A Preliminary Study Of The Moisture And Salt Distribution In The Cliff Of Mogao Grottoes At Dunhuang

Mogao grottoes are located at southeast of Dunhuang, 25 kilometers from Dunhuang city, dug in east cliff of Mingsha mountain, about 1600 meters long from south to north. Wall paintings and statues are existing in 492 caves, except 5 caves are located in the north area, the others are in the south area. The Mogao grottoes, the first National key heritage sites unit listed in 1961, and written on world heritage list by the UNESCO in 1987.Because of natural and human factors, the Wall paintings of Mogao grottoes are deteriorated by efflorescence, detachment, flaking and many other serious diseases. Many scholars think the deterioration is related to salts migration from the cliff to Wall paintings. We haven't fully understood about salts and water sources and no enough evidence to interpret the deterioration.We have investigated the moisture and salts distribution in cliff at a vertical range of 20 meters by dug a exploratory well on the top of the cliff. The relative humidity and temperature have been monitored in cave 108, and the moisture and salts have been investigated too. In order to measure and test the distribution of moisture at the top of cliff and the front ,we had a geophysical prospecting . The moisture and salts content in the cliff had a preliminary understanding though many works. It is good for study the deterioration process that in Wall paintings.Through the measurement of the samples taken from the exploratory well, there is a relation between the moisture distribution and formation of Mogao grottoes cliff, in fine-grained soils the moisture content is up to 24%, and even 2% in conglomerate. Salts in the gobi layer and surrounding rock of caves aggregated to the surface, the aggregated depth is about 0.6 meters.Through the study described in this thesis, a deeper understanding of the distribution of moisture and salt in the body of cliffs has been obtained, which is the foundation of a thorough understanding of the developing process of mural disease in Grottoes. It is of certain reference value for finding relevant protective measures, and therefore it is of great importance for the permanent protection of the murals in Mogao Grottoes. The result of the research can also be used for reference in solving the same salt problems of other grottoes and earth relics in the northwestern arid regions in China.