Paris les pieds dans l'eau : Iron viz Water - feeder 3 - 2018

I cannot help myself, I promised to step down and don't compete for a time... but I did it again :) I participated to the Ironviz
Here the details about this competitition : Make a splash in Iron Viz Water | Tableau Public

First I wondered what I subject I could possibly pick, and how to represent it. Because the subject was Water, I decided to do a viz on the Seine, or more precisely about the Seine's floods.

To do so I need maps, a lot of maps. This blog post will explain how to create those maps in Tableau, nothing fancy though.

1- Paris altitude map : This is probably the easier

This map shows some of the Paris monuments in an elevated map. I collected the information Google earth pro and I then copied them in Excel,
Once you connect Excel to tableau, this view is a dual axis : one drawing the profile and the other one representing the monuments. I tried to find the most similar icons possible and work out the colour. Even if it not always easy without a designer ( who draw them for you), the results is satisfactory. I had to modulate the position of the icons so they appear on top of the line.

Capture d’écran 2018-08-26 à 19.29.45.png




2-The Seine profile


This map is done by connecting a shapefile ( from https://www.data.gouv.fr/fr/datasets/dcpsl-hydrographie-1820-fleuves-rivieres/) for the Seine's mapping and an Excel file for marking the exact beginning  and end of the Seine ( in order that the comments point out exactly to them). A dual axis does the trick
For the first one, the geometry field in details, and for the second the departure and arrival.
The Map is a traditional Tableau map with a light style and without base to be able to colour the background.





3-Custom geography


To illustrate the fact that Paris is divided by the Seine in two parts, I create in Tableau this custom map. Having the postal code, I simply create a group of the different postal code matching the "right part" of the river and the ones matching the "left part". This group can then be used.
Capture d’écran 2018-08-26 à 21.42.51.png


4-Joining two shapefiles


In the journey of my viz, I wanted to compare the 1910's floods (dark blue) with the actual prevision for the same level of flood ( light blue). But I had two shapefiles and I don't have any software able to do the work. But with the new feature of Tableau, I can join the two shapefiles with the intersects option. Et voila ...
Capture d’écran 2018-08-26 à 22.05.40.png


5-Go further


To finish, the last map, I used in my viz is a join of differents geo datesources one for the floods and one for the monuments represented as the points. But here the difficulty comes from the fact that I had to create the latitude and longitude for the monuments. I had the streets localisation, but as you may know, I couldn't use it in Tableau. Tableau cannot (yet) to go below the postcode level.
So I connect my datasource to Alteryx, and in two simple steps ( I am an Alteryx beginner) I could use their geocoder to convert my streets in gps location, and used it in my viz.




Concerning the design of the full dashboard, I just choose to have a clear and epurate design only grey and of course blue ( for the water theme).

Hope you like it.


link to the viz : Tableau Public

Sources :
This viz has been done with free copyright icons and open data coming from the following websites :

- icons : www.colourbox.com
- protections in case of floods :
1- http//www.prefectures-regions.gouv.fr/ile-de-france/Region-et-institutions/L-action-de-l-Etat/Prevention-et-gestion-des-risques/Risques-naturels/Inondation/Crue-et-inondation-comment-s-en-proteger/#titre
2- https//www.lci.fr/societe/crues-vigicrues-mais-pourquoi-ne-peut-on-pas-empecher-la-seine-de-deborder-2076746.html
3-https//www.la-croix.com/Culture/Expositions/musees-parisiens-face-crue-Seine-2018-01-25-1200908760
- Other : wikipedia of course

Annabelle
August 25th 2018