Simulation of Decadal Alpine Permafrost Distributions in the Qilian Mountains

Permafrost distribution, as one of the physical geographical factors being sensitive to temperature, and climate change, is one of the most important climatic and environmental indexes. In mid-latitude mountainous regions, alpine permafrost distribution has a great impact on the majority of surface processes, and is also one of the important regulatory factors of geomorphologic processes and ultimately pattern. Understanding the spatial distribution and changing condition of alpine permafrost can provide a scientific basis for predicting geomorphologic and landscape change rules.

Qilian Mountains is located in the northeastern part of the Qinghai–Tibet Plateau (QTP) in China. It comprises one of the most important alpine permafrost distribution regions for the QTP. Previous studies have presented alpine permafrost distribution in the Qilian Mountains at different scales and periods. But with global warming, it is very important to acquire the dynamic distribution of alpine permafrost during a long time series.

Model simulation is a useful way for investigating alpine permafrost distributions, because these distributions can not be dependent on filed surveying solely. Thus, researchers selected the Map of Snow, Ice and Frozen Ground in China at 1:4,000,000 as a bench-mark map to assign the values of the distribution probability of alpine permafrost, topographical and meteorological factors to the sample points. Based on the values at the sample points, Logistic Regression Model (LM) was constructed and then used to simulate the decadal alpine permafrost distributions in the Qilian Mountains from 1960 to 2009. Moreover, the changing conditions of alpine permafrost in the Qilian Mountains during each adjoining two decades, as well as over the past 50 years, had also been analyzed.

The result showed that LM simulation in this research not only decreases the dependency on the field survey data, but achieves dynamic simulation of alpine permafrost distribution. The simulated areas of alpine permafrost in 1960s, 1970s, 1980s, 1990s and 2000s are 10.7×10⁴ km², 9.8×10⁴ km², 10.0×10⁴ km², 8.5×10⁴ km² and 8.7×10⁴ km² respectively. Therefore, the distribution of alpine permafrost presents an overall degraded tendency with two slight fluctuations. This research provides an effective way for studying the dynamic simulation of alpine permafrost distribution in different periods.

The main findings of this study have been published on Cold Regions Science and Technology, 2012, 73: 32-40. The paper is also archived at http://www.sciencedirect.com/science/article/pii/S0165232X11002680.

Spatial distribution change of alpine permafrost in the Qilian Mountains over past 50 years (a. from 1960s to 1970s; b. from 1970s to 1980s; c. from 1980s to 1990s; d. from 1990s to 2000s; e. from 1960s to 2000s).