In this New York Times article about the desertification of Northern China, there are some great drone-camera videos of the landscape. The article is light reading and the imagery is top notch. Have a look.
As the players have decided to undergo a journey of perhaps a hundred miles to return an old man to his hometown, I've taken a stab recently at the roughest, crudest possible first version of my own wilderness/travel damage system (as originally conceived by commenter Zzarchov, and implemented by Alexis here and elsewhere, and discussed here too.) Thus I find this kind of material inspiring. Traveling from place to place should not be a cakewalk for the characters. It should sap their energy and wear them down so that that every roadside inn, oasis, fellow traveler sharing food, or friendly forest creature is a boon.
So far my version is very simple. I'm just about ready to program basic clothing items into my economics system, so there will be a few different options for shirts, pants, types of shoes, and other things. The better protected you are, the more the base damage (which grows faster the more days you spend away from civilization) will be mitigated ... but spend too long in the wild, roughing it, traveling on backroads or in shitty weather, and the daily tick-tick-tick of a few damage here, a few damage there will catch up with even the hardiest character.
Luckily for my players there are a couple major towns along the way ... but they're only first level, and they're headed for areas with tropical and monsoon climates. I've lived in a monsoon area before and it was miserable enough without having to go trudging along dirt roads which are quickly turning to mud, knowing that you've probably no chance of finding a dry-ish place to camp tonight. In that scenario, any kind of shelter would be welcome. But, with some of your HP missing, you'd be in no shape to oust some bears or goblins to claim a cave ... unless you were really desperate.
Better to pay some cash at the inn, and go treasure hunting when the weather changes.