Evaluation of Freeze–Thaw Erosion in Tibet Based on Cloud Model

Abstract

Traditionally, studies on freeze–thaw erosion have used the analytic hierarchy process (AHP) to calculate the weight of evaluation factors, however, this method cannot accurately depict the fuzziness and randomness of the problem. To overcome this disadvantage, the present study has proposed an improved AHP method based on the cloud model to evaluate the impact factors in freeze–thaw erosion. To establish an improved evaluation method for freeze–thaw erosion in Tibet, the following six factors were selected: annual temperature range, average annual precipitation, slope, aspect, vegetation coverage, and topographic relief. The traditional AHP and the cloud model were combined to determine the weight of the impact factors, and a consistency check was performed. The comprehensive evaluation index model was used to evaluate the intensity of freeze–thaw erosion in Tibet. The results show that freeze–thaw erosion is extensive, stretching over approximately 66.1% of Tibet. The problem is the most serious in Ngari Prefecture and Nagqu. However, mild erosion and moderate erosion, accounting for 37.1% and 25.0%, respectively, of the total freeze–thaw erosion are the most widely distributed. The evaluation results for the freeze–thaw erosion was confirmed to be consistent with the actual situation. In brief, this study provided a new approach to evaluate the conditions of freeze–thaw erosion quantitively in Tibet.

Evaluating the sensitivity and influential factors of freeze-thaw erosion in Tibet, China

“…One of the serious hazards caused by Freeze-thaw changes is Freeze-thaw erosion. Freeze-thaw (FT) erosion refers to soil erosion resulting from FT alteration in slopes, trench walls, riverbeds, and canals in permafrost (Zhang et al, 2007;Hu et al, 2019). It mostly occurs at high latitudes and altitudes during late winter and early spring periods.…”

Evaluation of freeze–thaw erosion in Tibet based on the cloud model

“…According to the third national soil erosion remote-sensing survey data, the soil erosion area of 4.8474 million km2, of which freeze-thaw erosion accounts for 1.2782 million km2, is 13.31% of the total land area in China. It occurs mainly in the Northeast China, Northwest plateau, Qinghai-Tibet Plateau region [6][7][8]. In addition, the freeze-thaw erosion in Tibet is the most serious and extensive.…”

“…Sun et al summarized the effects of freeze-thaw on the physical and chemical properties of soil, wind erosion, and water erosion [25]. Jing et al discussed the definition, types, and characteristics of freeze-thaw erosion, and they used AHP to explore the distribution and characteristics of freeze-thaw erosion in Heilongjiang Province [6,8,26]. Using geographic information system (GIS) technology, Zhang et al analyzed and evaluated the freeze-thaw erosion in Sichuan Province [27].…”