Classification framework and empirical study of Earth Critical Zone at small-scale: A case study of Xixia County, Henan Province

The classification of Earth Critical Zone (CZ) helps understand the spatial distribution and regional differences in their occurrence and evolution. Besides, it can serve as the basis for observation and investigation. Therefore, it is necessary to divide the types of CZ. To further study the existing large-scale CZ classification, this paper took mountainous areas as the research object, constructed a set of small-scale CZ classification frameworks, and made an empirical study in Xixia County of Henan Province. The research results showed that a group of multi-level classification frameworks covering classification principles and indexes was established in the mountainous area, and the CZ of Xixia County was divided into 28 first-level types, 246 second-level types, and 722 third-level types. This classification has specific reference significance for scientific research and the comprehensive management of natural resources in the critical zones of the earth at different scales.