Mapping of moraine dammed glacial lakes and assessment of their areal changes in the central and eastern Himalayas using satellite data

The relatively rapid recession of glaciers in the Himalayas and formation of moraine dammed glacial lakes(MDGLs) in the recent past have increased the risk of glacier lake outburst floods(GLOF) in the countries of Nepal and Bhutan and in the mountainous territory of Sikkim in India. As a product of climate change and global warming, such a risk has not only raised the level of threats to the habitation and infrastructure of the region, but has also contributed to the worsening of the balance of the unique ecosystem that exists in this domain that sustains several of the highest mountain peaks of the world. This study attempts to present an up to date mapping of the MDGLs in the central and eastern Himalayan regions using remote sensing data, with an objective to analyse their surface area variations with time from 1990 through 2015, disaggregated over six episodes. The study also includes the evaluation for susceptibility of MDGLs to GLOF with the least criteria decision analysis(LCDA). Forty two major MDGLs, each having a lake surface area greater than 0.2 km2, that were identified in the Himalayan ranges of Nepal, Bhutan, and Sikkim, have been categorized according to their surface area expansion rates in space and time. The lakes have been identified as located within the elevation range of 3800 m and6800 m above mean sea level(a msl). With a total surface area of 37.9 km2, these MDGLs as a whole were observed to have expanded by an astonishing 43.6% in area over the 25 year period of this study. A factor is introduced to numerically sort the lakes in terms of their relative yearly expansion rates, based on their interpretation of their surface area extents from satellite imageries. Verification of predicted GLOF events in the past using this factor with the limited field data as reported in literature indicates that the present analysis may be considered a sufficiently reliable and rapid technique for assessing the potential bursting susceptibility of the MDGLs. The analysis also indicates that, as of now, there are eight MDGLs in the region which appear to be in highly vulnerable states and have high chances in causing potential GLOF events anytime in the recent future.     

山东蒙山与四川海螺沟冰川擦痕特征对比及成因分析

冰川擦痕在冰川遗迹的判断中具有极为重要的意义,其中以槽谷岩壁擦痕与冰碛砾石擦痕最为明显。槽谷岩壁擦痕具有细长密集、近似平行的特征;冰碛砾石擦痕具有短粗稀疏、方向杂乱的特征。除此之外,还有弧形擦痕、逆冲擦痕、新月形凿口、新月形裂纹、新月形裂口、颤痕等刻蚀遗迹的配套产出。经对比分析,蒙山发育的擦痕与四川海螺沟现代冰川谷内的擦痕具有完全的一致性,因此进一步确定了蒙山擦痕的冰川成因。     

天山乌鲁木齐河源1号冰川雪坑中pH值和电导率的季节变化及淋溶过程

自2002年9月14日至2004年9月28日,在天山乌鲁木齐河源1号冰川积累区雪坑中连续观测取样,频率为1次/周。对表层雪样品和粒雪坑样品的pH值和电导率进行了分析。结果表明,表层雪的pH值和电导率具有明显的季节变化趋势,与本区域的主导山谷风风向NE和ENE密切相关。在春季,由于尘暴发生频率的增加,表层雪的pH值呈现较强碱性,电导率达到最大值;在冬季,由于原生气溶胶向次生气溶胶的转化,pH值呈现较弱碱性,电导率达到最小值。在后沉积过程中（2003年10月4日至2004年9月8日）,雪坑中不同时期的pH值和电导率呈现不同的季节变化特征和淋溶过程。电导率的峰值P1进入粒雪冰的时间比与它相对应的大粒径（直径>10 μm）微粒的浓度峰值提前40天左右;在有的雪坑中,pH值和电导率的峰值出现在污化层附近,与污化层的位置有较好的一致性,说明污化层对可溶性离子的淋溶作用可能有一定的影响。相关分析表明,Ca2+是影响表层雪中pH值和电导率变化的最主要离子。     

Chemical characteristics of four kinds of water in the rongbuk glacier basin, Mount Qomolangma

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我国典型季风海洋性冰川区雪坑中主要阴、阳离子的来源

运用海盐示踪法、相关分析、趋势分析等方法,对我国两处典型季风海洋性冰川(海 螺沟1 号冰川和白水1 号冰川) 积累区雪坑主要化学离子来源进行了综合分析,结果表明： 两冰川区除Na⁺ 是海洋源外,其他离子主要是非海洋源;Cl^-、NO₃ ^-、SO₄ ^2- 、K⁺、Ca²⁺、Mg²⁺ 非 海洋源所占的比重,在海螺沟1 号冰川依次为52%、99%、100%、98%、99.9%、83%,白水 1 号冰川依次为68%、99%、100%、98%、99%、59%;分析认为,海螺沟1 号冰川离子的非 海洋源主要是大气环流远源物质和高原面物质输入,而白水1 号冰川除上述来源外,冰川区 近源物质输入对离子浓度贡献很大。两冰川区各离子具体来源存在较大的差异性并且阴、阳 离子来源的共源性较低,其主要原因是：(1) 冰川区内局地环境的差异,比如岩性、山谷风系 统、地形地貌等;(2) 两冰川区离子淋溶作用强度的差异,分析认为,海螺沟1 号冰川离子淋 溶作用较强;(3) 不同离子的来源方式、沉降方式、自身化学特征以及沉积后过程不同所致。     

14C dating and palaeoenvironment of the historic ‘little ice age’ glacier advance of Nigardsbreen Southwest Norway

Moss and grass remains associated with a well-developed in situ palaeosol buried beneath a moraine ridge in front of Nigardsbreen (Jostedalsbreen ice cap, southern Norway) have been ¹⁴C-dated. Pollen preserved with the plant remains suggests the existence of an agricultural landscape prior to the deposition of the moraine. The calibrated dates and the pollen spectra are in close accord with historically-documented evidence for the timing and palaeoenvironment of the ‘Little Ice Age’ advance of the glacier. Considerable potential is indicated for estimating the maximum ages of moraine ridges and for palaeoenvironmental reconstruction where such documentary evidence does not exist.     

Why is Shirase Glacier turning its flow direction eastward?

We applied an image correlation method to Japanese Earth Resources Satellite-1 (JERS-1) synthetic aperture radar (SAR) data obtained from 1996 to 1998 to examine flow velocity within Shirase Glacier, Antarctica. From the grounding line to the downstream region of the glacier, the obtained ice-flow velocity was systematically higher on the western streamline than the eastern. The differences between the two streamlines were 0.31 km/a in 1996 and 0.37 km/a in 1998, significantly larger than the error estimate of 0.03 km/a. The direction of ice flow was about 312° at the grounding line and changed to 327° at 10 km, 346° at 20 km and 2° at 30 km downstream from the grounding line. The total accumulated deflection is 50° to the east. Under the assumption of the conservation of ice mass across the glacier, the observed eastward change in flow direction can be explained by an asymmetric deepening of bedrock topography, that is, across the 8 km width of the glacier, the eastern side is 50 m (10%) deeper than the western side. This eastward turning of flow direction appears to be accelerated by tributary inlets, that flow to the north and northeast at 60–75% of the velocity of inlets on the western streamline.     

极地记录冰川和达尔克冰川流速的遥感监测研究

测定南极冰川的流速 ,对于研究南极冰雪物质平衡、南极环境变化及其对全球环境的影响有重大意义。本文论述了利用多时相卫星遥感影像监测冰川变化的原理和方法 ,通过对英格里特 .克里斯泰森海岸不同时期的遥感影像进行几何纠正和配准及叠加处理 ,测量和计算出极地记录冰川和达尔克冰川的平均流速 ,并对它们的变化特点进行了初步的分析和评价。     

OSL dating of glacial deposits during the Last Glacial in the Terskey-Alatoo Range, Kyrgyz Republic

Optically stimulated luminescence (OSL) dating was applied to glacial and loess deposits in the north flank of the Terskey-Alatoo Range, Kyrgyz Republic, to elucidate the glacier chronology of the central Asian mountains during the Last Glacial. Moraines in five parts of study area were classified into four stages (Terskey Stages I–IV) based on their geographical position and elevation, and their moraine rock weathering. According to this classification, the oldest moraines (Terskey Stage I) were at 2100–2250 m a.s.l. and the second-oldest moraines (Terskey Stage II) were at 2400–2700 m a.s.l. Quartz samples from moraines of these two stages were used for OSL dating. The OSL ages of the quartz samples indicate that glacier expansion in the Terskey Stage II occurred between 21 and 29 ka BP.     

小冬克玛底和海螺沟冰川的物质平衡(英)

Studying the mass balance on the Xiao Dongkemadi Glacier and Hailuogou Glacier shows that the mass balance variation of continent type glacier in the interior of the plateau is in the same phase with that of the marine type glacier in the southeast margin of the plateau. However, the mass balance in the continent type glacier is always positive, and the marine type glacier is in large negative mass balance. The continent type glacier is slow to climate change and the marine glacier is sensitive to climate change.