I did not understand how it is completely waterproof. What if there is rough weather? And how does it prevent water from entering in case there is standing water around the base?
There is a platform under the dome to prevent standing water from entering it. Further I would expect it would be best to build on a slight rise to mitigate this issue. As for the waterproofness of the shell, as long as the higher panels overlap those below them by a sufficient amount (maybe 10cm) then the dome will shed water in even heavy storms.