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Heterogeneity in supraglacial debris thickness and its role in glacier mass changes of the Mount Gongga

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Science China Earth Sciences 2016年第1期59卷 170-184页

作者： ZHANG Yong HIRABAYAshi Yukiko FUJITA Koji liu shi yin liu Qiao State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Institute of Engineering Innovation The University of Tokyo Graduate School of Environmental Studies Nagoya University Institute of Mountain Hazards and Environment Chinese Academy of Sciences

In the Tibetan Plateau, many glaciers have extensive covers of supraglacial debris in their ablation zones, which affects glacier response to climate change by altering ice melting and spatial patterns of mass loss. Insufficient debris thickness data make it difficult to analyze regional debris-cover effects. Maritime glaciers of the Mount Gongga have been characterized by a substantial reduction in glacier area and ice mass in recent decades. The thermal property of the debris layer estimated from remotely sensed data reveals that debris-covered glaciers are dominant in this region, on which the proportion of debris cover to total glacier area varies from 1.74% to 53.0%. Using a physically-based debris-cover effect assessment model, we found that although the presence of supraglacial debris has a significant insulating effect on heavily debris-covered glaciers, il accelerates ice melting on -10.2% of total ablation zone and produces rapid wastage of -25% of the debris-covered glaciers, leading to the similar mass losses between the debris-covered and debris-free glaciers. Widespread debris cover also facilitates the development of active terminus regions. Regional differences in debris-cover effects are apparent, highlighting the im- portance of debris cover for understanding glacier mass changes in the Tibetan Plateau and other mountain ranges around the world.

关键词： Debris-cover effect Ice melting Maritime glacier Glacier status Mount Gongga

Farmers' perceptions of and adaptations to drought in Herat Province, Afghanistan

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Journal of Mountain Science 2018年第8期15卷 1741-1756页

作者： Mohammad Wasim IQBAL Somchai DONJADEE Bancha KWANYUEN liu shi-yin Irrigation Technology Research Laboratory Department of Irrigation Engineering Faculty of Engineering at Kamphaeng Saen Kasetsart University Institute of International Rivers and Eco-security Yunnan University

Drought is a significant natural hazard in Herat Province, Afghanistan. The objective of this study was to explore farmers' perceptions of the drought's prevalence and characteristics, its socioeconomic and environmental impacts, their strategies for coping with and mitigating it, and types of conflicts and resolution mechanisms. A questionnaire was completed by 147 farming households. The results indicate that farmers' perceptions regarding drought are in line with the results obtained using the precipitation data. Even though the respondents have religious belief in interpreting the weather related issues, they also perceived drought as the climatic and environmental factors such as increased temperature, decreased precipitation, and other factors like war, financial weakness, deforestation, over-exploitation of groundwater, lack of electricity supply etc. The results show that drought has had serious economic impacts, including loss of employment and reduction in crop yield and livestock production, which have reduced farmers' livelihood options and weakened their financial situation. Social impacts have included migration, a sense of hopelessness and loss, conflicts over water, health problems, impacts on the schooling of children, malnutrition, and limits to food options. Significant environmental impacts such as an increase in temperature, pasture and forest degradation, deterioration of water quality, damage to fish and wildlife habitats, and groundwater depletion were also reported. Farmers used local techniques to adapt to drought and lessen its effects. Farmers perceived irrigation water to be a major source of conflict. Local elders, water-user associations, and formal courts were reported to be the most successful conflict resolution methods. It is expected that the results of this study will support policy makers within government and development agencies in Afghanistan to develop future drought adaptation policies.

关键词： Adaptation strategies Perception Agriculture Drought impacts Water conflict

TURBULENT FLOWS AROUND SAND DUNES IN ALLUVIAL RIVERS

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Journal of Hydrodynamics 2010年第1期22卷 103-109页

作者： liu shi-he yin Shu-ran GUO Wei College of Water Resource and Hydropower Wuhan University Wuhan 430072 China Yangtze River Scientific Research Institute Wuhan 430010 China

The sand dunes are typical bed forms of natural alluvial rivers. In this article, a vertical 2-D Reynolds stress model is established for the simulation of turbulent flows around sand dunes, and water-sand boundary conditions are set with particular attention. By numerical simulations, the following conclusions can be drawn. （1） The flow resistance in rivers with sand dunes could be divided into the sand-grain resistance and the sand dune resistance, and the sand-grain resistance coefficient mainly depends on Reynolds number, relative sand grain roughness and sand dune steepness. This coefficient in rivers with sand dunes would be larger than that calculated in a flat riverbed, and the steeper the sand dunes, the larger the sand-grain resistance coefficient. （2） The sand dune resistance coefficient mainly depends on the relative sand dune height and sand dune steepness, the steeper the sand dunes, the larger the sand dune resistance coefficient. （3） For the flat riverbed, the turbulent eddy viscosity coefficient and the sediment diffusion coefficient are approximately identical, but for the sand dune riverbed, in the vertical position, where the sediment diffusion coefficient reaches its maximum, it would be higher than the turbulent eddy viscosity coefficient.

关键词： sand dune flow resistance sediment diffusion coefficient eddy viscosity

Regimes of Runoff Components on the Debris-covered Koxkar Glacier in Western China

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Journal of Mountain Science 2015年第2期12卷 313-329页

作者： HAN Hai-dong DING Yong-jian liu shi-yin WANG Jian State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

By using a degree-day based distributed hydrological model, regimes of glacial runoff from the Koxkar glacier during 2007-2011 are simulated, and variations and characteristics of major hydrological components are discussed. The results show that the meltwater runoff contributes 67.4%, of the proglacial discharge, out of which snowmelt, clean ice melting, buried-ice ablation and ice-cliff backwasting account for 22.4%, 21.9%, 17.9% and 5.3% of the total melt runoff, respectively. Rainfall runoff is significant in mid-latitude glacierized mountain areas like Tianshan and Karakorum. In the Koxkar glacier catchment, about 11.5% of stream water is initiated from liquid precipitation. Spatial distributions for each glacial runoff component reveal the importance of climatic gradients, local topography and morphology on glacial runoff generation, and temporal variations of these components is closely related to the annual cycle of catchment meteorology and glacier storage. Four stages are recognized in the seasonal variations of glacier storage, reflecting changes in meltwater yields, meteorological conditions and drainage systems in the annual hydrological cycle.

关键词： Debris cover Meltwater Glacier Koxkar Runoff

Glacier Changes during the Past 40 Years in the West Kunlun Shan

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Journal of Mountain Science 2015年第2期12卷 344-357页

作者： BAO Wei-jia liu shi-yin WEI Jun-feng GUO Wan-qin State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Science University of Chinese Academy of Sciences

Recent studies on glaciers in the West Kunlun Shan, northwest Tibetan Plateau, have shown that they may be stable or retreating slightly. Here, we assess changes in the mass of the glaciers in the West Kunlun Shan(WKS) in an attempt to understand the processes that control their behavior. Glaciers over the recent 40 years(1970-2010) have shrunk 3.4±3.1%in area, based on a comparison between two Chinese glacier inventories. Variations of surface elevations, derived from ICESat-GLAS(Ice, Cloud, and Land Elevation Satellite-Geoscience Laser Altimeter System) elevation products(GLA14 data) using the robust linear-fit method, indicate that the glaciers have been gaining mass at a rate of 0.23±0.24 m w.e./a since 2003. The annual mass budget for the whole WKS range from 2003 to 2009 is estimated to be 0.71±0.62 Gt/a. This gain trend is confirmed by MOD10A1 albedo for the WKS region which shows a descent of the mean snowline altitude from 2003 to 2009.

关键词： Glacier change Mass balance West Kunlun Shan

Spatio-temporal changes in the six major glaciers of the Chitral River basin(Hindukush Region of Pakistan)between 2001 and 2018

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Journal of Mountain Science 2020年第3期17卷 572-587页

作者： Jawaria GUL Sher MUHAMMAD liu shi-yin Siddique ULLAH Shakeel AHMAD Huma HAYAT Adnan Ahmad TAHIR Department of Environmental Sciences COMSATS University Islamabad(CUI)Abbottabad Campus22060AbbottabadPakistan International Center for Integrated Mountain Development(ICIMOD) KathmanduNepal Institute of International Rivers and Eco-Security Yunnan UniversityKunmingChina Division of Environmental System Analysis School of EnvironmentTsinghua UniversityBeijing 100084 China

Glaciers in the northern Pakistan are a distinctive source of freshwater for the irrigation,drinking and industrial water supplies of the people living in those regions and downstream. These glaciers are under a direct global warming impact as indicated in many previous studies. In this study, we estimated the glacier dynamics in terms of Equilibrium Line Altitude(ELA), mass balance and the snout position variation using remote sensing data between 2001 and 2018. Six glaciers, having area≥ 20 km2 each, situated in the Chitral region(Hindukush Mountains) were investigated in this study. Digital Elevation Model(DEM) and available cloud-free continuous series of Landsat and Sentinel satellite images from minimum snow cover season were used to monitor the variability in the studied glaciers by keeping the status of glaciers in year 2001 as a reference. The annual climatic trends of mean temperature and total precipitation from Chitral weather station were detected using the nonparametric Mann-Kendall’s test. Results revealed a general increase in the ELA, decrease in the glacier mass balance and the retreat of snout *** upward shift in the ELA for the entire study area and data period was ~345 ± 93 m at a rate of^13 m.a-1 from the reference year’s position i.e.~4803 m asl. Estimated mean mass balance for the entire study area indicated a decline of-0.106 ± 0.295 m w.e. a-1. Periods of snout retreat and advance in different glaciers were found but the mean value over the entire study area was a retreat of-231 ± 140 *** obvious relationship was found between the glacier variation trends and the available gauged climatic data possibly due to the presence of debris cover in ablation zones of all the studied glaciers which provides insulation and reduces the immediate climatic effects.

关键词： Glacier dynamics Hindukush region Sentinel Landsat Mass balance Equilibrium Line Altitude Snout position

Lake inventory and potentially dangerous glacial lakes in the Nyang Qu Basin of China between 1970 and 2016

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Journal of Mountain Science 2020年第4期17卷 851-870页

作者： QI Miao-miao liu shi-yin YAO Xiao-jun Richard Grünwald GAO Yong-peng DUAN Hong-yu liu Juan Institute of International Rivers and Eco-Security Yunnan UniversityKunming 650091China Yunnan Key Laboratory of International Rivers and Transboundary Eco-security Kunming 650091China College of Geography and Environment Sciences Northwest Normal UniversityLanzhou 730070China

There are a large number of glaciers and lakes developed in the Nyang Qu Basin of China. Recent climate change has significant impacted on the high-mountain glacial environment. Rapid melting of glaciers contributes to the formation and expansion of moraine-dammed lakes which increase the probability of glacial lake outburst floods(GLOFs). We calculated a multi-temporal lake inventory based on(1) topographic maps in the 1970 s,(2) satellite imageries from 1990 to 2016,(3) First Chinese Glacier Inventory(FCGI),(4) Glacier Inventory of Southeastern Tibet(GIST) and(5) meteorological data. A total of 880 lakes(>0.01 km^2) have been mapped in 2016, with 318 being glacial lakes(GLs) and 462 non-glacier lakes(NGLs). Most of the lakes were mainly located at 4500 m a.s.l. and the lakes dominated by small lakes(<0.1 km^2) where the change of their actual sizes are more significant compared to the larger ones. Meanwhile, we found that there were 178 newly formed GLs and 51 of them had disappeared between 1970 and 2016. During the same period, there can be identified 157 newly formed GLs and 226 had disappeared. We additionally performed a hazard and risk assessment for GL in 2016 and exposed 14 potentially dangerous morainedammed lakes(PDMDLs), covering a total area of 5.88 km2 in the Nyang Qu Basin. There can be found 4 GLs with very high risk, 3 GLs with high risk, 4 GLs with medium risk and 4 GLs with low risk of GLOFs susceptibility. The findings of this study can be used for the future policy of risk management and also be adapted for promoting water resources management.

关键词： Lake Inventory Potentially dangerous moraine-dammed lakes(PDMDLs) Hazard assessment Tibetan Plateau Nyang Qu Basin

Glacier changes since the early 1960s, eastern Pamir, China

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Journal of Mountain Science 2016年第2期13卷 276-291页

作者： ZHANG Zhen XU Jun-li liu shi-yin GUO Wan-qin WEI Jun-feng FENG Tong State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China University of Chinese Academy of Sciences Beijing 100049 China

Glaciers in the eastern Pamir are important for water resources and the social and economic development of the *** the last 50 years,these glaciers have shrunk and lost ice mass due to climate *** order to understand recent glacier dynamics in the region,a new inventory was compiled from Landsat TM/ETM+ images acquired in2009,free of clouds and with minimal snow cover on the glacierized *** first glacier inventory of the area was also updated by digitizing glacier outlines from topographical maps that had been modified and verified using aerial *** glacier area decreased by 10.8%±1.1%,mainly attributed to an increase in air temperature,although precipitation,glacier size and topographic features also combined to affect the general shrinkage of the *** 19.3–21.4 km^3 estimated glacier mass loss has contributed to an increase in river runoff and water resources.

关键词： Glacier change Glacier inventory Eastern Pamir Remote sensing Mass loss

Vulnerability of mountain glaciers in China to climate change

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Advances in Climate Change Research 2015年第3期6卷 171-180页

作者： YANG Jian-Ping DING Yong-Jian liu shi-yin TAN Chun-Ping State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Key Laboratory of Eco-hydrology of Inland River Basin Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Mountain glaciers in China are an important water source for both China and adjoining countries, and therefore their adaptation to glacier change is crucial in relation to maintaining populations. This study aims to improve our understanding of glacial vulnerability to climate change to establish adaptation strategies. A glacial numerical model is developed using spatial principle component analysis （SPCA） supported by remote sensing （RS） and geographical information system （GIS） technologies. The model contains nine factors--slope, aspect, hillshade, elevation a.s.l., air temperature, precipitation, glacial area change percentage, glacial type and glacial area, describing topography, climate, and glacier characteristics. The vulnerability of glaciers to climate change is evaluated during the period of 1961-2007 on a regional scale, and in the 2030s and 2050s based on projections of air temperature and precipitation changes under the IPCC RCP6.0 scenario and of glacier change in the 21st century. Glacial vulnerability is graded into five levels： potential, light, medial, heavy, and very heavy, using natural breaks classification （NBC）. The spatial distribution of glacial vulnerability and its temporal changes in the 21st century for the RCP6.0 scenario are analyzed, and the factors influencing vulnerability are discussed. Results show that mountain glaciers in China are very vulnerable to climate change, and 41.2% of glacial areas fall into the levels of heavy and very heavy vulnerability in the period 1961-2007. This is mainly explained by topographical exposure and the high sensitivity of glaciers to climate change. Trends of glacial vulnerability are projected to decline in the 2030s and 2050s, but a declining trend is still high in some regions. In addition to topographical factors, variation in precipitation in the 2030s and 2050s is found to be crucial.

关键词： Mountain glaciers Climate change Vulnerability Projection