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巴丹吉林沙漠湖泊水化学空间分布特征 总被引：7，自引：2，他引：5
通过对巴丹吉林沙漠腹地拐子湖-地质公园一线51个湖泊水,8个泉水,12个井水及1个雨水水样的水化学成分分析,初步探讨了沙漠湖泊水化学分布特征及其影响因素.结果表明由东南边缘至腹地湖泊总体上依次呈硫酸盐型-碳酸盐型-氯化物型分布.东南边缘以Na+、Cl-、SO24-为主的湖泊因矿化度分异,形成Ca2+、Mg2+含量不同的三种亚型,其中高矿化度的Na-Cl-(SO4)型湖泊在腹地湖泊群中也有出现,表现出地理上的不连续分布;边缘若干湖泊受局部地理环境的影响水离子多含Na+、Cl-、CO32-+HCO3-.综合分析表明湖泊水化学型的空间分异与区域气候差异和气候变化有关,湖水直接或间接地接受当地降水补给,但不排除外源地下水补给对其有一定贡献.通过对比不同时段部分沙漠湖泊水化学特征发现近十年以来腹地湖泊补给源或受气候干暖化影响使其水化学特性较边缘湖泊的变化大. 相似文献
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雅鲁藏布江河谷风沙地貌形成机制与发育模式 总被引：14，自引：1，他引：13
雅鲁藏布江河谷风沙地貌有 4级 2 1个类型 .河谷区具有风沙地貌发育的环境条件 .由MM4中尺度气候模型模拟的河谷冬半年近地表流场和风矢量场从宏观上反映了有利于风沙沉积的河谷流场 ,在总体上制约了风沙地貌的分布区域与地貌部位 .沙丘、沙丘群发育主要有迎风阻滞沉积、背风回流沉积和弯道绕流沉积三种方式 ,经历了风力作用沙丘形成 水力作用沙丘消减的正、逆交替过程 ,并自初生带→主体带→消退带演化 ,最终以爬升沙丘 (片 )或下落沙丘形态消退或消亡 . 相似文献
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气生藻类在云南石林景观形成中的作用 总被引：4，自引：0，他引：4
对云南石林碳酸盐岩表面的气生藻类及其生物溶蚀作用进行了详细的野外考察和实验室研究. 通过运用光学显微镜(实体显微镜、生物显微镜)和电子显微镜对100多个藻类标本和岩石标本进行逐步观察、鉴定和统计, 重点分析了石林表面的藻类和藻类群落与石林溶蚀形态的关系和成因机制. 研究认为, 气生蓝藻有着积极的生物溶蚀作用, 能够影响喀斯特溶蚀形态的形成, 这种影响分为直接的和间接的. 直接的影响是指藻类对喀斯特形态形成的主动控制(藻生物控形作用), 主要反映在微形态(<10−3 m)及小形态(10−3~10−1 m)上, 分为藻个体控形作用和藻群落控形作用, 前者主要控制微形态, 后者主要控制微形态和较小的小形态; 间接的影响是指藻类对喀斯特形态形成的促进作用, 它贯穿于所有喀斯特形态形成的过程中. 藻类的生物溶蚀作用加速了整个石林喀斯特地貌的风化过程. 相似文献
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湖泊沉积储存有丰富的信息,常被用于指示气候变化。地震、洪水、滑坡或崩塌等自然灾害事件通常会在湖泊沉积中形成特征性的湖泊沉积扰动,可以使用湖泊地质学方法对其进行分析与识别。本文回顾了湖泊沉积研究历程,对典型自然灾害湖泊沉积特征进行系统总结,着重梳理介绍湖泊沉积中自然灾害事件识别方法。其中综合分析法集成了现阶段湖泊事件沉积识别的多种分析手段：(1)根据沉积相与异常事件沉积（EID）之间的关系判定其内源或外源成因;(2)根据对触发因素的排除,确定最可能的触发因素;(3)根据现有的识别标准,验证最可能触发因素的正确性。是目前识别湖泊扰动成因最有效的分析手段。本文还对湖泊沉积灾害事件研究的优势与不足及制约因素进行讨论,湖泊沉积具有连续性、敏感性和高分辨率的特点有助于对灾害事件进行研究,但对湖泊典型自然灾害事件沉积识别标志的建立仍然是制约湖泊异常事件沉积研究的关键。 相似文献
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《地震地质》2015,(4)
在雅鲁藏布江大峡谷入口河段,分布着多级含湖相沉积的阶地,在河床下还埋藏有巨厚的河湖相覆盖层。通过对阶地沉积和河床覆盖层浅部沉积物的光释光和14C测年,初步建立了河谷上部沉积的地层年代学框架,揭示出雅鲁藏布江大峡谷入口河段在末次盛冰期以来至少发育2期古堰塞湖(古堰塞湖Ⅰ,古堰塞湖Ⅱ),其沉积年龄分别为7~9ka、20~30ka,并形成2级连续的海拔高度分别为2906~2 956m、3100~3 060m的堆积阶地(T1,T2)。古堰塞湖的沉积时间与青藏高原地区末次冰期冰盛期和全新世早期低温事件相对应,推测是南迦巴瓦峰西坡的则隆弄冰川活动形成冰川堰塞坝堵塞河道的结果。古堰塞湖Ⅰ分布范围较小,在大渡卡—米瑞发育湖相沉积,湖尾大致在米林县城附近,沉积厚度5~8m。古堰塞湖Ⅱ发育范围较广,湖相沉积在大渡卡—卧龙均有出露,湖尾大致在朗县附近,最大沉积厚度超过100m。古堰塞湖Ⅱ被后期河流冲刷,可形成1~3级次级阶地。 相似文献
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Outburst susceptibility assessment of moraine‐dammed lakes in Western Himalaya using an analytic hierarchy process 
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下载免费PDF全文 Glacier retreat results in the formation and expansion, and sometimes outburst, of moraine‐dammed lakes worldwide. Sudden outburst floods from such lakes have caused enormous damage to settlements and infrastructure located downstream. Such lakes located in the Himalayan region are highly prone to outburst floods due to climatic conditions and geotectonic settings. In this study, multi‐temporal Landsat images from 2002–2014, digital elevation models (DEMs), geomorphic analysis and modelling were used to assess the changes in glacial lakes and the outburst susceptibility of moraine‐dammed lakes in the Chandra–Bhaga basin of the north‐western Indian Himalaya. An inventory of lakes was developed using satellite data, thematic maps and ground‐based investigations for the Chandra–Bhaga basin. The total area of all glacial lakes (size >5000 m2) increased by 47% from 2002 to 2014, with a pronounced increase of 57% for moraine‐dammed lakes. Sixteen moraine‐dammed lakes were identified and assessed for outburst susceptibility using the analytic hierarchy process (AHP). Forty‐one reported glacial lake outburst flood (GLOF) events from moraine‐dammed lakes in Himalayan regions were analysed, culminating in the identification of 11 critical factors for assessing outburst susceptibility using the AHP, including those related to the lake area and change, surrounding terrain characteristics, dam geometry, regional seismicity and rainfall history. The past three GLOF events in the Himalayan region were used to validate the method and to classify moraine‐dammed lakes as having very high, high, medium or low outburst susceptibility. Eight lakes classified as very high and high outburst susceptibility should be further investigated in detail. The proposed AHP‐based approach is suitable for first‐order identification of critical lakes for prioritising future detailed investigation and monitoring of moraine‐dammed glacial lakes in the Himalayan region. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Fuyuan An Tianyuan Chen Xiangzhong Li Xiangjun Liu Yixuan Wang Zongyan Chen E Chongyi 《地球表面变化过程与地形》2021,46(12):2421-2436
This study investigated a series of dammed lakes and downstream-adjacent alluvial fans in the upstream to middle reaches of the Golmud River in the eastern Kunlun Mountain, on the north-eastern Qinghai-Tibetan Plateau (QTP). An optically stimulated luminescence (OSL) chronology shows the sediments of five dammed lakes developed from c. 45–40, 30–25, 18–14, and 12–8 ka, corresponding to MIS 3b, late MIS 3a, Last Deglaciation, and early Holocene, respectively. The remote sensing data show these dammed lakes have a total area of 109.4 km2, with the lake volume of more than 4.0 km3. Symmetric alluvial fans from north–south tributary valleys produced OSL ages of c. 61–52, 42–31, 26–20, and 16–10 ka, corresponding to glaciation periods: the MIS 3c and MIS 3a, MIS 2, and the Last Deglaciation. This suggests that glacial activity is responsible for the alluvial fan development, where dammed rivers occurred first, but lake formation did not take place synchronously until later periods of strong hydrologic activity, resulting from northward intrusions of the Indian summer monsoon (ISM) or glacier melt. Thus, the blocking pattern is that river valleys were dammed during periods of glacial activity and lakes formed during wet periods. The lake formation and subsequent drainage may have resulted in: (i) impeded headwater incision and strengthening of downstream dissection; (ii) enriched the halite and potash in the distal Qarhan Salt Lake through hydrologic and hydrochemical processes of abundant water input, the salt lake expansion, salt redissolution from playa and final resedimentation during later dry periods. The alluvial-dammed lake pattern in the mountain-basin systems of eastern Kunlun Mountain offers a model for assessing the linkages between monsoon dynamics, geomorphic processes and distal salt lake evolutions in other arid regions. 相似文献
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OSL dating of past lake levels for a large dammed lake in southern Tibet and determination of possible controls on lake evolution 下载免费PDF全文
下载免费PDF全文 Fluvio‐lacustrine terraces along Phung Chu (river) on the central southern Tibetan Plateau indicate that a large palaeo‐dammed‐lake formerly existed in this area. Based on landscape survey, optically stimulated luminescence (OSL) dating and sedimentary analyses, this research shows that the Phung Chu was blocked and a dammed‐lake over 2500 km2 in size formed before 30 ka ago. OSL dating analysis suggests the fluvio‐lacustrine sediments were well bleached and yield accurate age estimates for two lake drainage events. The first drainage event took place after 30 ka, resulted in river incision and formed a high terrace at 50 m height from the present river level. The second drainage happened after 3.7 ka, resulted in further river incision and formed the second terrace at 25 m height from the present river level. According to the distribution of the fluvio‐lacustrine sediments, active normal faults (particularly the Kharta Fault) in this region and the high gradient slopes after Phung Chu enters the Yö Ri gorge, seismically‐induced landsliding is regarded as highly likely to have been the cause of river blockage and associated formation of a dammed‐lake, although glacial damming is also a possible cause. The volume of drainages from this dammed‐lake may have led to catastrophic flooding and analogous modern lakes represent significant geo‐hazard risks to down‐river human settlements. As dammed‐lakes are special phases in fluvial evolution, often involving river blockage, breakthrough and drastic catchment change, these processes can reveal how tectonic or climatic events modify landforms. However, such tectonic‐derived landform changes can also impact palaeo‐climate of the region. Thus this study has added new evidence regarding the evolutionary history of a dammed lake including its formation, duration, extent and final drainage, which is crucial for understanding its general landscape process mechanisms and for better assessing geo‐hazard risks. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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More than 2000 of mountain lakes covering more than 0.1 ha exist in a territory of Kyrgyzstan. Nearly 20% of them are dangerous because of instability of lake dams, frequent overflows and melting of buried ice inside the moraine dams. According to the Kyrgyz lake inventory, 328 lakes are at risk of outburst and 12 lakes are considered as actually dangerous. Since 1952 more than 70 disastrous cases of lake outbursts have occurred. The majority of the endangered lakes belong to one of the three genetic types: morainic-glacier, supraglacial and lake dammed by landslides and debris flows. Petrov, Adygine and Koltor lakes were selected and studied in the Tien-Shan Mountains as case studies of the most frequent genetic types of hazardous lakes. Observations were focused on the morphology of the lake basin and the surrounding relief, outflow pattern and processes controlling the development of lake. For the hazard assessment, evolution of glaciers and lakes was reconstructed using historical reports, aerial photographs and satellite images. 相似文献
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There are many episodes of multiple-level lacustrine terraces along the entrance of the Yarlung Zangbo Great Canyon. Besides, very thick fluvio-lacustrine sediments are buried beneath the cover of the riverbed. Optically stimulated luminescence and radiocarbon dating provide an approximate timeline of upper valley deposits and reveal at least two glacially dammed lake events (Ⅰ and Ⅱ) which have deposition ages of 7～9ka (Ⅰ) and 20～30ka(Ⅱ), respectively. The recent two episodes of glacially dammed lakes produced two steps of lacustrine terraces (T1, T2) correspondingly, which are of elevations 2906～2 956m and 3100～3 060m. The formation of paleo-dammed lakes reflects that the Zelunglung Glacier in the west slope of Mt. Namche Barwa had progressively advanced to block the Yarlung Tsangpo River during the early Holocene and the Last Glacial Maximum. The glacially dammed lake I has a relatively smaller extent. Its lacustrine sediments are distributed mainly from Datuoka to Mirui with maximum thickness about 5～8m. Its end is roughly at the south of Milin County. The glacially dammed lake Ⅱ occupies a large area with the end roughly nearby Lang County. Its sediments are exposed from Datuoka to Wolong with maximum thickness about 100m. After the later fluvial erosion, the lacustrine sediments of this lake formed 1～3 levels of secondary terraces. 相似文献
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Nico Mölg Christian Huggel Thilo Herold Florian Storck Simon Allen Wilfried Haeberli Yvonne Schaub Daniel Odermatt 《地球表面变化过程与地形》2021,46(13):2551-2564
Retreating glaciers give way to new landscapes with lakes as an important element. In this study, we combined available data on lake outlines with historical orthoimagery and glacier outlines for six time periods since the end of the Little Ice Age (LIA; ~1850). We generated a glacial lake inventory for modern times (2016) and traced the evolution of glacial lakes that formed in the deglaciated area since the LIA. In this deglaciated area, a total of 1192 lakes formed over the period of almost 170 years, 987 of them still in existence in 2016. Their total water surface in 2016 was 6.22 ± 0.25 km2. The largest lakes are > 0.4 km2 (40 ha) in size, while the majority (> 90%) are smaller than 0.01 km2. Annual increase rates in area and number peaked in 1946–1973, decreased towards the end of the 20th century, and reached a new high in the latest period 2006–2016. For a period of 43 years (1973–2016), we compared modelled overdeepenings from previous studies to actual lake genesis. For a better prioritization of formation probability, we included glacier-morphological criteria such as glacier width and visible crevassing. About 40% of the modelled overdeepened area actually got covered by lakes. The inclusion of morphological aspects clearly aided in defining a lake formation probability to be linked to each modelled overdeepening. Additional morphological variables, namely dam material and type, surface runoff, and freeboard, were compiled for a subset of larger and ice-contact lakes in 2016, constituting a basis for future hazard assessment. 相似文献
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Pressure‐driven,shoreline currents in a perennially ice‐covered,pro‐glacial lake in Antarctica,identified from a LiCl tracer injected into a pro‐glacial stream 下载免费PDF全文
下载免费PDF全文 The distribution of streamwater within ice‐covered lakes influences sub‐ice currents, biological activity and shoreline morphology. Perennially ice‐covered lakes in the McMurdo Dry Valleys, Antarctica, provide an excellent natural laboratory to study hydrologic–limnologic interactions under ice cover. For a 2 h period on 17 December 2012, we injected a lithium chloride tracer into Andersen Creek, a pro‐glacial stream flowing into Lake Hoare. Over 4 h, we collected 182 water samples from five stream sites and 15 ice boreholes. Geochemical data showed that interflow travelled West of the stream mouth along the shoreline and did not flow towards the lake interior. The chemistry of water from Andersen Creek was similar to the chemistry of water below shoreline ice. Additional evidence for Westward flow included the morphology of channels on the ice surface, the orientation of ripple marks in lake sediments at the stream mouth and equivalent temperatures between Andersen Creek and water below shoreline ice. Streamwater deflected to the right of the mouth of the stream, in the opposite direction predicted by the Coriolis force. Deflection of interflow was probably caused by the diurnal addition of glacial runoff and stream discharge to the Eastern edge of the lake, which created a strong pressure gradient sloping to the West. This flow directed stream momentum away from the lake interior, minimizing the impact of stream momentum on sub‐ice currents. It also transported dissolved nutrients and suspended sediments to the shoreline region instead of the lake interior, potentially affecting biological productivity and bedform development. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Indarri Falls is a spectacular travertine dam which impounds Lawn Hill Creek, a perennial karst stream draining the Barkly Tableland in northwest Queensland, Australia. The dam is at least 13·5 m high, making it the largest feature of its kind known in Australia. Carbonate precipitation at the falls is favoured by downstream changes in the bulk chemistry of the karst spring waters which feed the Creek, although deposition at the microenvironmental level may be encouraged by biological factors. The dam has dramatically altered the hydrology and geomorphology of the area, transforming the middle reaches of Lawn Hill Creek from a fluvial to a lacustrine environment. © 1997 by John Wiley & Sons, Ltd. 相似文献
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Swenja Rosenwinkel Angela Landgraf Wolfgang Schwanghart Friedrich Volkmer Atyrgul Dzhumabaeva Silke Merchel Georg Rugel Frank Preusser Oliver Korup 《地球表面变化过程与地形》2017,42(10):1535-1548
Elevated shorelines and lake sediments surrounding Issyk Kul, the world's second largest mountain lake, record fluctuating lake levels during Quaternary times. Together with bathymetric and geochemical data, these markers document alternating phases of lake closure and external drainage. The uppermost level of lake sediments requires a former damming of the lake's western outlet through the Boam gorge. We test previous hypothesised ice or landslide dam failures by exploring possible links between late Quaternary lake levels and outbursts. We review and recompile the chronology of reported changes in lake site, and offer new ages of abandoned shorelines using 14C in bivalve and gastropod shells, and plant detritus, as well as sand lenses in delta and river sediments using Infrared Stimulated Luminescence. Our dates are consistent with elevated lake levels between ~45 ka and 22 ka. Cosmogenic 10Be and 26Al exposure ages of fan terraces containing erratic boulders (>3 m) downstream of the gorge constrain the timing of floods to 20.5–18.5 ka, postdating a highstand of Issyk Kul. A flow‐competence analysis gives a peak discharge of >104 m3 s–1 for entraining and transporting these boulders. Palaeoflood modelling, however, shows that naturally dammed lakes unconnected to Issyk Kul could have produced such high discharges upon sudden emptying. Hence, although our data are consistent with hypotheses of catastrophic outburst floods, average lake‐level changes of up to 90 mm yr–1 in the past 150 years were highly variable without any outbursts, so that linking lake‐level drops to catastrophic dam breaks remains ambiguous using sedimentary archives alone. This constraint may readily apply to other Quaternary lakes of that size elsewhere. Nonetheless, our reconstructed Pleistocene floods are among the largest reported worldwide, and motivate further research into the palaeoflood hydrology of Central Asia. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Lakes are common in glaciated mountain regions and geomorphic principles suggest that lake modifications to water and sediment fluxes should affect downstream channels. Lakes in the Sawtooth Mountains, Idaho, USA, were created during glaciation and we sought to understand how and to what extent glacial morphology and lake disruption of fluxes control stream physical form and functions. First, we described downstream patterns in channel form including analyses of sediment entrainment and hydraulic geometry in one catchment with a lake. To expand on these observations and understand the role of glacial legacy, we collected data from 33 stream reaches throughout the region to compare channel form and functions among catchments with lakes, meadows (filled lakes), and no past or present lakes. Downstream hydraulic geometry relationships were weak for both the single catchment and regionally. Our data show that downstream patterns in sediment size, channel shape, sediment entrainment and channel hydraulic adjustment are explained by locations of sediment sources (hillslopes and tributaries) and sediment sinks (lakes). Stream reaches throughout the region are best differentiated by landscape position relative to lakes and meadows according to channel shape and sediment size, where outlets are wide and shallow with coarse sediment, and inlets are narrow and deep with finer sediment. Meadow outlets and lake outlets show similarities in the coarse‐sediment fraction and channel capacity, but meadow outlets have a smaller fine‐sediment fraction and nearly mobile sediment. Estimates of downstream recovery from lake effects on streams suggest 50 per cent recovery within 2–4 km downstream, but full recovery may not be reached within 20 km downstream. These results suggest that sediment sinks, such as lakes, in addition to sources, such as tributaries, are important local controls on mountain drainage networks. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献