Primary analysis on distribution characteristics of permafrost in the upper area of the Shule River Watershed, on the northeastern edge of the Qinghai-Tibetan Plateau

Taking the upstream of the Shule River Watershed, on the northeastern edge of the Qinghai-Tibetan Plateau in China as the study area, a primary analysis on the effects of influencing factors on the distribution of permafrost was carried out. Relationships between the ground temperatures of permafrost and the geographical and topographic factors longitude, latitude, elevation, slope and aspect were analyzed using the statistical method. An empirical-statistical model to be used to modeling the distribution of permafrost was developed, which took the factors latitude, elevation, slope and aspect as input variables, and the ground temperatures of permafrost as the output variable. Results of the calculation indicated that 83% of the upstream was underlain by the perennially frozen ground and the rest 17% by the seasonally frozen ground. Classify permafrost based on the calculated temperatures into four types: low-temperature permafrost (GT ≤-2°C), middle-temperature permafrost (-2°C<; GT ≤-1°C), high-temperature permafrost (-1°C<; GT ≤-5°C) and extremely-high-temperature permafrost (-0.5°C<; GT ≤0°C). Areal percentages of each type were 38%, 23%, 14%, and 8% in order.