1990—2020年那曲地区冰湖变化研究

基于Landsat遥感影像，采用目视解译的方法提取了青藏高原内部那曲地区冰湖和冰川1990、2000、2010及2020年4期边界数据，并分析近30年来该地区冰湖变化的特征与原因．结果表明:那曲地区现有冰湖255个，总面积（27.829±4.62） km2，冰湖主要集中在东南部，其次是西南部；1990—2020年，研究区新增冰湖72个，面积增长6.14 km2；冰湖扩张趋势明显，具体表现为低海拔地区（≤4 700 m）原有冰湖快速扩张，较高海拔地区（>5 100~5 700 m）新增冰湖集中出现；气温与降水是冰湖变化的关键因素，由于降水与气温分布及变化存在时空差异，冰湖变化呈现“南快北慢，逐期加快”的特征；冰湖与冰川的位置关系也会影响冰湖变化，离冰川位置越近，对冰湖发育越有利，同时与冰湖接触的冰川退缩速率相较于其余冰川有更大的退缩速率，但冰川与冰湖面积变化速率并无明显相关性． 

Changes in Glacial Lakes in Naqu from 1990 to 2020

Due to global warming and retreat of glaciers in recent years, the number and total area of glacial lakes in Qinghai-Tibet Plateau have increased rapidly, leading to increased frequency of glacial lake outburst floods (GLOF), threatening people’s property and livelihood in downstream regions．Remote sensing images from Landsat were subject to visual interpretation, to obtain the boundary of glacial lakes and glaciers in Naqu in 1990, 2000, 2010 and 2020．Characteristics and reasons for change in glacial lakes in Naqu in the past 30 years were then analyzed．A total of 255 glacial lakes were identified in Naqu, with a total area of (27.83 ± 4.62) km2．Glacial lakes were concentrated in the southeast and southwest of Naqu．Noticeable expansion of glacial lakes was found from 1990-2020, total number of glacial lakes increased by 72, and total surface area increased by 6.14 km2．Original glacial lakes expanded rapidly in the low altitude region (≤4700 m), newer glacial lakes were distributed in high altitude area (>5100-5700 m)．Temperature and precipitation were critical factors in the expansion of glacial lakes．Due to spatial and temporal differences in temperature and precipitation in Naqu, expansion of glacial lake was faster in the south, compared to the north, expansion rate of the whole region accelerated gradually．The location of glacial lakes could also affect the process of expansion．A closer distance of a glacial lake to the glacier favors its development．Glaciers connected to lakes shows higher melting rate．No evidence was found for a linear relationship between glacier and glacial lake area change．