青藏高原东南缘地貌差异性成因分析——以雅江地区为例  

Analysis of morphological variability on the southeastern Tibetan Plateau and its causes: A case study of the Yajiang area

作　　者：李阳阳 杨蓉[1,2] 徐陈超 LI Yangyang;YANG Rong;XU Chenchao(Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province,School of Earth Sciences,Zhejiang University,Hangzhou 310058,China;Structural Research Centre of Oil and Gas Bearing Basin of Ministry of Education,Hangzhou 310058,China)

机构地区：[1]浙江省地学大数据与地球深部资源重点实验室,浙江大学地球科学学院,杭州310058 [2]教育部含油气盆地构造研究中心,杭州310058

出　　处：《第四纪研究》2025年第1期117-131,共15页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41961134031)资助。

摘　　要：青藏高原东南缘雅砻江流域中段的雅江地区发育有低起伏的高原面,区域雅砻江支流长度及流域面积、高原面几何形态空间上呈现较大差异。为了揭示这一地貌差异性成因,本研究基于12.5 m的DEM地形数据提取该区域33个水系流域、计算其河流地貌相关特征参数(陡峭指数、χ、起伏度等)并进行地貌数值模拟,综合计算、模拟结果及进一步分析认为,在流域盆地内岩性、降水、构造条件都无显著差异下,由于雅江地区流域分水岭两侧地形起伏度具有空间差异性,导致分水岭迁移速率不同,促使河流塑造地貌能力存在差异,从而造成雅江地区地貌的差异性。分水岭两侧地形起伏度的差异是控制分水岭迁移的关键因素,且迁移速率与跨分水岭两侧地形起伏度差具有正相关性,同时分水岭在迁移过程中具有动态反复特征,瞬时迁移方向与长期迁移方向可能相悖。The Yajiang region in the middle section of the Yalong River drainage basin on the southeastern edge of the Tibetan Plateau features a gently undulating plateau surface.There are significant differences in the lengths of tributaries,basin areas,and geometric shapes of plateau surfaces in this region.To reveal the causes of these geomorphic differences,this study utilizes 12.5-meter DEM terrain data to extract the 12 watersheds from the Yalong River and 21 watersheds from its tributary,the Liqiu River.Then,we calculate river geomorphic parameters(channel steepness index,Chi,relief and slope),and conduct geomorphic numerical simulations using TopoToolbox Landscape Evolution Model.In the absence of significant differences in lithology,precipitation,and tectonic conditions within the basin,theχvalues on both sides of the watershed exhibit spatial variability and indicate that the watershed is in a state of disequilibrium.Additionally,the terrain relief on both sides of the watershed also shows spatial differences.The geomorphic numerical simulations further suggest that the difference in terrain relief on both sides of the watershed is a key factor controlling watershed migration.Moreover,the migration rate is positively correlated with the difference in terrain relief between the two sides of the watershed.Additionally,the watershed exhibits dynamic and repetitive characteristics during the migration process,and the instantaneous migration direction may contradict the long-term migration direction.Through comprehensive these analyses,we suggest that the spatial differences in terrain relief on both sides of the watershed in the Yajiang region lead to different rates of watershed migration.This discrepancy prompts variations in the river's geomorphic shaping ability,thereby causing differences in the geomorphology of the Yajiang region.

关 键 词：青藏高原东南缘 雅江地区 地貌演化 分水岭迁移 溯源侵蚀 数值模拟 

分 类 号：P534.63[天文地球—第四纪地质学] P512.31[天文地球—古生物学与地层学] P931.2[天文地球—地质学]