I am trying to replicate the map here https://www.cdc.gov/yellowfever/maps/africa.html I have downloaded land cover data, which is what the Northern countries are based on, from https://www.diva-gis.org/gdata, and used singleband psuedocolour in the symbology to achieve the look below.

However, I am not sure how to cover the entire area for those six countries yellow. Does anyone have any tips?

Saharan countries

  • does land cover drive Yellow fever areas? if so you need to select the required land cover type – Ian Turton Aug 5 '20 at 9:16
  • For those countries which border/contain the Sahara it does (who.int/ith/YFrisk.pdf?ua=1) "Classifications for areas with risk in Mauritania, Mali, Niger, Chad, Sudan, and Bolivia were evaluated in December 2008. The conservative vegetation line (described above in 3.1) that separated "barren or sparsely vegetated areas" (Sahara desert) from "open shrublands” was adopted and determined the northern boundary for areas with risk in Mauritania, Mali, Niger,nChad, and Sudan. " However, I am not sure how select these small squares and make them into one polygon – Sanch Aug 5 '20 at 9:27
  • I selected the areas which are mostly non desert and coloured them yellow. It doesn't quite match the maps produced by CDC and the WHO but the land cover has been assigned correctly (Posting my answer below) – Sanch Aug 25 '20 at 12:33

I have a solution which covers most of the area. Using the 'Majority filter' tool and setting the radius and % to 30, and then the 'single palette' for each value set to yellow, I am able to achieve the result below.enter image description here

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