Hydrogeological survey and slope erosion analysis for the preservation of Mogao cavas/World Heritage

年轻的多孔层理岩，如大狮身人面像遗址的始新世石灰岩和莫高窟的更新世砾岩，由于盐的再结晶、溶蚀和风的活动而迅速风化和侵蚀。为了对天然石碑的保护工作做出贡献，研究人员通过原位监测蒸发蒸腾作用，澄清了水和水分通过多孔介质和裂缝的运输。通过地质、微气候调查和卫星遥感，可以对遗产地的水文地质特征进行分析。电阻率测量方法可以很好地应用于吉萨和敦煌干旱地区，并提供了合理的含水率分布。马高石窟位于敦煌镇东南25公里处的明沙沙丘东麓。它东面向三尾山，大泉河在它前面流淌。这些洞穴是在大泉河西岸的悬崖上挖掘出来的。溶洞所在地层为冲积、洪积型酒泉砾岩，具有泥质和钙质胶结作用。岩洞壁画因盐重结晶而严重变质。它与岩层中水分的运动有关。莫高地区基底由前寒武纪花岗岩和片麻岩组成。通过卫星图像分析和地质调查，明确了地下水的运动受断裂系统的支配，地理性质是由南侵性构造运动决定的。

Young porous bedding rocks such as Eocene limestone at the Great Sphinx site and Pleistocene conglomerate at the Mogao Grottos are weathered and eroded rapidly by recrystallization of salt, slaking and wind activity. In order to contribute to the preservation work for natural stone monuments the investigators clarified the transport of water and moisture through porous media and fissures by monitoring evapotranspiration action in situ. Hydrogeological feature at heritage sites can be analyzed by geological and micro-climatic survey and remote sensing with satellite images. The electric resistivity measure could be applied well to both Giza and Dunhuang in aridity and provided the reasonable distribution of moisture content.Magao Grottos are located at the eastern foot of the Mingsha Dunes, 25km southeast of Dunhuang Town. It faces east toward Sanwei Mountain, and Daquan River runs in front of it.The caves were excavated into the cliff on the west bank of the Daquan River. The strata in which the caves were excavated are the alluvial and pluvial Jiuquan conglomerate in which there is argillaceous and calcareous cementation. The wall paintings in the caves are subject to the severe deterioration generated by recrystallization of salt. It relates with the movement of water/moisture in rock formation. The basement of Mogao Area consists of granite and gneiss formed in the Pre-Cambrian Age. Through the satellite image analysis and geological survey, it has been clarified that the movement of ground water is governed by the fault system and the geographical nature is specified by the aggressive tectonic movement from the south.