(ECNS) -- The Mogao Grottoes in Dunhuang were temporarily closed due to rainfall on Wednesday.
It was the second time this year that rain has forced the closure of the UNESCO world heritage site.
On July 7, the flooded Daquan River outside the caves cut off the only road leading to the site and forced its closure.
Experts say monitoring equipment has been installed in the Mogao Grottoes and once the humidity exceeds 63 percent, the site will be temporarily closed.
Glutenite, a supporting material for the murals in the caves, is prone to disintegration when exposed to water for a long time and can lead to rockfalls.