Last night’s post about Eric Thompson’s silly NZ Herald article highlighted one unresolved matter – the question of “what is Auckland’s population density?” I noted that according to Wikipedia, the urban density of Auckland is around 1250 people per square kilometre whereas Demographia states a density of around 2,200. I had to dig a bit deeper.
Once we recognise that we’re talking about the population of urban Auckland rather than the whole of what might be called the Auckland “region”, the population part of working out Auckland’s density is relatively settled. Furthermore, the “error” is pretty small when comparing statistical area, metropolitan area and urban area, because not too many people live right on the edge of the city in places that might fall one way or the other.
Where we see big differences is in the area of land taken up by parts of Auckland on the edge of the city that may not yet be urbanised, but fall within the urban statistical area or within the metropolitan urban limits. These areas are quite large in physical size, yet contain very few people – so can throw out our density measurements for the rest of the city.
The map below (from here) is useful in highlighting the different spatial extents we can use when trying to calculate Auckland’s population density: The different boundaries obviously provide us with different “sizes” for Auckland, when measuring population density. My feeling is certainly that the “urbanised area” is what’s most valid when talking about “Auckland’s population density” – particularly in terms of discussing whether the city’s density is too high, too low, supportive or unsupportive of different transport options and so forth. The urbanised area is the smallest of all, followed by the metropolitan area (the MUL) while the statistical urban area includes the rural parts to many Census Area Units that partly fall within the urbanised area. Obviously the region as a whole is the largest area of the lot – and is predominantly (by size) rural.
These different area extents lead to quite a wide variety in outcomes when we start to measure population density: Leaving aside the region’s density, we can see that there are still huge differences between – for example – the density of the ‘statistical urban area’ and the density of the ‘urbanised area’. Those rural parts to the census area units end up making an enormous difference. There’s not too much difference between the density of the metropolitan area and the urbanised area, presumably because most land within the urban limits has been urbanised.
Overall, it seems to me that the most accurate measurement of Auckland’s population density is 2,395 people per square kilometre (in 2006). Interestingly, this is a much much higher total than Australian cities such as Perth and Brisbane – similar to Sydney and higher than Vancouver.
If we look within Auckland’s urban area, there’s quite a variety of population density. Obviously densities are highest in the city centre and its immediate surrounding suburbs – because that’s where apartments are provided (and allowed). But even looking across just a part of the Auckland isthmus there seems relatively little pattern – at first glance – to many of the density results. The darker the colour the higher the density (map from here): However, if you start to fiddle around with the numbers to average out a few of the highs and lows – as was done in this report – you can start to see a few more obvious patterns: I’ve never quite seen Auckland’s density presented in this way before and I think it’s actually pretty damn useful when taking an overall look at the city’s structure. A greater number of ‘gradations’ would be useful to look at, particularly within that giant blob of the central-west isthmus.
Debates over Auckland’s population density will probably continue to rage forever, but hopefully this post may shed some light on the matter.