Ireland – Densest 1km² per County

I’ve been writing a lot about population density at the moment and it got me thinking about density in Ireland. We all know we’re pitiful in terms of other European countries and we know from census 2016 that we’re sitting at 70 persons per km². What I’m curious about is what’s the densest square kilometre in each county?

It is import to note that the densest square kilometre in each county below is the densest square kilometre from a predefined 1km² grid for the entire country which is manifestly different from the true densest square kilometre in each county but it’s the best data I have access to as a member of the public. If you want to read more about this issue it’s called the modifiable areal unit problem. A simple image to explain this is show below. From a predefined grid that’s draped over the country we can see that cell 3 would be the most dense 1km² however if a cell was placed where cell 5 is we can see that it would be densest 1km² by a large amount, that in a nutshell is the MAUP problem.

Grid Shortcomings

Grid Shortcomings

 

I used the ’16 census data to generate the below maps to answer the question for each county. What clearly stands out for me is that for a lot of counties it’s housing estates that make up the densest square kilometre. Hopefully with Project Ireland 2040 now in place we can start to do better and go towards sustainable densities throughout the country.

Carlow

1. Carlow

Hyperlinks to maps for each of the other counties:

  1. Carlow
  2. Cavan
  3. Clare
  4. Cork
  5. Donegal
  6. Dublin
  7. Galway
  8. Kerry
  9. Kildare
  10. Kilkenny
  11. Laois
  12. Leitrim
  13. Limerick
  14. Longford
  15. Louth
  16. Mayo
  17. Meath
  18. Monaghan
  19. Offaly
  20. Roscommon
  21. Sligo
  22. Tipperary
  23. Waterford
  24. Westmeath
  25. Wexford
  26. Wicklow

I realised with the above images that I forgot to include part of the label that showed where in each county the location was. Below are the same maps as above but they now include the location and the lat, long for each square kilometre. Maybe both versions can be used for a very nerdy quiz??

  1. Carlow
  2. Cavan
  3. Clare
  4. Cork
  5. Donegal
  6. Dublin
  7. Galway
  8. Kerry
  9. Kildare
  10. Kilkenny
  11. Laois
  12. Leitrim
  13. Limerick
  14. Longford
  15. Louth
  16. Mayo
  17. Meath
  18. Monaghan
  19. Offaly
  20. Roscommon
  21. Sligo
  22. Tipperary
  23. Waterford
  24. Westmeath
  25. Wexford
  26. Wicklow

Irish Census 2016 – Unpopulated Townlands

At some stage in the second half of 2020 the Central Statistics Office released the population for each townland in Ireland for both the 2011 and 2016 censuses. They had a category for both data that has been suppressed ‘-1′ and the townlands that were unpopulated ‘0′. I think it’s a safe assumption that if you read (or have stumbled upon my blog) that you too might be interested in maps of unpopulated places. Below is the static map I posted on Twitter and Reddit and (by popular demand – read as two random people on Reddit) I’ve also included a slippy map that you can examine at your leisure.

Irish Census 2016 - Unpopulated Townlands

Irish Census 2016 – Unpopulated Townlands

 

 

Cork City – Street Types

I was reading Alasdair Rae’s street types blog post yesterday and I thought about doing something similar for Ireland. I didn’t have much time today so I said I’d put something quick together for Cork City. Alasdair was lucky that he could use the amazing open data from the UK’s Ordnance Survey. For Ireland, we don’t have anything similar from our national mapping agency but fear not because it’s OpenStreetMap to the rescue. In my humble opinion individuals often spend far too much time trying to get a usable output from overpass-turbo when there’s an easier way. What I did was download the .osm.pbf file for Ireland from Geofabrik. Windows Subsystem for Linux has been a lifesaver since it came along, most of the heavy lifting I can now do through it. The steps I followed are as follows:

1. Download the .osm.pbf file using wget.

Wget Download

Wget Download

2. Install the osmium-tool

Osmium-Tool

Osmium-Tool

 

 

 

 

3.Filter out just the ‘highways’ from the dataset and save it to a new .osm.pbf file

Filter Highways

Filter Highways

 

 

 

 

4. Convert the .osm.pbf file to a new shapefile ( I don’t normally use shapefile but converting to a geopackage was causing some issues in this instance).

Save as Shapefile

Save as Shapefile

 

 

 

 

 

5. Reproject the shapefile to EPSG:2157 (Irish Transverse Mercator).

Reproject to ITM

Reproject to ITM

 

 

 

 

 

 

I could have made this more efficient again by combining some of these actions (such as save as a new shapefile and reprojecting), I did it this way to make the process easier to explain.

Next I brought the dataset into QGIS and extracted an area just for Cork City. The main issue I then has was how to ascertain what road types occur most frequently. I exported the Cork City extract as a CSV and imported it into Excel. I then used a generic formula from the folks at exceljet to extract the last work from the ‘name’ column. I then counted the frequency of the extracted work in a pivot table to get an idea of the types I’d like to use.

Frequency of Road Types

Frequency of Road Types

 

 

 

 

 

 

The last thing I did was to create a new field using an expression to find the various road types in the ‘name’ column from the OSM data. The expression I used is the below:

CASE
	WHEN "name" LIKE '%Road%' then 1
	WHEN "name" LIKE '%Park%' then 2
	WHEN "name" LIKE '%Street%' then 3
	WHEN "name" LIKE '%Avenue%' then 4
	WHEN "name" LIKE '%Court%' then 5
	WHEN "name" LIKE '%Drive%' then 6
	WHEN "name" LIKE '%Hill%' then 7
	WHEN "name" LIKE '%Lawn%' then 8
	WHEN "name" LIKE '%Estate%' then 9
	WHEN "name" LIKE '%Place%' then 10
	WHEN "name" LIKE '%Lane%' then 11
	ELSE 0
END

I then symbolised the data and exported it. The final product is below. Obviously this was a pretty quick and dirty way to do it and if I create an atlas for every major town in Ireland I will use PostGIS which will allow me to count the frequencies and create the new field with ease.

Cork City - Road Types

Cork City – Road Types

Unpopulated Areas

I was hiking at the weekend and it got me thinking about the unpopulated areas of Ireland. I’ve seen maps made for the 2011 census showing the square kilometres that have no usual resident population but I hadn’t seen one for the 2016 census so I put together the below. I purposefully omitted Northern Ireland because the data is nine years old. If anybody would like the replicate the below just leave a comment and I can do a YouTube tutorial or post on here on how I put it together.

 

The Unpopulated Areas of Ireland

The Unpopulated Areas of Ireland

Development in Ireland

A topic that I think about frequently is the physical changes Ireland has gone through over the last 10 or 20 years. I’ve covered it before in this blog but I’m going to look at it again today. I think you could ask anybody around the country where the development in their town has been during the Celtic Tiger and this current boom period (well, up until the Covid-19 outbreak anyway) and they would easily be able to tell tell you.

It’s true that we have national indicators from the Central Statistics Office identifying where the most planning permissions have been granted as well as data from the Department of Housing, Planning and Local Government on new ESB connections to show where new homes have been constructed. I was looking for something that would give an idea of the physical development that has occurred in the last 20 years.

Enter the CORINE Land Cover Inventory. It started in 1985 as a way for the European Environment Agency (based in Copenhagen) to monitor the main land uses in the Union. As a little factoid, it stands for Coordination of Information on the Environment. It contains 44 land use classes and the cell size is 100 metres. It already contains layers that show the change between different years but it didn’t contain any change layer from 2000 to 2018. I wasn’t interested in the 44 classes, in fact I was only interested in the categories shown below. I decided to omit construction sites, dump sites and a few other inconsequential categories. These are the main categories that will show development in Ireland between those years.

111 – Continuous urban fabric
112 – Discontinuous urban fabric
121 – Industrial or commercial units
122 – Road and rail networks and associated land
123 – Port areas
124 – Airports

I used the the wonderful r.reclass GRASS tool in QGIS in order to reclassify the rasters for both the year 2000 and the year 2018 to combine these categories. I then used raster algebra in order to subtract the year 2000 from the year 2018 raster in order to show the actual change. Below is a GIF showing the process for an area of North Kerry and Cork.

QGIS Process Example

QGIS Process Example

I create the below map in A1 so you can zoom in to get a good sense of what 18 years of development looks like in a particular county.

Ireland-Development Between 2000 & 2018

Ireland-Development Between 2000 & 2018

Here is a link to the PDF version if you would rather.

*Update*

I redid the map showing the development up to the year 2000 as a separate colour. I’ve also added a legend.

Development in Ireland

Development in Ireland

Here is a link to the PDF of this version.

Finally, after a few unsuccessful attempts at converting the final raster to vector I used the gdal_polygonize tool which did it seamlessly without any loss of the smaller cells. Below is the final layer as a web map that you can make full screen.

There are a few interesting area that were developed in those 18 years such as Aughinish Alumina in Co. Limerick:

Aughinish Alumina

Aughinish Alumina

There are also a few windfarms such as this one in Tyrone:

Windfarm in Tyrone

Windfarm in Tyrone

Peatlands of Ireland

I was thinking the other week about the amount of bogs around Europe after the collapse of a trial against turf cutters in Galway. I put the below map and tweet together in a few minutes that shows the peatlands of Europe. The outlines of Iceland, Ireland, Northern England, Scandinavia and Scotland are visible from their peat cover alone. The data comes from the European Commission’s CORINE land cover dataset.

After completing the above I thought I’d put together a map showing the peat cover in Ireland. Besides from the CORINE land cover dataset I used a DEM from the European Space Agency to create the hillshade and the administrative data comes from Ordnance Survey Ireland and OpenDataNI. The dataset doesn’t differentiate between raised and blanket bogs but for my purposes that’s okay.

Below is the finished map. I tried something new and used abbreviated county name labels à la various maps for the USA where the state names are abbreviated. I think it works well.

Peatlands of Ireland

 

I was thinking since I posted this that there’s a bit of work involved to figure out the order of peat per county so I created a graph. For any GIS folks out there, I quickly unioned the county layer and the peat layer and then calculated the area in square kilometres for the peat and exported this as a CSV. I then used Matplotlib to create the below graph. If you’d like to know more about simple workflows like these just reach out to me on Twitter (@pearoid).

Peat Area per County in km²