tarp tenting - what goes on the ground?

newbie question of the day...
for the grand canyon camping trip we are planning on not bringing tents, but bringing tarps to sleep under. (actually, I'll be making them from silnylon that I just purchased).

So, my question is, when sleeping under tarps for protection, what do you put on the ground? And - what do you do if it rains? How do you keep your ground dry if it rains?

I usually have a full length blue foam pad, and just use that. (since I use same inside my hammock). A piece of painters dropcloth plastic works fine as a groundsheet though. some swear by a piece of tyvek. I often use just the full length pad.

As for keeping the ground dry - that's what the tarp is for - rain comes from an upwards direction ya know - however if you were thinking about what comes underneath - well there's the trick - make sure you pick a good site - if you pick a good site that isn't a bowl, (i.e you're on top of a little mound ) nothing will come into it. I find a groundsheet is only really needed if the ground is already wet when you set up.

OTOH, this can take a fair bit of practice. if you haven't tarped before on the ground what will help you is

1) A larger tarp - it's a lot easier to stay dry under an 8x10 than an 8x5.

2) some practice. pick a suitable area in your yard, or nearby, and sleep under it in a rainstorm.

I am planning on making 8x10 tarps.



I will certainly be giving that a try. At a minimum to practice setup and testing waterproofness.

I had a recommendation when camping last fall for a fundraising event to use dollar store shower curtains as a ground cloth.

I guess I've car camped in enough places that were supposedly "flat camp sites" (this past weekend included) where even with the rain the ground under the tarp area still ended up with mini streams and puddles.

It is all a new learning process.

Where are you camping?