, not a count of flights over the suburb - and a square is only rated where enough traffic was seen to measure it. Altitudes are above mean sea level. Flight paths change with runway use, weather, season and airspace design. This is a record of observed traffic; it is not a noise contour and not a planning control.
Cowan at a glance
How Cowan is zoned
Buying in Cowan? The zoning, flood and bushfire lines on the section 10.7 certificate attached to the contract are mapped controls - see our s10.7 certificate guide.
Across its 33.7 km², Cowan is highly constrained by planning overlays. About 7% of the suburb sits within a mapped flood overlay, and 95% is flagged bushfire-prone. There are 20 heritage-listed sites on record, and the dominant land-use zone is National Parks and Nature Reserves. The median lot measures about 851 m² across 313 parcels.
Who lives in Cowan
Census 2021 figures published by the ABS for the Cowan suburb boundary itself, not a wider region.
Socio-economic standing
ABS SEIFA 2021 ranks every Australian suburb. Decile 1 is the most disadvantaged tenth of the country, decile 10 the least.
Score 1059, and decile 9 within New South Wales. The national average is 1000.
Age profile
Share of Cowan's 631 residents in each ABS age band.
Population trend, 2001 to 2025
Estimated resident population of Berowra - Brooklyn - Cowan, the wider ABS statistical area containing Cowan. There is no annual population series published at suburb level, so this describes the surrounding area rather than Cowan itself.
11,707 in 2001 to 11,761 in 2025, up 0%.
Source: ABS Census 2021 and SEIFA 2021 (Suburbs and Localities), Regional Population (SA2), CC BY 4.0. Small counts are randomly adjusted by the ABS.
Cowan data sources and coverage
“Not mapped” means we hold no source layer for this suburb - never an all-clear.
| Dataset | Coverage | Publisher |
|---|---|---|
| Flood mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Bushfire-prone mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Zoning | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Heritage and environment | Mapped where published | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Aircraft noise contours (ANEF) | Not held | NSW Government spatial services, NSW ePlanning and published council flood studies, Defence |
| Observed flight paths | Observed | adsb.lol, under the Open Database License |
| Demographics | Available | Australian Bureau of Statistics (2021 Census and SEIFA) |
Profile last materially updated 3 October 2026. See the methodology and full source list. Source data changes over time and critical decisions should be checked with the responsible authority.
Check a specific Cowan address
See exactly which overlays touch a single property - the interactive map is free. Need it on paper? A full planning PDF is just $9.
Aircraft have been seen below 3,000 ft over about 78% of Cowan. The report's Aircraft Overflight page narrows that to the address itself: how many aircraft a day, how low, and at what heights.
Published flood models are held over parts of Cowan. The free check tells you whether one reaches an address; where it does, a Flood Model Report is +$9 with the planning report.
Building or pricing a slab? The $119 geotechnical desktop report covers geology, soils, bores and an indicative AS 2870 site class for a Cowan lot.
See what's in the $9 report →Cowan planning - frequently asked
Is Cowan flood-prone?
About 7% of Cowan falls within a mapped flood overlay, against the council-wide suburb average of 10%. Published flood models are held over parts of Cowan; the free check on the Flood Model Report page says whether one reaches a given address.
Is Cowan bushfire-prone?
Around 95% of Cowan is mapped as bushfire-prone, compared with a Hornsby average of 70%.
Is Cowan under a flight path?
Aircraft were observed below 3,000 ft over about 78% of Cowan, and over about 91% at any altitude up to 10,000 ft, in the period sampled (4 Sep 2026 to 2 Oct 2026). The lowest measured aircraft was at 500 ft, with an average of 2,500 ft. At the busiest point in the suburb about 12 aircraft a day were recorded passing over one 500 m square. Traffic is sampled rather than watched continuously and flight paths change with runway use, weather and season; the ANEF contour is the planning instrument.
What is the zoning in Cowan?
The dominant planning zone in Cowan is National Parks and Nature Reserves, though the suburb also includes Infrastructure and Environmental Management.
Does Cowan have heritage-listed places?
Cowan has 20 heritage-listed places on record.
What is the typical lot size in Cowan?
Across 313 surveyed parcels in Cowan, the median lot size is about 851 m². There are also 7 registered easements mapped in the suburb.
Does Cowan have a train station?
Yes - Cowan has 1 train station: Cowan Station. It is also served by 15 bus stops.
What is the population of Cowan?
At the 2021 Census Cowan had 631 usual residents, with a median age of 41 and an average household size of 2.9 people. The wider Berowra - Brooklyn - Cowan statistical area, which contains Cowan, went from 11,707 people in 2001 to 11,761 in 2025, up 0%.
Is Cowan an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), Cowan scores 1059 and sits in decile 9 of 10 nationally and decile 9 within New South Wales (decile 1 is the most disadvantaged tenth, decile 10 the least).
What is the median household income in Cowan?
Median household income in Cowan was $2,250 a week at the 2021 Census, against $2,468 for the typical suburb in Hornsby. Median rent was $515 a week and the median mortgage repayment $2,290 a month.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| Berowra Waters | 2.7 km | 84% | 59% |
| Berowra Heights | 4.9 km | 3% | 87% |
| Brooklyn | 5.7 km | 16% | 72% |
| Cottage Point Northern Beaches |
6.2 km | 0% | 99% |
| Mooney Mooney Central Coast |
6.2 km | 80% | 31% |
| Milsons Passage | 6.3 km | 77% | 44% |
| Cheero Point Central Coast |
6.6 km | 6% | 94% |
| Dangar Island | 6.9 km | 6% | 56% |
| Berowra | 6.9 km | 0% | 87% |
| Cogra Bay Central Coast |
7.1 km | 9% | 100% |