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A three‐dimensional numerical modelling system is developed to study transformation processes of water resources in alluvial fan and river basin along the middle reaches of the Heihe River Basin, Northwest China, an arid and semi‐arid region. Integrating land utilization, remote sensing and geographic information systems, we have developed a numerical modelling system that can be used to quantify the effects of land use and anthropogenic activities on the groundwater system as well as to investigate the interaction between surface water and groundwater. Various hydraulic measurements are used to identify and calibrate the hydraulic boundary conditions and spatial distributions of hydraulic parameters. In the modelling study, various water exchanges and human effects on the watershed system are considered. These include water exchange between surface water and groundwater, groundwater pumping, lateral water recharges from mountain areas, land utilization, and infiltration and evaporation in the irrigation and non‐irrigation areas. The modelling system provides a quantitative method to describe spatial and temporal distributions and transformations between various water resources, and it has application to other watersheds in arid and semi‐arid areas. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Bill Fitches 《Geological Journal》2011,46(4):364-373
On the Isle of Man, the Early Devonian Peel Sandstones and Early Carboniferous limestones have been deformed in places by folds, cleavage and other structures. The structures in the Peel Sandstones have been attributed to pre‐lithification deformation associated with slumping of the red beds. Here, they are re‐interpreted to be products of post‐lithification deformation, inferred from small‐scale structures and fabrics, which took place in a localized thrust zone. Compression was approximately NW–SE and translation towards the SE. That deformation may have also produced some of the late structures in the Lower Palaeozoic rocks of the island. The minimum age of these post‐Early Devonian structures is unknown but is probably pre‐Carboniferous: they may represent the mid‐Devonian Acadian deformation. The Carboniferous succession is folded in places and contains stylolites and stylolitic cleavage. A stress regime with E–W to WNW–ESE compression is inferred. These structures have orientations and morphologies shown to resemble those in neighbouring parts of southern Britain, where they are attributed mainly to mid‐ to late‐Carboniferous Variscan events. Alternatively, some or all of them might be products of late Mesozoic and Tertiary tectonics recognized elsewhere in the region. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Jon K. Hillier S. F. Green N. McBride J. P. Schwanethal F. Postberg R. Srama S. Kempf G. Moragas-Klostermeyer J. A. M. McDonnell E. Grün 《Monthly notices of the Royal Astronomical Society》2007,377(4):1588-1596
We present the first in situ direct measurement of the composition of particles in Saturn's rings. The Cassini cosmic dust analyser (CDA) measured the mass spectra of nearly 300 impacting dust particles during the 2004 October E ring crossing. An initial interpretation of the data shows that the particles are predominantly water ice, with minor contributions from possible combinations of silicates, carbon dioxide, ammonia, molecular nitrogen, hydrocarbons and perhaps carbon monoxide. This places constraints on both the composition of Enceladus, the main source of the E ring, as well as the grain formation mechanisms. 相似文献
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This analysis of a backward integration traceability scheme for red chillies developed by a multinational food company in India emphasizes spatial integration and differentiation within contract farming. The scheme is premised on the procurement of identically credentialed produce from 10 different sites in two states and incorporates growers in highly flexible and place‐contingent modes. Interviews with corporate informants and farmers reveal this flexibility to be the result of a two‐way process of risk management between the company and growers. The company spread its geographical exposure by initiating production across a number of far‐flung cultivation sites, and growers cultivate chillies for the company within the context of diverse agricultural systems, thereby mitigating dependence. The scheme has had positive impacts for participants, but has more complex implications for the evolution of agrarian landscapes in India. The selective enrolment of participants through ‘progressive farmer’ networks acts to reorganize rural spaces by generating new geographies of advantage and opportunity. 相似文献
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Stefano Mottola William D. Sears Anders Erikson Alan W. Harris Jim W. Young Gerhard Hahn Mats Dahlgren Beatrice E. A. Mueller Bill Owen Ricardo Gil-Hutton Javier Licandro M. Antonietta Barucci Claudia Angeli Gerhard Neukum Claes-Ingvar Lagerkvist J. Felix Lahulla 《Planetary and Space Science》1995,43(12)
CCD photometry of the NEAR mission fly-by target 253 Mathilde is presented. Measurements taken during 52 nights of observations, from February to June 1995, allow a rotation period of 17.406±0.010 days and a lightcurve amplitude of 0.45±0.02 mag to be determined. A B-V color index of 0.67±0.02 and a V-R of 0.35±0.02 are measured, which are compatible with C-type membership. The determination of the phase relation results in H = 10.28±0.03 and G = 0.12±0.06. Indications that the lightcurve is not strictly singly-periodic are found. A power-spectrum analysis detects a secondary frequency f2 = 0.0322±0.0010 d−1, which is interpreted as evidence for a complex rotation state. 相似文献
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