The 1786 earthquake-triggered landslide dam and subsequent dam-break flood on the Dadu River, southwestern China — Reply     

F.C. Dai  C.F. Lee  J.H. Deng  L.G. Tham 《Geomorphology》2006,73(3-4):277-278

A short reply to discussion by Chanson.  相似文献   

Dual simulations of fluid flow and seismic wave propagation in a fractured network: effects of pore pressure on seismic signature   总被引：1，自引：0，他引：1  

S. Vlastos  E. Liu  I. G. Main  M. Schoenberg  C. Narteau  X. Y. Li  B. Maillot 《Geophysical Journal International》2006,166(2):825-838

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Global positioning system: A field guide for the social sciences – John Spencer, Erian G. Frizzelle, Philip H. Page and John B. Vogler     

X. X. Lu 《Singapore journal of tropical geography》2006,27(1):104-106

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GIS-based flood hazard mapping at different administrative scales: A case study in Gangetic West Bengal, India   总被引：4，自引：0，他引：4  

Joy Sanyal  X.X. Lu 《Singapore journal of tropical geography》2006,27(2):207-220

This paper addresses the need for an efficient and cost-effective methodology for preparing flood hazard maps in data poor countries, particularly those under a monsoon regime where floods pose a recurrent danger. Taking Gangetic West Bengal, India, as an example and using available historical data from government agencies, the study compiled a regional map indicating hazard prone subregional areas for further detailed investigation, thereby isolating actual high risk localities. Using a GIS (Geographical Information System), a composite hazard index was devised incorporating variables of flood frequency, population density, transportation networks, access to potable water, and availability of high ground and maximum risk zones were mapped accordingly. A digital elevation model derived from high resolution imagery available in the public domain was used to calculate elevated areas suitable for temporary shelter during a flood. Selecting administrative units of analysis at the lowest possible scales – rural development blocks (regional) and revenue villages (subregional) – also ensures that hazard mapping is prepared in line with the existing rural planning and administrative authorities responsible for remedial intervention.  相似文献   

Vertical distribution and water solubility of phosphorus and heavy metals in sediments of the St. Lucie Estuary, South Florida, USA   总被引：2，自引：0，他引：2  

Z. L. He  M. Zhang  P. J. Stoffella  X. E. Yang 《Environmental Geology》2006,50(2):250-260

Accumulation and distribution of heavy metals and phosphorus in sediments impact water quality. There has been an increasing concern regarding fish health in the St. Lucie Estuary, which is related to increased inputs of nutrients and metals in recent decades. To investigate vertical changes of contaminants (P, Cd, Cr, Co, Cu, Ni, Pb, Zn, and Mn) in sediments of the St. Lucie Estuary in South Florida, 117 layer samples from six of the 210 to 420 cm depth cores were analyzed for their total and water-soluble P and heavy metals, clay, total Fe, Al, K, Ca, Mg, Na, and pH. Principal component analysis (PCA) was used in two sets of analytical data (total and water-soluble contaminant concentrations) to document changes of contaminants in each core of sediments. The PCA of total contaminants and minerals resulted in two factors (principal components). The first and second factors accounted for 61.7 and 17.2 % of the total variation in all variables, and contrast indicators associated with contaminants of P, Cd, Co, Cr, Ni, Pb, Zn, and Mn and accumulation of Fe and Al oxides, respectively. The first factor could be used for overall assessment of P and heavy metal contamination, and was higher in the upper 45–90 cm than the lower depths of each core. The concentrations of P and heavy metals in the surface layers of sediments significantly increased, as compared with those in the sediments deeper than 45–90 cm. The PCA of water-soluble contaminants developed two factors. The second factor (Cu–P) was higher in the upper than the lower depths of the sediment, whereas the highest score of the first factor (Cd–Co–Cr–Ni–Pb–Zn–Mn) occurred below 100 cm. The water-soluble Cu and P concentrations were mainly dependent on their total concentrations in the sediments, whereas the water-soluble Cd, Co, Cr, Ni, Pb, Zn, and Mn concentrations were mainly controlled by pH.  相似文献   

Energy transfer among Pb, Ce and Mn in fluorescent calcite from Kuerle, Xinjiang, China     

Aierken Sidike  X.-M. Wang  Alifu Sawuti  H.-J. Zhu  I. Kusachi  N. Yamashita 《Physics and Chemistry of Minerals》2006,33(8-9):559-566

Natural calcite from Kuerle, Xinjiang, China, shows orange-red fluorescence when exposed to short-wave ultraviolet (UV) light (Hg 253.7 nm). Photoluminescence (PL) emission and excitation spectra of the calcite are observed at room temperature in detail. The PL emission spectrum under 208 nm excitation consists of three bands: two UV bands at 325 and 355 nm and an orange-red band at 620 nm. The three bands are ascribed to Pb²⁺, Ce³⁺ and Mn²⁺, respectively, as activators. The Pb²⁺ excitation band is observed at 243 nm, and the Ce³⁺ excitation band at 295 nm. The Pb²⁺ excitation band is also observed by monitoring the Ce³⁺ fluorescence, and the Pb²⁺ and Ce³⁺ excitation bands, in addition to six Mn²⁺ excitation bands, are also observed by monitoring the Mn²⁺ fluorescence. These indicate that four types of the energy transfer can occur in calcite through the following processes: (1) Pb²⁺ → Ce³⁺, (2) Pb²⁺ → Mn²⁺, (3) Ce³⁺ → Mn²⁺ and (4) Pb²⁺ → Ce³⁺ → Mn²⁺.  相似文献   

中国岩溶洞穴数据库建设研究   总被引：4，自引：0，他引：4  

陈伟海  朱德浩  戴爱德 《国土资源信息化》2005,(1):14-17

为了有效地保护和利用洞穴这一具有多方面价值的、不可再生的国土资源而建立了中 国岩溶洞穴数据库,首期完成900个洞穴数据建库工作。数据库中含有图、文、声、 像等方面的数字化信息,数据容量2500MB,作为非商业数据,可通过授权共享,为 科研机构、旅游行业和公众提供服务。  相似文献   

The thermodynamic influence of subgrid orography in a global climate model     

S. Ghan  X. Bian  A. Hunt  A. Coleman 《Climate Dynamics》2002,20(1):31-44

Assessments of the impacts of climate change typically require information at scales of 10 km or less. Such a resolution in global climate simulations is unlikely for at least two decades. We have developed an alternative to explicit resolution that provides a framework for meeting the needs of climate change impact assessment much sooner. We have applied to a global climate model a physically based subgrid-scale treatment of the influence of orography on temperature, clouds, precipitation, and land surface hydrology. The treatment represents subgrid variations in surface elevation in terms of fractional area distributions of discrete elevation classes. For each class it calculates the height rise/descent of air parcels traveling through the grid cell, and applies the influence of the rise/descent to the temperature and humidity profiles of the elevation class. Cloud, radiative, and surface processes are calculated separately for each elevation class using the same physical parametrizations used by the model without the subgrid orography parametrization. The simulated climate fields for each elevation class can then be distributed in post-processing according to the spatial distribution of surface elevation within each grid cell. Parallel 10-year simulations with and without the subgrid treatment have been performed. The simulated temperature, precipitation and snow water are mapped to 2.5-minute (~5 km) resolution and compared with gridded analyses of station measurements. The simulation with the subgrid scheme produces a much more realistic distribution of snow water and significantly more realistic distributions of temperature and precipitation than the simulation without the subgrid scheme. Moreover, the 250-km grid cell means of most other fields are virtually unchanged by the subgrid scheme. This suggests that the tuning of the climate model without the subgrid scheme is also applicable to the model with the scheme.  相似文献   

西藏蛇绿岩中二种合金矿物新变种   总被引：5，自引：0，他引：5  

白文吉  施倪承  杨经绥  方青松  代明泉  熊明  颜秉刚 《矿物学报》2002,22(3):201-206

在西藏雅鲁藏布江蛇绿岩带的东部，距拉萨200km的泽当罗莎蛇绿岩的铬铁矿中，发现有种类繁多的合金矿物，铬铁镍矿和依铁镍矿就是其中二种。铬铁镍矿分子式：Ni0.41Fe0.35Cr0.24，为等轴晶系，空间群为Fm3m，晶胞参数a=0.35622(2)nm。铱铁镍矿分子式：Ni0.66Fe0.18Ir0.16，属等轴晶系，空间群Oh^5-Fm3m，晶胞参数a=0.46486(4)mm。  相似文献   

Horizontal and vertical components of earthquake ground motions at liquefiable sites   总被引：1，自引：0，他引：1  

J. Yang  T. Sato  S. Savidis  X. S. Li 《Soil Dynamics and Earthquake Engineering》2002,22(3)

Field observations on ground motions from recent earthquakes imply that current knowledge is limited with regard to relating vertical and horizontal motions at liquefiable sites. This paper describes a study with the purpose of clarifying this emerging issue to some extent. A series of numerical analyses is carried out on a liquefiable soil deposit with a verified, fully coupled, nonlinear procedure. It is shown that the transformation of vertical motions in the deposit differs considerably from the transformation of horizontal motions. Both the amplitude and frequency content of the horizontal motions are strongly dependent on the shaking level or the associated nonlinear soil behavior. The transfer function for vertical motions is however likely to be independent of the intensity of input motions; no reduction in the amplitude occurs even in the case of strong shaking. The results are shown to be in consistence with the laboratory observations on shaking table tests and recent field observations that less nonlinearity exists for vertical motions. It is also shown that the possibility exists for using information on spectral ratios between the horizontal and vertical surface motions to quickly identify in situ soil behavior and liquefaction that are not readily covered by conventional field or laboratory experimentation procedures.  相似文献