Orginal Article

# 近46年松木希错流域冰川和湖泊变化及原因分析

1. 商丘师范学院环境与规划学院,商丘 476000
2. 中国科学院青藏高原研究所,北京 100085

# Glaciers and lake changes (1968-2013) and their causes in the Songmuxi Co Basin, Northwest Tibetan Plateau

LI Zhiguo12, LU Jie1, SHI Benlin1, LI Hongzhong1, ZHANG Yanwei1, LI Lin1

1. Shangqiu Normal University, Shangqiu 476000, Henan, China
2. Institute of Tibetan Plateau Research, Beijing 100085, China

Abstract

The Tibetan Plateau and its surroundings contain the largest number of glaciers outside the Polar Regions and are known as the world's "third pole". Glacial and lake changes in the third pole not only lead to changes in atmospheric circulation patterns in the region and the northern hemisphere but also affect agriculture, power generation and the water supplies of 1.5 billion people in the surrounding areas across ten countries. Hence, the situation of the glaciers and lakes of the third pole has attracted attention worldwide. While the Himalaya glaciers are largely retreating, the recent evolution of the Karakoram glaciers, widely acknowledged as peculiar, remains poorly understood. Glacial lakes showed a trend of expansion and the great lakes were shrinking in the Himalayas; but lakes in the Karakoram were considered stable. The causes and mechanisms of the complex and regionally heterogeneous behavior of glacier and lake change between the Karakorum and Himalayas are poorly understood. The Songmuxi Co Basin lies in the transitional zone between the Karakorum and Himalayas, and the glaciers and lakes have a significant impact on the local water supply and ecosystem. In this work, glacial and lake changes in the Songmuxi Co Basin, southern Karakoram Mountains were detected based on 1:50000 topographic maps, Landsat MSS/TM/ETM+/OLI remote sensing data and GIS techniques. The annual temperature, precipitation, potential annual evaporation at Shiquanhe, Hetian and Yutian stations from 1968 to 2013 were used to analyze climate change and its impact on glaciers and lakes area change. The results can be drawn as follows. (1) From 1968 to 2013, the total glacier area decreased from 139.25 km2 to 137.27 km2, a total loss of 1.98 km2, or 1.42% of the entire glacial area in 1968. In addition, there has been an accelerating trend of glacier retreat since 2001. (2) The area of Songmuxi Co expanded from 25.05 km2 in 1968 to 32.62 km2 in 2013. The overall increase was 7.57 km2, which was 30.22% of the lake area in 1968. The lake area expansion and glaciers retreat have a good coupling on a decadal scale. (3) From 1968 to 2013, the decreased potential evapotranspiration in the lake and increased precipitation are of the first and second factors which lead to lake area expansion. The increase in melt water from glaciers and frozen soil due to climate warming had no great impact on lake area expansion on the interannual scale while it may had some impact on the decadal one.

Keywords： glacier ; lake ; climate change ; Songmuxi Co

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LI Zhiguo, LU Jie, SHI Benlin, LI Hongzhong, ZHANG Yanwei, LI Lin. Glaciers and lake changes (1968-2013) and their causes in the Songmuxi Co Basin, Northwest Tibetan Plateau[J]. 地理研究, 2015, 34(11): 2095-2104 https://doi.org/10.11821/dlyj201511008

## 2 研究区概况

Fig. 1   Location of the Songmuxi Co Basin

## 3 数据来源与研究方法

### 3.1 遥感数据来源

Tab. 1   Data sources in this study

MSS157/0361976/11/2076 m
TM145/0361991/11/17、2010/11/13、2011/11/0928.5 m
ETM+145/0362001/10/20、2002/11/24、2005/11/16、2006/11/03、2007/11/03、2008/11/08、2013/01/06、2013/03/11、2013/04/20、2013/06/07、2013/07/0928.5 m
ETM+146/0362000/10/03、2003/10/17、2004/11/04、2009/11/02、2013/01/29、2013/05/2128.5 m
OLI145/0362013/08/01、2013/09/11、2013/09/1830 m
OLI146/0362013/09/27、2013/11/05、2013/11/3030 m

### 3.3 精度评价

Tab. 2   Glacier area variation in the Songmuxi Co Basin from 1968 to 2013

(km2)

1968139.25
1976139.22±0.007-0.03±0.007-0.004-0.02-0.003
1991138.71±0.013-0.51±0.013-0.034-0.37-0.03
2001138.38±0.016-0.33±0.016-0.033-0.24-0.02
2013137.27±0.02-1.11±0.02-0.093-0.80-0.07

Tab. 3   Lake extent change of Songmuxi Co from 1968 to 2013

196825.05
197625.62±0.0070.57±0.0070.0712.280.28
199125.86±0.0130.24±0.0130.0160.960.06
200128.74±0.0162.88±0.0160.28811.501.05
201332.62±0.023.88±0.020.32315.491.29

Tab. 4   Monthly lake extent change of Songmuxi Co in 2013

## 4 结果分析

### 4.2 湖泊面积变化

1 $∶$5万地形图数字化结果表明,1968年松木希错面积为25.05 km2,2013年面积为32.62±0.02 km2,湖泊规模不断扩张,共增加7.57 km2,扩张百分比为30.22%（表3）。具体而言,松木希错面积先由1968年的面积增大至1976年的25.62 km2,年平均扩大速率为0.071 km2·a-1;1976-1991年进入缓慢扩张时期,年平均扩张速率为0.016 km2·a-1。1991年之后,松木希错进入快速扩张时期,1991-2001年、2001-2013年分别扩张2.88 km2和3.88 km2,面积平均扩张速率分别为0.288 km2·a-1、0.323 km2·a-1,扩张速率越来越快。2001-2013年面积平均扩张速率分别为1968-1976年、1976-1991年和1991-2001年面积平均扩张速率的4.5倍、20.2倍和1.1倍。

## 5 讨论

### 5.1 气候变化对冰川、湖泊变化的影响

5.1.1 气候变化对湖泊变化的影响 研究中采用狮泉河站、和田站和于田站3个气象台站的年平均气温（T）、年降水量（P）和年潜在蒸散量（PAE）数据进行分析,AW、MW和MPAE分别指T、P和PAE多年（1968-2013年）平均值,T1、T2、T3和T4分别指1968-1976年、1976-1991年、1991-2001年和2001-2013年四4个阶段气温的平均值,年降水量和年蒸散量4个阶段的平均值标号与此类似（图2）。

Fig. 2   Variations in the annual mean temperature, precipitation and potential annual evaporation at Shiquanhe, Hetian and Yutian stations from 1968 to 2013

1968-2013年,狮泉河站、和田站和于田站3个气象台站年平均气温均呈增加趋势,斜率分别为0.052℃·a-1R²=0.5522）、0.048℃·a-1R²=0.5809）和0.054℃·a-1R²=0.1831）。其中狮泉河站与和田站在1968-1976年、1976-1991年、1991-2001年和2001-2013年四个阶段的平均气温呈持续上升趋势,但于田站1968-1976年、1976-1991年为下降,而1991-2001年、2001-2013年为上升阶段（图2）。升温可能导致冰川、冻土的消融,增加融水对湖泊的补给。

1968-2013年,三站中仅狮泉河站年降水量呈下降趋势,斜率为-0.423 mm·a-1R²=0.0352）;和田、于田两个台站均呈增加趋势,斜率分别为0.476 mm·a-1R²=0.0594）、0.547 mm·a-1R²=0.0453）（图2）。将图2表3对比,可以发现和田站和于田站降水变化与松木希错面积变化具有很好的一致性,这可能与流域主要受西风环流控制有关;而狮泉河站的降水变化与松木希错面积变化不具有协同性,可能源于狮泉河站与流域间的熊彩岗日地区山体高大有较强的阻隔作用造成降水方面的差异性。

Fig. 3   Lake area change and variations of the annual mean temperature, precipitation and potential annual evaporation at Shiquanhe, Hetian and Yutian stations from 2000 to 2013

Tab. 5   The linear regression of the lake area and climatic factors at the three stations from 2000 to 2013

y湖泊面积=-0.478x狮泉河年平均温度+30.8730.189
y湖泊面积=0.899x和田年平均温度+17.6030.131
y湖泊面积=-0.050x于田年平均温度+30.6820.000
y湖泊面积=0.004x狮泉河年降水量+29.7830.012
y湖泊面积=0.001x和田年降水量+30.0000.001
y湖泊面积=0.006x于田年降水量+29.7110.036
y湖泊面积=0.011x狮泉河年潜在蒸发+16.8410.163
y湖泊面积=-0.002x和田年潜在蒸发+32.4010.002
y湖泊面积=-0.011x于田年潜在蒸发+42.9690.128

Fig. 4   Lake area change and variations of the monthly mean temperature, precipitation and potential annual evaporation at Shiquanhe, Hetian and Yutian stations in 2013

5.1.2 冰川与冻土变化对湖泊变化的影响 狮泉河站、和田站和于田站3个气象台站年平均气温均呈增加趋势,那么可能会导致冰川和冻土的消融增加。对照表2表3可知,在较长时段上湖泊的面积加速扩张与冰川的加速消融相对应。表2中的冰川退缩数据说明该地区的冰川退缩较小,加之5.1.1节中证明于田站温度和湖泊面积扩张呈负相关关系,这样尽管在没有研究区冻土观测数据的情况下,也可推断冰川与冻土消融对湖泊水量的贡献不大,在年际尺度上无法体现。但在年代际尺度上,升温引起的冰川和冻土消融量增加对湖泊水量的贡献不容忽视。以表2中的数据结合Liu等[24]的经验公式V=0.034S1.43,来冰川消融量增加的贡献。冰的密度取0.9 g·cm-3,计算可得1968-1976年、1976-1991年、1991-2001年、2001-2013年冰川退缩贡献的水量分别为1.0×108 m3、1.9×108 m3、1.2×108 m3和4.0×108 m3。冻土方面虽然没有直接的数据,但考虑温度上升,冻土消融应该与冰川消融增加类似,会使湖泊水量有一定的增加。

## 6 结论

（1）1968-2013年,松木希错流域内冰川面积共减少1.98 km2,减少百分比为1.42%。而且,有两条小冰川消失,冰川自2001年开始呈现加速退缩状态,为1968-2013年平均退缩速率的2倍。

（2）松木希错面积在1968-2013年不断扩张,共扩张7.57 km2,扩张百分比为30.22%。研究发现松木希错面积扩张存在阶段性。松木希错先由1968年的25.05 km2增大至1976年的25.62±0.007 km2,年平均扩大速率为0.0713 km2·a-1;1976-1991进入缓慢扩张时期,年平均扩张速率为0.016 km2·a-1;自1991年,松木希错进入快速扩张时期,1991-2001年、2001-2013年分别扩张2.88 km2和3.88 km2,面积平均扩张速率分别为0.288 km2·a-1、0.323 km2·a-1,扩张速率明显加快。2001-2013年面积平均扩张速率分别为1968-1976年、1976-1991年和1991-2001年面积平均扩张速率的4.5倍、20.2倍和1.1倍。

（3）虽然尚无法从水量平衡角度量化松木希错湖泊水量变化及各输入输出要素变化的贡献值,但经过分析认为松木希错湖泊动态变化主要是由气候变化导致的,其中湖面潜在蒸散量减少和降水增加分别是导致湖泊近46年扩张的第一和第二影响因素,而升温引起的冰川、冻土融水增加有一定贡献,但影响较小且在年际尺度上不显著。由于研究区内缺乏气象、冰川物质平衡、湖泊水位和水深、河流水文、地下水、冻土等长期监测连续资料,因此本文的结论有一定的局限性,需要在未来增加站点监测,并卫星遥感数据进行深化研究。

The authors have declared that no competing interests exist.

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