The Two Main Mechanisms of Glacier Lake Outburst Flood in Tibet,China

With the global warming,the disasters of Glacier Lake Outburst Flood(GLOF) have taken place frequently in Tibet in recent years and attracted more and more attention.A systematic survey was conducted on the 19 GLOFs in Tibet to study their two main mechanisms.Investigations indicated that all the events occurred in end-moraine lakes,and the outburst occurred partially and instantly.And the breach had the shape of an arc or a trapezoid in overflow outburst and its top width was 3-5 times more than the height.The two main mechanisms of GLOFs in Tibetan end-moraine Lake were overflow and piping,and the overflow mechanism caused by iceberg collapse was dominated in most cases.A formula was proposed to calculate the critical thickness of iceberg tongue that determines the collapse.Granular analysis of the moraine materials revealed that seepage deformation is crucial in the outburst process.Finally,we conducted a case study of the Guangxiecuo Lake to show its possible process of outburst and estimated the peak discharge of the resulted flood.

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.

Response of Glacier and Lake Covariations to Climate Change in Mapam Yumco Basin on Tibetan Plateau during 1974-2003

The study of spatial and temporal covariances of glaciers and lakes would help us to understand the impact of climate change within a basin in Tibet. This study focuses on glacier and lake variations in the Mapam Yumco （玛旁雍错） basin （covering 7 786.44 km^2） by integrating series of spatial data from topographic maps and digital satellite images at four different times： 1974, 1990, 1999, and 2003. The results indicate that： （1） decreased lakes, retreated glaciers, enlarged lakes and advanced glaciers co-exist in the basin during the last 30 years; （2） glacier recession was accelerated in recent years due to the warmer climate; （3） lake areas in the basin are both reduced and enlarged by an accelerated speed with more water supplies from speeding melt glaciers or frozen ground in the last three decades.

Glacier extent changes and possible causes in the Hala Lake Basin of Qinghai-Tibet Plateau

Glacier is a common sensitivity indicator of environmental and global climate change.Examining the relationship between glacier area and climate change will help reveal glacier change mechanisms and future trends.Glacier changes are also of great significance to the regulation of regional water resources.This study selected the Hala Lake Basin in the northeastern Qinhai-Tibet Plateau as a study area,and examined the relationships between the temporal and spatial change of glaciers in the northeastern Qinghai-Tibet Plateau and climate change based on remote sensing imagery,climatological data,and topographic data during the past 30 years.Results showed that glacier area in the Hala Lake basin fluctuated and decreased from106.24 km2 in 1986 to 78.84 km2 in 2015,with a decreasing rate of 0.94 km2·yr-1.The number of glacier patches,mean patch area,and largest patch index all decreased from 1986 to 2015,while the splitting index increased from 1986 to 2015,indicating that the landscape fragmentation of glacier in the Hala Lake Basin was increasing significantly during the study period.Glacier area change was mainly concentrated in the slopes>25°with an altitude of 4500-5000 m,and the retreating rate of glacier of sunny slope was obviously higher than that of shady slope.Geometric center of glacier in the basin moved from southwest to northeast towards high altitude.Results of the response of glacier extent to climate change showed that temperature was the dominant factor affecting glacier area dynamic change in the Hala Lake Basin.It is predicted that in future several years,the glacier area will decrease and fragment continually as a result of global warming on the Tibetan Plateau.

THE RESEARCHES OF GLACIER LAKE OUTBURST FLOODS OF THE YARKANT RIVER IN XINJIANG

The Jokulhlaup of the Yarkant River (Yarkant He) is usually csused by the sudden discharge of the glacier-dammed lake and the mode of the discharge is the rapid expansion of the subglacial channel. Keyajir (Kyagar) Glacier and Telamukanli Glacier are on the upper reaches of the Keleqin (Shaksgam) River, the chief birthplaces of this kind of flood. Up to the end of this century, since the global climate has become warmer, the glaciers have accordingly shrunk and become thinner, with the result that the size and dimensions of the glacier-dammed lakes and their outburst floods have diminished. All these simply reveal the mystery of the Jokulhlaups of the Yarkant River in Xinjiang.

CLIMATIC TREND INDICATED BY VARIATIONS OF GLACIERS AND LAKES IN THE TIANSHAN MOUNTAINS

Under the control of geographical environment and the influence ofmodified west air mass, the mass balance of glaciers in the Tianshan Mountains hascontinously decreased since the 1970s. However, the lake level has increased gradually duo to the increase of precipitation. The interaction between temperature andprecipitation resulted in a normal and slightly more total amount of water resources inthe areas of the Tianshan Mountains. It is estimated that this climatic trend will lastto the early stage of the next century.

1976-2016年普若岗日冰川和流域湖泊变化及其对气候变化的响应

基于藏北地区普若岗日冰川1976-2016年多时相Landsat系列卫星影像数据,以及气温、降水量数据,采用ARCGIS空间分析、线性趋势分析、相关分析等方法,研究了普若岗日冰川和流域湖泊面积变化及其对气候变化的响应。结果表明:近41年普若岗日冰川面积呈显著退缩趋势,41年内冰川面积减少了52.32 km^(2),减小率为12.01%;冰川西北部退缩最为严重,冰川面积减少了12.29 km^(2),减小率为15.77%;且冰川西北部、北部、东部和东南部末端消融显著;其他区域也有不同程度的退缩。流域湖泊面积呈显著增长趋势,共增长了27.17 km^(2),增长率为22.22%;流域气温总体上呈显著增加趋势,平均每10年增加0.48℃;降水量呈不显著上升趋势,平均每10年增加15 mm。降水对冰川和流域湖泊面积影响较小,温度的持续升高是冰川和流域湖泊变化的主要因素。

基于Sentinel-2影像的巴尔托洛冰川冰面湖研究

冰面湖是冰川的重要组成部分,是冰川消融的指示器,不仅对全球气候变化响应迅速,而且对了解和掌握区域水资源信息意义重大。本文基于Sentinel-2遥感数据,利用随机森林算法,对巴尔托洛冰川冰面湖进行识别提取,并基于提取结果分析研究区冰面湖的空间分布特征,以及冰面湖面积、数量与冰川高程的关系。本文冰面湖提取的准确率达96.07%,完整率达92.18%,错误率为11.59%;识别出巴尔托洛冰川冰面湖567个,面积为249.46~37134 m^(2);冰面湖多分布在距冰川末端3~26 km处,其中海拔3800~4300 m之间冰面湖数量最多,面积普遍较大,平均面积为1922 m^(2);随着高程的升高,冰面湖的数量和面积逐渐减少,在高程5300 m以上冰面湖数量仅为15个,平均面积为356 m^(2);高程升高导致冰面温度降低,是冰面湖数量和面积骤减的主要原因。

1990—2020年波曲流域冰川冰湖时空变化及其对气候变化的响应

基于Landsat TM/ETM+/OLI遥感影像和数字高程模型(DEM)数据,结合比值阈值法与目视解译提取了1990—2020年波曲流域冰川边界,同时利用归一化水体指数与目视解译提取波曲流域冰湖数据,分析近30 a波曲流域冰川冰湖空间分布与变化特征以及母冰川-冰湖相对位置变化关系,探究波曲流域冰川冰湖协同演化及其与气候变化的响应关系。结果表明:(1)1990—2020年波曲流域冰川加速退缩,尤其是近10 a来冰川加速退缩趋势更为显著;波曲流域冰川主要分布在海拔5500~6100 m范围内,规模上看,大规模(≥10 km^(2))冰川数量保持稳定,小规模(≤0.5 km^(2))冰川数量呈增加趋势。(2)近30 a波曲流域冰湖数量、面积均不断增加,冰湖面积扩张率为74.24%;冰湖主要分布在海拔4900~5300 m之间,大冰湖(≥0.07 km^(2))面积不断扩张;小冰湖(≤0.03 km^(2))数量增加显著。(3)与母冰川相连冰湖是最重要的冰湖扩张类型,该类型冰湖面积增长量占总冰湖增量的72.08%。(4)近30 a波曲流域气温缓慢上升,降水量总体略微下降。气温上升和降水量下降是造成冰川退缩重要因素,同时冰川融水促进冰湖扩张。通过波曲流域冰川-冰湖分布面积、变化特征及其协同演化关系的探究为流域冰川面积变化趋势和冰湖溃决灾害的预测及防治提供数据支撑。

布加岗日碑加冰前湖沉积记录的冰川变化研究

掌握过去长时间尺度的冰川变化特征是客观理解现代和准确预估未来冰川变化趋势的重要依据.冰前湖沉积物是连续反演过去冰川变化历史的良好介质;然而,因研究薄弱,青藏高原冰前湖沉积物组分变化与冰川运动的关系仍不明确,极大限制了古冰川变化研究的发展.本文利用布加岗日冰川接触型湖泊−碑加湖156 cm沉积钻孔和湖区冰川沉积物,通过粒度、元素、210Pb和137Cs分析,结合1968−2021年上游碑加冰川末端变化遥感影像解译,明确了冰川运动对沉积物组分输入的影响,在此基础上重建了1817年以来的冰川变化历史.结果表明,碑加湖钻孔样品的粒度由主峰众数粒径为9.9、31、160和520μm的4个端元(EM1、EM2、EM3、EM4)组成.其中,EM4组分主要由冰川前进对冰碛碎屑的压碎作用产生,EM3~EM1组分输入和冰川退缩、冰流加速对冰碛碎屑的磨蚀作用有关;冰舌末端距离钻孔的远近造成沉积物中EM1~EM4组分含量具有梯次变化特征.相比之下,元素主成分1(PC1,方差信息解释量为46%)对冰川变化的响应程度不及粒度端元数据.粒度端元组分含量变化揭示,碑加冰川在1817−1842年前进,之后持续退缩,体现了小冰期最后一次降温和小冰期结束后全球变暖的影响.本文结果表明,借助端元分析,冰前湖沉积物粒度组成及其含量变化是研究青藏高原冰川变化的强有力指标.

近30 a东昆仑阿牙克库木湖水量变化及其补给关系研究

随着青藏高原气候变暖,高原湖泊数量和面积均表现出显著增加趋势,东昆仑-库木库里盆地湖泊扩张亦十分明显。阿牙克库木湖是库木库里盆地最大盐湖,新疆第三次综合科学考察表明,该湖泊已扩张为新疆最大湖泊。基于科考资料,结合遥感卫星资料,对阿牙克库木湖扩张及其流域冰川、冻土、气温和降水等要素进行分析,探讨湖泊水量及其补给水源的关系。结果表明:(1)1990―2023年,阿牙克库木湖面积从623.03 km^(2)扩张至1141.67 km^(2),2002―2023年湖面水位上升了7.28 m,对应水储量增加了66.64×10^(8)m^(3)。(2)1990―2023年,阿牙克库木湖流域冰川面积减少了16.4 km^(2),体积减少了1.96 km^(3)。截止2023年,流域分布冰川451条,总面积为324.26 km^(2)。(3)2010年青藏高原冻土分布图显示,流域分布多年冻土12395 km^(2),季节冻土10652 km^(2)。(4)水量平衡分析表明,冰川和冻土融水径流分别占阿牙克库木湖总入湖水量的9%和5%,季节冻土和多年冻土区降水径流占比为67%,湖面降水量直接补给占比为19%。总体而言,湖泊的扩张主要是流域降水量增加所致。研究揭示了库木库里盆地地表水文过程,可为当地政府优化水资源配置和管理提供参考。

喜马拉雅山入湖冰川物质变化研究综述

入湖冰川在喜马拉雅山地区广泛分布,其快速消融和末端崩解,是该地区冰湖溃决洪水最重要的触发因子和影响因素。近年来入湖冰川整体处于物质持续且加速亏损状态,1975—2000年入湖冰川物质平衡为-0.33±0.07 m w.e.·a^(-1),近10 a达到-0.56±0.08 m w.e.·a^(-1),其平均物质损失速率-0.45±0.08 m w.e.·a^(-1)。入湖冰川物质损失速率明显高于其他类型冰川,末端消融及崩解是其主要原因。当前冰川末端水下物质损失仍无法准确估算,广泛应用于入海冰川末端消融模拟的羽流模型,为估算入湖冰川末端湖-冰物/热交换过程研究提供了可行方法,其中冰下融水径流量、冰川末端切面形态、湖水温度和密度是影响羽流模型估算结果的重要参数。基于羽流模型评估冰川末端水下消融特征,为准确评估未来情境下冰川物质变化奠定基础。

Zhangmu and Gyirong ports under the threat of glacial lake outburst flood

The Himalayas are prone to glacial lake outburst floods,which can pose a severe threat to downstream villages and infrastructure.The Zhangmu and Gyirong land treaty ports are located on the China-Nepal border in the central Himalayas.In recent years,the expansion of glacial lakes has increased the threat of these two port regions.This article describes the results of mapping the glacial lakes larger than 0.01 km^2 in the Zhangmu and Gyirong port regions and analyzes their change.It provides a comprehensive assessment of potentially dangerous glacial lakes and predicts the development of future glacial lakes.From 1988 to 2019,the glacial lakes in these port regions underwent"expansion",and moraine-dammed lakes show the most significant expansion trend.A total of eleven potentially dangerous glacial lakes are identified based on the assessment criteria and historical outburst events;most expanded by more than 150%from 1988 to 2019,with some by over 500%.The Cirenmaco,a moraine-dammed lake,is extremely prone to overtopping due to ice avalanches or the melting of dead ice in the dam.For other large lakes,such as the Jialongco,Gangxico and Galongco,ice avalanches may likely cause the lakes to burst besides self-destructive failure.The potential dangers of the Youmojianco glacial lakes,including lakes Nos.9,10 and 11,will increase in the future.In addition,the glacier-bed topography model predicts that 113 glacial lakes with a size larger than 0.01 km^2,a total area of 11.88 km2 and a total volume of 6.37×10^9 m^3 will form in the study area by the end of the 21 century.Due to global warming,the glacial lakes in the Zhangmu and Gyirong port regions will continue to grow in the short term,and hence the risk of glacial lake outburst floods will increase.

1990—2020年科西河流域冰川冰湖遥感监测

科西河流域冰川和冰湖较为发育,随着全球气候变暖,冰川融水成为冰湖扩张的重要补给,同时会引发冰湖溃决洪水(GLOF)等自然灾害,给当地居民生产生活带来巨大损失。因此,对该区域冰川冰湖的时空分布规律和变化特征的研究具有现实意义。本文基于Landsat系列遥感影像和数字高程模型,分析了1990—2020年科西河流域冰川冰湖面积时空分布与变化特征,并结合气象格点数据和GLOF事件,探究科西河流域冰川冰湖对气候变化响应及其与GLOF事件关系。结果表明:(1)1990—2020年科西河流域冰川面积呈加速退缩的趋势,近10年加速退缩趋势进一步加强。(2)科西河流域冰川主要分布在海拔4800~6800 m范围内,而在坡度上,主要分布在5°~20°。(3)1990—2020年科西河流域冰湖呈加速扩张的趋势,冰湖面积共扩张了26.09 km^(2),其中面积>0.25 km^(2)的冰湖扩张迅速;与冰川相连的冰湖面积扩张显著,面积增长率为49.39%。(4)1990—2020年科西河流域共11条冰湖发生溃决,溃决冰湖分布面积较小,介于0.02~0.7 km^(2)。(5)1990—2020年科西河流域气温和降水量呈波动增长趋势,降水增加不足以弥补温度引起的冰川退缩,致使科西河流域冰川加速退缩,冰湖加速扩张,冰湖溃决事件频发。

长江源区湖泊-冰川变化特征及其对气候变化的响应

湖泊是气候变化的敏感指示器,研究其动态变化对揭示全球气候变化及水资源利用与管理具有重要意义。本文以长江源区多尔索洞错-米提江占木错为研究对象,应用Landsat-5/7/8卫星和高分遥感影像,分析了1989—2021年湖泊面积变化的时空特征,并探讨了冰湖-冰川对气候变化的响应。结果表明,1989—2021年间,多尔索洞错-米提江占木错湖泊平均面积为1011.37 km^(2),由1989年的872.07km^(2)扩张至2021年的1119.5 km^(2),平均扩张率为8.62 km^(2)·a^(-1)。从年代际变化来看,21世纪初期湖泊面积扩张最明显,尤其是在湖泊北部、西北部及南部地区;20世纪90年代增长最为缓慢。1990—2020年各拉丹冬冰川面积从1990年的797.85 km^(2)缩小至2020年的766.19 km^(2),减少了31.66 km^(2),缩减率为1.106 km^(2)·a^(-1)。2004年之前,气温升高引起的冰川融水是多尔索洞错-米提江占木错湖泊面积变化的主要因素,对湖泊面积变化的平均贡献率为66.8%;2004年之后,降水在多尔索洞错-米提江占木错湖泊面积变化因素中起主导作用,降水对湖泊面积变化的平均贡献率为57.8%。

Modelling Chorabari Lake outburst flood, Kedarnath, India

In this study, the Glacier Lake Outburst Flood(GLOF) that occurred over Kedarnath in June 2013 was modeled using integrated observations from the field and Remote Sensing(RS). The lake breach parameters such as area, depth, breach, and height have been estimated from the field observations and Remote Sensing(RS) data. A number of modelling approaches, including Snow Melt Runoff Model(SRM), Modified Single Flow model(MSF), Watershed Management System(WMS), Simplified Dam Breach Model(SMPDBK) and BREACH were used to model the GLOF. Estimations from SRM produced a runoff of about 22.7 m3 during 16–17, June 2013 over Chorabari Lake. Bathymetry data reported that the lake got filled to its maximum capacity(3822.7 m3) due to excess discharge. Hydrograph obtained from the BREACH model revealed a peak discharge of about 1699 m3/s during an intense water flow episode that lasted for 10–15 minutes on 17 th June 2013. Excess discharge from heavy rainfall and snowmelt into the lake increased its hydrostatic pressure and the lake breached cataclysmically.

Dynamic changes in lakes in the Hoh Xil region before and after the 2011 outburst of Zonag Lake

Zonag, Kusai, Hedin Noel and Yanhu Lakes are independent inland lakes in the Hoh Xil region on the Qinghai-Tibet Plateau. In September2011, Zonag Lake burst after the water level had increased for many years. Floods flowed through Kusai and Hedin Noel Lakes into Yanhu Lake; since then, the four small endorheic catchments merged into one larger catchment. This hydrological process caused the rapid shrinkage of Zonag Lake and continuous expansion of Yanhu Lake. In this study,based on satellite images, meteorological data and field investigations, we examined the dynamic changes in the four lakes and analyzed the influencing factors. The results showed that before 2011, the trends in the four lake areas were similar and displayed several stages. The change in the area of Zonag Lake corresponded well to the change in annual precipitation(AP), but the magnitude of the change was less than that of a non-glacier-fed lake. Although increased precipitation was the dominant factor that caused Zonag Lake to expand, increased glacier melting and permafrost thawing due to climate warming also had significant effects. After the 2011 outburst of Zonag Lake, due to the increasing AP and accelerating glacier melting, the increases in water volume of the three lakes were absorbed by Yanhu Lake, and Yanhu Lake expanded considerably. According to the rapid growth rates in water level and lake area, Yanhu Lake is likely to burst in 1-2 years.

Middle-Late Pleistocene Glacial Lakes in the Grand Canyon of the Tsangpo River,Tibet

Many moraines formed between Daduka and Chibai in the Tsangpo River valley since Middle Pleistocene. A prominent set of lacustrine and alluvial terraces on the valley margin along both the Tsangpo and Nyang Rivers formed during Quaternary glacial epoch demonstrate lakes were created by damming of the river. Research was conducted on the geological environment, contained sediments, spatial distribution, timing, and formation and destruction of these paleolakes. The lacustrine sediments 14C （10537±268 aBP at Linzhi Brick and Tile Factory, 22510±580 aBP and 13925±204 aBP at Bengga, 21096±1466 aBP at Yusong） and a series of ESR （electron spin resonance） ages at Linzhi town and previous data by other experts, paleolakes persisted for 691±305 kaBP middle Pleistocene ice age, 75-40 kaBP the early stage of last glacier, 27-8 kaBP Last Glacier Maximum （LGM）, existence time of lakes gradually shorten represents glacial scale and dam moraine supply potential gradually cut down, paleolakes and dam scale also gradually diminished. This article calculated the average lacustrine sedimentary rate of Gega paleolake in LGM was 12.5 mm/a, demonstrates Mount Namjagbarwa uplifted strongly at the same time, the sedimentary rate of Gega paleolake is more larger than that of enclosed lakes of plateau inland shows the climatic variation of Mount Namjagbarwa is more larger and plateau margin uplifted more quicker than plateau inland. This article analyzed formation and decay cause about the Zelunglung glacier on the west flank of Mount Namjagbarwa got into the Tsangpo River valley and blocked it for tectonic and climatic factors. There is a site of blocking the valley from Gega to Chibai. This article according to moraines and lacustrine sediments yielded paleolakes scale： the lowest lake base altitude 2850 m, the highest lake surface altitude 3585 m, 3240 m and 3180 m, area 2885 km2, 820 km2 and 810 km2, lake maximum depth of 735 m, 390 m and 330 m. We disclose the reason that previous experts discovered there were different age moraines dividing line of altitude 3180 m at the entrance of the Tsangpo Grand Canyon is dammed lake erosive decay under altitude 3180 m moraines in the last glacier era covering moraines in the early ice age of late Pleistocene, top 3180 m in the last glacier moraine remained because ancient dammed lakes didn＇t erode it under 3180 m moraines in the early ice age of late Pleistocene exposed. The reason of the top elevation 3585 m moraines in the middle Pleistocene ice age likes that of altitude 3180 m. There were three times dammed lakes by glacier blocking the Tsangpo River during Quaternary glacial period. During other glacial and interglacial period the Zelunglung glacier often extended the valley but moraine supplemental speed of the dam was smaller than that of fluvial erosion and moraine movement, dam quickly disappeared and didn＇t form stable lake.

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.

青藏高原冰湖溃决灾害隐患识别、发育规律及危险性评价

青藏高原是全球冰湖溃决灾害发生最频繁的区域之一,冰湖溃决对人类及工程建设安全造成严重威胁。以2015-2018年Landsat 8 OLI_TIRS等遥感影像及数据为基础,对青藏高原40000余条冰川10 km范围内且面积大于900 m^(2)的冰湖进行了遥感解译,分析了冰湖分布与发育特征,建立了冰湖溃决隐患的识别指标体系,利用突变级数法(CPM)对隐患点进行了危险性分级评价。结果表明:①青藏高原发育冰湖16481处,海拔分布在5000~5500 m之间的冰湖占总量的43.69%;面积集中在100~500 km^(2)之间的占总量的47.40%;行政分布上主要分布在西藏自治区,有12664个,占总量的76.84%;流域上主要分布在雅鲁藏布江流域,有8321个,占总量的50.49%。②识别出冰湖灾害隐患点369个,其中低危险点126个,中危险点177个,高危险点66个。③冰湖溃决隐患点面积多为0.1~0.2 km^(2);海拔主要分布在5000~5500 m之间;与母冰川距离大多小于100 m;冰碛坝宽度一般小于300 m,背水坡坡度大多小于50°;冰湖溃决隐患点的母冰川冰舌端坡度分布在10°~20°之间;绝大多数冰湖溃决的方向朝向北方。