>>204901>>204807 here. (>>204903 is somebody else)My answer is no. The ground does NOT normally get wet under the tarp when it rains. Rain comes from the sky, not the ground.
There is one instance where the ground might get wet under the tarp during a rainstorm, and that is if you actually camp in a dry stream bed or dry puddle (some people are stupid enough to do this, though, which is why double-wall tents come with bathtub floors these days).
Generally, you need to try to look at the contours of the ground before choosing a campsite. The flat, relatively elevated, rocky soil in
>>204807 would not start puddling water, no matter how much it rains, and yes, I've been in some pretty heavy storms in a tarp and no, water didn't just start seeping up from the ground or flowing like a river into the tarp. Water will soak into the soil, and then flow downhill through the soil (as opposed to over it, which only happens with predictable types of soil).
I don't take many pictures of just the ground, so it's hard to illustrate this on an image board with the photos I have handy, but if you look in the picture to the left, you can sort of see that there are little trenches on either side of the dirt roadway. These kinds of features can be found in all kinds of terrain, and not just on dirt roads, but basically that's what you want to avoid when choosing a campsite because the soil there will fill up with water if it rains hard enough, get saturated with no place to drain off excess water, and start puddling. Ideally, you should pitch a tarp on relatively elevated ground with rocky or sandy soil. It's not really hard to find campsites like this. In fact, I labeled one possible site on pic related, although this is all, admittedly, pretty low ground for camping.
