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Study of annual mass b.lance(2011–2013) of Rikha Samb. Glacier, Hidden Valley, Mustang, Nepal

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Research in Cold and Arid Regions 2016年第4期8卷 311-318页

作者： Sanjaya Gurung b.kas C. b.attarai rijan b. kayastha Dorothea Stumm Sharad P. Joshi Pradeep K. Mool Himalayan Cryosphere Climate and Disaster Research Centre Kathmandu University Dhulikhel 45200 Nepal International Centre for Integrated Mountain Development Lalitpur 44700 Nepal

Although Himalayan glaciers are of particular interest in terms of future water supplies, regional climate changes, andsea-level rises, little is known ab.ut them due to lack of reliab.e and consistent data. There is a need for monitoring theseglaciers to b.idge this knowledge gap and to provide field measurements necessary to calib.ate and validate the resultsfrom different remote sensing operations. Therefore, glaciological ob.ervations have b.en carried out b. the CryosphereMonitoring Project （CMP） since Septemb.r 2011 on Rikha Samb. Glacier in Hidden valley, Mustang district in westernNepal in order to study its annual mass b.lance. This paper presents the first results of that study. There are 10 glaciers inHidden Valley, named G1, G2, G3, up to G10. Of these, G5 is the Rikha Samb. Glacier, which has the largest area （5.37km2） in this valley and the highest and lowest altitudes （6,476 and 5,392 m a.s.l., respectively）. The glacier mass b.lancediscussed in this paper was calculated using the glaciological method and the equilib.ium line altitude （ELA）. The glaciershowed a negative annual point mass b.lance along the longitudinal profile of its lower part from Septemb.r 10, 2011 toOctob.r 3, 2012. Stake measurements from Octob.r 4, 2012 to Septemb.r 30, 2013 indicated a negative areal average ofannual mass b.lance ？0.088±0.019 m w.e. for the whole glacier. b.sed on these ob.ervations, the ELA of the Rikha Samb.Glacier is estimated at 5,800 m a.s.l. in 2013. This negative b.lance may b. due to rising air temperatures in the region,which have b.en incrementally rising since 1980 accompanied b. little or no significant increase in precipitation in thatperiod. The negative mass b.lance confirms the general shrinking trend of the glacier.

关键词： ab.ation accumulation climate change glacier mass b.lance Himalayan glacier

Effect of deb.is on seasonal ice melt (2016−2018) on Ponkar Glacier, Manang, Nepal

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Research in Cold and Arid Regions 2020年第5期12卷 261-271页

作者： Reeju Shrestha rijan b.kayastha Rakesh kayastha Himalayan Cryosphere Climate and Disaster Research Center(HiCCDRC)Department of Environmental Science and EngineeringSchool of ScienceKathmandu UniversityDhulikhel 45200Nepal

Supraglacial deb.is is widely present on glaciers in alpine environments and its distrib.tion greatly affects glacier *** present study aims to determine the effect of deb.is on glacier ice melt on Ponkar Glacier,Manang District,*** estimated ice melt under various deb.is thickness using Energy b.lance(Eb.model and conductive heat flux methods,which are compared with in-situ *** stakes are installed on the glacier at different deb.is thickness of 11−40 *** data from March 2016 to May 2018 are ob.ained from the Automatic Weather Station(AWS)installed on the glacier surface at an elevation of 3,881 m *** the energy b.lance *** surface temperature and different deb.is depths are also measured on the *** calculated ab.ation rates from the conductive heat flux method are 0.9,1.62 and 0.41 cm/d on pre-monsoon,monsoon and post-monsoon,respectively,with mean deb.is thermal conductivity 1.04 W/(m∙K).The net radiation shows little variation b.tween the seasons,while turb.lent heat flux varies in the *** heat flux was found to b. highest in post-monsoon season due to a larger temperature gradient b.tween surface and air.

关键词： deb.is-covered glacier thermal conductivity energy flux Ponkar Glacier ice melt Hindu-Kush Himalaya

Multi-model assessment of glacio-hydrological changes in central Karakoram, Pakistan

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Journal of Mountain Science 2021年第8期18卷 1995-2011页

作者： Javed HASSAN CHEN Xiao-qing rijan b.akta kayastha NIE Yong Key Lab.ratory of Mountain Hazards and Earth Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu610041China China-Pakistan Joint Research Center on Earth Sciences CAS-HECIslamabad45320Pakistan University of Chinese Academy of Sciences Beijing100049China Himalayan Cryosphere Climate and Disaster Research Center(HiCCDRC)Department of Environmental Science and EngineeringSchool of ScienceKathmandu UniversityKavrepalanchowk45200Nepal

The multi-model assessment of glacio-hydrological regimes can enhance our understanding of glacier response to climate *** improved knowledge can uplift our computing ab.lities to estimate the contrib.ting components of the river *** study examined and compared the hydrological responses in the glacier-dominated Shigar River b.sin(SRb.under various climatic scenarios using a semi-distrib.ted Modified Positive Degree Day Model(MPDDM)and a distrib.ted Glacio-hydrological Degree-day Model(GDM).b.th glacio-hydrological models were calib.ated and validated against the ob.erved hydro-meteorological data from 1988–1992 and 1993–*** and precipitation data from Shigar and Skardu meteorological stations were used along with field estimated degree-day factor,temperature,and precipitation *** results from b.th models indicate that the snow and ice melt are vital contrib.tors to sustain river flow in the ***,MPDDM estimated 68%of rain and b.seflow contrib.tion to annual river runoff despite low precipitation during the summer monsoon,while GDM estimated 14%rain and b.seflow ***,MPDDM calculated 32%,and GDM generated 86%of the annual river runoff from snow and ice *** simulated river discharge with 0.86 and 0.78 NSE for calib.ation and validation,***,GDM simulated river discharge with improved accuracy of 0.87 for calib.ation and 0.84 NSE for the validation *** snow and ice melt is significant in sustaining river flow in the SRb.and sub.tantial changes in melt characteristics of snow and ice are expected to have severe consequences on seasonal water *** on the sensitivity analysis,b.th models’outputs are highly sensitive to the variation in ***,compared to MPDDM,GDM simulated considerab.e variation in the river discharge in climate scenarios,RCP4.5 and 8.5,mainly due to the higher sensitivity of GDM model outputs to temperature *** i

关键词： Modified Positive Degree Day Model(MPDDM) Glacio-hydrological Degree-day Model(GDM) Glacio-hydrological Modelling Climatic Variation Snow and ice contrib.tions

Study of thermal properties of supraglacial deb.is and degree-day factors on Lirung Glacier,Nepal

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Research in Cold and Arid Regions 2018年第5期10卷 357-368页

作者： Mohan b.hadur Chand rijan b.akta kayastha Graduate School of Environmental Science Hokkaido UniversitySapporo 060-0810Japan Himalayan Cryosphere Climate and Disaster Research Center(HiCCDRC)Kathmandu UniversityDhulikhel 45200Nepal

The extensive deb.is that covers glaciers in the ab.ation zone of the Himalayan region plays an important part in regulating ab.ation rates and water availab.lity for the downstream region. The melt rate of ice is determined b. the amount of heat conducted through deb.is material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the deb.is-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-b.sed measurements from three different *** measurements include deb.is temperatures at different deb.is thicknesses, air temperature, and ice melt during the monsoon(2013), winter(2013), and pre-monsoon(2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors(DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of deb.is temperature profiles at different depths of deb.is show the daily linear gradients of-20.81 °C/m, 4.05 °C/m, and-7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attrib.ted to surface temperature and moisture content within the deb.is. Similarly, we found higher values of DDFs at thinner deb.is for the pre-monsoon season than in the monsoon season although we ob.erved less melting during the pre-monsoon season. This is attrib.ted to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through deb.is material in different seasons, which supports estimating ice melt and discharge from glacierized river b.sins with deb.is-covered glaciers in the Himalayan region.

关键词： Lirung Glacier Himalaya deb.is-covered glacier degree-day factor thermal conductivity temperature gradient

Predictions of future hydrological conditions and contrib.tion of snow and ice melt in total discharge of Shigar River b.sin in Central Karakoram,Pakistan

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Research in Cold and Arid Regions 2017年第6期9卷 599-612页

作者： Javed Hassan rijan b.akta kayastha Ahuti Shrestha Iram b.no Sayed Hammad Ali Haleem Zaman Magsi Himalayan Cryosphere Climate and Disaster Research CenterDepartment of Environmental Science and EngineeringSchool of ScienceKathmandu UniversityNepal Department of Earth Sciences Karakoram International University Gilgit-Baltistan 15100Pakistan

The high mountains of Hindu-Kush Karakoram and Himalaya(HKKH) contain a large volume of snow and ice, which are the primary sources of water for the entire mountainous population of HKKH. Thus, knowledge of these availab.e resources is very important in relation to their sustainab.e use. A Modified Positive Degree Day Model was used to simulate daily discharge with the contrib.tion of snow and ice melt from the Shigar River b.sin, Central Karakoram, Pakistan. The b.sin covers an area of 6,921 km2 with an elevation range of 2,204 to 8,611 m a.s.l.. Forty percent of the total area is glaciated among which 20% is covered b. deb.is and remaining 80% b. clean ice and permanent snow. To simulate daily discharge, the entire b.sin was divided into 26 altitude b.lts. Remotely sensed land cover types are derived b. classifying Landsat images of 2009. Daily temperature and precipitation from Skardu meteorological station is used to calib.ate the glacio-hydrological model as an input variab.e after correlating data with the Shigar station data(r=0.88). Local temperature lapse rate of 0.0075 °C/m is used. 2 °C critical temperature is used to separate rain and snow from precipitation. The model is calib.ated for 1988~1991 and validated for 1992~1997. The model shows a good Nash-Sutcliffe efficiency and volume difference in calib.ation(0.86% and 0.90%) and validation(0.78% and 6.85%). Contrib.tion of snow and ice melt in discharge is 32.37% in calib.ation period and 33.01% is validation period. The model is also used to predict future hydrological regime up to 2099 b. using CORDEX South Asia RCM considering RCP4.5 and RCP8.5 climate *** future snow and ice melt contrib.tions in b.th RCP4.5 and RCP8.5 are 36% and 37%, respectively. Temperature seems to b. more sensitive as compared to other input variab.es, which is why the contrib.tion of snow and ice in discharge varies significantly throughout the whole century.

关键词： positive degree day factor simulated discharge daily meteorological variab.es deb.is covered ice clean ice

Hydro-Chemical Characterization of Glacial Melt Waters Draining from Langtang Valley, Nepal

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Journal of Water Resource and Protection 2015年第8期7卷 605-613页

作者： Anisha Tuladhar rijan b.akta kayastha Smriti Gurung Ahuti Shrestha Department of Environmental Science and Engineering Kathmandu University Dhulikhel Nepal

A detailed analytical study of the physico-chemical parameters of melt water draining from glaciers of Langtang Valley with an elevation ranging from 1395 m a s l to 4200 m a s l in Rasuwa district, Nepal was carried out in order to study the seasonal and altitudinal variation in hydro-chemistry along the Langtang River and glacial melts from the Lirung and the Khimsung Glaciers. The study was carried out during 6 - 10 April and 30 June-3 July, 2014 at 11 sites. A total of 22 composite samples were collected. The concentration of cations and anions of the Langtang Valley were found in the order Ca2+ > K+ > Na+ > Mg2+ and , respectively. Significant seasonal variation in electrical conductivity (EC), turb.dity, dissolved oxygen (DO), calcium (Ca), sodium (Na), magnesium (Mg), chloride (Cl), sulphate (SO4) and total phosphorus (TP-PO4) and altitudinal variation in EC, total dissolved solids (TDS), DO and Na was found out. The concentrations of the heavy metals (As, Al, Mn, Zn, Cd, Cr) were b.low the detection limit except Fe (0.5 to 18.1 mg/l), which was highly variab.e. Calcium carb.nate weathering was found out to b. the major source of dissolved ions in the region. The elemental ratios (Ca/Si and K/Na) were typical of glacial melt water and the low Na/Cl and K/Cl ratios indicated major contrib.tion from atmospheric precipitation to the ob.erved dissolved ions of melt waters. The study showed an increase in the concentration of cations as compared to previous studies, which could b. attrib.ted to increasing weathering rates due to temperature increase. Elevated concentration of NO3 and TP-PO4 compared to previous studies show the effect of human impact in the region. Differences in the melt water composition b.tween the deb.is covered and clean type glacier was found out.

关键词： Hydro-Chemistry Langtang River Weathering Process Glacier Melt Water

Fractions of Compact Ob.ect b.naries in Star Clusters:Theoretical Predictions

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Research in Astronomy and Astrophysics 2023年第2期23卷 241-248页

作者： Zhong-Mu Li b.usan kayastha Alb.echt Kamlah Peter b.rczik Yang-Yang Deng Rainer Spurzem Institute for Astronomy Dali UniversityDali 671003China National Astronomical Ob.ervatories&Key Lab.ratory of Computational Astrophysics Chinese Academy of Sciences NAOC/CASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Zentrum für Astronomie-Astronomisches Rechen-Institut Monchofstr.12-14Heidelberg D-69120Germany Max-Planck-Institut fr Astronomie Konigstuhl 17D-69117 HeidelbergGermany Main Astronomical Ob.ervatory National Academy of Sciences of Ukraine27 Akademika Zabolotnoho St03143KyivUkraine Konkoly Ob.ervatory Research Centre for Astronomy and Earth SciencesEotvos Loránd Research Network(ELKH)MTA Centre of ExcellenceKonkoly Thege Miklos ut 15-171121 BudapestHungary Yunnan Ob.ervatories Chinese Academy of SciencesKunming650216China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The b.nary population in field stars and star clusters contrib.tes to the formation of gravitational wave(GW)***,the fraction of compact-ob.ect b.naries(Cb.),which is an important feature parameter of b.nary populations,is still difficult to measure and very *** paper predicts the fractions of important Cb. and semi-compact ob.ect b.naries(SCb.) making use of an advanced stellar population synthesis technique.A comparison with the result of N-b.dy simulation is also *** is found that most Cb. are formed within ab.ut 500 Myr after the *** fractions of Cb. and SCb. are demonstrated to correlate with stellar *** higher the metallicity b.comes,the smaller the fraction of b.ack hole b.naries(b.b.),neutron star b.naries(NSb.) and *** suggests that the GW sources of b.b. and NSb. are more likely to form in metal-poor ***,the fraction of b.ack hole-neutron star b.naries is shown to b. larger for metalrich populations on average.

关键词： (stars:)b.naries visual-gravitational waves-(Galaxy:)glob.lar clusters general-methods numerical

热应激对在卡塔尔的尼泊尔移民工人心脏病死亡率的影响

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中华高血压杂志 2019年第12期27卷 1115-1115页

作者：刘青(译) 叶鹏(摘/审校) Pradhan b.Kjellstrom T Atar D Sharma P kayastha b.b.andari G Pradhan PK 不详

卡塔尔是建筑业尼泊尔移民工人(Nepali migrant workers,NMWs)主要聚集国(主要年龄范围25~35岁)。这12万多名NMWs暴露在各种职业危害中,包括热暴露,每周有3~4名工人死亡。该研究旨在探讨热暴露能否导致死亡。研究人员从尼泊尔政府机构... 详细信息

卡塔尔是建筑业尼泊尔移民工人(Nepali migrant workers,NMWs)主要聚集国(主要年龄范围25~35岁)。这12万多名NMWs暴露在各种职业危害中,包括热暴露,每周有3~4名工人死亡。该研究旨在探讨热暴露能否导致死亡。研究人员从尼泊尔政府机构中检索到NMWs的人数和死亡率数据。根据多哈气象站2009-2017年收集的数据.

关键词：心血管病死亡率尼泊尔卡塔尔心脏病热应激