Based on Landsat TM/ETM+/OLI remote sensing images in the period from 2000 to 2014,the vectorized boundary of 111 lakes with areas greater than 10 km2 in northwest China were obtained by artificial visual interpretation technology and the causes of lake variations were analyzed.Several conclusions can be drawn from the present study:(1)From 2000 to 2014,the lakes in northwest China have expanded,with lake areas increasing from 1.58 × 104 km2 to 1.74 × 104 km2.(2) The lakes showed an overall expansion trend;however,several regional differences were noted and,thus,as shown in the figure 4,the study area could be divided into five sub-regions based on changes in the area of the lakes.The lakes in northern Xinjiang Uygur Autonomous Region and southern Qinghai Province remained stable.The lakes showing an expanding trend were widely distributed in the Inner Mongolia-Xin Jiang Lake Zone and the Tibetan Plateau Lake Zone.This region from west to east included the Tarim Basin,northern piedmont of Kunlun Mountains,Altun Mountains,Hoh Xil,Qaidam Basin,southern piedmont of Qilian Mountains,and the northern Three-River source region.The lakes that were shrinking were primarily located in two regions that consisted of the central northern Xinjiang including Junggar Basin and the Turpan Depression,and the northern Karakorum Mountains.(3) The reasons behind the lake area changes in the different regions differed owing to the complex environment in the study area.For the region where the lakes were expanding,an increase in precipitation and melt water from glaciers and frozen soil due to climate warming were the dominant factors behind the changes.The state of glacier mass balance and human activities played an important role in the region where the lakes were shrinking in area,while in the region where the lakes remained stable,the topographic characteristics of the lakes such as intensive hydraulic connection between lakes and rivers were the main factors behind the observed results.%以2000-2014年Landsat TM、ETM+以及OLI影像为基础,通过人工目视解译方法提取我国西北地区111个面积10.0 km2以上湖泊矢量数据,并对湖泊面积变化总体趋势、空间分异特征以及成因进行分析.结果表明:(1) 2000-2014年期间,西北地区湖泊总面积呈整体增加的态势,由1.58×104 km2增加为1.74×104 km2.(2)在研究时段内,我国西北地区湖泊面积在整体增加的同时也表现出明显的空间差异.根据湖泊面积变化不同,研究区可以被划分为稳定、扩张、萎缩3种类型和5个区域:新疆维吾尔自治区北部与青海省南部为湖泊面积稳定区;塔里木盆地、昆仑山北麓、阿尔金山、柴达木盆地、可可西里地区、祁连山南麓至三江源北部大片区域为湖泊面积扩张区;由准噶尔盆地和吐鲁番盆地组成的北疆中部地区和喀喇昆仑山北坡山区为湖泊萎缩区.(3)受研究区复杂的自然人文环境影响,在不同区域引起湖泊面积变化的原因不尽相同:总体而言,降水增加、气温上升导致的冰川融水增加和冻土水分释放是湖泊面积呈现扩张趋势地区的最主要原因;在湖泊面积稳定区,湖泊所处的地形条件以及湖泊与河流间强烈的水量交换起着关键作用;日益增强的人类活动是湖泊萎缩区的主要影响要素,但在喀喇昆仑山北坡地区,冰川物质平衡状态的变化也可能发挥着重要作用.
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