Response of the soil hydrothermal process to difference underlying conditions in the Beiluhe permafrost region

The changes in hydrothermal dynamics under different underlying conditions are the important aspect of hydrological and ecological processes, and engineering stability in permafrost regions. This study monitored the temperature and moisture of soil at a depth range from 0 to 80 cm beneath the barren, alpine steppe, and alpine meadow at the Beiluhe Basin on the Qinghai–Tibet Plateau. The freezing and thawing process and hydrothermal dynamic changes were analyzed within the test range. In a year, the freezing and thawing process controlled the pattern of hydrothermal changes. The properties of ground surface affected the hydrothermal change process in various stages. In the freeze stages, moisture and the absolute value of ground temperature showed an exponential relationship. In the thawing stages, moisture may increase, decrease, or remain stable in different temperature ranges. This process is affected by precipitation, solar radiation, and so on. At a 0–30 cm depth range, moisture increased linearly with precipitation. At 0–20 cm depth range, precipitation had a significant effect on the ground temperature changes. With the same rainfall condition, the decline of ground temperature corresponds with solar radiation flux. Results confirmed that ground properties were important factors that control the soil moisture and temperature change in the permafrost region.