Only thing I noticed abotu the rivers is the top one on the western side of the southern continent - looks like it splits up, or is this supposed to be a delta?
(And Deltas don't necessarily lie in bays, they often enought build some kind of a peninsula with all the stuff the bring into the sea, look at the Nile for example )

About the colourscheme: I think the red yould be a bit brighter, at least if you a planning to do such thin circles.
Which brings me to the next point: The diameter of the ring tells the population total while the piechart (or better: doughnut-chart ) tells how many already died. But what information is coded in the (for the lack of a better word right now 'thickness' of the ring? Does it even have one? If not: Maybe you can use it to tell the time since the plague has struck the city. For example: 1mm means one year since the first plage death in the city. You could also do that with the colour, though, which might make tracking the path of the pandemic easier when looking at the whole map.

But looking good so far!

(One question: are you using GIS? Could make the chart part easier.)