Impacts of climate change on glacial water resources and hydrological cycles in the Yangtze River source region, the Qinghai-Tibetan Plateau, China: A Progress Report     

YongPing Shen  GuoYa Wang  GenXu Wang  JianChen Pu  Xin Wang 《寒旱区科学》2009,1(6):0475-0495

The Yangtze River Source Region has an area of 137,704 km2.Its mean annual runoff of 12.52 billion m3,which was recorded by the Chumda Hydrological Station in 1961-2000,accounts for only 0.13 percent of the Yangtze River’s total annual streamflow.The extensive rivers,lakes,wetlands,glaciers,snow fields,and permafrost of the Yangtze River Source Region,as well as the region’s vast alpine grasslands,play a critical role in storing and regulating the flow of water not only in the upper Yangtze River watershed of Qinghai,Sichuan,the Tibet Autonomous Region (TAR) (Tibet) and Yunnan,but also throughout the entire lower Yangtze River basin.Climate change has been the dominant factor in recent fluctuation in the volume of the Yangtze River Source Region’s glacier resources.The Chumda Hydrological Station on the lower Tongtian River has registered a mean annual glacial meltwater of 1.13 billion m3 for the period 1961-2000,makes up 9 percent of the total annual runoff.Glacial meltwater makes up a significant percentage of streamflow in the Yangtze River Source Region,the major rivers of the upper Yangtze River Source Region:the Togto,Dam Chu,Garchu,and Bi Chu (Bu Chu) rivers all originate at large glaciers along the Tanggula Range.Glaciers in the Yangtze River Source Region are typical continental-type glaciers with most glacial meltwater flow occurring June-August;the close correlation between June-August river flows and temperature illustrates the important role of glacial meltwater in feeding rivers.Glaciers in the source region have undergone a long period of rapid ablation beginning in 1993.Examination of flow and temperature data for the 1961-2000 period shows that the annual melting period for glacial ice,snow,and frozen ground in the Yangtze River Source Region now begins earlier because of increasing spring temperatures,resulting in the reduction of summer flood season peak runoffs;meanwhile,increased rates of glacier ablation have resulted in more uneven annual distribution of runoff in the source region.T  相似文献   

Gravity change observed in a local gravity network and its implication to seasonal precipitation in Dali county,Yunnan province,China     

Xin Zhou  Wenke Sun  Hui Li  Shuhei Okubo  Shaoan Sun  Lelin Xing  Dongzhi Liu  Chongyang Shen 《地震学报(英文版)》2014,(1):79-88

This study investigates data-processing methods and examines the precipitation effect on gravity measurements at the Dali gravity network, established in 2005. High-quality gravity data were collected during four measurement campaigns. To use the gravity data validly, some geophysical corrections must be considered carefully. We first discuss data-processing methods using weighted leastsquares adjustment with the constraint of the absolute gravity datum. Results indicate that the gravity precision can be improved if all absolute gravity data are used as constraints and if calibration functions of relative gravimeters are modeled within the observation function. Using this data-processing scheme, the mean point gravity precision is better than 12 lgal. After determining the best data-processing scheme, we then process the gravity data obtained in the four measurement campaigns, and obtain gravity changes in three time periods. Results show that the gravity has a remarkable change of more than 50 lgal in the first time period from Apr–May of 2005 to Aug–Sept of 2007. To interpret the large gravity change, a mean water mass change(0.6 m in height) is assumed in the ETOPO1 topographic model. Calculations of the precipitation effect on gravity show that it can reach the same order of the observed gravity change. It is regarded as a main source of the remarkable gravity change in the Dali gravity network, suggesting that the precipitation effect on gravity measurements must be considered carefully.  相似文献   

Geochronology and Geochemistry of Mafic Dikes from Hainan Island and Tectonic Implications     

CAO Jianjin  HU Ruizhong  LIU Shen  XIE Guiqing 《《地质学报》英文版》2009,83(6):1064-1073

Abstract: In the present study, the major and trace element compositions, as well as Sr, Nd isotopic compositions and K-Ar age data in mafic dikes from Hainan Island, China, have been analyzed. Whole-rock K-Ar dating yielded a magmatic duration of 61–98 Ma for mafic dikes. Mafic dikes have a very high concentration of incompatible elements, for example, Ba, Rb, Sr, K, rare earth elements, and especially light rare earth elements (LREE), and negative anomalies of Nb, Ta, and Ti in the normalized trace element patterns. The initial 87Sr/86Sr ratios and εSr(t) of the mafic dikes are 0.70634–0.71193 and +27.7 to +112.2, respectively. In the 87Sr/86Sr versus εNd(t) diagram, the Hainan Island mafic dikes plot between fields for depleted mantle and enriched mantle type 2. All these characteristics show that the mantle (source region) of mafic dikes in this area experienced metasomatism by fluids relatively enriched in LREE and large ion lithophile elements. The genesis of Hainan Island mafic dikes is explained as a result of the mixing of asthenospheric mantle with lithospheric mantle that experienced metasomatism by the subduction of the Pacific Plate. This is different from the Hainan Island Cenozoic basalts mainly derived from depleted asthenospheric mantle, and possibly, minor metasomatised lithospheric mantle. This study suggests that the Mesozoic and Cenozoic lithospheric revolutions in Hainan Island can be divided into three stages: (1) the compression orogenesis stage before 98 Ma. The dominant factor during this stage is the subduction of the ancient Pacific Plate beneath this area. The lithospheric mantle changed into enriched mantle type 2 by metasomatism; (2) the thinning and extension stage during 61–98 Ma. The dominant factor during this stage is that the asthenospheric mantle invaded and corroded the lithospheric mantle; and (3) the large-scale thinning and extension stage after 61 Ma. The large-scale asthenospheric upwelling results in the strong erupting of Cenozoic basalts, large-scale thinning of the lithosphere, the southward translating and counterclockwise rotating of Hainan Island, and the opening of the South China Sea.  相似文献   

美国地震学会通报(BSSA)2008年四川汶川地震专集介绍     

Klinger Y  Ji C  Shen Z-K  Bakun W H  李平恩 《国际地震动态》2010,(12):1-5

四川汶川MW7．9地震发生在2008年5月12日北京时间14时28分（国际协调时问6时28分）。地震的突然来袭令人措手不及,因为这个位于青藏高原边缘的地区并没有被列为地震高危险区。地震造成了巨大破坏：400多万居民无家可归,伤亡人数超过8万,并有重大的经济损失。这次地震是中国近几个世纪以来最大的地震灾难之一,  相似文献   

K-Ar Geochronology of Mesozoic Mafic Dikes in Shandong Province, Eastern China: Implications for Crustal Extension   总被引：3，自引：0，他引：3  

LIU Shen  HU Ruizhong  ZHAO Junhong  FENG Caixia Institute of Geochemistry  Chinese Academy of Sciences  Guiyang  Guizhou 《《地质学报》英文版》2004,78(6):1207-1213

Based on K-Ar isotope analyses, Mesozoic mafic (and alkali ultramafic) dikes from western and eastern Shandong Province, China, are dated at 88.2±1.70 Ma to 169.5±3.7 Ma with the majority of ages ranging from 90 Ma to 140 Ma. The emplacement of the dikes suggests a major Yanshanian (Cretaceous) crustal extension in Shandong province. Together with other available age data, this study suggests four periods of crustal extension at about 80 Ma, 100 Ma, 120 Ma and 140 Ma, respectively. Besides the effect of collapse of the Yanshanian orogenic belt on the emplacement of the mafic dikes in Shandong in the Cretaceous, the mantle plume and the extensive left-lateral advection and extension of the Tanlu fault also have controlled the crustal extension and the emplacement of the mafic dikes in eastern Shandong and western Shandong, respectively.  相似文献   

Response of the Melting Urumqi Glacier No. 1 in Eastern Tianshan to Climate Change   总被引：2，自引：0，他引：2  

Li Zhongqin  Shen Yongping  Li Huilin  Dong Zhiwen  Wang Liwei 《气候变化研究进展》2008,4(00):67-72

 Current glacier recession under the global warming has aroused world-wide attention. Initiated from 1958, the observations of Urumqi Glacier No. 1 at the headwaters of Urumqi River in eastern Tianshan promise the best datasets of the glacier and the climate changes in China. Taking Urumqi Glacier No. 1 as an example, we analyzed the response of the glacier to the climate change. The results show that over the past 50 years, the glacier has changed remarkably in the aspects of snow-firn stratigraphy, ice formation zone, ice temperature, area and terminus position, etc. These changes are apparently the results of temperature rise in this area. The glacier recession continued throughout the entire observed time period, and showed an accelerated tendency since 1985. Meltwater runoff also increased 84.2% over the last 20 years.  相似文献   

波控岬间海岸平衡剖面形态及其地形学意义     

陈子Shen 《南海研究与开发》1999,(1):5-11

对粤东后江岬间海岸１９９２年和１９９２年７条重复地形剖面分析结果表明,当前各剖面年净冲淤变化很小,剖面分别与Ｂｏｄｇｅ和Ｌｅｅ平衡剖面模式符合良好,拟合的平衡剖面闭合水深反映了在海区波候条件作用下泥沙运动的临界水深。  相似文献   

The impact of human activities on the flushing properties of a semi-enclosed lagoon: Xiaohai, Hainan, China   总被引：1，自引：0，他引：1  

Gong W  Shen J  Jia J 《Marine environmental research》2008,65(1):62-76

In this study, a Lagrangian particle tracking model driven by hydrodynamic fields was used to investigate the changes of flushing properties in Xiaohai Lagoon resulting from natural evolution and influences of human activities. Comparisons of residence times between 1936 and 2001 indicate that the flushing efficiency of the lagoon has deteriorated greatly during the past seven decades. Over this period, the average residence time of the lagoon has increased from 45 to 71 days, an increase of 59%. The Lagrangian residual velocity has decreased from 1936 to 2001 in the large portions of the lagoon, and the spatial distribution pattern of the residual current has changed significantly. The well-developed horizontal circulations in 1936 disappeared. Instead, the horizontal Lagrangian residual velocity showed uniformly seaward motion with reduced velocity in 2001. Human activities have incurred great impacts on the deterioration of flushing efficiency. The reduction of river inflow imposed the most significant impact, causing an increase of average residence time by 33%. The land reclamation in the lagoon came as the second most significant factor, causing an increase of 15%. Closure of the North Opening had posed minor impact. The model results suggest that restoring the river inflow, as well as the dredging of the tidal channel and the inner lagoon, should be the top proprieties for future water quality management.  相似文献   

GPS DATA INVERSION OF KINEMATIC MODEL OF MAIN FAULTS IN YUNNAN     

Shen Chongyang  Wu Yun  Wang Qi  You Xinzhao  Qiao Xuejun 《大地测量与地球动力学》2003,23(Z1)

1　IntroductionThemodernspacegeodesytechnology (GPSes pecially)israpidlydeveloping ,andisabletoprecise lymonitorongoingsurfacechangeprocessatun precedentedspatialandtemporalresolution .Soithasgraduallybecomethemostsuitabletooltoob servegeodynamicalphenomena[1 - 5] .Theearthquakepreparationandoccurrencearecloselyrelatedtofaultanditsmovement.Activefaultanditsquantitativeanalysisisstillthepredomi nantfieldofseismologicalresearch[6,7] .Faultdislo cationmaycausecrustaldeformationaroundit.Onthebas…  相似文献   

Study of the Difference between Seismogenic Deformation and Deformation by Permanent Tectonic Movement     

Shen Ping  Zheng ZhizhenInstitute of Geophysics  SSB  Beijing  ChinaCenter for Seismic Data  Information  SSB  Beijing  China 《中国地震研究》1998,(1)

Ground deformation may be caused by crustal movement and non-crustal movement.The non-crustal movements include those caused by temperature,rainfall,ground water,etc.Deformation caused by crustal movement includes seismogenic deformation(that appearing in the process of earthquake preparation and that directly caused by the earthquake)and general tectonic activities.The key point in the study of the relationship between ground deformation and earthquakes is how to eliminate information of deformation caused by non-crustal movement and permanent(or slow)tectonic deformation in observed data.In this paper an analysis is made on the short leveling data recorded at Dahuichang Deformation-Observing Station,Beijing,for 22 years(1970-1991)by using the LMS algorithm method after lateral adaptive filtering of the modern digital signal processing technique.Eliminating the approximate annual variation in deformation caused by non-crustal movement such as temperature,rainfall,ground water,etc.,a unified standard is  相似文献