天山东段冰雪消融与产汇流水文过程—

引用本文

孙美平, 姚晓军, 李忠勤, 张明军. 天山东段冰雪消融与产汇流水文过程——以乌鲁木齐河源区为例. 69(7): 945-957
SUN Meiping, YAO Xiaojun, LI Zhongqin, ZHANG Mingjun. Hydrological process of glacier and snow melting and runoff in Urumqi River source region, eastern Tianshan Mountains, China. Acte Geographica Sinica, 69(7): 945-957 复制到剪切板

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天山东段冰雪消融与产汇流水文过程——以乌鲁木齐河源区为例

孙美平¹, 姚晓军¹, 李忠勤², 张明军¹

1. 西北师范大学地理与环境科学学院, 兰州 730070

2. 中国科学院寒区旱区环境与工程研究所冰冻圈科学国家重点实验室, 兰州 730000

作者简介：孙美平 (1981-), 女, 辽宁沈阳人, 讲师, 博士, 主要从事寒区水文过程与气候变化影响评估研究。 E-mail: sunmeiping1982@163.com

基金:国家科技支撑计划 (2012BAC19B07); 甘肃省高等学校科研项目 (2013A-018); 西北师范大学青年教师科研能力提升计划骨干项目 (NWNU-LKQN-12-20)

摘要

应用天山北坡乌鲁木齐河源区1号冰川、空冰斗和总控3个水文断面2011年5-9月每10 min实测水位数据、15 min的气温、降水数据、1号冰川消融及空冰斗区积雪观测数据,采用排除和不排除降水对冰雪消融产流影响的研究方法,系统分析了不同冰川覆盖率下水文断面冰雪消融特征及产汇流过程。结果表明：(1) 乌鲁木齐河源区3个水文断面流量昼夜差异明显,1号冰川水文断面白天径流大于夜晚径流,空冰斗和总控断面则相反;3个断面流量亦具有显著日变化过程,且流量峰值大小和到来的时间存在差异。(2) 在排除与不排除降水两种天气影响下,1号冰川最大流量滞后最高气温分别为1~3 h和0~1 h;空冰斗断面分别为10~16 h和13 h,总控断面分别为5~11 h和6~7 h,反映了1号冰川从消融产流到汇流时间最短,空冰斗积雪消融产流时间最长,总控位于二者之间,同时亦反映伴随降水过程冰雪融水汇流迅速,即从产流到汇流时间有一定的缩短。(3) 影响3个水文断面流量变化的因素不同,冰川区热量条件是影响1号冰川水文断面的关键,1号冰川在过去20余年间,冰内、冰下排水道变得更为单一,对融水的阻滞和贮存作用弱化,融水汇流过程变得更为迅速。(4) 冰川覆盖山区流域水文断面在冰川消融期的流量过程线变化及最大流量与最高气温时滞变化规律在一定程度上对于认识冰川覆盖率有差异背景下的流域下垫面水系演化、冰雪消融过程及水文断面径流补给具有重要的指示意义。

关键词: 冰雪消融; 产汇流; 水文过程; 乌鲁木齐河; 天山

Hydrological process of glacier and snow melting and runoff in Urumqi River source region, eastern Tianshan Mountains, China

SUN Meiping¹, YAO Xiaojun¹, LI Zhongqin², ZHANG Mingjun¹

1. Geography and Environment College of Northwest Normal University, Lanzhou 730070, China

2. State Key Laboratory of Cryosphere Science, Cold and Arid Regions Environmental and Engineering Research Institute, CAS, Lanzhou 730000, China

Fund:National Science-technology Support Plan Projects, No.2012BAC19B07; Scientific Research Project of Higher Learning Institution in Gansu Province, No.2013A-018; Project of Scientific Ability Promoting of Young Teachers of Northwest Normal University, No.NWNU-LKQN-12-20

Abstract

In this study, the hydrological processes were used to analyze the differences between the glacierized catchment and the non-glacierized catchment of the eastern Tianshan Mountains in the melting season (May-September) in 2011, from two perspectives in regard to and regardless of the influence of precipitation on discharge. The data included the observed hydrological data (10 minutes interval), meteorological data (15 minutes interval), glacier melting and snow observation materials from Urumqi Glacier No.1, Empty Cirque and Zongkong gauging sites in the Urumqi River source region. The results showed that there was difference in the discharge among three gauging sites. The daily discharge was more than the night value at Glacier No.1 gauging site, but it was on the contrary at Zongkong and Empty Cirque gauging sites. Moreover, the discharge at three gauging sites presented an obvious daily variation process, and their peak time points were different. With no consideration of precipitation, the delay time between the maximum discharge and the highest temperature was 1-3 h, 10-16 h and 5-11 h at Glacier No.1, Empty Cirque and Zongkong gauging sites, respectively. If the precipitation was taken into account, the corresponding delay time at three gauging sites was 0-1 h, 13 h and 6-7 h, respectively. The comparison proved that the duration from the discharge generation to confluence was the shortest in the glacierized catchment and the hydrological process became shorter along with the increase of precipitation. Factors influencing discharge change of three gauging sites were different. For Glacier No.1 station, the discharge change was mainly influenced by heat conditions in the glacierized region and the discharge showed an accelerated growth, when the temperature in the melting season was more than 5^oC. In comparison, it was found that the englacial and subglacial drainage channel of Glacier No.1 became simpler during the past 20 years. Its weaker retardant and storage on the glacier melting water resulted in the quick discharge confluence. The result also demonstrated the discharge curve and the lag time between the maximum discharge and the highest temperature could reveal the drainage system evolution and the process of glacier and snow melting in different glacier coverage to some extent.

Keyword: glacier and snow melting; runoff generation and confluence; hydrological process; Urumqi River; Tianshan Mountains

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1 引言

冰雪消融产汇流过程研究是冰川径流模拟中确定水文特征参数的前提, 亦是寒区水文研究的核心问题^{[1, 2, 3]}。冰雪融水产生于冰川和积雪区, 受下垫面差异影响, 融水在下垫面的存贮和流动过程亦不同^{[4, 5]}。目前, 国际上对于冰雪消融产汇流过程的研究主要包括应用染色示踪试验和基于水文气象观测数据的统计分析两种方法^{[6, 7, 8, 9, 10]}。如Schuler等于2000年在瑞士Unteraargletscher冰川通过投放染色示踪剂探测消融期冰下水系通道的水力状况、汇流速度和融水经冰下过程及到达水文断面时间^[7]。Hasnain等亦采用相同方法对印度Dokriani冰川开展了研究, 指出融水径流在7-8月中旬最大, 并认为流量变大主要与消融期冰川排水系统最发育有关, 9月份流量减少, 原因是这一时期冰下通道变窄形成慢速排水系统^[8]。Singh等应用统计分析方法, 对喜马拉雅山南坡Dokriani冰川和Gangotri冰川融水的汇流滞后效应及产汇流水文过程进行了较系统研究, 发现两条冰川在1996-1998年和2000-2003年最大流量滞后最高气温 (即最强消融期) 时间分别为3~6 h和4~7.5 h, 且滞后时间随着冰川消融逐渐缩短^[6]。

我国对于冰川消融区排水系统特征研究始于20世纪80年代末, 康尔泗在乌鲁木齐河源1号冰川 (以下简称为1号冰川) 开展了盐示踪试验, 发现投盐7个地点的冰川融水流到水文断面时间在7 min~2 h之间, 表明1号冰川冰内、冰下排水道较单一^[11]。在气候变暖背景下, 1号冰川呈加速退缩趋势^[12], 并在1993年分为东西两支冰川, 冰川面积、长度、物质平衡和平衡线高度都发生了显著变化, 其中平衡线高度由1959-1996年的4042 m上升至1997-2008年的4106 m^[13]。冰川平衡线高度的上升势必导致冰川粒雪区和积雪区面积减小以及冰川厚度减薄, 使得融水在冰川上的汇流过程相应发生变化, 进而影响冰川融水径流特征。诸如1号冰川在过去的20余年间冰川冰内、冰下排水系统是否亦发生了显著变化, 河源区其他2个水文断面的冰雪消融产汇流变化特征等问题亟需得到回答。为此, 我们通过对乌鲁木齐河源区3个水文断面 (1号冰川、空冰斗和总控) 2011年整个消融期 (5-9月) 高时间分辨率水文、气象数据及1号冰川消融与空冰斗的积雪观测资料分析, 探讨河源区不同冰川覆盖率下冰川和积雪消融的产流和汇流过程, 以期从微观层面认识乌鲁木齐河源区各种水文要素变化的物理机制, 从而为我国冰川径流模拟及冰川动力学过程研究提供参考。

2 研究区概况

乌鲁木齐河源区 (以下简称为乌河源区) 位于天山东段北坡, 流域山势高、坡降大, 最高点为天格尔II峰, 海拔4479 m。流域3600 m以上日均气温在0° C以下, 年平均降水量为337.5 mm, 除冰雪覆盖外, 主要是裸岩和倒石堆^[14]。早在上世纪50年代末, 中国科学院天山冰川观测试验站就在乌河源区布设了3个水文断面及相应的气象观测场 (图1), 开展了长期的冰川、水文和气象等要素观测^[15]。其中1号冰川水文断面位于1号冰川冰舌末端下游300 m处, 海拔3693 m, 用于监测1号冰川融水径流, 该水文断面控制流域面积为3.34 km², 流域近一半区域为冰川所覆盖。空冰斗位于1号冰川北侧, 冰斗四周斗壁环绕, 底部平缓, 呈围椅状, 长2 km, 宽1.5 km, 至全新世大暖期, 冰川完全消融, 冰斗空出, 现主要为冰川消退后发育的岩屑堆覆盖, 空冰斗水文断面位于空冰斗排水道上, 海拔3805 m, 控制流域面积1.68 km², 该水文断面主要用于观测融雪径流^[16]。总控水文断面架设在乌河源区大西沟和罗布道沟汇合处, 海拔3405 m, 用于监测河源区降水和7条冰川以及周围高山积雪总融水径流, 流域面积28.90 km², 总控流域既分布有冰川 (覆盖率为19.4%), 还有裸露基岩以及广泛发育的羊背岩和鼓丘等冰缘地貌。

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	图1 乌鲁木齐河源区位置与冰川分布 (底图为SPOT5影像, 获取日期为2005年9月7日)Fig. 1 The location of Urumqi River source region and the glacier distribution(the base map is the SPOT 5 image acquired on September 7, 2005)

3 数据与方法

3.1 数据

本研究所用的水文数据和气象数据均由中国科学院天山冰川观测试验站提供, 其中水文数据为乌河源区3个水文断面每10 min的水位数据, 时限为2011年整个消融期 (5-9月), 气象数据为同时段水文站附近自动气象站采集的每15 min气温、降水数据。其中流量数据先由Hobo自记水位计读出水位, 再由各水文断面水位— 流量关系曲线转换而得。

3.2 研究方法

(1) 排除降水对冰雪融水产汇流过程影响采用Singh等人提出的研究方法^[6], 即从2011年5-9月中挑选出连续几日晴天或降水量不超过2β mm的时段, 并分析这些时段内最大流量与最高气温出现的时间差。

(2) 不排除降水对冰雪融水产汇流过程影响采用Jobard和Dzikowski提出的分析方法^[17], 以每日为时间窗口, 对逐时流量— 气温做交叉相关 (Cross correlation), 分析径流同气温变化间的时滞关系, 计算方法如下：

$\begin{matrix} r_{xy} (k) = \frac{C_{xy} (k)}{σ_{x} σ_{y}} \end{matrix}$ (1)

$\begin{matrix} C_{xy} (k) = \frac{1}{n} \overset{n}{\sum_{i = 1}} (x_{i + k} - μ_{x}) (y_{i} - μ_{y}) \end{matrix}$ (2)

(3)

(4)

式中, x, y分别为气温与流量时序数据; μ _x, μ _y分别为气温与流量数据均值; σ _x和σ _y分别为这两时序数据的均方差, C_xy(k) 为气温和流量两时间序列在时滞k下的互协方差, n为1日内的样本数, 此处取值为24; r_xy(k) 表示时滞为k (取值为0, 1, 2, …, 20, 假设时滞不超过20 h) 时气温和径流的交叉相关系数, 变化范围在-1~1之间。对于逐日数据系列, 交叉相关系数r_xy(k) 最大值对应的k值即为当日径流相对于气温的时滞 (以下简写为Q-T时滞)。

4 结果分析

4.1 冰雪消融日变化

图2为1号冰川、空冰斗和总控3个水文断面在消融期实测的白天径流 (9-20时)、夜晚径流 (21-次日8时) 与日流量变化。显然, 这3个水文断面昼夜流量差异明显, 整体表现为1号冰川水文断面白天径流大于夜晚径流, 而空冰斗和总控断面则相反; 3个水文断面在6-8月白天和夜晚径流变化幅度远大于5月和9月, 且6-7月份昼夜流量差异最大。3个水文断面的流量亦具有显著日变化过程, 整体上呈现出从0时至23时流量由减少到增加再到减少的日变化周期。其中1号冰川水文断面最大流量出现时间在14-18时, 最小流量在8-10时; 空冰斗水文断面最大流量出现在23时— 次日凌晨1时, 最小流量在13-15时; 总控断面最大流量在21时— 次日凌晨1时, 最小流量出现在13-18时。3个水文断面最大流量与最小流量出现的月份也不同, 具体表现为1号冰川和总控2个水文断面最大流量出现在7月份, 空冰斗水文断面最大流量出现在6月份; 3个水文断面最小流量均出现在5月份, 由于1号冰川和空冰斗水文断面仅在5月下旬零星观测到径流且数据不连续, 因此没有在图2上加以表示。从各水文断面最小流量出现到最大流量出现的时间间隔 (表1) 来看, 1号冰川水文断面流量由“ 谷值” 到“ 峰值” 所需时间最短, 为5~8 h; 其次是总控水文断面, 时间间隔为7~8 h; 空冰斗水文断面最小流量至最大流量的平均时间间隔最长, 尤其是在7月份, 为12 h。此外, 在强烈消融期的7、8月份, 3个水文断面最小流量到最大流量需要的时间比消融初期 (5月) 和末期 (9月) 缩短了约1~3 h。Fountain和Walder的研究表明, 与积雪区和粒雪区相比, 水流速度在冰川区往往较大^[18]。如第2小节所述, 乌河源区3个水文断面控制流域下垫面状况差异显著, 随着1号冰川消融的进行, 冰川积雪区和粒雪区面积减小、冰川厚度减薄, 降低了积雪区和粒雪区的保水性能, 从而加速了融水在冰川上的平均传输速度, 这可解释1号冰川水文断面最小流量出现到最大流量出现时间间隔小于其他2个水文断面的原因。

表1 三个水文断面日最大流量和最小流量出现的时间及二者间隔时长 Tab. 1 The time and its duration that daily maximum and minimum discharge that occurred at the three gauging sites

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	图2 乌河源区2011年消融期3个水文断面 (a) 白天和夜晚径流对比及 (b) 日流量变化Fig. 2 The comparison of daytime and nighttime discharges and mean diurnal variation in discharge during the ablation season at the three gauging sites

4.2 冰雪融水的汇流滞后效应

为进一步明晰乌鲁木齐河源区冰雪消融产汇流特征与气温、降水之间的关系, 以下从排除降水和不排除降水影响两个角度分别对冰面汇流、融雪径流和高山汇流进行阐述。

4.2.1 冰面汇流冰面汇流是指1号冰川融水径流, 图3给出了该水文断面在2011年6-9月连续几日晴天流量和气温逐时变化。需要说明的是, 在消融初期5月份没有出现连续3天以上无降水的天气, 所以在分析中5月份没再考虑。从流量过程线变化可以发现, 在排除降水天气影响下, 1号冰川水文断面6-8月流量过程线相对比较平滑, 但到9月份, 流量过程线呈直线阶梯式波动变化。这在一定程度上较好地反映了1号水文断面控制流域下垫面的水系演化过程。如Hock等指出, 冰川融水的汇流滞后时间受积雪面积大小和排水系统强弱影响很大^[4]。在消融初期, 1号冰川表面上的积雪层首先开始消融, 并以数量众多的孔状形式向下传递热量, 同时洞与洞之间的区域也逐渐融化 (图4a)。随着气温升高、消融加强, 融化地带逐渐由冰舌末端地区向冰川海拔较高的地区迁移, 积雪面积减小, 积雪层变薄, 冰川开始大面积消融。实地观测发现, 在2011年8月2日, 1号冰川东支4055 m和西支4120 m以下区域的冰面完全暴露 (图4d), 此时冰川作用区的排水系统发育完善, 排水路径在粒雪区及冰川上变得逐渐稳定 (图4b), 冰雪融水和液态降水流动速度加快 (图4c), 冰川融水从产流到汇流时间越来越短, 流量线相应变得连续且平滑。到消融末期, 气温降低, 冰雪消融强度相应降低, 流量变小, 流域下垫面排水通道变窄或冻结, 冰川融水断断续续出现, 继而导致1号冰川水文断面流量过程线变得不再平滑。

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	图3 连续几日晴天里1号冰川水文断面流量 (实线)和气温 (虚线) 在各时刻的变化Fig. 3 Diurnal variation in discharge (solid line) and temperature (dashed line) of Glacier No.1 gauging site in the clear weather days

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	图4 1号冰川 (a) 东支消融花杆观测, (b) 东支消融区辐射观测, (c) 东支冰面消融观测及 (d) 2011年8月2日冰川全貌 (照片由王文彬、金爽提供)Fig. 4 Ablation stack observation (a), radiation observation (b) and surface ablation observation of east branch (c); the full view of Glacier No.1 (d) on August 2, 2011

从1号冰川水文断面流量和架设在该断面附近的自动气象站记录的气温变化上看, 在排除降水影响下, 该水文断面在6月份和9月份的Q-T时滞为1~3 h, 在消融中期的7月份, 最大流量和最高气温几乎同时出现, 而到强烈消融期的8月份, 流量日变化峰值较气温日变化峰值有所提前。通常, 冰川融水的流量峰值出现在最大融化量 (即最高气温) 之后的数小时内, 1号冰川流量峰值与气温峰值在8月份的这种异常现象主要与消融期冰川表面受到高含量冰尘影响有关。已有研究表明^{[19, 20]}, 随着冰川消融, 雪冰内气溶胶粉尘与冰碛物等杂质在冰川表面的聚集作用加强, 冰尘 (Cryoconite) 大量的积累降低了冰面反照率, 提高了冰川对辐射能量的吸收效率, 从而加剧了冰川消融。由图4c和图4d可知, 1号冰川在8月份表面污化现象十分严重, 这导致冰川表面在一定温度下就能快速消融, 从而使流量峰值提前。

在不排除降水影响下, 1号冰川水文断面在2011年消融期的Q-T时滞在1 h左右, 较排除降水影响下Q-T时滞缩短。在6月中旬前, Q-T时滞在4~18 h之间有少许分布 (图5), 反映出在消融初始阶段, 冰内冰下水系通道尚不发育, 冰川区产流到冰川末端水文断面需要的时间较长。而在7、8月份, Q-T时滞大部分为0 h, 即最大流量和最高气温同时出现, 表明在降水和高温并存的这两个月份是冰内及冰下水系通道最为发育的时段, 冰川消融速率达到峰值, 相应二者日最大互相关系数也大。此外, 日最大互相关系数变化与降水变化呈现为反向关系, 即在降水量大的当天或次日, 最大互相关系数小, 进一步说明在消融期虽然降水可在一定程度上缩短Q-T时滞, 但气温是影响1号冰川水文断面流量的关键要素, 这与孙美平等应用小波方差方法对1号冰川融水径流变化及原因分析得到的结论是一致的^[21]。对比康尔泗的研究结果^[11]可知, 1号冰川在1989-2011年的20余年间, 其冰内、冰下排水道变得更为单一, 融水汇流过程亦变得更为迅速, 1号冰川对融水的阻滞和贮存作用进一步弱化。

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	图5 1号冰川水文断面2011年消融期Q-T时滞和日最大互相关系数变化Fig. 5 The variation of daily time lag between discharge and air temperature and daily maximum correlation coefficient at Glacier No.1 gauging site during the ablation season in 2011

4.2.2 裸露山坡汇流裸露山坡汇流是指空冰斗融雪径流。由于空冰斗海拔高于1号冰川, 因此空冰斗内的积雪消融时间略晚一些。已有研究表明, 空冰斗径流大小主要取决于夏季降水的多寡, 但据T-200B雨量筒观测结果, 乌河源区5-9月降水形态中有近80%为固态降水, 即形成瞬时降雪, 因此该区域气温大小亦起着不可忽视的作用^{[22, 23]}。对空冰斗水文断面的气象资料统计发现, 空冰斗流域在2011年5月、8月和9月份大部分时间里都有降水。根据积雪观测场内的A-E排雪尺记录 (图6), 空冰斗区积雪持续时间为6~7个月, 积雪平均厚度在4月中旬达到最大, 冰斗两侧积雪厚度大于中部区域。为此, 在排除降水影响下, 对6-7月连续几日晴天流量和气温逐时变化 (图7) 分析发现, 空冰斗水文断面流量过程线呈直线阶梯式的上升或下降波动, 与1号冰川水文断面在这两个月的流量曲线差异明显, 这可能与空冰斗水文断面的径流组分有关。

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	图6 2011年4月23日空冰斗积雪厚度空间分布Fig. 6 The spatial distribution of snow thickness in Kongbingdou region on April 23, 2011

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	图7 连续几日晴天里空冰斗水文断面流量 (实线) 和气温 (虚线) 各时刻变化Fig. 7 Diurnal variation in discharge (solid line) and temperature (dashed line) of empty cirque gauging site in the clear weather days

由于空冰斗区的径流主要为融雪径流, 在没有降水天气里, 只能靠前期存留的积雪消融来补给径流。从该水文断面的流量和气温曲线变化关系上看, 最大流量出现时间较最高气温出现时间滞后10~16 h, 而在不排除降水对融雪汇流影响下, 空冰斗水文断面消融期Q-T时滞为13 h左右, 7月中旬以前滞后时间较分散 (图8)。这一区域的Q-T时滞较大主要与冰斗区积雪及底部岩屑堆的持水能力强有关, 在积雪从消融到产流再到汇流到水文断面这一过程中, 融雪径流并非与融雪同时开始^[6], 我们采用Snow fork雪特性分析仪对空冰斗A-E排积雪垂直剖面 (图6) 上的雪密度及雪的含水率测量结果表明, 空冰斗区的积雪密度介于0.05~0.22 g/cm³之间, 潮雪和湿雪比例少、大部分为新干雪, 表明空冰斗区积雪层对蓄积雪水的作用相当强, 造成积雪融化过程与出水过程显著不同, 在时间上推迟半天以上。此外, 图8中日最大互相关系数在研究时段内均较小, 平均值不到0.5, 表明在消融期气温并不是控制空冰斗水文断面流量的主要因子。

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	图8 空冰斗水文断面2011年消融期Q-T时滞和日最大互相关系数变化Fig. 8 The variation of daily time lag between discharge and air temperature and daily maximum correlation coefficient at empty cirque gauging site during the ablation season in 2011

4.2.3 高山汇流高山汇流是指总控水文断面径流, 由断面控制流域内的山坡汇流和河网汇流两部分组成。图9和图10分别为总控水文断面在2011年消融期排除降水天气的流量和气温变化以及不排除降水影响下流量— 气温时滞和最大互相关系数变化。显然, 在消融初期5月份, 总控水文断面流量过程线多呈直线变化, 这主要与这一时期 (5月25-29日) 正值积雪大面积消融, 部分冰川区粒雪亦开始消融, 流域下垫面的消融通道、水系等发育还不完善有关。在无持续降水天气时期, 总控水文断面的流量只有靠积雪和冰川区粒雪消融补给径流, 二者只有在高气温天气才能消融, 因此在流量过程线上体现为直线阶段式变化。

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	图9 连续几日晴天里总控流量 (实线) 和气温 (虚线) 各时刻变化Fig. 9 Diurnal variation in discharge (solid line) and temperature (dashed line) of Zongkong gauging site in the clear weather days

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	图10 总控水文断面2011年消融期Q-T时滞和日最大互相关系数变化Fig. 10 The variation of daily time lag between discharge and air temperature and daily maximum correlation coefficient at Zongkong gauging site in the ablation season in 2011

在排除降水天气影响下, 总控水文断面在消融期Q-T时滞为5~11 h, 而在不排除降水对冰雪融水汇流影响条件下, 总控水文断面在6月底前Q-T时滞有下降趋势, 进入7月基本稳定在6~7 h, 表现出随着消融进行, Q-T时滞有减小趋势。Q-T时滞发生变化的原因可能是在消融初始阶段, 河源区降水大都为固态降水, 积雪面积较大, 反照率较强, 冰川消融强度不大, 较少的冰雪融水流速小, 从而导致最大流量滞后最高气温时间较长。随着时间推移, 流域内积雪面积变小, 冰川裸冰面积增大, 反照率减小, 伴随气温快速升高, 使得消融强度增大, 冰川融水流量增大, 流速变大, 下垫面的排水系统越发完善, 相应流量— 气温滞后时间缩短。

5 讨论

5.1 乌河源区3个水文断面冰雪消融产汇流过程比较

对比乌河源区3个水文断面在排除降水和不排除降水两种天气下的Q-T时滞, 均反映出伴随降水过程出现, 汇流速度加快, 汇流时间相应缩短, 但降水形态对产汇流特征影响较大。当降水为液态时, 降雨在冰面上迅速产流, 同时亦加速了冰川消融, 较大流量使得流速加大, 进而缩短汇流时间。当降水为固态时, 降雪当天往往伴随着气温降低, 地面反照率增大使得冰川消融所需能量增多, 消融量减少, 冰川融水流速减小, 汇流时间变长, 次日, 随着天气好转, 气温升高, 新降雪大量消融, 融水量加大, 流速加快, 从而使得汇流时间变短。此外, Q-T时滞变化也反映出1号冰川和总控两个水文断面控制流域内下垫面排水系统的演变, 即经历了由消融初期的慢速排水系统演化为消融中期的快速排水系统再回归为消融末期的慢速排水系统发展过程。

乌河源区3个水文断面流量过程线和Q-T时滞的显著差异表明其各自控制流域的冰雪消融产汇流过程不同。1号冰川和总控两个水文断面控制流域内都有冰川覆盖, 其中1号断面冰川覆盖率高达50%左右, 总控水文断面冰川覆盖率接近20%, 这两个水文断面在5月和9月流量曲线呈直线阶梯式波动变化, 6-8月流量过程线较为光滑, 反映出在消融初期和末期, 这两个断面控制流域排水系统不发育, 冰雪消融量小, 对水文断面的补给不连续; 而在强烈消融期, 冰川区粒雪和老冰大量消融, 排水系统发育, 径流补给连续。空冰斗断面在消融中期6~7月, 流量过程线呈大范围直线阶梯式波动变化, 尽管空冰斗与1号冰川两个水文断面控制流域面积相当, 但前者冰川覆盖率为0, 径流补给仅靠积雪消融。据已有对冰雪消融度日因子研究及1号冰川消融观测资料, 冰川冰消融的度日因子大于粒雪和新雪消融度日因子^[28], 因此, 在同样的气温条件下, 1号冰川消融量要远大于空冰斗积雪消融量, 从而表现出1号水文断面冰川径流过程线陡涨陡落, 而空冰斗融雪径流缓涨缓落。对乌河源区3个水文断面径流过程分析表明, 消融期的流量过程线变化及最大流量与最高气温时滞变化规律在一定程度上对于认识冰川覆盖率有差异背景下的流域下垫面水系演化、冰雪消融过程及水文断面径流补给具有重要的指示意义。

3个水文断面流量与气温和降水要素, 表现出两个时间尺度上的统计关系 (图11)。具体为1号冰川断面在小时时间尺度上, 流量与气温就呈现出显著指数关系, 当气温大于5 ^oC时, 流量呈加速增长, 充分说明了热量是影响该水文断面的决定性因素; 空冰斗断面在天时间尺度上, 流量与降水具有较好的正相关关系, 表明降水是裸露山坡径流的根本来源。总控水文断面流量与气温和降水关系较复杂, 兼具1号冰川和空冰斗两个断面特征, 亦在天时间尺度上, 表现出流量与气温、降水都具有正相关关系, 但相关程度不如前面两个断面, 进一步反映出水量和热量共同影响高山径流。

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	图11 乌河源区1号冰川 (a)、空冰斗 (b) 和总控 (c) 水文断面2011年消融期流量与降水、气温关系Fig. 11 Fitting curve between discharge and precipitation / temperature at the three gauging sites in the ablation period of 2011

5.2 1号冰川与其它冰川的产汇流特征比较

为进一步探讨冰川消融及产汇流普遍特征, 我们将1号冰川与国内其它4条冰川 (横断山海螺沟冰川、喜马拉雅山绒布冰川、天山科其喀尔巴西冰川和祁连山七一冰川) 及国外2条冰川 (印度Gangotri冰川和法国Baounet冰川) 进行对比分析 (表2)。显然, 表2中的这6条冰川最大流量与最高气温出现的时间差、最大和最小流量出现的时间均不同, 且Q-T时滞均比1号冰川大。在这6条冰川中, 只有七一冰川的消融与产汇流特征与1号冰川相近, 该冰川流量最大时间出现在17时, Q-T时滞为2 h。尽管科其喀尔巴西冰川和绒布冰川也都是亚大陆型冰川, 但这两条冰川规模都比1号冰川大的多, 其冰川融水流经冰内、冰下水系到水文断面的最大流量滞后最高气温时间长, 分别为4~10 h和9~14 h。绒布冰川是珠峰北坡最大的一条冰川, 面积为203 km², 流域冰川覆盖率高达68%, 在列出的4条亚大陆型冰川和2条海洋型冰川中, 该冰川的融水最大流量出现时间滞后最高气温时间最长, 流量最大时间出现在凌晨0~1 h, 最小流量出现在12~15 h, 表明该冰川储水性能明显强于1号冰川。对于海螺沟和Gangotri这2条海洋型冰川而言, Gangotri冰川Q-T时滞较短, 尽管冰川面积很大, 但由于其位于喜马拉雅山南坡, 年降水量充沛, 冰下水系通道发育使得该冰川融水径流的汇流时间短^[6]。上述分析表明, 冰川从开始消融经产流再到汇流过程十分复杂, 其所需时间长短与冰川类型、规模和区域气候特征、水文断面与冰川末端的远近等都存在着密切关系。

表2 1号冰川产汇流特征与其它冰川的比较 Tab. 2 The comparison of glacial meltwater runoff characteristics among seven glaciers

6 结论

(1) 乌河源区3个水文断面昼夜流量差异明显, 1号冰川水文断面白天径流大于夜晚径流, 而空冰斗和总控断面反之。3个水文断面流量具有显著日变化过程, 1号冰川水文断面最大流量出现时间在14-18时, 最小流量出现在8-10时; 空冰斗水文断面最大流量出现在23-次日凌晨1时, 最小流量在13-15时; 总控水文断面最大流量出现在21-次日凌晨1时, 最小流量在13-18时。此外, 消融期3个水文断面的日流量变化表现出流量峰值的大小和到来的时间不同, 在消融中期, 流量峰值高, 出现时间早; 而在消融初期和末期, 流量峰值低, 出现时间较晚。

(2) 乌河源区3个水文断面在排除降水和不排除降水天气影响下, 1号冰川最大流量滞后最高气温分别为1~3 h和0~1 h; 空冰斗断面分别为10~16 h和13 h, 总控断面分别为5~11 h和6~7 h, 反映出1号冰川从消融产流到汇流时间最短, 空冰斗积雪消融产流时间最长, 总控位于二者之间。同时也说明伴随降水过程冰雪融水汇流迅速, 冰雪消融从产流到汇流时间有一定的缩短。

(3) 冰川覆盖山区流域水文断面在冰川消融期的流量过程线变化及最大流量与最高气温时滞变化规律在一定程度上对于认识冰川覆盖率有差异背景下的流域下垫面水系演化、冰雪消融过程及水文断面径流补给具有重要的指示意义。1号冰川在过去20余年间, 冰内、冰下排水道变得更为单一, 对融水的阻滞和贮存作用弱化, 融水汇流过程变得更为迅速。1号冰川与七一冰川产汇流特征较为相近, 与海螺沟冰川、绒布冰川、科其喀尔巴西冰川和Gangotri冰川的差异明显, 表明冰川产汇流特征不仅与水热条件有关, 而且与冰川类型、规模密切相关。

(4) 影响3个水文断面流量变化的因素不同, 1号冰川水文断面流量变化受控于冰川区热量条件, 当消融期时气温大于5 ^oC时, 流量呈加速增长。对于空冰斗断面, 降水量多寡是导致径流变化的主导因素。总控水文断面流量大小与气温和降水关系比较复杂, 既表现出1号冰川断面的流量— 气温指数关系, 又表现出空冰斗断面的流量— 降水线性关系, 但相关程度都比二者的小, 这可能与总控断面控制流域冰川覆盖率介于二者之间有关。

The authors have declared that no competing interests exist.

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[4]	Hock R, Hooke R L. Evolution of the internal drainage system in the lower part of the ablation area of Storglaciaren, Sweden. Geological Society of America Bulletin, 1993, 105(4): 537-546. [本文引用:2] [JCR: 4.286]
[5]	Zhang Yong, Liu Shiyin, Ding Yongjian. Glacier meltwater and runoff modelling, Keqicar Baqi Glacier, southwestern Tien Shan, China. Journal of Glaciology, 2007, 53(180): 91-98. [本文引用:1] [JCR: 2.882]
[6]	Singh P, Haritashya U K, Kumar N et al. Hydrological characteristics of the Gangotri Glacier, central Himalayas, India. Journal of Hydrology, 2006, 327: 55-67. [本文引用:5] [JCR: 2.964]
[7]	Schuler T, Fischer U H, Gudmundsson G H. Diurnal variability of subglacial drainage conditions as revealed by tracer experiments. Journal of Geophysical Research, 2004, 109, F02008, doi: DOI:10.1029/2003JF000082. [本文引用:2]
[8]	Hasnain S I, Jose P G, Ahmad S et al. Character of the subglacial drainage system in the ablation area of Dokriani glacier, India, as revealed by dye-tracer studies. Journal of Hydrology, 2001, 248: 216-223. [本文引用:2] [JCR: 2.964]
[9]	Liu Qiao, Liu Shiyin. Tracer tests of englacial and subglacial drainage system evolution and a case study at the Hailuogou glacier. Journal of Glaciology and Geocryology, 2012, 34(5): 1206-1219. [刘巧, 刘时银. 冰内及冰下水系演化的示踪试验及其应用研究. 冰川冻土, 2012, 34(5): 1206-1219. ] [本文引用:1] [CJCR: 1.301]
[10]	Gao Mingjie, Han Tiand ing, Ye Baisheng et al. Characteristics of melt water discharge in the Glacier No. 1 basin, headwater of Urumqi River. Journal of Hydrology, 2013, 489: 180-188. [本文引用:1] [JCR: 2.964]
[11]	Kang Ersi. A preliminary study on the drainage system in the ablation area of the Glacier No. 1 at the source of Urumqi River. Journal of Glaciology and Geocryology, 1991, 13(3): 219-228. [康尔泗. 乌鲁木齐河源1号冰川消融区排水系统初探. 冰川冻土, 1991, 13(3): 219-228. ] [本文引用:2] [CJCR: 1.301]
[12]	Li Zhongqin, Li Huilin, Chen Yaning. Mechanisms and simulation of accelerated shrinkage of continental glaciers: a case study of Urumqi Glacier No. 1 in eastern Tianshan, Central Asia. Journal of Earth Science, 2011, 22(4): 423-430. [本文引用:1] [JCR: 0.395] [CJCR: 0.519]
[13]	Sun Meiping, Li Zhongqin, Yao Xiaojun et al. Rapid shrinkage and hydrological response of a typical continental glacier in the arid region of northwest China. Ecohydrology, 2012, 6(6): 909-916. [本文引用:1] [JCR: 2.775]
[14]	Tianshan Glaciological Station, Lanzhou Institute of Glaciology and Geocryology, CAS; Runoff Experimental Station, Hydrological Bureau of Xinjiang Uygur Autonomous Region, Research Team of Water Resources in Urumqi Region. Formation and Estimation of Mountain Water Resources in the Urumqi River Basin. Beijing: Science Press, 1992. [中国科学院兰州冰川冻土研究所天山冰川观测试验站, 新疆维吾尔自治区水利厅水文总站径流观测实验站, 乌鲁木齐地区水资源若干问题研究队. 乌鲁木齐河山区水资源形成和估算. 北京: 科学出版社, 1992. ] [本文引用:1]
[15]	Li Zhongqin. Recent Research and Application of Urumqi Glacier No. 1. Beijing: China Meteorological Press, 2011. [李忠勤. 天山乌鲁木齐河源1号冰川近期研究与应用. 北京: 气象出版社, 2011. ] [本文引用:1]
[16]	Tianshan Glaciological Station. Annual Report of Tianshan Glaciological Station. Vol. 18. Lanzhou: Tianshan Glaciological Station, 2008. [天山冰川站. 天山冰川站年报: 18卷. 兰州: 中国科学院天山站, 2008. ] [本文引用:1]
[17]	Jobard S, Dzikowski M. Evolution of glacial flow and drainage during the ablation season. Journal of Hydrology, 2006, 330: 663-671. [本文引用:1]
[18]	Fountain A G, Walder J S. Water flow through temperate glaciers. Reviews of Geophysics, 1998, 36: 299-328. [本文引用:1] [JCR: 13.906]
[19]	Takeuchi N, Li Zhongqin. Characteristics of surface dust on Urumqi Glacier No. 1 in the Tien Shan Mountains, China. Arctic, Antarctic, and Alpine Research, 2008, 40(4): 744-750. [本文引用:1]
[20]	Xu Hui, Li Zhongqin, Takeuchi N et al. Characteristics and formation analysis of the cryoconite granules: Take the Urumqi Glacier No. 1 as an example. Journal of Glaciology and Geocryology, 2013, 35(5): 1118-1125. [许慧, 李忠勤, Takeuchi N 等. 冰尘结构特征及形成分析: 以乌鲁木齐河源1号冰川为例. 冰川冻土, 2013, 35(5): 1118-1125. ] [本文引用:1] [CJCR: 1.301]
[21]	Sun Meiping, Li Zhongqin, Yao Xiaojun et al. Analysis on runoff variation of Glacier No. 1 at the headwaters of Urumqi River from 1959 to 2008. Journal of Natural Resources, 2012, 27(3): 650-660. [孙美平, 李忠勤, 姚晓军等. 1959-2008年乌鲁木齐河源1号冰川融水径流变化及其原因分析. 自然资源学报, 2012, 27(3): 650-660. ] [本文引用:1] [CJCR: 2.407]
[22]	Sun Meiping, Li Zhongqin, Yao Xiaojun et al. Runoff variation and mechanism at headwaters of Urumqi river in recent 50 years. Arid Land Geography, 2012, 35(3): 430-437. [孙美平, 李忠勤, 姚晓军等. 近50a来乌鲁木齐河源区径流变化及其机理研究. 干旱区地理, 2012, 35(3): 430-437. ] [本文引用:1] [CJCR: 1.445]
[23]	Han Tiand ing, Ding Yongjian, Jiao Keqin et al. Analysis of the extremum of snow and glacier meltwater runoff at the headwaters of the Urumqi River. Journal of Glaciology and Geocryology, 2005, 27(2): 276-281. [韩添丁, 丁永建, 焦克勤等. 天山乌鲁木齐河源冰雪径流的极值分析. 冰川冻土, 2005, 27(2): 276-281. ] [本文引用:1] [CJCR: 1.301]
[24]	Liu Qiao, Liu Shiyin. Seasonal evolution of englacial and subglacial drainage system of temperate glacier revealed by hydrological analysis. Journal of Glaciology and Geocryology, 2009, 31(5): 857-864. [刘巧, 刘时银. 温冰川冰内及冰下水系季节演化及其水文学分析. 冰川冻土, 2009, 31(5): 857-864. ] [本文引用:1] [CJCR: 1.301]
[25]	Liu Weigang, Ren Jiawen, Qin Xiang et al. hydrological characteristics of the runoff yield and runoff confluence in the Rongbuk Glacier catchment in Mt. Qomolangma, central Himalayas, China. Journal of Glaciology and Geocryology, 2010, 32(2): 367-372. [刘伟刚, 任贾文, 秦翔等. 珠穆朗玛峰绒布冰川消融与产汇流水文特征分析. 冰川冻土, 2010, 32(2): 367-372. ] [本文引用:1] [CJCR: 1.301]
[26]	Han Haidong, Liu Shiyin, Wang Jian et al. Glacial runoff characteristics of the Koxkar Glacier, Tuomuer-Khan Tengri Mountain Ranges, China. Environmental Earth Sciences, 2009, 61(4): 665-674. [本文引用:1] [JCR: 1.445]
[27]	Song Gaoju, Wang Ninglian, Chen Liang et al. Analysis of the recent features of the meltwater runoff from the Qiyi Glacier, Qilian Mountains. Journal of Glaciology and Geocryology, 2008, 30(2): 321-328. [宋高举, 王宁练, 陈亮等. 祁连山近期七一冰川融水径流特征分析. 冰川冻土, 2008, 30(2): 321-328. ] [本文引用:1] [CJCR: 1.301]
[28]	Cui Yuhuan, Ye Baisheng, Wang Jie et al. Analysis of the spatial-temporal variation of the positive degree-day factors on the Glacier No. 1 at the headwaters of the Urumqi River. Journal of Glaciology and Geocryology, 2010, 32(2): 265-274. [崔玉环, 叶柏生, 王杰等. 乌鲁木齐河源1号冰川度日因子时空变化特征. 冰川冻土, 2010, 32(2): 265-274. ] [本文引用:1] [CJCR: 1.301]

2005

3.419

0.0

... 1 引言冰雪消融产汇流过程研究是冰川径流模拟中确定水文特征参数的前提,亦是寒区水文研究的核心问题^[1,2,3] ...

2000

0.0

... 1 引言冰雪消融产汇流过程研究是冰川径流模拟中确定水文特征参数的前提,亦是寒区水文研究的核心问题^[1,2,3] ...

2010

9.737

0.0

... 1 引言冰雪消融产汇流过程研究是冰川径流模拟中确定水文特征参数的前提,亦是寒区水文研究的核心问题^[1,2,3] ...

1993

4.286

0.0

... 冰雪融水产生于冰川和积雪区,受下垫面差异影响,融水在下垫面的存贮和流动过程亦不同^[4,5] ...

... 如Hock等指出,冰川融水的汇流滞后时间受积雪面积大小和排水系统强弱影响很大^[4] ...

2007

2.882

0.0

... 冰雪融水产生于冰川和积雪区,受下垫面差异影响,融水在下垫面的存贮和流动过程亦不同^[4,5] ...

2006

2.964

0.0

Singh

, Haritashya U

, Kumar

et al. Hydrological characteristics of the Gangotri Glacier, central Himalayas, India. Journal of Hydrology, 2006, 327: 55-67.

... 目前,国际上对于冰雪消融产汇流过程的研究主要包括应用染色示踪试验和基于水文气象观测数据的统计分析两种方法^[6,7,8,9,10] ...

... 5 h,且滞后时间随着冰川消融逐渐缩短^[6] ...

... 2 研究方法(1) 排除降水对冰雪融水产汇流过程影响采用Singh等人提出的研究方法^[6],即从2011年5-9月中挑选出连续几日晴天或降水量不超过2#cod#x003b2 ...

... 这一区域的Q-T时滞较大主要与冰斗区积雪及底部岩屑堆的持水能力强有关,在积雪从消融到产流再到汇流到水文断面这一过程中,融雪径流并非与融雪同时开始^[6],我们采用Snow fork雪特性分析仪对空冰斗A-E排积雪垂直剖面 (图6) 上的雪密度及雪的含水率测量结果表明,空冰斗区的积雪密度介于0 ...

... 对于海螺沟和Gangotri这2条海洋型冰川而言,Gangotri冰川Q-T时滞较短,尽管冰川面积很大,但由于其位于喜马拉雅山南坡,年降水量充沛,冰下水系通道发育使得该冰川融水径流的汇流时间短^[6] ...

2004

0.0

... 目前,国际上对于冰雪消融产汇流过程的研究主要包括应用染色示踪试验和基于水文气象观测数据的统计分析两种方法^[6,7,8,9,10] ...

... 如Schuler等于2000年在瑞士Unteraargletscher冰川通过投放染色示踪剂探测消融期冰下水系通道的水力状况、汇流速度和融水经冰下过程及到达水文断面时间^[7] ...

2001

2.964

0.0

Hasnain S

, Jose P

, Ahmad

et al. Character of the subglacial drainage system in the ablation area of Dokriani glacier, India, as revealed by dye-tracer studies. Journal of Hydrology, 2001, 248: 216-223.

... 目前,国际上对于冰雪消融产汇流过程的研究主要包括应用染色示踪试验和基于水文气象观测数据的统计分析两种方法^[6,7,8,9,10] ...

... Hasnain等亦采用相同方法对印度Dokriani冰川开展了研究,指出融水径流在7-8月中旬最大,并认为流量变大主要与消融期冰川排水系统最发育有关,9月份流量减少,原因是这一时期冰下通道变窄形成慢速排水系统^[8] ...

2012

0.0

1.301

Liu

Qiao

, Liu

Shiyin.

Tracer tests of englacial and subglacial drainage system evolution and a case study at the Hailuogou glacier.

Journal of Glaciology and Geocryology, 2012, 34(5): 1206-1219.

[刘巧, 刘时银. 冰内及冰下水系演化的示踪试验及其应用研究. 冰川冻土, 2012, 34(5): 1206-1219. ]

Dye tracer test was widely used in study of englacial and subglacial drainage system. Tracer test provides information about hydraulic conditions of a drainage system if the tracer transport is identical to the flow of individual water particle. In this study, formation and seasonal evolution of subglacial drainage system in the lower ablation area of Hailuogou Glacier were revealed by repeated dye tracer tests during the 2009 ablation season. Between 10 April and 28 October in 2009, 18 dye tracer tests were carried out in the lower ablation area of Hailuogou Glacier. Using a simple advection-dispersion model, the transit velocity, the hydrodynamic dispersion coefficient and the degree of tracer spreading were deduced. Transit velocity varies from 0.148 to 0.555 m5s -1 , which is typical of those found at other glaciers. Derived dispersivity shows a relatively high value than thoset found in other glaciers ranging from 27.05 to 287.49 m 2 5s -1 . Seasonal changes of those indexes indicate that hydraulic efficiency of the subglacial drainage system in the lower ablation area of the glacier experiences low-high-low during the ablation period. Based on the well relationships between calculated channel cross-section area ( A ) and air temperature, precipitation and discharge, a simple regression model is obtained to deduce continuous seasonal change of A . The results show that A , which is also the index of the size of subglacial channel, is larger in middle summer than that in the earlier and later ablation seasons.

1. Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu Sichuan 610041, China; 2. State Key Laboratory of Cryospheric Sciences, Institute of Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou Gansu 730000, China

简要回顾和介绍了示踪试验方法在冰内及冰下水系演化研究中的应用, 并以ADM模型为例, 对示踪剂扩散模型进行了敏感性试验分析, 分析了不同参数组合条件对示踪剂浓度变化过程的影响. 在海螺沟冰川消融区下游冰舌段开展了示踪试验, 通过对一个固定入水口消融期整个过程的重复投放试验, 获取了每次独立示踪试验示踪剂的浓度变化过程, 并用ADM扩散模型反演了示踪剂传播速度、水力扩散系数以及平均排水通道面积等相关指标, 揭示了海螺沟冰川此冰舌段冰下排水系统的季节变化过程.

... 目前,国际上对于冰雪消融产汇流过程的研究主要包括应用染色示踪试验和基于水文气象观测数据的统计分析两种方法^[6,7,8,9,10] ...

2013

2.964

0.0

Gao

Mingjie

, Han

Tiand ing

, Ye

Baisheng

et al. Characteristics of melt water discharge in the Glacier No. 1 basin, headwater of Urumqi River. Journal of Hydrology, 2013, 489: 180-188.

... 目前,国际上对于冰雪消融产汇流过程的研究主要包括应用染色示踪试验和基于水文气象观测数据的统计分析两种方法^[6,7,8,9,10] ...

1991

0.0

1.301

Kang

Ersi.

A preliminary study on the drainage system in the ablation area of the Glacier No. 1 at the source of Urumqi River.

Journal of Glaciology and Geocryology, 1991, 13(3): 219-228.

[康尔泗. 乌鲁木齐河源1号冰川消融区排水系统初探. 冰川冻土, 1991, 13(3): 219-228. ]

The water channels are developed on the glacial surface and at the glacial sides, some meltwater runs into or under the glacier throuth the crevasses, the moulins and the glacial sides, through the englacial-subglacial water channels and finally out off the glacier, forming the glacial drainage system. The salt tracer experiment was conducted at the Glacier No.1, 7 injection points of which were distributed on the ablation area and the accumulation areaimmediatly above the equilibrum line, the one dimensional dispersion equation is employed to calculate the curves of the salt condensation versus time and the dispersion coefficient. The observation and calculation show that the confluence of meltwater is rather rapid in the ablation area. It only takes 1-2 hours for the meltwater to run to the glacial gauge station during the period of complete development of the glacial drainage system, but in the accumulation area, the retardation of the snow and firn layers to meltwater runoff should be considered. The storage function of the glacier to meltwater runoff is weak, it makes the meltwater runoff nearly all drained out off the glacier, after a short time stay in the drainage system. The anabranches, flow eddies and the retardation of sediments to runoff exist in the drainage system, it makes the observed curves of the salt condensation versus time lower and extending time longer than that of calculated curves, but the prolonged time is generally only in several to 15 minutes, even in the accumulation area hear the equilibrium line is only in about 60 minutes. The dispersion equation can basically be applied to simulate the curves of salt condensation versus time of the salt tracer experiment, this clarifies that the englacial-subglacial water channels are rather unitary, instead of complex divergence. The dispersion coefficient of the drainage system in the ablation area is calculated generally to be 0.5-1.5 m 2 / s.

Lanzhou Institute of Glaciology and Geocryology, Chinese Academy of Sciences

1号冰川冰面和冰侧排水道发育,部分融水流入冰裂隙和冰面融洞,经冰内、冰下水道流出冰川。根据盐示踪试验和扩散方程的计算,得出1号冰川冰内、冰下排水道较单一,冰川对融水的阻滞和贮存作用不强,而对融水的汇流作用过程较迅速的结论。

... 我国对于冰川消融区排水系统特征研究始于20世纪80年代末,康尔泗在乌鲁木齐河源1号冰川 (以下简称为1号冰川) 开展了盐示踪试验,发现投盐7个地点的冰川融水流到水文断面时间在7 min~2 h之间,表明1号冰川冰内、冰下排水道较单一^[11] ...

... 对比康尔泗的研究结果^[11]可知,1号冰川在1989-2011年的20余年间,其冰内、冰下排水道变得更为单一,融水汇流过程亦变得更为迅速,1号冰川对融水的阻滞和贮存作用进一步弱化 ...

2011

0.395

0.519

Zhongqin

, Li

Huilin

, Chen

Yaning

. Mechanisms and simulation of accelerated shrinkage of continental glaciers: a case study of Urumqi Glacier No. 1 in eastern Tianshan, Central Asia. Journal of Earth Science, 2011, 22(4): 423-430.

Abstract Similar to most mountain glaciers in the world, Urumqi Glacier No. 1 (UG1), the best observed glacier in China with continued glaciological and climatological monitoring records of longer than 50 years has experienced an accelerated recession during the past several decades. The purpose of this study is to investigate the acceleration of recession. By taking UG1 as an example, we analyze the generic mechanisms of acceleration of shrinkage of continental mountain glaciers. The results indicate that the acceleration of mass loss of UG1 commenced first in 1985 and second in 1996 and that the latter was more vigorous. The air temperature rises during melting season, the ice temperature augment of the glacier and the albedo reduction on the glacier surface are considered responsible for the accelerated recession. In addition, the simulations of the accelerated shrinkage of UG1 are introduced in this article.

1. State Key Laboratory of Cryospheric Sciences/Tianshan Glaciological Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China 2. College of Geography and Environment Sciences, Northwest Normal University, Lanzhou, 730070, China 3. Key Laboratory of Oasis Ecology and Desert Environment, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China

... 在气候变暖背景下,1号冰川呈加速退缩趋势^[12],并在1993年分为东西两支冰川,冰川面积、长度、物质平衡和平衡线高度都发生了显著变化,其中平衡线高度由1959-1996年的4042 m上升至1997-2008年的4106 m^[13] ...

2012

2.775

0.0

1992

0.0

... 5 mm,除冰雪覆盖外,主要是裸岩和倒石堆^[14] ...

2011

0.0

... 早在上世纪50年代末,中国科学院天山冰川观测试验站就在乌河源区布设了3个水文断面及相应的气象观测场 (图1),开展了长期的冰川、水文和气象等要素观测^[15] ...

2008

0.0

... 68 km²,该水文断面主要用于观测融雪径流^[16] ...

2006

0.0

Jobard

, Dzikowski

Evolution of glacial flow and drainage during the ablation season.

Journal of Hydrology, 2006, 330: 663-671.

... (2) 不排除降水对冰雪融水产汇流过程影响采用Jobard和Dzikowski提出的分析方法^[17],以每日为时间窗口,对逐时流量#cod#x02014 ...

1998

13.906

0.0

Fountain A

, Walder J

Water flow through temperate glaciers.

Reviews of Geophysics, 1998, 36: 299-328.

> Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier-induced floods, and the prediction of runoff from glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn-free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, spawned by water flow along the bottoms of near-surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a limited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. Their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open-channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically. An upglacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cavities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of ∼200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20–30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Stored water may also be released abruptly and catastrophically in the form of outburst floods.

... Fountain和Walder的研究表明,与积雪区和粒雪区相比,水流速度在冰川区往往较大^[18] ...

2008

0.0

... 已有研究表明^[19,20],随着冰川消融,雪冰内气溶胶粉尘与冰碛物等杂质在冰川表面的聚集作用加强,冰尘 (Cryoconite) 大量的积累降低了冰面反照率,提高了冰川对辐射能量的吸收效率,从而加剧了冰川消融 ...

2013

0.0

1.301

Hui

, Li

Zhongqin

, Takeuchi

et al. Characteristics and formation analysis of the cryoconite granules: Take the Urumqi Glacier No. 1 as an example. Journal of Glaciology and Geocryology, 2013, 35(5): 1118-1125.

[许慧, 李忠勤, Takeuchi N 等. 冰尘结构特征及形成分析: 以乌鲁木齐河源1号冰川为例. 冰川冻土, 2013, 35(5): 1118-1125. ]

5 ice samples were taken from the Ürümqi Glacier No.1, Tian Shan, China from July 2007 to June 2010. The samples were analyzed for the structure, formation process of cryoconite granules, cyanobacteria species and characteristics of mineral particles in cryoconite. It is found that granules were distributed over the entire ice surface of the ablation area, and ranged in size from 0.26 to 3.5 mm (mean 1.1 mm). It mainly consisted of organic matter, mineral particles and microbes. Microscopy of a thin section revealed four inner structures. Type Ⅰ, most granules had concentric layers of dense organic matter, which are probably derived from annual growth of the granules by the activity of cyanobacteria. Type Ⅱ, some granules contained two or more sub granules. Type Ⅲ, there were also granules that had no specific internal structure. Type Ⅳ, some granules had relatively large mineral particles at their center. The 16S rRNA genes were amplified from the total DNA by PCR with bacteria-specific primers and constructed a clone library. Positive clones were randomly selected from the library and identified by restriction fragment length polymorphism(RFLP). The unique RFLP pattern corresponded sequences were sequenced, BLAST and then constructed phylogenetic tree. In total, 247 positive clones were screened and grouped into 10 Operational Taxonomic Units (OTUs). 10 OTUs were divided into 3 phyla with Blast analysis and RDP classifer: Oscillatoriales, Chroococcales, Unclassified. Oscillatoriales(91%) was the absolutely dominant group. Mean mass concentration of mineral particles is d μ m. Volume size distributions of mineral particles showed single-model structures having volume median diameters from 3 to 25 μ m. There have abundant organic matter and microbe in cryoconite. Thus, the main factor of lower albedo is organic part, include organic matter and microbes.

1. State Key Laboratory of Cryospheric Sciences/Tianshan Glaciological Station, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou Gansu 730000, China; 2. College of Geography and Environment Sciences, Northwest Normal University, Lanzhou Gansu 730070, China; 3. Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba 263-8522, Japan

利用2007-2010年夏季在乌鲁木齐河源1号冰川采集的5个冰样, 对冰样中冰尘的特征、冰尘中蓝藻的种类及冰尘中无机矿物颗粒的粒度特征进行了分析研究. 研究表明: 冰尘为棕色球状聚合体, 粒径为0.27~3.5 mm, 分布在冰川消融区表面, 其组成成分为有机质、无机矿物颗粒和微生物. 冰尘有4种主要的内部结构: 类型Ⅰ, 具有同心层结构的冰尘;类型Ⅱ, 带有亚颗粒的冰尘;类型Ⅲ, 内部无明显结构的冰尘;类型Ⅳ, 中心位置处具有较大无机颗粒的冰尘. 冰尘中无机矿物颗粒的数量主要分布在 d μ m的范围内, 且体积分布的粒径众数介于3~25 μ m之间. 同时, 对冰尘中的蓝藻进行了16S rRNA基因序列的系统发育分析, 共从蓝藻16S rRNA基因文库中筛选了247个阳性克隆, RFLP分型得到10个不同的OTUs. BLAST比对, 系统发育分析将这10个OTUs归为颤藻目(Oscillatoriales)、色球藻目(Chroococcales)、未定种(Unclassified). 颤藻目为绝对优势类群, 占整个基因克隆文库的91%. 经估算, 冰尘中存在大量的有机物质和微生物, 无机矿物颗粒只占了很小的比例, 表明影响冰川消融区表面反照率的主要因素为冰尘中的有机部分, 包括有机物质和微生物.

2012

0.0

2.407

... 此外,日最大互相关系数变化与降水变化呈现为反向关系,即在降水量大的当天或次日,最大互相关系数小,进一步说明在消融期虽然降水可在一定程度上缩短Q-T时滞,但气温是影响1号冰川水文断面流量的关键要素,这与孙美平等应用小波方差方法对1号冰川融水径流变化及原因分析得到的结论是一致的^[21] ...

2012

0.0

1.445

Sun

Meiping

, Li

Zhongqin

, Yao

Xiaojun

et al. Runoff variation and mechanism at headwaters of Urumqi river in recent 50 years. Arid Land Geography, 2012, 35(3): 430-437.

[孙美平, 李忠勤, 姚晓军等. 近50a来乌鲁木齐河源区径流变化及其机理研究. 干旱区地理, 2012, 35(3): 430-437. ]

Runoff generated at the headwaters of Urumqi River provides the principal water resource to the middle and lower reaches and Urumqi city．Study on the longterm observation of runoff change is of great significance for the reasonable utilization of water resources and development of good watershed management strategies in the arid region of northwest China．Here we systematically analyzed variation in runoff from three hydrological stations located at the source area of Urumqi River in recent 50 years，and revealed the possible causes，relating it to changes in climatic conditions and glacier mass loss．The results showed that there were generally increasing trends in runoff of these three hydrological stations; whereas the runoff of Zongkong station exhibited no significant increase over the study period．Factors influencing runoff change of three hydrological stations were different．For Glacier No.1 station，the runoff change was mainly controlled by heat conditions in glacieriezd region and the runoff showed an accelerated growth when the temperature in the melt season was more than 2 ℃．The runoff at the station included not only the immediate and direct response of glacier to climate change，but also the indirect and lagged response．And changes in volume loss of Glacier No.1 corresponded well with the runoff variations．For Empty Cirque hydrological station，the snow melt water and rainfall were source of runoff，so precipitation was the dominating factor affecting runoff change．However，the air temperature also should not be ignored．Under the condition of lower temperature and plentiful precipitation，the limited snow melt would only produce less runoff．The relation between runoff and climate change was somewhat more complicated for Zongkong station．Against the background of temperature rising and precipitation increasing，runoff showed a drop tendency in recent years which might be related to many factors，such as actual evapotranspiration enhancing，runoff peak appearing due to rapidly glacier recession，underground leakage increasing caused by extensively permafrost melts，etc.

1 Geography and Environment College of Northwest Normal University，Lanzhou 730070，Gansu，China；2 State Key Laboratory of Cryosphere Science, Cold and Arid Regions Environmental and Engineering Research Institute/ Tianshan Glacier Observation Experimental Station，CAS，Lanzhou 730000，Gansu，China

乌鲁木齐河源区径流是供给中下游地区和乌鲁木齐市的重要水源。通过对河源区3个水文断面（1号冰川、空冰斗和总控）有观测记录以来的径流变化研究，一方面提供径流观测的最新资料，使人们对乌鲁木齐河源区径流近期变化有新的认识；另一方面通过对气候、冰川变化的综合分析，揭示乌鲁木齐河源区径流近50 a变化事实和可能的原因。结果表明：河源区3个水文断面径流自有观测记录以来整体上呈增加趋势，其中总控水文断面径流虽有增加，但不显著。影响3个水文断面径流变化的因素不同，1号冰川水文断面径流变化受控于冰川区热量条件，当消融期气温大于2 ℃时，径流呈加速增长。1号冰川径流不仅包含了冰川对气候变化的瞬时响应，也包含了冰川对气候变化的滞后响应，由冰川物质平衡和面积计算的冰川体积损失量变化较好地验证了径流变化。对于空冰斗融雪径流，降水量多寡是导致径流变化的主导因素，但冰斗区固态降水多，气温亦起着不可忽视的作用。总控水文断面径流大小与气温和降水关系比较复杂，表现为近年来气温和降水增加，径流却有下降趋势，这可能与河源区实际蒸散增强、冰川快速退缩导致径流峰值已经出现、大范围冻土消融导致的地下渗漏量增多等原因有关。

... 已有研究表明,空冰斗径流大小主要取决于夏季降水的多寡,但据T-200B雨量筒观测结果,乌河源区5-9月降水形态中有近80%为固态降水,即形成瞬时降雪,因此该区域气温大小亦起着不可忽视的作用^[22,23] ...

2005

0.0

1.301

Han

Tiand ing

, Ding

Yongjian

, Jiao

Keqin

et al. Analysis of the extremum of snow and glacier meltwater runoff at the headwaters of the Urumqi River. Journal of Glaciology and Geocryology, 2005, 27(2): 276-281.

[韩添丁, 丁永建, 焦克勤等. 天山乌鲁木齐河源冰雪径流的极值分析. 冰川冻土, 2005, 27(2): 276-281. ]

The extremum of snow and ice meltwater runoff is analyzed in this paper, based on the observation (1980-2002) at the headwaters of the Ürüqi River, Tianshan Mountains. It is revealed that there is a slight increase of the extremum at the Glacier No.1 and the Ice-Free Cirque Stations in spring, but a decrease of that in the total-Control Station; and there is an increase of the extremum at the Ice-Free Cirque and the Total-Control Stations in summer, but a decrease at the Glacier No.1 Station. Analysis of the extreme (maximum/minimum) runoff series and the correlative temperature shows temperature is the principal factor to the extremum in spring, both temperature and precipitation control the maximum runoff in summer, and relative low air temperature after a major precipitation results in the minimum runoff.

Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou Gansu 730000, China

利用乌鲁木齐河源区近20多年的水文气象实测资料, 研究了河源区冰川、季节积雪和夏季降水等形成径流极值(极大值和极小值)的时空变化特征, 并对其产生过程及其与气温、降水等气象要素的关系进行初步分析. 结果表明: 春季(5月)1号冰川水文点和空冰斗水文点极大值径流呈现出轻微增大的趋势, 总控水文点表现为减小的趋势; 夏季(6~8月)径流极大值变化显示, 空冰斗和总控水文点有增大趋势, 1号冰川水文点总体为轻微的减小趋势. 春季径流极值的主要影响因素是气温; 夏季极大值径流是气温和降水综合作用的结果, 而极小值径流主要源于大降水(雪)后的相对较低气温的影响.

2009

0.0

1.301

Liu

Qiao

, Liu

Shiyin.

Seasonal evolution of englacial and subglacial drainage system of temperate glacier revealed by hydrological analysis.

Journal of Glaciology and Geocryology, 2009, 31(5): 857-864.

[刘巧, 刘时银. 温冰川冰内及冰下水系季节演化及其水文学分析. 冰川冻土, 2009, 31(5): 857-864. ]

针对温冰川冰内及冰下水系（又称冰川排水系统）演化及其水力过程，回顾了我国曾20世纪90年代在典型温冰川海螺沟冰川开展钻孔试验及关于冰下河堵溃问题的水文学分析，然后主要从水文学角度，探讨了消融期温冰川冰内及冰下水系的演化过程及其在径流过程曲线上的反映. 利用径流-气温交叉相关分析方法，计算了海螺沟冰川2003-2005年逐日Q～T时滞，其季节变化在一定程度上指示了冰内及冰下水系季节演化过程及其水力状况，并针对典型时段，重点探讨了二者之间的相关性.

2010

0.0

1.301

Liu

Weigang

, Ren

Jiawen

, Qin

Xiang

et al. hydrological characteristics of the runoff yield and runoff confluence in the Rongbuk Glacier catchment in Mt. Qomolangma, central Himalayas, China. Journal of Glaciology and Geocryology, 2010, 32(2): 367-372.

[刘伟刚, 任贾文, 秦翔等. 珠穆朗玛峰绒布冰川消融与产汇流水文特征分析. 冰川冻土, 2010, 32(2): 367-372. ]

分析珠穆朗玛峰峰绒布冰川强消融期6月的日径流资料可知，由于绒布冰川末端冰湖较为发育、冰川面积较大，冰川末端水文站显示白天流量小于晚上流量，冰川储水性较强. 最大流量出现时间滞后於最高气温（消融最强）时间9~14h. 随着消融强度增大，冰川排水系统发育越来越完善，滞后时间缩短. 据2005年定日县气象站无降水日日平均气温资料和同期珠穆朗玛峰绒布河日均径流量，获得气温驱动下绒布河日均径流量表达式；利用1959年珠峰科考时一个水文年中无降水日绒布河日均流量资料和同期定日县气象站日均气温检验该表达式表明，该表达式在利用定日无降水日日均气温模拟绒布河径流量时表现较好. 绒布河的径流可分割成两部分：冰川融水补给和降水补给. 根据1959年降水驱动产生的流量，得出降水对河流补给贡献率为19.2%，冰川融水补给率为80.8%.

2009

1.445

0.0

2008

0.0

1.301

Song

Gaoju

, Wang

Ninglian

, Chen

Liang

et al. Analysis of the recent features of the meltwater runoff from the Qiyi Glacier, Qilian Mountains. Journal of Glaciology and Geocryology, 2008, 30(2): 321-328.

[宋高举, 王宁练, 陈亮等. 祁连山近期七一冰川融水径流特征分析. 冰川冻土, 2008, 30(2): 321-328. ]

利用2006年8月1日～9月30日的实测水文数据，对“七一”冰川融水径流产汇流特征进行了分析，并揭示出该冰川日消融特征. 通过对冰川融水量的估算以及径流模数的计算，经与过去的观测结果进行对比，表明近些年来“七一”冰川消融强度和消融量都在增大，而且2006年消融量为近几年观测的最大值.虽然不同年份消融量不一样，但“七一”冰川总的趋势是一直处于萎缩状态，随着全球变暖，“七一”冰川的萎缩可能将继续下去. 通过对设立在沿冰川下游方向两个不同的水文断面进行对比分析，结果表明“七一”冰川融水径流在向下游运动过程中有部分水入渗为河谷潜流，观测期内两个相距不到2km的水文断面间渗漏损耗占近1/3左右.

2010

0.0

1.301

Cui

Yuhuan

, Ye

Baisheng

, Wang

Jie

et al. Analysis of the spatial-temporal variation of the positive degree-day factors on the Glacier No. 1 at the headwaters of the Urumqi River. Journal of Glaciology and Geocryology, 2010, 32(2): 265-274.

[崔玉环, 叶柏生, 王杰等. 乌鲁木齐河源1号冰川度日因子时空变化特征. 冰川冻土, 2010, 32(2): 265-274. ]

度日模型是估算冰川消融的一种简单而有效的方法, 度日因子是该模型的重要参数，反映了单位正积温产生的冰雪消融量，其时空变化特征对不同模型模拟冰雪消融过程的精度有较大影响. 根据乌鲁木齐河源1号冰川22a的物质平衡花杆观测资料和大西沟气象站气象资料，分析了该冰川度日因子的时空变化规律及其影响因素. 结果表明：时间尺度上，融雪度日因子年际变化不大，融冰度日因子随年际变化有增加趋势，且这种增加趋势在冰川中下部要比冰川上部明显；空间尺度上，随海拔升高，度日因子具有明显的下降趋势；2000-2004年与1983-1989年相比，1号冰川东、西支夏季物质平衡变化量分别为-240mm和-290mm,其中气候变化直接引起的变化量为-206mm和-175mm.

... 据已有对冰雪消融度日因子研究及1号冰川消融观测资料,冰川冰消融的度日因子大于粒雪和新雪消融度日因子^[28],因此,在同样的气温条件下,1号冰川消融量要远大于空冰斗积雪消融量,从而表现出1号水文断面冰川径流过程线陡涨陡落,而空冰斗融雪径流缓涨缓落 ...