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| Relationship between vertical zonality and spatial allocation of geological hazards in alpine glacial geomorphology |
| SHEN Yanjun1，2，PENG Jianbing1，CHEN Xing2，LI Zhenhong1 |
| (1. Department of Geological Engineering and Geomatics，Chang?an University，Xi?an，Shaanxi 710054，China；2. College of Geology and Environment，Xi?an University of Science and Technology，Xi?an，Shaanxi 710054，China) |
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Abstract Due to the large vertical drop，the alpine glacier geomorphology is affected by vertical climatic conditions and local hydrothermal environment，resulting in typical vertical zoning characteristics. As an external dynamic form of dynamic equilibrium instability of epigenetic lithosphere，geological hazards must be closely related to its endowment of tectonic geomorphology and climatic environment. Based on the geomorphological features and statistical analysis of geological disasters in the glacial geomorphology of the Tibetan Plateau，this paper combed the typical characteristics of vertical zonation and endowment of each geomorphological unit，and then constructed the spatial allocation relationship between vertical zonation and geological disasters in alpine glacial geomorphology. The main results are as follows：(1) Alpine glacial geomorphology can be divided according to“four lines”，such as snow line，ice line，rain line and alpine tundra line，and there is a significant difference in boundary height between continental and marine glacial geomorphology. (2) The planation surface is important provenance of geological hazards in alpine glacial geomorphology area，which is obviously different due to the difference of glacier type. Specifically，there are two-grade planation plane provenance areas on mountain top and plateau surface in continental glacier area，while there are three-grade planation plane provenance areas on mountain top，Piedmont erosion surface and river valley erosion surface in marine glacier area. (3) There are typical vertical zoning characteristics of geological disasters in alpine glacial geomorphology according to the boundary mark of “four lines”. According to the boundary of “four lines”，the mode of dynamic geological action and altitude can be divided into：ultra-high ice erosion type(above snow line/ice-rock interaction zone). There are four types: high erosion type(between snow line and ice line/ice-water-cuttings interaction zone)，middle freeze-thaw denudation type(near ice line/ice-water-soil interaction zone) and low precipitation erosion type(below the alpine tundra line/water-soil-biological interaction zone). (4) There is a certain chain amplification effect of geological disasters between different boundary zones. the representative chain assemblage relationships are as follows：① ice(snow) rock avalanche→glocial lake and outburst flood→strong replenishment type mud flow；② ice(snow) rock avalanche→ice and snow debris flow→barrier lake and mountain torrent；③ moraine accumulation landslide→ice and snow debris flow→strong replenishment mud flow. The study can provide a basic reference for the regional and zonal prevention and control of major engineering geological disasters such as Belt and Road Initiative and Sichuan-Tibet Railway.
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2023, Vol. 42 
