Hydrogeological explanation of seepage diseases in stone grottoes: a case study of Maijishan Grottoes, China

This research studied the seepage diseases (water discharge and salt precipitation) in Maijishan Grottoes from the perspective of hydrogeology. Maijishan Grottoes is one of the extent large group of grottoes in China, where its cliff, on mount Maiji, the carrier of the grottoes, has been reinforced by concrete cover in a large area. As a case study, the physical and chemical processes of the seepage are deduced through the relationships between the flow rate of discharge water (DW) and precipitation, and through the water chemistry diversity including pH, electrical conductivity (EC), and Ionic composition between DW and rainwater (RW) and a controlled spring water (SW). Constructive results are obtained. Firstly, a perched aquifer is confirmed in the mount. All the RW will gather at the aquifer, and then discharge through 3 independent routes that connect the aquifer and grotto site. 3 kinds of water discharge response to precipitation are defined to correspond to the 3 routs: Immediate Response (I.Resp), Delay Response (D.Resp), and Stealth Response (S.Resp), these responses make up the majority of the DW. On the other hand, 2-staged chemical evolution is also been confirmed during the seepage, where stage I took place in the aquifer and stage II took place at shallow, the concrete only participate in the chemical evolution at stage II, resulted in high pH [7.77, 11.69] and EC [513, 3540] (µS/cm) in DW compared to the SW and RW.