西南某巨型水电站坝区推覆断层研究

马家河坝断层发育于金沙江某巨型水电站库区,距坝址最近仅3km,且沿江两岸出露,主断面不同部分和次级断层结构样式和变形特征复杂。所以对断层的认识一直是大坝稳定性评价的重点也是争论的焦点。通过大比例尺野外填图、开挖平硐和室内构造解析获得了大量新资料,认为该断层是一个发育在地台内部的小型推覆构造。首次厘定了断层几何学和运动学特征和影响范围,分析了断层的动力学机制。这对大坝的施工和蓄水后的安全运行有重大意义。     

Flood occurrence hazard forecasting based on geographical information system

The application of Geographical Information system (GIS) in modeling flood and its prediction in catchments offers considerable potential. Several examples illustrate simple GIS techniques to produce flood hazard indices or its zonation using hydrologic-type models. Existing flood models can also be loosely coupled to a GIS, such as the HMS (Hydrological Modeling System) model. Forethermore, models can be fully integrated into a GIS by embedded coupling, such as the SCS (Soil Conservation Service) model. Installation of flood forecasting systems in watersheds with incomplete hydrometric data may reduce the flood-induced damages. In this study Geographical Information system used to up to date the watershed data and estimation of SCS model parameters which is sensible to considered the real time flood forecasting in Kasilian catchment of Mazandaran province. The main aim of this paper is to investigate the possibility of the linkage between GIS with a comprehensive hydrologic model, especially HMS. The use of GIS could produce a suitable agreement between observed results (extracted rainfall and runoff data of 1992, 1995 and 1996 from the related stations) with the calculated results of the hydrological model. The obtained results from rainfall-runoff process simulations of the model in this research showed that submergibility of the main watershed, Kasillian, does not depend on the outlet discharge rate of each one of its watershed independently. But it is related to how those two outlet hydrographs from main river watershed are combined. The model is capable of showing the flood characteristics temporally and spatially in each cross section of the channel network.     

Migrant worker centers: contending with downgrading in the low-wage labor market

Mass migration to major USA cities is reworking patterns of ethnic jobholding and labor market segmentation. Employers in a variety of industries have turned to recent migrants, many of whom are not authorized to work in the USA, as a stable labor supply for low-wage jobs. As a result, many migrant workers enter urban economies through precarious jobs in low-wage industries and the informal economy where they often endure routine violations of labor and employment laws. This paper examines the activities of a “migrant worker center” in improving wages and working conditions in migrant labor markets. Through a case study of a worker center located in a port-of-entry immigrant neighborhood on Chicago’s Southwest Side, we examine the geographies of the low-wage labor market and the problems that have arisen for workers who hold jobs that effectively exist beyond the reach of government regulation. We argue that migrant worker centers will likely emerge as a key resource for workers who are drawn to global cities by the promise of economic opportunity yet confront harsh conditions in the local labor markets in which they are employed.     

MAPSTORE与ARC／INFO数据转换的方法研究

GIS空间数据具有多源性的特征，为数据综合利用和数据共享带来不便，解决多格式数据源集成一直是近年来GIS应用系统开发中需要解决的重要问题。ARC／INFO软件是当前众多地理信息系统软件中功能最强、市场占有率最高的软件。E00格式作为一种空间数据转换的事实上的标准，对于自主版权的GIS软件MapStore来说，实现两者的数据转换具有重要意义。本文分析了MapStore与ARC／INFO空间数据模型的组织特征，在比较分析的基础上设计了转换方案，并就实现过程中的关键技术进行了论述。     

Determination of Rare Earth Elements, Y, Th, Zr, Hf, Nb and Ta in Geological Reference Materials G-2, G-3, SCo-1 and WGB-1 by Sodium Peroxide Sintering and Inductively Coupled Plasma-Mass Spectrometry

Data are reported for rare earth elements (REE), Y, Th, Zr, Hf, Nb and Ta in four geological reference materials using sodium peroxide (Na₂O₂) sintering and inductively coupled plasma-mass spectrometry. The described procedure was used by students during their thesis work. A compilation of their reference material data acquired over one year of laboratory work demonstrates the ease and reliability of the method and the high reproducibility of the analytical results. Relative standard deviations of up to thirty six measurements of one reference material were lower than 5% for Y and the REE. Reproduciblities of Zr, Hf, Nb, Ta and Th were higher at between 5% and 10%, and can be attributed to the inhomogeneous distribution of zircon and other trace mineral phases and uncorrected drift effects. The concentration data are compared to reference and literature values and demonstrate that the procedure is also accurate. New data on G-3 show some systematic deviations from G-2, which are statistically significant.     

Determination of the "Difficult" Elements Ag, B, Ge, Mo, Sn, Tl and W in Geochemical Reference Samples and Silicate Rocks of the GeoPT Proficiency Testing Series by DC Arc Atomic Emission Spectrometry

Reference samples of rocks from the Institute of Geochemistry, Irkutsk (IGI) and the Research Institute of Applied Physics, Irkutsk University (RIAP) and silicate rocks from the GeoPT proficiency testing series were analysed with the aim of determining Ag, B, Ge, Mo, Sn, Tl and W abundances by an atomic-emission method with air-stabilized D.C. arc excitation. Many of the results reported are without recommended or assigned values. The results are compared with compilation data from the literature and, where possible, with assigned values for samples of the Geo PT series.     

On the Issues of Scale,Resolution, and Fractal Analysis in the Mapping Sciences*

Scale and resolution have long been key issues in geography. The rapid development of analytical cartography, GIS, and remote sensing (the mapping sciences) in the last decade has forced the issues of scale and resolution to be treated formally and better defined. This paper addresses the problem of scale and resolution in geographical studies, with special reference to the mapping sciences. The fractal concept is introduced, and its use in identifying the scale and resolution problem is discussed. The implications of the scale and resolution problem on studies of global change and modeling are also explored.     

A spatial dynamic model of population changes in a vulnerable coastal environment

This study developed a spatial dynamic model to examine the coupled natural–human responses in the form of changes in population and associated developed land area in the Lower Mississippi River Basin region. The goal was to identify key socioeconomic factors (utility) and environmental factors (hazard damages, elevation, and subsidence rate) that affected population changes, as well as to examine how population changes affected the local utility and the local environment reciprocally. We first applied areal interpolation techniques with the volume-preserving property to transform all the data at Year 2000 into a unified 3 km by 3 km cellular space. We then built an Elastic Net model to extract 12 variables from a set of 33 for the spatial dynamic model. Afterward, we calibrated the neighborhood effects with a genetic algorithm and use the spatial dynamic model to simulate population and developed land area in 2010. Furthermore, we took a Monte Carlo approach for analyzing the uncertainty of the model outcome. Our accuracy assessment shows that the model on average slightly overpredicts the number of population and the developed land percentage at 2010, as indicated by the low values of mean absolute deviation (MAD) due to quantity. On the other hand, the MADs due to allocation are larger than the MADs due to quantity, with most outliers found in the New Orleans region where population and urban development declined significantly during 2000–2010 after Hurricane Katrina. The proposed model sheds light on the complex relationships between coastal hazards and human responses and provides useful insights to strategic development for coastal sustainability.