Is it allowed to change the surface during the tournament for a division?

In case of bad weather circumstances its up to the organizer & head umpire to go on playing indoor and change surface.

In addition for 2017/18:

If there is a chance to play the finals of 1.000 and 500 points tournaments on public places with many spectators, organisers are allowed to change the venue and the surface compared to matches prior to the finals.