摘要
多年冻土对气候变化极为敏感,其冻融过程直接影响青藏高原的生态环境与工程稳定性。本文基于青藏高原长江源地区九个不同局地因素条件场地(涵盖不同土壤含水量、植被盖度及坡向)2016年9月—2024年8月的观测数据,讨论了气温、近地表温度及冻融循环的动态变化特征,分析了不同局地因素条件下冻融侵蚀强度的空间差异和时间变化特征。结果表明:(1)研究区气温整体呈轻微升温趋势(0.08℃·a^(-1)),而近地表温度增温更为显著(0.16℃·a^(-1)),冻融循环在高含水量和高植被覆盖下更频繁;(2)冻融侵蚀强度整体呈现从“强烈侵蚀”向“中度侵蚀”的减弱趋势,且受局地因素强烈调控,其中高含水量会加剧侵蚀,高植被覆盖度则能有效削弱侵蚀,沙层覆盖和阳坡条件下的侵蚀最为剧烈;(3)土壤可蚀性和植被盖度是影响近地表冻融侵蚀强度的关键因子,其作用强于坡向差异。本研究揭示了局地尺度下局地因素对冻融过程和侵蚀强度的调节作用,可为青藏高原冻融侵蚀风险评估与生态环境保护提供科学支撑。
Freeze-thaw erosion represents a critical geomorphic process in the permafrost regions of the Qinghai-Xizang Plateau,where pronounced near-surface hydrothermal gradients and heterogeneous microenvironments jointly regulate soil thermal regimes,freeze-thaw cycling,and erosion intensity.However,existing regionalscale assessments,typically based on kilometer-scale datasets,fail to adequately capture microenvironmental variations relevant to engineering and ecological stability.Long-term observations from September 2016 to August 2024 were collected at nine sites in the source area of the Yangtze River,representing different local environmental conditions and covering a range of soil water contents,vegetation cover,and slope aspect.Based on this,the dynamic variations of air temperature,near-surface ground temperature,and freeze-thaw cycles were investigated,and the spatial heterogeneity and temporal evolution of freeze-thaw erosion intensity under different local environmental conditions were analyzed.The results showed that:(1)Air temperature exhibited a slight warming trend(0.08℃·a^(-1)),while near-surface ground temperature increased more markedly(0.16℃·a^(-1)),with freeze-thaw cycles occurring more frequently under higher soil water content and denser vegetation cover.(2)Freeze-thaw erosion intensity showed an overall weakening trend,shifting from severe erosion toward moderate erosion,and was strongly regulated by local environmental conditions.Specifically,high soil water content enhanced erosion,while high vegetation cover mitigated it.The most intense erosion occurred on sandy surfaces and south-facing slopes.(3)Soil erodibility and vegetation cover were identified as the key factors controlling near-surface freeze-thaw erosion intensity,exerting stronger effects than slope aspect.These findings highlight the regulating role of local environmental conditions in freeze-thaw processes and erosion intensity,providing scientific support for freeze-thaw erosion risk assessment and ecological conservation on the Qinghai-Xizang Plateau.
作者
李诺成
林战举
谷强
范星文
李文娇
王旭辉
王雁鹤
LI Nuocheng;LIN Zhanju;GU Qiang;FAN Xingwen;LI Wenjiao;WANG Xuhui;WANG Yanhe(State Key Laboratory of Cryospheric Science and Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Xining Natural Resources Comprehensive Survey Centre,China Geological Survey(CGS),Xining 810000,China)
出处
《冰川冻土》
2025年第5期1290-1304,共15页
Journal of Glaciology and Geocryology
基金
甘肃省科技重大专项计划项目(22ZD6FA004)
冰冻圈科学与冻土工程全国重点实验室自主部署项目(CSFSE-ZZ-2401)
青海重点研发与转化计划-科技援青项目(2025-QY-225)资助。
关键词
青藏高原
长江源
多年冻土
近地表
冻融侵蚀强度
Qinghai-Xizang Plateau
source area of Yangtze River
permafrost
near-surface
freeze-thaw erosion intensity
