警惕青藏高原上的冰湖溃决洪水灾害

全球气候变暖直接导致冰川消融退缩，由此产生的冰川融水不仅会引起海平面上升、水资源变化等环境问题，而且会导致大量冰湖的形成和扩张，从而加剧冰湖溃决洪水等冰川灾害的发生频率和影响程度。     

西藏念青唐古拉山东段冰湖的时空分布特征及其影响因素探讨

冰湖是研究气候变化的重要指标之一,了解冰湖分布和变化的特征,对认识冰湖与气候之间关系和研究冰湖溃决泥石流灾害有着重要意义。本文拟利用1976年、1988年、2001年和2013年四个期次冰川、冰湖的遥感解译结果进行分析,得出1976年至2013年念青唐古拉山东段冰川与冰湖发育分布特征,对念青唐古拉山区东段冰川消融以及气候垂直变化具有一定的指示作用,同时为冰湖溃决泥石流灾害的预测预警提供依据。     

基于遥感与GIS的朋曲流域冰川及冰湖变化研究

由于全球变暖，冰川正逐年退缩，随之引发的冰湖溃决洪水已不容忽视，但静态和孤立地研究冰湖已不能满足人们对冰湖信息的需求．本文基于20世纪70年代的地形图数据和2000年以来的ASTER遥感影像数据，使用GIS手段矢量化朋曲流域20世纪70年代和近期的冰川及冰湖的空间分布，并进行编目．对于获得的空间数据分析结果表明，在过去30年里该区冰川面积减少近9％，冰湖面积则增加了13％，在此基础上比较二者的联系和变化，识别出了24个可能发生溃决的冰湖，这为朋曲流域建立一套冰湖溃决预警系统提供依据；同时，对于研究其他类似地区的冰湖溃决现象也具有指导意义。     

贵州修文河流域径流变化特征分析

以贵州修文径流站近30年的实测月径流资料及气象同期实测数据为基础,结合M-K突变检验、小波分析法以及偏相关分析法,探究喀斯特小流域径流变化特征。研究表明:1985—2012年,修文河流域径流年际变化呈不显著的上升趋势。季节波动差异明显,夏季流量最大,秋季次之,春季再次之,冬季径流最小;月均变化趋势呈现先上升后下降变化趋势,整体趋近于n型变化。年际变化周期大致为3年、5年和10年。在全球气候变暖的背景下,降雨对径流影响最大,呈显著正相关量,与气温并不显著。     

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．      

节能让生活更美好:“3·27地球一小时”熄灯环保

<正>干旱、雪灾、洪水……已经成了2009年全球气候的代名词。全球气候变暖所导致的极端天气正在频频发生,这不能不让我们陷入对环境问题的深思。面对全球气候变暖、冰川消融、环境恶化,我们能做点什么?在哥本哈根气候大会召开前夕,我国宣布了未来碳排放控制目标:到2020年单位国     

基于MODIS的玛纳斯河流域冰川积雪覆盖变化特征的分析

为分析玛纳斯河流域冰川积雪覆盖的变化特征,应对气候变化条件下区域水资源的变化,以MODIS数据为基础,利用归一化差分积雪指数方法提取了玛纳斯河流域的冰川积雪覆盖面积,研究了该流域1998—2006年的冰川积雪覆盖变化。结果表明：该流域的年际冰川积雪覆盖区域的平均海拔高度在1998—2002年表现为下降过程,在2002—2006年表现为上升过程;1998～2001年冰川积雪面积有一个缓慢增大的过程,而自2001年以后,出现了年均8km^2左右稳步减小的过程;另外,该流域冰川积雪面积与平均温度、降水分别呈显著负相关和正相关关系。这说明气候变暖对玛纳斯河流域山区冰川积雪的消融有明显促进作用。     

新疆冰湖溃决灾害风险评价与预警研究

受全球气候变暖及人类活动的影响,冰湖溃决灾害已成为当前新疆地区经济可持续发展中的突出问题之一。利用1977(MSS)～2015年Landsat影像、2015年的Google Earth高精度影像和DEM等数据解译获取新疆冰湖的时空分布信息,并选取导致冰湖溃决的主要影响因子,运用MATLAB和SPSS等软件,利用西北地区已有冰湖数据作为训练样本拟合评价方程,建立了新疆冰湖溃决风险评价模型和基于BP神经网络算法的预警模型。结果表明:(1)1977年以来新疆三大山系中冰湖的数量和面积不断增加,冰湖数量上增加了62.0%,冰湖面积增长率为0.98 km~2·a~(-1),但增长率呈现逐年减小的趋势;(2)对分布在新疆范围内的17个典型冰湖溃决风险评价的结果显示:有5个冰湖为高危风险、5个冰湖为中等风险、7个冰湖为低等风险,新疆大约29%的冰湖需要进行实时监测。     

新疆气候转型及其对全球变化的影响

随着全球变暖趋势的发展，新疆气候也发生着相应转变，主要表现在：气温上升；降水增加；冰川消融；河川径流增加；湖泊水位上升，面积扩大；洪水灾害频繁；沙土暴天气减少；土壤盐渍化趋势加重等。气候转型的原因可能是，空气中水汽增加和有利的天气形势；全球显变暖驱动水循环加快。     

新疆冰湖溃决灾害风险评价与预警

受全球气候变暖及人类活动的影响,冰湖溃决灾害已成为当前新疆地区经济可持续发展中的突出问题之一。利用1977(MSS)～2015年Landsat影像、2015年的Google Earth高精度影像和DEM等数据解译获取新疆冰湖的时空分布信息,并选取导致冰湖溃决的主要影响因子,运用MATLAB和SPSS等软件,利用西北地区已有冰湖数据作为训练样本拟合评价方程,建立了新疆冰湖溃决风险评价模型和基于BP神经网络算法的预警模型。结果表明:(1)1977年以来新疆三大山系中冰湖的数量和面积不断增加,冰湖数量上增加了62.0%,冰湖面积增长率为0.98 km~2·a~(-1),但增长率呈现逐年减小的趋势;(2)对分布在新疆范围内的17个典型冰湖溃决风险评价的结果显示:有5个冰湖为高危风险、5个冰湖为中等风险、7个冰湖为低等风险,新疆大约29%的冰湖需要进行实时监测。     

Response of Zhadang Glacier runoff in Nam Co Basin,Tibet, to changes in air temperature and precipitation form

This paper describes 2007/2008 inter-annual changes in runoff from the Zhadang Glacier located on the northern slope of Nyainqêntanglha Range, Tibet, and analyzes their causes. Precipitation increased by 17.9% in summer months of 2008 compared with the same period in 2007, drainage basin runoff decreased by 33.3%, and glacial meltwater decreased by 53.8%. Change in positive accumulated air temperature explained approximately half of the inter-annual difference in glacial meltwater using a de-gree-day model. This suggests that the glacier is extremely sensitive to changes in air temperature. Energy balance analysis showed that change in glacier surface albedo, considered to be caused by difference in precipitation form, resulted in the large inter-annual difference in glacial meltwater. It was shown statistically that precipitation form in the summer months of 2007 was mainly rainfall which comprised 71.5% of total precipitation, while during the same period in 2008 rainfall accounted for 30.7%, with the majority of precipitation falling as snow. Precipitation form should be considered an independent factor when analyzing glacier sensitivity to climate change or forecasting the runoff from certain glaciers.     

Quick ice mass loss and abrupt retreat of the maritime glaciers in the Kangri Karpo Mountains,southeast Tibetan Plateau

The maritime glaciers are sensitive to climate change because of high annual precipitation and high air temperature in the region. A combined comprehensive study was carried out based on glacier mass balance observation, GPS-based glacier terminus position survey, glacier Ground Penetrating Radar, topography maps and RS satellite images in the Kangri Karpo Mountains, Southeast Tibet. The study revealed a strong ice mass loss and quick glacier retreat since the 1970s. Ata Glacier, one glacier from the south slope of the Kangri Karpo Mountains, has formed a 6-km-long terminal moraine zone at the end of the glacier since the 1970s, and the accelerating retreat is largely due to the strong glacier surface melting. Mass balance study on the other four glaciers on the northern side of the Kangri Karpo Mountains shows that they are in large negative mass balance and the glaciers had retreated 15--19 m from May 2006 to May 2007. The in-situ glacier observation also shows that the glacier retreat is more obvious in small glaciers. The enhanced ice mass deficit caused by climate warming and the ongoing extinction of many small glaciers in this region could seriously affect the water resources, environ- ments, local climate and regional sustainable development in the near future.     

A high-resolution environmental change record since 19 cal ka BP in Pumoyum Co,southern Tibet

A 380-cm-long sediment core was acquired from the deep water area of Pumoyum Co, southern Tibet. Twenty-five plant residue samples were selected, and organic carbon stable isotopes were obtained using the AMS ¹⁴C chronological method. The ¹⁴C age and carbon reservoir effect were calibrated with surface sedimentation rate measurements using ²¹⁰Pb dating. Results showed that the core sediment deposited over 19 cal ka BP. Based on a multi-proxy analysis of TOC and IC contents, grain size and pollen assemblage data, the palaeoclimatic evolution of Pumoyum Co was reconstructed since the last glacial. Pumoyum Co was a shallow lake prior to 16.2 cal ka BP; although the glacier around the lake began to melt due to increasing temperatures, climate was still cold and dry. In the interval of 16.2–11.8 cal ka BP, the sedimentary environment fluctuated drastically and frequently. Two cold-events occurred at 14.2 and 11.8 cal ka BP, and these may correspond to the Older Dryas and the Younger Dryas events, respectively. After 11.8 cal ka BP, Pumoyun Co developed into the deep lake as it is now. The lake water temperature was relatively lower at that time because of influx of cold water from glacial meltwater entering the lake. As a result, the multi-proxy indicators showed no sign of warm conditions. Comparisons between the sedimentary record of Pumoyum Co with that of other lakes of the same age in southern Tibet indicate a warmer climate following the last deglaciation influenced the southeastern Tibetan Plateau. These results imply that the southwest Asian monsoon gradually became stronger since the deglaciation during its expansion to the inner plateau. The glacial-supplied water of the lake responded sensitively to cold-events. The entire southern Tibet region was dominantly influenced climatically by the southwest Asian monsoon during the Holocene.     

A distributed surface energy and mass balance model and its application to a mountain glacier in China

Based on the field observations on Qiyi Glacier during the warm season of 2007, using a digital elevation model (DEM, 15 m resolution), we developed a distributed surface energy- and mass-balance model with an hourly resolution. The model described the effect of topography on shortwave solar radiation, and used a new parameterization for glacier albedo. The model was applied to Qiyi Glacier in the Qilian Mountain, China, for the period 20 : 00 30 June to 12 : 00 10 October 2007, to simulate the firn-line changes, the temporal and spatial variations of mass balance, and the glacial meltwater runoff. The results indicated that the patterns of altitudinal profile of glacier mass-balance were affected mainly by the altitudinal profile of albedo, and the status of the glacier mass balance was influenced directly by the values of albedo. The parameter sensitivity test showed that the model was sensitive to the air temperature lapse rate and precipitation gradient, and also sensitive to the threshold temperature for solid/liquid precipitation. Furthermore, the climate sensitivity test showed that the mass balance was more sensitive to air temperature than precipitation, and the response of mass balance to air temperature change was nonlinear while the response to precipitation change linearly. The negative mass balance trend of the glacier can not be reversed when precipitation increases by 20% and meanwhile air temperature rises by 1°C.     

基于RAMMS的冰湖溃决型泥石流演进模拟及危害性

冰湖溃决型泥石流作为目前西藏境内最主要的地质灾害之一,对下游工程的建设与运营造成潜在威胁。以西藏洛隆县冻错曲冰湖为例,基于现场调查、遥感解译、特征值计算和数值模拟方法,对冻错曲冰湖泥石流孕灾条件、动力学特征及溃决演进过程进行研究,分析其对下游工程建设的影响。采用无量纲堵塞指数(dimensionless blockage index, DBI)方法对冻错曲冰湖堰塞体稳定性进行评价,结果表明该堰塞体位于非稳定区与稳定区之间,存在发生溃决的风险。基于三维动态模拟软件RAMMS的Voellmy-Salm单相流模型,模拟分析了冻错曲冰湖泥石流在2种溃决模式下的演进过程。模拟结果显示：冻错曲冰湖泥石流溃决演进过程可归纳为初始溃决、加速运动、减速运动、沟口停淤4个阶段;2种溃决模式下冰湖溃决影响范围都经过拟建工程位置,潜在威胁区泥石流平均深度分别为4.87 m和8.26 m;在瞬时全部溃决场景下,冰湖溃决泥石流在拟建工程处最大流速为5.74 m/s,最大流量为2 843.38 m³/s。研究成果有助于评价冰湖溃决型泥石流的危害性,并为工程防治设计提供参考。     

冰碛湖库容数学模型的计算方法

全球气候的变暖致使冰湖溃决灾害频繁发生,严重威胁高原地区人民生命财产安全,随之对于冰湖溃决的研究也愈发深入,冰湖库容量作为冰湖研究基础参数,对冰湖危险性评价、冰湖溃决洪峰流量以及模拟洪水演进具有不可代替的作用。计算冰湖库容的方法主要有实地测量和冰碛湖库容计算公式,由于冰碛湖多位于高山极高山地区,对每个冰湖进行实地测量难以实现,传统冰湖库容的计算方法是基于大量冰湖参数与冰湖库容的统计关系,建立冰碛湖库容经验公式,虽然其拟合优度相对较高,但其相关性只能衡量冰碛湖面积和冰碛湖库容在统计规律上的一致性,对于精确计算冰碛湖库容仍有难以完成。本文通过文献资料整理、结合实地考察对湖盆形态模拟分析,将典型冰碛湖湖盆分为三段,通过模拟建立数学模型,以冰湖面积为约束条件,抽象成数学中的曲面立体模型,分别计算其形态体积,由此推算出计算冰湖体积的表达式V=0.0717w²l (w-冰碛湖湖宽;l-冰碛湖整体长度),并利用该模型验证了公式的有效精确性,为我国喜马拉雅山地区冰碛湖库容计算提供理论参考。     

西藏普兰地区第四纪以来冰锯作用研究

为了验证西藏普兰地区冰川作用对地形演化的影响, 选取纳木那尼峰、喜马拉雅山和冈底斯山3个区域, 利用数字高程模型(DEM)数据和遥感影像, 对现代冰川与末次冰盛期(LGM)古冰川平衡线高度(ELA)、冰川作用区坡度与高程的关系以及冰川分布的高程频谱进行计算和分析。结果显示, 研究区内冰川剥蚀作用显著、坡度降低最明显的地带位于LGM古冰川平衡线附近, 并在一定程度上限制山脉的高度。根据冰川地貌特征参数和前人研究结果, 认为气候是影响冰锯作用的主要因素。冰期时, 研究区内西风急流南移, 风速增强, 降水量增多, 为冰川发育创造良好条件, 冰锯作用也增强。对于构造抬升强烈的山脉(如纳木那尼峰), 虽然冰锯作用得到加强, 但是构造抬升增加的山脉高度不会完全被冰锯作用抵消。     

Discovery of Quaternary glacial evidence of Snow Mountain in Taiwan, China

There are glacial remains of three different periods on the main peak of Snow Mountain in Taiwan province, including cirque lake, crosswall, polished surface, striation, moraine etc. These three different periods were called, respectively, Shanzhuang ((44.25 ±3.72) kaBP), Shuiyuan ((18.26 ±1.52) kaBP), and Xueshan glacial stages (the late period of last glaciation). It is characterized by the earlier glacier broad in scale.