The Evolution of Ground Water     

by Mary P. Anderson 《Ground water》2009,47(4):469-469

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Nonlinear Flow in Karst Formations     

by David A. Chin  René M. Price  Vincent J. DiFrenna 《Ground water》2009,47(5):669-674

The variation of effective hydraulic conductivity as a function of specific discharge in several 0.2-m and 0.3-m cubes of Key Largo Limestone was investigated. The experimental results closely match the Forchheimer equation. Defining the pore-size length scale in terms of Forchheimer parameters, it is demonstrated that significant deviations from Darcian flow will occur when the Reynolds number exceeds 0.11. A particular threshold model previously proposed for use in karstic formations does not show strong agreement with the data near the onset of nonlinear flow.  相似文献   

Unfinished Business in Geothermal Energy   总被引：1，自引：0，他引：1  

by Grant Ferguson 《Ground water》2009,47(2):167-167

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Investigation of Transport Processes inside Karst Aquifer by Means of STATIS   总被引：1，自引：0，他引：1  

by M. Fournier  A. Motelay-Massei  N. Massei  M. Aubert  M. Bakalowicz  and J.P. Dupont 《Ground water》2009,47(3):391-400

Environmental data sets are often multidimensional and consequently display complex structure. This article shows the limitations of principal component analysis (PCA) for the study of such three-dimensional (3D) data sets. These limitations can be resolved by the use of the statistical tool STATIS. The inlet (a swallow hole) and the outlet (a spring) of a karst system of the Western Paris basin were sampled during three rain events of various intensities. These 3D geochemical data sets (variables × sites × dates) for a karst system were analyzed by STATIS method to identify hydrological processes. STATIS proceeds in three steps (interstructure, compromise, and intrastructure), which allows us to focus the analysis of hydrologic systems at different temporal and spatial scales. Compromise plane shows that suspended matter and flood are not simultaneous and highlights a rapid flow, characterized by turbidity and phosphate, which represents a point source contamination, and a ground water flow contaminated by nitrate. Intrastructure plane allows us to compare hydrochemical variations between the swallow hole and the spring lead. By this way, hydrological processes such as direct transfer and resuspension of intrakarstic sediments before and after the flood were identified what cannot be realized by comparison of inlet and outlet breakthrough curves. Finally, results obtained from the same data set by STATIS and a coupled study using PCA and normalized hysteresis curves were compared. This comparison shows the efficiency of STATIS at the identification of transport processes and vulnerability of karst system and its potential for hydrological applications.  相似文献   

Inferring Heterogeneity in Aquitards Using High-Resolution δD and δ¹⁸O Profiles     

by M. Jim Hendry  L.I. Wassenaar 《Ground water》2009,47(5):639-645

Vertical depth profiles of pore water isotopes (δD and δ¹⁸O) in clay-rich aquitards have been used to show that solute transport is dominated by molecular diffusion, to define the timing of geologic events, and to estimate vertical hydraulic conductivity. The interpretation of the isotopic profiles in these studies was based on pore water samples collected from piezometers installed in nests (typically 4 to 15 piezometers) over depths of 10 to 80 m. Data from piezometer nests generally have poor vertical resolution (meters), raising questions about their capacity to reveal the impact of finer scale heterogeneities such as permeable sand bodies or fractured till zones on solute transport. Here, we used high-resolution (30-cm) depth profiles of δD and δ¹⁸O from two continuously cored boreholes in a till aquitard to provide new insights into the effects of sand bodies on solute transport. High-resolution core-derived profiles indicate that such heterogeneities can cause major deviations from one-dimensional diffusion profiles. Further, comparison of piezometer-measured values with best-fit diffusion trends shows subtle deviations, suggesting the presence of heterogeneities that should not be ignored. High-resolution profiles also more clearly defined the contact between the highly fractured oxidized zone and the underlying unoxidized zone than the piezometers.  相似文献   

Shake‐table test performance of an inertial force‐limiting floor anchorage system          下载免费PDF全文

Zhi Zhang  Robert B. Fleischman  Jose I. Restrepo  Gabriele Guerrini  Arpit Nema  Dichuan Zhang  Ulina Shakya  Georgios Tsampras  Richard Sause 《地震工程与结构动力学》2018,47(10):1987-2011

A new floor connecting system developed for low‐damage seismic‐resistant building structures is described herein. The system, termed Inertial Force‐Limiting Floor Anchorage System (IFAS), is intended to limit the lateral forces in buildings during an earthquake. This objective is accomplished by providing limited‐strength deformable connections between the floor system and the primary elements of the lateral force‐resisting system. The connections transform the seismic demands from inertial forces into relative displacements between the floors and lateral force‐resisting system. This paper presents the IFAS performance in a shake‐table testing program that provides a direct comparison with an equivalent conventional rigidly anchored‐floor structure. The test structure is a half‐scale, 4‐story reinforced concrete flat‐plate shear wall structure. Precast hybrid rocking walls and special precast columns were used for test repeatability in a 22‐input strong ground‐motion sequence. The structure was purposely designed with an eccentric wall layout to examine the performance of the system in coupled translational‐torsional response. The test results indicated a seismic demand reduction in the lateral force‐resisting system of the IFAS structure relative to the conventional structure, including reduced shear wall base rotation, shear wall and column inter‐story drift, and, in some cases, floor accelerations. These results indicate the potential for the IFAS to minimize damage to the primary structural and non‐structural components during earthquakes.  相似文献   

Detection of temperature variability and trends in the lower troposphere over Delhi: A study of joint influence of ENSO and Land use/ Land cover during 1980–2015     

Mansi Janmaijaya  RB Singh  SK Dhaka 《Singapore journal of tropical geography》2019,40(1):111-123

A study of radiosonde observations for temperature at 850 hPa over Delhi for a period of 35 years was conducted. The influence of atmospheric oscillations and geophysical events like El Niño‐Southern Oscillation (ENSO) on tropospheric temperature variability showed indicative trends for changing urban climate in Delhi. The inter‐annual variation in surface temperature and its relationship with land use changes and land cover changes (LULCC) was also examined. LULCC and urban expansion into peripheral areas of Delhi (towards the West, North, North‐West and South) at the cost of agricultural and wasteland was found to be extensive. The upper range of the surface temperature has shifted by ~6°C. The post‐monsoon and winter months from November to February have experienced a considerable increase in the average temperature in the period examined. The monsoon months from June to September have undergone cooling of ~0.5°C–1°C at 850 hPa. An inverse relationship exists between the Southern Oscillation Index (SOI) and the monthly averaged temperature. The temperature of the atmosphere over Delhi at 850 hPa has increased only marginally (~ 0.3°C) for the time period 1980–2015. Bi‐modal peaks were the most peculiar features observed in mean monthly temperature variation during 2000–2009.  相似文献   

Edgar Hynes Thompson: a collection of centenary reminiscences     

Collected  compiled by K. B. Atkinson 《The Photogrammetric Record》2010,25(129):55-68

The idea for this collection of memories of E. H. Thompson began as a suggestion to potential contributors for anything from "a couple of sentences to a couple of paragraphs". Both their willingness to write and the length of some contributions show how influential Thompson has been in the lives of so many of his colleagues and students. Contributors include two past-presidents of the International Society for Photogrammetry and Remote Sensing and six past-presidents of the Photogrammetric Society. Three longer essays are published as separate contributions to this feature.  相似文献   

Seismic vulnerability and loss assessment of the Nepalese Pagoda temples     

Manjip Shakya  Humberto Varum  Romeu Vicente  Aníbal Costa 《Bulletin of Earthquake Engineering》2015,13(7):2197-2223

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Correlation of the lower devonian rocks of australasia     

D. L. Strusz with contribution by M. R. Banks  G. Bischoff  B. J. Cooper  R. A. Cooper  P. G. Flood  E. D. Gill  J. S. Jell  J. W. Pickett  N. M. Savage  D. L. Sherwin  J. A. Talent  B. D. Webby & A. J. Wright 《Australian Journal of Earth Sciences》2013,60(4):427-455

Alkali basaltic rocks from the Southern Highlands, N.S.W., contain oxide phases of both high and low pressure origin. The two phases are readily distinguished using chemical and textural criteria.

Chemical data for low‐pressure Fe‐Ti oxides indicate that oxygen fugacities of the host lavas range from 10‐^12.8 to 10‐⁸ atm at 950° to 1110°C. In most cases, the oxygen fugacities of the individual lava flows appear to be principally a function of temperature and intrinsic chemical equilibria existing at the time of formation of the basaltic liquid. However, some relatively differentiated flows shows a high degree of oxidation due to volatile enrichment with fractionation. Rare glassy flows show dendritic crystallization of Fe‐Ti oxides. Most flows in which abundant olivine was the first phase to be precipitated also contain Cr‐rich spinels associated, and apparently coeval, with the earliest‐crystallizing olivine.  相似文献