中国第四纪冰川研究的现状与争议——兼记首届“中国第四纪冰川与环境变化”研讨会

冰川是塑造地表形态最积极的外营力之一, 对第四纪冰期与间冰期旋回中冰川进退留下的丰富且形态独特的冰川地形的研究, 不仅能重建古冰川时空演化的规律, 在构造活跃的山区还可为山体抬升提供重要的理论参考. 2012年8月, 中国从事冰川地貌与环境变化研究的学者相聚兰州, 总结了以技术定年为主要特征的第四纪冰川研究新阶段取得的成绩与突破, 并探讨了现阶段工作的重点及未来的发展方向. 与会代表认为, 可对冰川地形进行直接定年的测年技术的发展与应用, 促进了我国第四纪冰川研究的发展, 现阶段及今后应着重加强与开展如下几个方面工作: 1)精确年代学框架的建立是现阶段我国第四纪冰川研究的重点; 2)青藏高原及周边山地最老冰碛的追溯及其年代测定是回答我国第四纪冰川开始发育的关键, 也是理解青藏高原构造抬升与冰期气候耦合的内在要求; 3)我国东部(105° E以东)第四纪冰川与环境问题需作进一步的研究与澄清, 科普工作亟待加强.     

地下水超采致海平面上升

近日,日本科学家发现,除气候变化和冰川融化外,对地下水的使用也是导致海平而上升的一个重要原因。研究表明,     

中国东北第四纪冰川研究新进展:遗迹厘定、新发现与冰期模式

东北是否发育第四纪冰川及其范围、性质与冰期问题,始终没有定论。在对长白山及大兴安岭冰川遗迹厘定基础上,进行了专项调查,并采用地理信息系统(GIS)、遥感(RS)及全球定位系统(GPS)的3S技术,采取钻探测图、孢粉、泥砾粒度与渗透性分析及14C定年等方法,在长白山及大兴安岭发现了冰蚀谷及泥砾堆积等新的冰川遗迹,进一步肯定了两座山地第四纪冰川的存在及其多期性。在小兴安岭首次发现冰蚀岩墙等冰川遗迹,填补了研究空白,证明小兴安岭也曾发育第四纪冰川。综合多种信息,确定长白山与大兴安岭分别有4次冰期和3次间冰期,小兴安岭至少有1次冰期。最后构建了可以与国际对比的冰期序列,重建了区域第四纪冰川环境演化模式:早更新世早期冷干,中晚期偏暖湿;中更新世早期冷湿,中晚期暖湿;晚更新世早期冷稍湿,中期暖湿,晚期冷干。     

近50 年来天山地区典型冰川厚度及储量变化

冰川储量变化与冰川水资源量变化以及冰川对河川径流的贡献量密切相关。在GPR-3S技术支持下, 本研究基于雷达测厚数据、不同时期的高分辨率遥感影像、地形图及实测资料, 分析了天山三个典型地区四条代表性冰川近期厚度及储量变化特征, 并通过对比探讨了造成变化差异的可能原因。结果表明, 1962-2006 年乌鲁木齐河源1 号冰川厚度平均减薄0.15m a^-1, 冰储量亏损26.2×10⁶ m³, 冰川末端平均退缩3.8 m a^-1;博格达峰南坡的黑沟8 号冰川在1986-2009 年间, 冰舌平均减薄0.57 m a^-1, 冰储量损失了25.5×10⁶ m³, 末端平均退缩11.0 m a^-1;位于博格达峰北坡的四工河4 号冰川在1962-2009 年间冰舌平均减薄0.32 m a^-1, 冰储量亏损14.0×10⁶ m³, 末端平均后退8.0 m a^-1;1964-2008 年间, 托木尔峰青冰滩72 号冰川冰舌平均减薄0.22 m a^-1, 由此至少造成冰储量亏损14.1×10⁶ m³, 末端退缩达40.0 m a^-1。对比分析显示, 青冰滩72 号冰川消融退缩最为强烈, 黑沟8 号冰川次之, 与乌鲁木齐河源1 号冰川、科其喀尔冰川相差不大, 稍大于四工河4 号冰川和哈密庙尔沟冰川。这种差异可能与区域气候变化和冰川物理特征有直接关系。     

祁连山东段冷龙岭地区宁缠河3号冰川变化研究

2009年7月对祁连山东段冷龙岭地区宁缠河3号冰川进行了野外考察, 对冰川周围布设测量控制网, 并利用GPS-RTK技术测量了冰川表面高程与面积、 末端等信息, 同时使用加拿大EKKO型探地雷达测量了冰川厚度. 结合1972年航测1973年调绘出版的地形图以及1995年与2009年两景TM影像等资料, 分析研究了宁缠河3号冰川自1972年以来的变化. 结果表明: 宁缠河3号冰川近37 a以来萎缩严重, 冰川末端退缩约6%, 面积减小13.1%, 冰川体积减少35.3%; 冰川主要以减薄的形式在萎缩, 冰川平均厚度由1972年的36.8 m, 减为2009年的27.4 m. 周边站点气象资料表明, 该区域近几十年来出现不同程度的升温, 是导致冰川快速萎缩的主要原因.     

地面多基线数字摄影测量在冰川测量中的应用 ——以博格达峰黑沟8号冰川为例

冰川的监测一直是冰川学研究的重要内容, 2008年对天山东段博格达峰南坡的黑沟8号冰川末端进行了地面多基线数字摄影测量, 获取了该冰川末端的影像, 以及与之相配套的控制信息. 在Lensphoto多基线数字摄影测量系统中, 测得了冰川末端的0.11 km² DEM数据. 采用同期测量的GPS数据检验得知, 摄影测量所得DEM数据在高程上的平均误差为1.92 m, 标准偏差为3.47 m. 地面旋转多基线数字摄影测量是一种非常有效的冰川测量手段, 可以在典型冰川测量和冰川重要部位(例如冰川末端、 冰崖等)的测量中发挥作用.     

Improvement of glacial lakes detection under shadow environment using ASTER data in Himalayas, Nepal

The detection of glacial lake change in the Himalayas, Nepal is extremely significant since the glacial lake change is one of the crucial indicators of global climate change in this area, where is the most sensitive area of the global climate changes. In the Himalayas, some of glacial lakes are covered by the dark mountains′ shadow because of their location. Therefore, these lakes can not be detected by conventional method such as Normalized Difference Water Index (NDWI), because the reflectance feature of shadowed glacial lake is different comparing to the ones which are located in the open flat area. The shadow causes two major problems: 1) glacial lakes which are covered by shadow completely result in underestimation of the number of glacial lakes; 2) glacial lakes which are partly identified are considered to undervalue the area of glacial lakes. The aim of this study is to develop a new model, named Detection of Shadowed Glacial Lakes (DSGL) model, to identify glacial lakes under the shadow environment by using Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) data in the Himalayas, Nepal. The DSGL model is based on integration of two different modifications of NDWI, namely NDWIs model and NDWI she model. NDWIs is defined as integration of the NDWI and slope analysis and used for detecting non-shadowed lake in the mountain area. The NDWIshe is proposed as a new methodology to overcome the weakness of NDWIs on identifying shadowed lakes in highly elevated mountainous area such as the Himalayas. The first step of the NDWIshe is to enhance the data from ASTER 1B using the histogram equalization (HE) method, and its outcome product is named ASTER he . We used the ASTER he for calculating the NDWI he and the NDWIshe . Integrated with terrain analysis using Digital Elevation Model (DEM) data, the NDWI she can be used to identify the shadowed glacial lakes in the Himalayas. NDWIs value of 0.41 is used to identify the glacier lake (NDWIs≥0.41), and 0.3 of NDWIshe is used to identify the shadowed glacier lake (NDWIshe≤0.3). The DSGL model was proved to be able to classify the glacial lakes more accurately, while the NDWI model had tendency to underestimate the presence of actual glacial lakes. Correct classification rate regarding the products from NDWI model and DSGL model were 57% and 99%, respectively. The results of this paper demonstrated that the DSGL model is promising to detect glacial lakes in the shadowed environment at high mountains.     

The response of lake-glacier variations to climate change in Nam Co Catchment,central Tibetan Plateau,during 1970–2000

Based upon the 1970 aero-photo topographic map, and TM/ETM satellite images taken in 1991 and 2000, the authors artificially interpreted boundaries of lake and glaciers in Nam Co Catchment, and quantified lake-glacier area variations in different stages by ＂integrated method＂ with the support of GIS. Results show that from 1970 to 2000, lake area increased from 1942.34 km^2 to 1979.79 km^2 at a rate of 1.27 km^2/a, while glacier area decreased from 167.62 km^2 to 141.88 km^2 at a rate of 0.86 km^2/a. The increasing rate of lake in 1991-2000 was 1.76 km^2/a that was faster than 1.03 km^2/a in 1970-1991, while in the same period of time, the shrinking rates of glaciers were 0.97 km^2/a and 0.80 km^2/a respectively. Important factors, relevant to lake and glacier response to the climate, such as air temperature, precipitation, potential evapotranspiration and their values in warm and cold seasons, were discussed. The result suggests that temperature increasing is the main reason for the accelerated melting of glaciers. Lake expansion is mainly induced by the increase of the glacier melting water, increase of precipitation and obvious decrease of potential evapotranspiration. Precipitation, evaporation and their linkages with lake enlargement on regional scale need to be thoroughly studied under the background of global warming and glacier retreating.     

福建第四纪不可能有冰川活动

根据已有研究的文献资料,对福建第四纪冰期时没有冰川活动进行论证．首先从早、中、晚更新世的化石研究资料,阐明福建地层古生物资料不支持“冰川说”;然后根据福建从北到南各地大量现存的第三纪以至古生代的喜暖孑遗植物,说明第四纪福建南北都没有冰川活动;再从福建的纬度和海拔2方面,证明福建第四纪不具备形成冰川的温度条件;最后指出所谓的冰臼,实为河水冲刷侵蚀而成的壶穴．     

近50年黑河流域的冰川变化遥感分析

黑河流域作为中国西北地区第二大内陆流域,其景观类型完整、流域规模适中、社会生态环境问题典型,已成为寒区、旱区水文与水资源研究的热点地区。本研究结合1：5 万地形图、Landsat TM/ETM+遥感影像及数字高程模型数据,运用面向对象的图像信息自动提取方法,建立冰川信息提取知识规则,对近50 年黑河流域的冰川变化进行遥感分析。结果表明：（1）20 世纪60 年代黑河流域内的967 条冰川到2010 年左右,减少为800 条冰川,减少数量明显;冰川面积由361.69 km²退缩为231.17 km²,共减少130.51 km²,退缩率为36.08%,平均每条冰川面积退缩0.14 km²。（2）黑河流域冰川分布及变化存在显著的区域差异性,黑河冰川退缩率比北大河大16%左右;冰川末端主要分布在4300~4400 m、4400~4500 m和4500~4600 m海拔区间内。（3）与西部其他山地冰川相比,黑河流域冰川退缩率较高。（4）根据流域内6 个气象站资料分析表明,降水增加对冰川的补给无法弥补气温上升导致的冰川消融所带来的物质损失,是黑河流域冰川普遍萎缩的关键因素。