The statues in the caves of the North Grottoes appear mottled due to the water.
Photo by Ai Qinglong
The picture shows the North Grotto Temple from the perspective of aerial photography.
Photo by Ai Qinglong
China News Service, Qingyang, Gansu, May 22 (Ai Qinglong) Recently, the reporter came to the North Grotto Temple in Qingyang City, Gansu Province. From the perspective of aerial photography, the southern end has been covered by a dark waterproof protective shed.
In everyone's impression, the Loess Plateau is dry and rainy, but why did the North Grotto Temple start a "waterproof" project?
Cui Huiping, deputy director of the Protection Research Office of the Institute of Cultural Relics Protection of Gansu North Grottoes Temple, said that the large annual rainfall where the cave is located, coupled with the good permeability of the yellow sandstone, has caused the statues of the cave to be affected by flooding.
The North Grotto Temple was built in the second year of Yongping in the Northern Wei Dynasty, and it has been continuously expanded over the generations to form a group of grottoes with dense caves.
There are 308 large and small cave niches and more than 2,000 grotto statues, which are distributed on the yellow sandstone cliffs on both sides of the Pu River, and occupy an important position in the art of Chinese Buddhist grottoes.
In 2017, in order to strengthen the protection, Gansu put the reorganization system of the North Grottoes Temple under the management of the Dunhuang Academy.
In the North Grotto Temple, multi-volume and multi-structure scaffolding supports the protection shed, and the outline of the cave niche is looming.
According to Cui Huiping, the waterproofing project is experimental and will be completed in March 2021. It can cover and block the cliff body to the greatest extent, protect the caves on the cliff face, and prevent the erosion and damage of the grottoes by rainwater.
On site, the construction of the main body of the protection shed adopts the floor-standing, full-height and fully-enclosed fastener-type double-row steel pipe scaffolding. The shed surface is welded with resin tile roof and steel structure square tube, so that rainwater can be quickly drained to the cornice.
In addition, the protection shed is high in the south and low in the north, and the cornice of the rain-proof shed is equipped with a water intercepting groove for unified drainage. The northernmost end of the groove is connected to the drainage pipe, which can ensure the smoothness of the drainage, and prevent the running water from directly draining, hitting the ground of the cave area.
Cui Huiping once published the article "Analysis and Research on the Current Situation of Rock Mass Seepage in the North Grotto Temple". She pointed out that the cracks in the rock mass where the grottoes are located are crisscrossed. The rainy season is from July to September every year. As time goes on, rainwater spreads to various cracks in the cave from different distances, and flows out at the leak point on the cave wall, and the seepage time sometimes lasts for several months.
After the leakage, through water evaporation, calcium precipitation, etc., calcium deposits will be formed on the cave wall and the surface of the statue, thus covering the original appearance of the statue and making the grotto cultural relics lose their original artistic value.
Cui Huiping explained that the construction of an "umbrella" is not unfamiliar to the North Grotto Temple, but it was the first time that an "umbrella" covering an area of 600 square meters was built only for individual special caves.
Cui Huiping compared the changes in the construction of the protection shed at the southern end and said that the monitoring data for a period of one year is still in the process of analysis, but according to human observation, the waterproof effect of the protection shed is obvious.
It is reported that in order to ensure the viewing quality of the grottoes, the next step, the North Grotto Temple Cultural Relics Protection Research Institute will adjust the shape and color of the protection shed, and strive to ensure waterproofness and viewing quality without affecting the environmental appearance of the caves.
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