巴基斯坦卡拉奇─海得拉巴区域地震危险性预测   总被引：1，自引：0，他引：1  

Shahid A. Khan 《地震研究》1995,(3)

本文讨论了巴基斯坦的地震构造，潜在震源和历史与现代地震活动性，并在此基础上使用确定性和概率性两种方法计算了各发震断层５０年内最大可能的地震在卡拉奇和海得拉巴两城市将引起的地面峰值加速度以及５０年内超越概率为１４％的等加速度区划图。  相似文献   

Appraisal of regional and index flood quantile estimators     

J. R. Stedinger  L. -H. Lu 《Stochastic Hydrology and Hydraulics》1995,9(1):49-75

Our results illustrate the performance of at-site and regional GEV/PWM flood quantile estimators in regions with different coefficients of variation, degrees of regional heterogeneity, record lengths, and number of sites. Analytic approximations of bias and variance are employed. For realistic GEV distributions and short records, the index-flood quantile estimator performs better than a 2-parameter GEV/PWM quantile estimator with a regional shape parameter, or a 3-parameter at-site GEV/PWM quantile estimator, in both humid and especially in arid regions, as long as the degree of regional heterogeneity is moderate. As regional heterogeneity or record lengths increases, 2-parameter estimators quickly dominate. Flood frequency models that assign probabilities larger than 2% to negative flows are unrealistic; experiments employing such distributions provide questionable results. This appraisal generally demonstrates the value of regionalizing estimators of the shape of a flood distribution, and sometimes the coefficient of variation.  相似文献   

生态屏障约束下的综合功能区划研究——以云南省昭通市为例(英文)     

杜瑜  王传胜  赵海英  杨晓光 《地理学报(英文版)》2007,(3)

Ecological shelter zones reconstruction is an ecosystem restoration and conserva-tion project aimed to the ecological safety of nations,regions and basins. Reconstruction of ecological shelter zones of the upper reaches of the Yangtze River became one of the most important tasks of Western Development strategy. This article,taking Zhaotong as an exam-ple,studies the functional regionalization of ecological shelter zones. The study supplies a case for functional regionalization of small and medium regions whose main tasks are envi-ronment reservation. With the guidance of theories of functional regionalization,and based on the analysis of Zhaotong's natural,ecological and socioeconomic factors,the paper suggests five principles for factors selection. These principles include: (1) reversing order evaluation; (2) selecting main factors; (3) keeping the integrality of administrative regions of towns; and (4) making the products acceptable by local government. To analyze spatial status of selected factors,LUCC data in 2002,1:50,000 relief maps and town-unit socioeconomic statistical data in 2004 are used. RS and GIS tools are also applied to melt traditional and modern geo-graphical methods. This would be useful to functional regionalization research in mountain-ous areas. As a conclusion,the leading functional regions of ecological conservation or economic development are suggested,respectively. Zhaotong city is divided into two-level functional regions. The first-level includes three leading functional regions and they will lead developing direction of sub-regions. The second-level includes eight sub-regions,which are policy implemented regions,and will supply guidance to Zhaotong's ecological shelter zones reconstruction.  相似文献   

Crust and Upper Mantle Structure in the Caribbean Region by Group Velocity Tomography and Regionalization     

O'Leary González  Leonardo Alvarez  Mariangela Guidarelli  Giuliano F. Panza 《Pure and Applied Geophysics》2007,164(10):1985-2007

An overview of the crust and upper mantle structure of Central America and the Caribbean region is presented as a result of the processing of more than 200 seismograms recorded by digital broadband stations from SSSN and GSN seismic networks. Group velocity dispersion curves are obtained in the period range from 10s to 40s by FTAN analysis of the fundamental mode of the Rayleigh waves; the error of these measurements varies from 0.06 and 0.09 km/s. From the dispersion curve, seven tomographic maps at different periods and with average spatial resolution of 500 km are obtained. Using the logical combinatorial classification techniques, eight main groups of dispersion curves are determined from the tomographic maps and eleven main regions, each one characterized by one kind of dispersion curves, are identified. The average dispersion curves obtained for each region are extended to 150s by adding data from a larger-scale tomographic study (Vdovin et al., 1999) and inverted using a nonlinear procedure. A set of models of the S-wave velocity vs. depth in the crust and upper mantle is found as a result of the inversion process. In six regions we identify a typically oceanic crust and upper mantle structure, while in the other two the models are consistent with the presence of a continental structure. Two regions, located over the major geological zones of the accretionary crust of the Caribbean region, are characterized by a peculiar crust and upper mantle structure, indicating the presence of lithospheric roots reaching, at least, about 200 km of depth.  相似文献   

盐城地区大棚反季节蔬菜生产的温度条件及其应用   总被引：3，自引：2，他引：3       下载免费PDF全文

蒋名淑  朱傅详等 《气象科学》2002,22(2):236-241

通过平行对比观测试验，分析得出了我市塑料大棚不同层次的增温效应，以及晴雨天气转换时大棚内的各项温度的变化情况，并根据大彬的几种主要蔬菜适宜生长的气象指标，对我市沿海地区大棚的反季节蔬菜生产作出各类蔬菜棚内的适宜生长期，为利用大棚进行反季节蔬菜生产提供了科学依据。  相似文献   

中国经济区研究述评     

张莉 《地理与地理信息科学》2001,17(2):39-45

回顾改革开放以来我国几个具有代表性的综合经济区划方案 ,总结 2 0年来中国经济区研究的发展趋势 ,并探讨经济区的范围、边界 ,以及经济区研究的方向和意义等问题  相似文献   

Classification of seismic strain estimates in the Mediterranean region from a 'bootstrap' approach     

Marcello Viti  Dario Albarello  Enzo Mantovani 《Geophysical Journal International》2001,146(2):399-415

  相似文献   

玛曲国家级生态功能保护区分区研究   总被引：5，自引：1，他引：4  

黄国勇  韩茂莉  陈兴鹏 《地理与地理信息科学》2003,19(2):82-85,92

该文以遥感和地理信息系统作为信息获取与处理工具,并利用2000年TM遥感影像为基础信息源,分析玛曲国家级生态功能保护区特征。根据整体性、发生统一性、生态功能相对一致性、主导性和方便管理等分区原则,依照研究区生态服务功能的不同以及生态系统受胁迫程度的差异,运用自上而下的序列划分法对其进行了两级分区,得出了4个一级区6个二级区的分类系统,针对区域的特征和主要生态问题,提出相应的建设目标和措施。  相似文献   

Singularity and Nonnormality in the Classification of Compositional Data     

Geoffrey C. Bohling  John C. Davis  Ricardo A. Olea  Jan Harff 《Mathematical Geology》1998,30(1):5-20

Geologists may want to classify compositional data and express the classification as a map. Regionalized classification is a tool that can be used for this purpose, but it incorporates discriminant analysis, which requires the computation and inversion of a covariance matrix. Covariance matrices of compositional data always will be singular (noninvertible) because of the unit-sum constraint. Fortunately, discriminant analyses can be calculated using a pseudo-inverse of the singular covariance matrix; this is done automatically by some statistical packages such as SAS. Granulometric data from the Darss Sill region of the Baltic Sea is used to explore how the pseudo-inversion procedure influences discriminant analysis results, comparing the algorithm used by SAS to the more conventional Moore–Penrose algorithm. Logratio transforms have been recommended to overcome problems associated with analysis of compositional data, including singularity. A regionalized classification of the Darss Sill data after logratio transformation is different only slightly from one based on raw granulometric data, suggesting that closure problems do not influence severely regionalized classification of compositional data.  相似文献   

Derivation of a curve number and kinematic-wave based flood frequency distribution     

R. S. KUROTHE  N. K. GOEL  B. S. MATHUR 《水文科学杂志》2013,58(4):571-584

Abstract

The physically-based flood frequency models use readily available rainfall data and catchment characteristics to derive the flood frequency distribution. In the present study, a new physically-based flood frequency distribution has been developed. This model uses bivariate exponential distribution for rainfall intensity and duration, and the Soil Conservation Service-Curve Number (SCS-CN) method for deriving the probability density function (pdf) of effective rainfall. The effective rainfall-runoff model is based on kinematic-wave theory. The results of application of this derived model to three Indian basins indicate that the model is a useful alternative for estimating flood flow quantiles at ungauged sites.  相似文献