过去30a青藏高原东部多年冻土退化区地表水体变化特征OA

[Objective]As a region characterized by extensive permafrost,the Qinghai-Xizang Plateau has underg-one significant environmental changes under global climate change.Surface water dynamics serve as sensitive indi-cators of permafrost degradation.This study investigates surface water changes over the past 30 years in a typical permafrost degradation area of the eastern Qinghai-Xizang Plateau,distinguishes variations between permafrost and seasonally frozen ground zones,and analyzes their relationships with temperature and precipitation.[Methods]Landsat 5 and Landsat 8 satellite images from 1995 to 2024(August data only)were processed using Google Earth Engine(GEE)to remove clouds and high-reflectance interference through median-pixel compositing.An empirical annual mean ground temperature model,corrected for slope and aspect,was applied to classify permafrost and sea-sonally frozen ground zones.Surface water bodies were extracted using the Normalized Difference Water Index(ND-WI)with an Otsu global-local thresholding method.The results were further refined using slope and hillshade data derived from the ASTER Global Digital Elevation Model(GDEM).Surface water bodies were classified by area into four categories:≤0.001,(0.001,0.01],(0.01,1],and(1,100]km2.Monthly temperature and precipitation data from local meteorological stations were used to analyze correlations with water body metrics.[Results]Permafrost and seasonally frozen ground zones accounted for approximately 63％and 37％of the study area,respectively,with a classification accuracy of 88.1％as confirmed by field surveys.Between 1995 and 2024,the total number of water bodies increased by 40％,mainly driven by small water bodies(≤0.01 km2),while the total water surface area expanded by 29％,dominated by large water bodies((1,100]km2).In permafrost zones,the number of water bodies increased by 85％,primarily due to small water bodies formed by thaw-induced subsidence,whereas the ar-ea increased by 28％.Seasonally frozen ground zones showed a moderate 16％increase in the total number of water bodies and a 28％increase in area,largely attributable to larger water bodies.Correlation analysis revealed signifi-cant positive relationships between temperature and water body metrics(r＞0.75),with smaller water bodies exhibi-ting the highest temperature sensitivity.Conversely,precipitation generally had weak or negative correlations with water dynamics,particularly in permafrost zones,where heavy rainfall often promoted drainage and lake outflow.Seasonally frozen ground zones showed limited sensitivity to precipitation due to higher infiltration rates.[Conclu-sion]Rising temperatures primarily drive the expansion of surface water,exceeding the effects of precipitation.Permafrost zones are highly sensitive to warming,as indicated by rapid increases in small water bodies,whereas seasonally frozen ground zones maintain stable water body counts with area expansion driven by larger lakes.Precip-itation plays a secondary or even negative role in water dynamics.The distinct responses of water bodies under dif-ferent freeze-thaw conditions highlight the complexity of hydrological changes driven by climate warming,providing crucial insights for future environmental predictions and resource management on the Qinghai-Xizang Plateau.