Estimation of Hydraulic Environment Behind the Mogao Grottoes Based on Geophysical Explorations and Laboratory Experiment

Abstract

There is moisture movement under the ground as a factor contributing to salt damage at the arid regions. Some parts of wall paintings of the Dunhuang Mogao Grottoes, which is a World Heritage site, have been seriously damaged by the crystallization of salts. This damage is likely to have been caused by short-term factors such as rainwater and flooding, and a long-term factor, namely, groundwater movement. In order to preserve the grottoes, it is important to know the relationship between underground moisture and salts. The purpose of this study is to understand the moisture content and salinity in conglomerate layers behind the Mogao Grottoes by the geophysical explorations and laboratory experiment. The resistivity characteristics of the field sample focused on water saturation with salinity were determined by laboratory tests. By obtaining the distribution of water saturation from the electric resistivity method in the study site, the moisture content in the ground was estimated. To confirm the reliability of the estimation, RI-density log was implemented. These results indicate there is relationship between the hydric environment and salinity concentration in each depth behind the Mogao Grottos.