Spatiotemporal evolution characteristics of freeze-thaw erosion intensity in the high-cold mountainous areas of Northwestern Yunnan from 2017 to 2023.

Freeze-thaw erosion is a prevalent surface process in cold regions, driven by the cyclic freezing and thawing of soil and rock. This process results in land degradation, soil erosion, and a range of ecological and environmental challenges, posing significant threats to the ecological security and socio-economic development of high-altitude mountainous areas. This study focuses on the high-cold mountainous regions of northwestern Yunnan, employing multi-source remote sensing data and geographic information system (GIS) technologies. Eight key evaluation factors were considered, including annual freeze-thaw cycle duration, daily average phase-change water volume, annual precipitation, slope, aspect, vegetation coverage, soil type, and soil erodibility. By integrating expert scoring with principal component analysis, a comprehensive system was developed to identify and assess the intensity of freeze-thaw erosion zones in the region. The spatiotemporal evolution of freeze-thaw erosion intensity from 2017 to 2023 was systematically analyzed. The findings suggest that high-altitude regions face considerably greater erosion intensity, attributed to lower temperatures and frequent freeze-thaw cycles. In contrast, low-altitude areas are comparatively less affected. This reflects the intricate interplay of climatic and environmental dynamics. Over the 7-year period, areas of mild and moderate erosion expanded significantly, whereas regions of minimal and intense erosion showed a decline. Annual precipitation and freeze-thaw cycle duration emerged as the primary factors influencing the spatial distribution of erosion intensity. This study offers valuable insights and decision-making support for ecological conservation and disaster mitigation in the high-cold mountainous areas of northwestern Yunnan.