The giant sleeping Buddha statue of the Dazu Rock Carvings in Chongqing Municipality Photo: VCG

In the misty Sichuan Basin, Southwest China, the carved cliffs of the Dazu Rock Carvings have borne silent scars from centuries of humidity and rain. Water seeps into the ancient stone, etching delicate figures, feeding microbial growth, and hastening weathering - persistent challenges to the endurance of this UNESCO World Heritage site.

Yet decades of conservation, driven by technology and multidisciplinary research, are now slowing the pace of deterioration. 

Jiang Siwei, director of the Dazu Rock Carvings Research Institute, presented interim results from a multidisciplinary water-damage control project at the recently concluded International Forum on Cave Temple Conservation 2025. After five years of follow-up monitoring, typical seepage points on the surface of the giant sleeping Buddha statue had stopped and salt crystallization on the statue had significantly eased, laying a solid foundation for the next phase of the overall restoration work of the statue.

"Advances in technology are continually opening new possibilities for the preservation of cultural heritage. The comprehensive water-damage management system at the Dazu Rock Carvings extensively integrates proven technologies from multiple disciplines and practical applications," Jiang told Global Times.

The Dazu Rock Carvings illustrate China's broader cave-temple preservation efforts. A nationwide survey has documented 2,155 cave temples and 3,831 cliffside sculptures, including the Mogao Grottoes in Dunhuang, Gansu Province, the Yungang Grottoes in Shanxi Province, the Longmen Grottoes in Luoyang, Henan Province, and the Dazu Rock Carvings in Chongqing city - all UNESCO World Heritage sites.

On August 19, China's National Cultural Heritage Administration announced that major risks to the country's key cave temples have largely been mitigated, and a preliminary systematic, integrated national framework for their protection has been established after more than 70 years of efforts. 

China's approaches to cave temples conservation have also extended beyond its borders, to the restoration of Cambodia's Angkor Wat temples for instance, Dunhuang's Belt and Road partnerships and a China-Italy stone conservation lab, according to the Xinhua News Agency.

"China has developed comprehensive 'Chinese approaches' to cave temple conservation that integrate philosophy, technology, and practical application," Liu Hanlong, an academician at the Chinese Academy of Engineering and a professor at Chongqing University, told Global Times. 

Tech aids conservation

Technology has been integral to managing water damage at the Dazu Rock Carvings. The conservation team employed detailed geological survey techniques, including ground-penetrating radar and electromagnetic wave CT, to identify seepage sources and map underground flow paths and discharge channels.

For the first time, the team also applied curtain grouting, a method commonly used in hydraulic engineering. By partially blocking underground water pathways, the technique redirects fissure water away from the grottoes' sculptures.

"Principles of cultural relic conservation, along with appropriate techniques, are essential to ensuring effective preservation measures," Jiang said. 

Conservation efforts must also be tailored to the specific problem and use suitable techniques. "When introducing curtain grouting from hydraulic engineering into grotto water-damage control, we carefully select composite grouting materials that are compatible with the artifacts, durable, and environmentally safe. Rigorous preliminary testing is carried out, and the conditions for their use are also clearly defined," added Jiang.

At the forum, Liu shared the application of microbial mineralization technology developed by his team in the preservation of cultural relics.

He told Global Times that the microbial mineralization technology draws on biochemical principles for the preservation of cultural relics, which is a comprehensive interdisciplinary field that involves geotechnical engineering, material science, microbiology, chemistry, and heritage conservation.

According to Liu, this new technology offers enhanced strength, color consistency, and weather resistance compared to traditional restoration materials. It has been successfully applied to several major historical and cultural sites protected at the national level. For example, by utilizing this technology, his team contributed to the restoration of a Ming Dynasty (1368-1644) incense burner at the Dazu Rock Carvings.

At the Longmen Grottoes, a newly inaugurated heritage scientific conservation center featuring state-of-the-art research facilities, including specialized laboratories for mechanics and more has been in operation. The center also has high-tech instrumentation such as 3D printers.

Digital innovation

Digital tools have immortalized China's cave temple treasures in virtual space. Through systematic application of 3D digitization, Longmen Grottoes has pioneered a complete workflow for the virtual reconstruction of dispersed heritage, achieving digital reintegration of fragmented statues.

Su Bomin, director of the Dunhuang Academy, presented a province-wide digital monitoring platform at the forum encompassing six major grotto sites, providing key data to track dynamic changes comprehensively and preemptively identify potential risks.

The "Digital Library Cave" platform, developed by the Dunhuang Academy, was launched in May 2025, integrating 74,651 artifact records and sharing over 9,900 manuscripts, more than 60,700 images, and 8.4 million characters.

Su shared at the forum that the Dunhuang Academy has launched a digital initiative for the Dunhuang cultural relics dispersed overseas. The project has now made substantial progress, securing a large number of high-resolution digital resources from collections of Dunhuang artifacts held abroad.

According to Su, China has developed a comprehensive approach to cave temple and heritage conservation, which has won high praise and recognition from international experts on various occasions.

"Through exchanges with experts from different countries and disciplines, we can learn from one another and work together to protect humanity's shared cultural heritage," noted Su.