In choosing a map projection that would work best with a hex-design, I went with the world viewed from the two poles. I've explained this before regarding mapmaking, but giving a quick explanation, the world is like two sides of a hexagonal coin, the top and the bottom. I don't have an image of the world depicted as a hexagram (more's the pity) so I'll have to show two circles instead:
This means that the distortion is greatest towards the Equator . . . but I solve this problem by having the inhabitants of the planet dwell in an illusionary haze that supposes that the world is a sphere and that the universe acts in accordance with that supposed truth. It is important to always remember, this is my D&D world, not a pure representation of any so-called 'real world' that may exist elsewhere.
Because I've been mapping in the northern hemisphere, I'm used to designing my maps leading away from the north pole, thus managing the distortion the hex-map creates habitually with this in mind. To map a portion of the southern hemisphere, I had to reverse my thinking and design the maps leading towards the south pole, since I did not want to turn the map upside down in representing it (we're used to having north be generally at the top of the map, even in the southern hemisphere). This actually gave me a headache. It is difficult to explain why - since I can't express the problem fully in my own mind. Let's just say it made it hard to determine the exact shape of the sheet maps regarding that 60-degree turn that happens as one circumnavigates my hex-map world (see the mapmaking link above). Thankfully, Paraguay was not on a parallel that required that turn.
Once figuring it out, however, I began laying out the hex elevation details for the necessary maps. In a close-up view of either this new map on the wiki or this one, there are little numbers in the corner of every hex. This is the elevation in feet above sea level for that hex (though there are variances within the hex that I have to imagine, though that isn't important right now). If the number is in italics, then this indicates the highest habitated elevation in the hex (not the highest point, just the highest point at which people live). Numbers not in italics represent the lowest elevation.
In making any map, I have to start by diligently placing these numbers in every hex. Initially, every hex is tagged with the lowest elevation; the black circles on the maps linked above indicate that these hexes do not contain rivers and that the numbers should be altered from highest to lowest. The difference this makes gives a good indication of the elevation changes from hex to hex, aiding in the maps representing the world.
The more information I have regarding elevations, the more precise I can plot the course of the rivers. With Paraguay, the plan was to determine the basin of rivers that ultimately drain into the region - the Parana River from the east, the Paraguay River from the north and the much smaller Pilcomayo River from the west, among other smaller tributaries. To do this, I needed to know where the continental divide existed between the Paraguay-Parana basin and the Amazon basin, to the north.
This proved difficult, because much of central South America is empty. Very, very empty.
Google Earth helps with this. I could tell from images that most of the Amazon basin leading up to the heights of central Mato Grosso is full of hills and low mountains. I could then speculate that the dividing country between the river basins was mostly hilly jungle - human access is dependent upon river travel. Therefore, virtually anything for which I don't have data (meaning there are no habitations there) could be counted as inaccessible higher altitude jungle.
This is a bit obscure. Let me show the size of the Paraguay-Parana basin by showing the dimensions of what I needed to lay out in order to determine it:
Looking at it in one piece for the first time (I've been looking at it in seven sections), it actually looks smaller than I supposed. Ah well. It still makes the largest river basin system I've mapped, so that's something.
The scattering of green hexes across the top of the map are those hexes for which I have no information for the latitude/longitude of that hex. The hex is therefore colored to either be a highland (dark green) or a lowland valley (light green) in accordance with the vegetation. The greenish-brown hexes in the Paraguay map on the previous post indicate a Chaco vegetation, what's called a xerophytic open forest (on this post, it is similar to the image for 'Di - caatinga,' except that it's much flatter and much wetter). The darker green hexes represent a galleria-type forest, a mix of tall grass and jungle trees, a sort of dense savanna. South Mato Grosso and all of Mato Grosso do Sul provinces correspond to that circular area of pink-orange (the upper Paraguay basin), something I'm pointing out because mato grosso in Portuguese means "thick bush."
Steadily, with Google Earth, the data I could use from the hexes I did have information for and a little fudging here and there (it is my world, remember; I can fudge if I need to), I did get the various limits of each basin (Pilcomayo, Paraguay, Parana, etc) worked out. After that, it was just a matter of calculating the river sizes and drawing the rivers out. Well, sort of.
See, I felt I had to plot some of the towns in Mato Grosso and eastern Bolivia in order to get those rivers properly placed (a bit more information helps). Brazil was easier, the upper Parana valley is well inhabited. Plotting towns means investigating towns, researching their origin and establishing their political backgrounds.
Now, I absolutely wanted a Spanish/Portuguese presence in South America, so I felt that any town that was founded before 1650 had to exist, regardless of the circumstances. 1650, incidentally, is the historical year on which my world is based - and there are many Spanish colonies founded before that year. None of them, however, happen to be in Mato Grosso . . . or eastern Bolivia and western Paraguay. Or eastern Paraguay, for that matter.
In Part II of this post, I will write about what I did about that. Making a map of Paraguay isn't enough. Some considerable thought has to be applied to what lives there.