羌塘自然保护区湖泊变化及其原因分析

Change of the Lakes in the Qiangtang Nature Reserve

选取西藏羌塘自然保护区MSS、TM、ETM+数据和1∶100 000地形图,以85°E为中心线,将研究区划分为东西两部分,解译该区域面积大于1 km2的所有湖泊。结果表明:1975—1990年,羌塘自然保护区湖泊呈退缩状态,湖泊个数由388个减少为277个,面积由6 603.3 km2减少到5 539.7 km2,面积减少达16.1%;2005年,湖泊个数比1990年增加164个,达441个,湖泊总面积9 652.2 km2,比1990年增加4 112.5 km2,增幅74.2%。在区域上,表现为东部变化幅度大于西部。同时,重点分析了研究区附近的狮泉河、改则、班戈、申扎、那曲、安多6个气象站1978—2007年的数据。结果显示:6个代表气象站年平均气温、年平均最高气温、年降水量均呈上升趋势,其中东部上升幅度较大,西部变化不明显;年蒸发量呈减少趋势。降水是影响湖泊变化最主要的因素。

Based on the MSS data in the 1970s, TM data in the 1990s and ETM data at the beginning of the 21st century in the Qiangtang Nature Reserve in Tibet, in this paper the area and spatiotemporal variation of the lakes larger than 1 km2 in the nature reserve were interpret with remote sensing analysis. The results show that the lakes in the Qiangtang Nature Reserve were in a shrinkage during the period from 1975 to 1990, their number was de- creased from 388 to 277, their total area was reduced from 6 603.3 km2 to 5 539.7 km2（ reduced by 16.1% ）, but thereafter until 2000, area of the lakes was enlarged dramatically. Number of the lakes was increased by 164 and to 441, total area of the lakes was enlarged to 9 652.2 km2 and by 4 112.5 km2 （ enlarged by 74.2% ） compared with that in 1990. Regionally, change of the lakes in the east was significantly higher than that in the west. The average daily and monthly temperature, average monthly maximum and minimum temperature, monthly precipitation and e- vaporation at 6 meteorological stations including Shiquanhe, Gaize, Bange, Shenza, Naqu and Anduo were ana- lyzed, and the results revealed that the temperature at the 6 stations was increased; precipitation was significantly increased in the east, and its change was not significant in the west; annual evaporation was in a decrease trend. It is considered that precipitation was the most important factor affecting the change of the lakes, and then temperature and evaporation.