In the case of a heavy wind, is there any way to prevent the schach from simply flying away? It can be quite a pain if it falls down, in addition to the danger that it might get ruined.
I have had the map rip when trying to tie it down but it has been kept well by putting slats on top of the mats over the entire length or width of the mats. That weighs it down without allowing it to pull apart.
Note that only a couple of slats are needed and it is the mat that makes the entire covering.
The mats need to have boards underneath to hold them up and the boards underneath will support the slats above the mat so that they will not fall through the mats.
If you're using bamboo mats on wooden slats (quite common), try looping the end of the mat around the slat, thereby hooking the schach on.
We had a nice storm this year, which would have totally brought down the schach if not for this. But as you can see here, it managed to hang in there. :)
(Notice the giant Chile pepper in the middle. :))