Analysis of the Characteristics of Glacier and Fluvial Interaction Valley in the Eastern Section of Tanggula Mountains
The analysis of valley cross section morphology is an important method to distinguish the effects of glaciers and rivers.The mathematical methods commonly used in the past include morphological ratio,quadratic term expression and power function model.A new method has emerged in recent years,which is the V-index method.In order to verify the effec-tiveness of these methods in distinguishing glacial and non-glacial areas(i.e.,areas of fluvial action),the ArcGIS 10.6 software is applied to extract 5 448 cross-sections from Bujiagangri area in the eastern part of Tanggula Mountains,and the cross-section morphology of whole valley and truncated valley is analyzed by Matlab software.The results are as follows.Firstly,in terms of V-index and b value in the power function model,the average value of whole valley and truncated valley in the glacial region is greater than that in the non-glacial region.For the c value and shape ratio in the quadratic polynomial model,the average values of whole valley and truncated valley in the glacial region are smaller than those in the non-glacial region.These statistical results show that the glacier area is closer to ″U″ shape in the transverse section of the valley,while the non-glacier area is closer to ″V″ shape.Secondly,the results of logistic regression analysis show that the V-index of trun-cated valley is the most accurate index to judge glacial and non-glacial areas,with a prediction accuracy of 62.0%.
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