## 1 Introduction
(2022) [23] combined frequency domain reflectometry (FDR) and ERT to conduct point-scale field measurements of soil water content and temperature associated with freeze-thaw and snowmelt infiltration. They concluded that, in addition to meteorological conditions and land management practices, freeze-thaw cycles also contribute substantially to soil erosion processes. [PERSON] and [PERSON] (2024) [24] monitored seasonal variations in ground resistivity, unfrozen water content, and ground temperature at a high-latitude site in western Greenland, and quantified the relationship between clayey soil resistivity and unfrozen water content. [PERSON] et al. (2024) [25] applied ERT to examine moisture migration in ground improved with geosynthetic-encased stone columns (GESCs) subjected to freeze-thaw cycles, revealing that moisture tended to migrate upward and outward from the reinforcement zone during freezing, and inward during thawing. [PERSON] et al. (2025) [26] investigated the formation and frost heave behavior of frozen soils under liquid-nitrogen-induced rapid freezing, incorporating nondestructive monitoring techniques such as ERT to analyze the coupled thermo-hydro-mechanical processes, with results indicating discontinuous frost heave displacements. [PERSON] et al. (2025) [27] employed an integrated geophysical approach combining GPR, ERT, ambient noise seismic interferometry (ANSI), and UAV-based infrared thermography to assess frozen soil conditions in the Tuotuo River Basin on the Qinghai-Tibet Plateau, providing a comparative evaluation of each method's strengths and limitations. Despite these advancements, existing studies remain limited in their investigation of the evolution of soil electrical properties under low-temperature conditions, particularly the dominant role of unfrozen water content in governing electrical resistivity. Moreover, prior work has often considered the influence of soil moisture on electrical conductivity in isolation, whereas in natural high-altitude frozen ground environments, significant coupling exists among key parameters such as initial water content, dry density, and temperature. This lack of systematic analysis on the combined effects of these three factors on soil resistivity hampers the development of reliable quantitative inversion models for ERT surveys under complex field conditions [28; 29; 30]. To address these challenges, this study targets typical clayey sand from the Qinghai-Tibet Plateau, integrating laboratory freeze-thaw experiments with long-term field resistivity imaging observations. It explores the coupled control mechanisms of initial volumetric water content, dry density, and temperature on soil resistivity under low-temperature conditions. The freezing and thawing points of soil samples with varying initial volumetric water contents were determined, and the functional relationship between unfrozen water content and resistivity was quantified. Furthermore, high-density resistivity forward modeling was conducted to optimize deployment schemes for plateau surveys. Based on these efforts, field ERT tests were implemented to assess the spatiotemporal evolution of frozen soils on the Qinghai-Tibet Plateau.