Draw Circle for Population Population

You may not know it, only you've probably seen the Valeriepieris circumvolve - it'south that circumvolve on a map of the globe, alongside the text 'At that place are more people living inside this circle than exterior of it'. The name 'Valeriepieris' is from the Reddit username of the person who posted it and in 2015 the circle was looked at in more detail by Danny Quah of the London Schoolhouse of Economics under the heading 'The world's tightest cluster of people'. But of course it's non actually a circumvolve because it wasn't drawn on a globe and it's also a bit out of date now then I thought I'd look at this topic because I like global population density stuff. I'll brainstorm by posting a map of what I'1000 calling 'The Yuxi Circle' and and so I'll explicate everything else below that - with lots of maps. Equally in the original circumvolve, I decided to use a radius of four,000 km, or just nether 2,500 miles. Why Yuxi? Well, out of all the cities I looked at (more than i,500 worldwide), Yuxi had the highest population within 4000km - just over 55% of the earth's population equally of 2020. All maps were done in QGIS, which I have been experimenting with a lot more lately considering I just launched Map Academy on Udemy, to help more people get upwardly and running with maps and information.

The Yuxi Circumvolve on a world

The shape in a higher place is a circumvolve considering it'due south plotted on a world but in the examples beneath you can run across how it looks when fatigued on different kinds of apartment map projections.

A web Mercator projection

Robinson project

WGS84

Winkel Tripel

There is more than one Yuxi in China, just the 1 on the map is in Yunnan province and has a population of nearly ii.v one thousand thousand. Obviously, when you lot draw a simple 4000km buffer you always go a lot of body of water, so I too tried to see what kind of ellipse I could describe around Yuxi that all the same included more than half of the world population - see below for the results of this.

The Yuxi Ellipse with the Yuxi Circle behind information technology

More than one-half the world lives in the Yuxi Ellipse

Okay, so what else? Well quite a lot actually but for now permit's do something dissimilar.

When looking at this I started to recall 'what if someone built a tool like True Size Of just then also combined information technology with NASA's SEDAC Population Interpretation Service?', where you lot could have the shape of one country, overlay it somewhere else in the earth, and so go the population within it. Well, I had a footling go at this with the lower 48 United states of america states, which I moved s - and scaled geodesically - and then calculated the population within it when placed over China and Republic of india. I also did this with the US flipped horizontally, merely because the US due west declension is a reasonably close fit for the Chinese eastward coast when yous do this. Quite interesting results I call up - and a lot of people in the US this style - and still a lot of empty space!

Please someone build a web tool for this

Overnice littoral alignment here

Okay, and so then I wondered - considering I've been looking at coastal things in the Uk only also globally - 'how far in from the coast exercise yous have to go until you capture more than 50% of the world'due south population?

Well, I got 200km for that (124 miles). This was washed using the very latest WorldPop 1km gridded population data, from 2020, simply similar the residual of the maps.

More fifty% of the world lives here.

Okay, fine. Now I was thinking even more silly thoughts - like 'where is the world'south centre of population'? This is not easy to summate at a global level, just I did do a chip of research earlier attempting it and then my beginning endeavor was totally wrong because I didn't do it on on a spherical world. The internet doesn't have any neat answers on this, simply you can notice a few things if you look hard enough and they say something forth the lines of Almaty, Kazakhstan or thereabouts.

Well, I got a world centre of population of just by Aktobe in Kazakhstan, using 1km gridded 2020 population data. Is this correct? Well, it is based on a complete 1km dataset and a spherical world just remember that I'm but some guy on the cyberspace and before you go and locate your global business concern at that place because of my assay you might want to double bank check the data yourself, although it is a scrap tricky. Only I'1000 fairly confident that the global eye of population is either hither or close to it - certainly in this region is what I'd say.

Middle of the human world? Possibly.

Hey, what about my city? Why oasis't you washed a 4000km hulk map of my favourite identify? Well, information technology would take taken a long, long fourth dimension to do everywhere but I did practice a few more so encounter beneath for that. I calculated over 1,500 4000km population circles overall and 148 had populations of 4 billion or greater within 4000km - including cities in Prc (loads), Vietnam (e.g. Hanoi), Myanmar (Mandalay), Vientiane (Laos), Bangladesh (Chattogram), India (Agartala) and Bhutan (Thimpu). I take to say, despite taking a while to do all this, I have constitute information technology pretty interesting so I hope you practice likewise. Merely call up that the white line shapes on all the maps below (and above) are actually circles - only they volition only look similar circles when plotted on a earth.

That's all for today. I did all the maps in QGIS (complimentary GIS software) using open information - if you lot want to larn how to use QGIS, check out my Map University form.

Notes: does any of this look different if y'all employ a different information source? Well, I ran the analysis over again using the GHSL2015 1km population data and still Yuxi came out on top. I only included capitals plus those cities with 400,000 people or more and then y'all could practise this forever with settlements of all sizes but I had to draw the line somewhere otherwise information technology would accept taken forever, plus I thought using larger cities makes some kind of sense. The data I used is WorldPop 2020 1km grid data and that gives the states a globe population of 7.8 billion. How exercise we bargain with the projection of rasters event if we demand to? Well, we use the GHSL warp tool for that. Why do the shapes seem to differ in size? That's to do with where they are in the world in terms of latitude. The further due north or south they are, the more distorted the shapes will be, simply they are all circles when plotted on a globe. You can check this out yourself if you measure it manually on Google Maps. Did I use a geodesic buffer? Aye, and I think I got it right merely feel free to check my results. The backdrop mapping is NASA's blue marble from August 2004, converted to greyscale. Some places I didn't do maps for because the circumvolve crossed the international date line and and then the outcome was messy, and these include Toyko (1.82 billion inside 4,000km), Auckland (26.8 one thousand thousand inside 4,000km), Sydney (49.i million within 4,000km), Melbourne (49.5 one thousand thousand within 4,000km). WorldPop information is open data, licensed nether the Artistic Eatables Attribution 4.0 International License (CC BY 4.0).

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Source: http://www.statsmapsnpix.com/2022/02/the-yuxi-circle.html

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