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Climate change over the Yarlung Zangbo River Basin during 1961–2005

YOU Qinglong,KANG Shichang,WU Yanhong,YAN Yuping,

地理学报 , 2007,
Abstract: The Yarlung Zangbo River (YR) is the highest great river in the world, and its basin is one of the centers of human economic activity in Tibet. Using 10 meteorological stations over the YR basin in 1961–2005, the spatial and temporal characteristics of temperature and precipitation as well as potential evapotranspiration are analyzed. The results are as follows. (1) The annual and four seasonal mean air temperature shows statistically significant in-creasing trend, the tendency is more significant in winter and fall. The warming in Lhasa river basin is most significant. (2) The precipitation is decreasing from the 1960s to the 1980s and increasing since the 1980s. From 1961 to 2005, the annual and four seasonal mean precipi-tation is increasing but not statistically significant, especially in fall and spring. The increasing precipitation rates are more pronounced in Niyangqu and Palong Zangbo river basins, the closer to the upper YR is, the less precipitation increasing rate would be. (3) The annual and four seasonal mean potential evapotranspiration has decreased, especially after the 1980s, and most of it happens in winter and spring. The decreasing trend is most significant in the middle YR and Nianchu river basin. (4) Compared with the Mt. Qomolangma region, Tibetan Plateau, China and global average, the magnitudes of warming trend over the YR basin since the 1970s exceed those areas in the same period, and compared with the Tibetan Plateau, the magnitudes of precipitation increasing and potential evapotranspiration decreasing are larger, suggesting that the YR basin is one of the most sensitive areas to global warming.
Temporal and spatial variations of δ18O in precipitation of the Yarlung Zangbo River Basin

LIU Zhongfang,TIAN Lide,YAO Tandong,GONG Tongliang,YIN Changliang,YU Wusheng,

地理学报 , 2007,
Abstract: This paper reveals the temporal and spatial variations of stable isotope in precipita-tion of the Yarlung Zangbo River Basin based on the variations of δ18O in precipitation at four stations (Lhaze, Nugesha, Yangcun and Nuxia) in 2005. The results show that δ18O of pre-cipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of δ18O occurs in spring prior to monsoon precipitation, and the lower value occurs during monsoon precipitation. From the spatial variations, with the altitude-effect and rainout process during moisture transport along the Yarlung Zangbo River Valley, 18O of precipitation is gradually depleted. Thus, δ18O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of δ18O in precipitation is approximately 0.34‰/100m and 0.7‰/100km for the two reasons. During monsoon precipitation, spatial variation of δ18O in precipitation is dominated by the amount effect in the large scale synoptic condition.
Glacial distribution and mass balance in the Yarlung Zangbo River and its influence on lakes
TanDong Yao,ZhiGuo Li,Wei Yang,XueJun Guo,LiPing Zhu,ShiChang Kang,YanHong Wu,WuSheng Yu
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-3213-5
Abstract: Glaciers in the Yarlung Zangbo River witness severe glacial retreat nowadays, which gives important influence on lake processes in the region. We have studied glacial distribution, glacial mass balance and found large deficit in glacial mass and its impact in the region. Our study also integrated the variation in glacial-fed lakes of the Nam Co and Ranwu Lake, and presented an initial assessment of the impact of glacial mass balance on lakes. The study has shown a significant contribution of glacial melting to recent lake expansion and lake level rising.
Mercury speciation and spatial distribution in surface waters of the Yarlung Zangbo River, Tibet
Wei Zheng,ShiChang Kang,XinBin Feng,QiangGong Zhang,ChaoLiu Li
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-010-4001-y
Abstract: The Yarlung Zangbo River is the highest river in the world. It flows from west to east through the southern part of Tibet. The mercury (Hg) speciation and distribution in surface waters and soils near the bank of the Yarlung Zangbo River and its two tributaries, the Lhasa and Niyang Rivers, were investigated in June 2007. Simultaneously, major water quality parameters were also measured at the same stations. Total Hg (THg) and total methylmercury (TMeHg) concentrations in surface waters of the Yarlung Zangbo River ranged from 1.46 to 4.99 ng/L and from 0.06 to 0.29 ng/L, respectively, representing the background levels in river systems of the Tibetan Plateau. Particulate Hg (PHg) accounted for 69% of the THg, and the two Hg species had a significant relationship (r=0.990, P<0.01). Approximately 61% of the spatial distribution of THg was controlled by the concentrations of total suspended particles (TSP). Reactive Hg (RHg) concentrations ranged from 0.10 to 0.36 ng/L, and this fraction may play a weak role in terms of the transport and fate of Hg in surface waters. Dissolved methylmercury (DMeHg) constituted 71% of the TMeHg and was significantly correlated with TMeHg (r=0.746, P<0.01). The spatial distribution of TMeHg is not strongly affected by environmental factors such as THg, RHg, temperature, pH, dissolved organic carbon (DOC), and TSP. In addition, the inflow of both the Lhasa and Niyang Rivers probably influences the concentrations of THg in surface waters of the mainstream, but such an effect is not obvious for TMeHg.
Evolution Trend and Causation Analysis of the Runoff Evolution in the Yarlung Zangbo River Basin

LIU Jian,YAO Zhi-jun,CHEN Chuan-you,

自然资源学报 , 2007,
Abstract: This paper makes use of the monthly natural runoff data from1956 to 2000, the monthly air temperature data and precipitation data from 1956 to 2004 to analyze the evolution characteristics of the runoff in the Yarlung Zangbo River basin in the later half of the 20th century and the relation between runoff evolution and climatic change.The results show that the interannual evolution of the runoff in the Yarlung Zangbo River basin is stable,but the intraannual distribution of the runoff is extremely uneven, the maximum monthly runoff accounts for 30.1%, while the minimum runoff only accounts for 2.1%, and indication of the great difference in the runoff between low water season and flood water season.The climate in the Yarlung Zangbo River basin is calefactive, and the increasing trend of the precipitation is obvious, having the same evolution periods with runoff.After elementary analysis of the decadal runoff in the Yarlung Zangbo River basin,we found that the increase of the water supply is mainly controlled by climate change,but is also affected by the changes of the earth surface conditions in the basin and maybe a representation of the long period of variation of high and low stream flow. Relevant data are required to validate and analyze this kind of periodic variations.
Trend of Surface Humid Index in the Middle Reaches of the Yarlung Zangbo River over Tibet in Recent 40 Years

DU Jun,HU Jun,CHEN Hu,Sonam Ngotrupd,

自然资源学报 , 2006,
Abstract: Humidity index can be expressed by two factors which indicate input and output of atmospheric moist under natural conditions:Precipitation and potential evaporation,represent the change of water and energy balance.In order to clarify the present situation of the environment and regional variations,research has been done on surface wetness in Tibet.The result provides scientific basis for exploring reasons of environmental change over the past 30 years in Tibet and further research on future climatic change.Based on data of monthly maximum temperature,minimum temperature,precipitation,wind speed,relative humidity and sunshine duration from four meteorological stations in the middle reaches of the Yarlung Zangbo River(Brahmaputra)over Tibet from 1961 to 2000,data of the maximum potential evaporation was computed by Penman,Monteith Model,and the surface humid index was obtained.The linear trend,inter,decadal variation and the seasonal difference of the surface humid index were analyzed,and the its relationship with precipitation and temperature was discussed.The results indicated that an obvious linear trend of the warming of annual and seasonal mean temperature existed during the last 40 years,especially the warming was more obvious in winter.Annual precipitation presented a decreasing trend in the first 20 years(1961-1980) and an obvious increasing trend in the last 20 years(1981-2000).Since 1981,precipitation has increased significantly in the flood season(from May to September),with a mean increase of 8.6mm/a.For potential evaporation in the 1960s and the 1970s,the increasing trend was more significant,but the most significant decrease occurred in the 1980s and the 1990s.Also,the rate of pan evaporation over the Yarlung Zangbo River had,on average,steadily decreased,it is particularly so from 1983 to 2000,with a decreasing rate of 22.1mm/a.From the 1960s to the early 1980s,the ground surface showed a drying trend.While from the mid to the late 1980s and the 1990s,the ground surface presented a wetting trend due to precipitation increase and the maximum potential evaporation decrease.The results showed that the cold wet occurred in the 1960s and the warm wett in the 1990s.

WU Chang-de,ZHU Hong,DENG Zong-ce,CUI Jun-wen,

地球学报 , 1990,
Abstract: The Yarlung Zangbo fracture zone is a key unit of the Yarlung Zangbo suture zone along which the oceanic lithosphere between Indian plate and Eurasian plate subducted and the two plates finally collided. In Tibet the fracture zone is very large with a length of 1500 km and a width more than 10 km. There exist a large-scale ophiolite zone of remainder of the oceanic crust, high P/T metamorphic belt and melanges along the frature zone. Through the studies of the structural deformation of rocks in the frature zone and the nearby area, and the geotectonic setting we may distinguish the history of development of the frature zone into the following four main stages; 1) The subduction stage before the ophiolite took its present position (before 90 Ma). 2) The subduction stage during the ophiolite took its present place (about 90 Ma to Eocene Epoch). 3) The collision stage of Indian plate and Eurasian plate(after Eocene). 4) Strike sliping, the present stage.
Evidences of rapid erosion driven by climate in the Yarlung Zangbo (Tsangpo) Great Canyon, the eastern Himalayan syntaxis
XiangJiang Yu,JianQing Ji,JunFeng Gong,DongXia Sun,JianChun Qing,LiNing Wang,DaLai Zhong,ZhiCheng Zhang
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4419-x
Abstract: Climate and tectonism are both particularly intense in the Yarlung Zangbo (Tsangpo) Great Canyon in the eastern Himalayan syntaxis, which is characterized by the most rapid landscape evolution of anywhere in the world. Thus, the eastern Himalayan syntaxis is one of the best locations to study the interactions between climate and tectonics. This paper investigates the cooling ages of the Doxong La-Baibung profile using apatite fission track (AFT) dating on 11 bedrock samples at elevations ranging from 4210 to 710 m. There are topographic, climatic, metamorphic, and thermochronological gradients in the profile, providing good conditions to study interactions between climate and tectonics. AFT ages ranged from 4.6±0.6 Ma to 1.7±0.3 Ma, and the mean fission track lengths ranged from 11.0 to 12.4 μm. It was found that the cooling rates revealed by AFT ages increased with decreasing elevation. However, the tendency of the cooling rates revealed by the 40Ar-39Ar ages was different from that indicated by the AFT ages. Moreover, for most districts of the eastern Himalayan syntaxis, the compiled AFT age distribution correlates well with the annual average precipitation, indicating the coupling of the cooling and erosion rates of the near-surface rock and precipitation. The geothermal history modeling results indicate an obvious increase in the cooling and erosion rate between 1.0 and 0.5 Ma. This age is consistent with other research findings for this time, when the vapor channel of the Yarlung Zangbo Great Canyon began to take effect. These evidences suggest that climate, especially precipitation, has acting as a key factor influencing the rapid cooling and erosion in the Yarlung Zangbo Great Canyon since 1–0.5 Ma.
Characteristics of the Seed Bank of Sophora moorcroftiana Population in the Middle Reach of Yarlung Zangbo River, Tibet

LIU Zhi-Min,

生态学报 , 2002,
Abstract: Sophora moorcroftiana, an endemic shrub in Tibet, colonizes the terraces, lower slopes and sand dunes in the middle reach of the Yarlung Zangbo River. The soil seed bank characteristics of Sophora moorcroftiana in the middle reach of the Yarlung Zangbo River were discussed in this paper. The objectives are (1) to reveal the variations of soil seed banks among different regions, different plots and different sub-plots; (2) to determine the influences of wind force,floodwater, gravity and cutting on seed...
Apatite fission track dating evidence for tectonic movement of Yarlung Zangbo Thrust Zone
Wanming Yuan,Zengqian Hou,Shicheng Wang,Shengrong Li
Chinese Science Bulletin , 2002, DOI: 10.1360/02tb9173
Abstract: Fission track geological chronology is an effective method of study on tectonic movement of fault zone. Apatite fission track (AFT) dating analyses of 9-apatite and 4-zircon samples collected from Lhasa to Langkazi, ~70-km-long in SN provide an understanding of the age and the uplifting of both sides of the Yarlung Zangbo Thrust Zone (YZTZ) in this work. The AFT ages range from ~37 to 14 Ma, indicating the time of major tectono-thermal events, i.e. the continent-continent collision along the YZTZ. Based on the relationship between the AFT ages and the sample elevations, there were two tectonic active periods: ~37–20 Ma and 20–14 Ma. In the first period the tectonic event did not bring on differential uplifting. Rapid differential uplifting with rapid cooling, resulting from thrusting, took place in the second period. The vertical displacement was ~1020 m and total ~2.9 km of overburden has been removed from the present-day surface since cooling below ~100°C began. The maximum cooling and denudation occurred at a rate of ~7°C/ Ma and ~207 m/Ma respectively since ~14 Ma. The zircon fission track analysis demonstrates that the temperature of tectono-thermal events did not exceed 310°C.
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