Mapping the susceptibility to freeze-thaw deterioration and regionalization of freeze-thaw environments of earthen sites in China: A preliminary study.

Earthen sites in China are widely exposed to freeze-thaw environments. There is a lack of knowledge about the spatial distribution patterns of freeze-thaw deterioration and environments, as well as preventive conservation strategies and subsequent refined research on the freeze-thaw deterioration of earthen sites. In this study, the freeze-thaw deterioration process of earthen sites was divided into two periods. Thirteen relevant factors were selected, and using the GIS-FAHP method, a susceptibility map for freeze-thaw deterioration of earthen sites in China was created. The Jenks Natural Breaks method was then employed to categorize the areas into five susceptibility levels: very low (24.6 %), low (18.2 %), moderate (24.2 %), high (18.2 %) and very high (14.8 %). Based on the susceptibility map, the three-level regionalization scheme for freeze-thaw environments of earthen sites in China was systematically developed, taking into account the differences in freeze-thaw deterioration susceptibility and natural landscape within the geomorphological units, and the environmental codes were assigned to third level small-regions. The freeze-thaw environments of earthen sites in China were finally divided into 5 major-regions, 20 sub-regions and 42 small-regions. The results showed that in the area east of the Heihe-Tengchong line, the susceptibility to freeze-thaw deterioration showed latitudinal correlation, and the susceptibility gradually increased from south to north; in the area west of the Heihe-Tengchong line, the susceptibility to freeze-thaw deterioration exhibited strong zonal characteristics. Among the provincial administrative units, Gansu Province and Xinjiang Uighur Autonomous Region have the most complex freeze-thaw environments, while Qinghai, Tibet, Sichuan and Heilongjiang Provinces have the harshest freeze-thaw environments. This study can support regional management and prevention of freeze-thaw deterioration and deterioration studies of earthen sites in China.