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

Junfu Fan,Jiahao Chen,Liusheng Han,Yuke Zhou,Xiao Yu,Taoying Hu

doi:10.1007/s11707-021-0873-1

Abstract

Freeze–thaw erosion can lead to accelerated soil loss, which is an important factor related to soil erosion in cold regions. Tibet is a typical region that is seriously affected by freeze–thaw erosion. Traditionally, the analytic hierarchy process (AHP) method is used to calculate the weight of the factors in evaluations of freeze–thaw erosion, but this method cannot accurately depict the fuzziness and randomness of the problem. To overcome this disadvantage, this study proposed an improved AHP method based on the cloud model for the evaluation of the factors impacting freeze–thaw erosion. To establish an improved evaluation method for freeze–thaw erosion in Tibet, the following six factors were selected: mean annual air temperature, mean annual ground surface temperature, average annual precipitation, aspect, vegetation coverage, and topographic relief. The traditional AHP and the cloud model were combined to assign the weights of the impacting 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. Moreover, mild erosion and moderate erosion are the most widely distributed erosion intensity levels, accounting for 36.4% and 34.4% of the total freeze–thaw erosion, respectively. The intensity of freeze–thaw erosion gradually increased from slight erosion in the northwest to severe erosion in the southeast of the study region. The evaluation results for the intensity and distribution of freeze–thaw erosion in Tibet were confirmed to be consistent with the actual situation. In brief, this study supplies a new approach for quantitatively evaluating the intensity of freeze–thaw erosion in Tibet.

Highlights

Freeze–thaw erosion occurs mainly in cold and high-latitude or high-altitude regions because of temperature changes [1]
Sun et al [53] summarized the natural factors that contribute to freeze–thaw erosion: (1) temperature, given that the annual average ground temperature and ground temperature range in the region are decisive; (2) soil texture and soil moisture content; (3) vegetation, which can mitigate some of the effects; and (4) terrain and aspect, which have an influence on the type and degree of erosion
The operability and relevance of the pertinent indicators was considered on the basis of previous studies, and the freeze–thaw erosion evaluation system was constructed in relation to the following six indicators: annual temperature range, average annual precipitation, slope, aspect, vegetation coverage, and topographic relief

Summary

Introduction

Freeze–thaw erosion occurs mainly in cold and high-latitude or high-altitude regions because of temperature changes [1]. The third most frequently occurring type of erosion after water and wind erosion [4,5], freeze–thaw erosion is common in the areas of soil erosion in China It is found mainly in the permafrost region at high altitudes, high latitudes, and extreme cold. According to the third national soil erosion remote-sensing survey data, the soil erosion area of 4.8474 million km, of which freeze–thaw erosion accounts for 1.2782 million km, 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]. Increased attention to the prevention and treatment of freeze–thaw erosion and the protection of Tibet’s ecological environment is important

Methods

Results

Conclusion