Marsh-creek connectivity: Fish use of a tidal salt marsh in Southern California     

Janelle M. West  Joy B. Zedler 《Estuaries and Coasts》2000,23(5):699-710

Salt marsh habitats influenced by southern California's mixed, semi-diurnal tides are, on average, accessible to fishes less than 16% of the time. However, five species (four natives, one oxotic) and a variety of juvenile and adult size classes were collected on the marsh surface during a year-long sampling from June 1997 through June 1998 at Sweetwater Marsh National Wildlife Refuge on San Diego Bay.Fundulus parvipinis andGillichthys mirabilis were the most abundant fish species using the marsh. Analyses of their guts revealed that the marsh surface provides a rich foraging area for fishes on high spring tides.F. parvipinnis with marsh access consumed six times as much food as fishes restricted to creek habitats (on a g-food g-fish^?1 basis) and also fed on additional prey types. Because the salt marsh is an important foraging area for fishes, we recommend that restoration projects (especially those intended to mitigate lost fish habitat) include vegetated areas with interconnecting tidal creeks.  相似文献   

A Generalized Representation of the Electromagnetic Fields In A Layered Earth     

David E. Boerner  G. F. West 《Geophysical Journal International》1989,97(3):529-547

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Probabilistic analysis of rock slope stability and random properties of discontinuity parameters, Interstate Highway 40, Western North Carolina, USA   总被引：1，自引：0，他引：1  

Hyuck-Jin Park  Terry R. West  Ik Woo 《Engineering Geology》2005,79(3-4):230-250

Probabilistic analysis has been used as an effective tool to evaluate uncertainty so prevalent in variables governing rock slope stability. In this study a probabilistic analysis procedure and related algorithms were developed by extending the Monte Carlo simulation. The approach was used to analyze rock slope stability for Interstate Highway 40 (I-40), North Carolina, USA. This probabilistic approach consists of two parts: analysis of available geotechnical data to obtain random properties of discontinuity parameters; and probabilistic analysis of slope stability based on parameters with random properties. Random geometric and strength parameters for discontinuities were derived from field measurements and analysis using the statistical inference method or obtained from experience and engineering judgment of parameters. Specifically, this study shows that a certain amount of experience and engineering judgment can be utilized to determine random properties of discontinuity parameters. Probabilistic stability analysis is accomplished using statistical parameters and probability density functions for each discontinuity parameter. Then, the two requisite conditions, kinematic and kinetic instability for evaluating rock slope stability, are determined and evaluated separately, and subsequently the two probabilities are combined to provide an overall stability measure. Following the probabilistic analysis to account for variation in parameters, results of the probabilistic analyses were compared to those of a deterministic analysis, illustrating deficiencies in the latter procedure. Two geometries for the cut slopes on I-40 were evaluated, the original 75° slope and the 50° slope which has developed over the past 40 years of weathering.  相似文献   

The short term climatic sensitivity of carbonate and silicate weathering fluxes: Insight from seasonal variations in river chemistry   总被引：2，自引：0，他引：2  

Edward T. Tipper  Mike J. Bickle  A. Joshua West  Hazel J. Chapman 《Geochimica et cosmochimica acta》2006,70(11):2737-2754

Large seasonal variations in the dissolved load of the headwater tributaries of the Marsyandi river (Nepal Himalaya) for major cations and ⁸⁷Sr/⁸⁶Sr ratios are interpreted to result from a greater dissolution of carbonate relative to silicate at high runoff. There is up to a 0.003 decrease in strontium isotope ratios and a factor of 3 reduction in the Si(OH)₄/Ca ratio during the monsoon. These variations, in small rivers sampling uniform lithologies, result from a different response of carbonate and silicate mineral dissolution to climatic forcing. Similar trends are observed in compiled literature data, from both Indian and Nepalese Himalayan rivers. Carbonate weathering is more sensitive to monsoonal runoff because of its faster dissolution kinetics. Silicate weathering increases relative to carbonate during the dry season, and may be more predominant in groundwater with longer water-rock interaction times. Despite this kinetic effect, silicate weathering fluxes are dominated by the monsoon flux, when between 50% and 70% of total annual silicate weathering flux occurs.  相似文献   

A relation between abrasiveness and quartz content for some Coal Measures sediments     

G. West 《Geotechnical and Geological Engineering》1986,4(1):73-78

Conclusions 1. For a limited range of Coal Measures sediments, it has been shown that a good relation exists between the abrasiveness of the rocks and their quartz content.2. In this instance it was not possible to make any correlation with cutter wear, but it would be expected from the above result that the higher the quartz content of the rock the greater would be the wear on the cutters.  相似文献   

International symposium on Deccan Trap and other flood eruptions     

W. D. West 《Bulletin of Volcanology》1971,35(3):513-518

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Efficient Generation Portfolio Construction Using Time-Varying Correlations     

R. Gupta  J. M. West 《Natural Resources Research》2014,23(2):267-283

We constructed a procurement portfolio for the Indian power sector using two variants of the dynamic conditional correlation GARCH model to derive time-varying correlations between major coal indices. We used prices and qualities of observed cargos to adjust indices for quality gaps as well as for freight costs and power plant efficiency factors. Using the relative homogeneity of the energy content of imports from Australia, South Africa, and Indonesia, we found that the regional seaborne market is highly correlated during normal economic conditions, while suffering brief departures in correlation during demand and supply shocks. Our results show that the buying behavior of power producers is aligned with the mean-variance efficient portfolio of delivered prices using time-varying correlation estimates, but not free-on-board coal index prices. This study challenges the notion that thermal coal importers only source material with a freight price advantage and highlights the importance of coal quality gaps in power production.  相似文献   

An open source,server-side framework for analytical web mapping and its application to health     

Simon Moncrieff  Geoff West  James Cosford  Narelle Mullan  Andrew Jardine 《International Journal of Digital Earth》2014,7(4):294-315

In this paper, we detail the design and the implementation of an open source, server-side web mapping framework for the analysis of health data. The framework forms part of a larger project, the goal of which is to provide an analytical web geographical information system (GIS) that enables health experts to analyse spatial aspects of health data. The aim of the framework is to provide a method for the dynamic and flexible spatial visualisation of health data to facilitate data exploration and analysis. Consequently, a dynamic thematic web mapping technique, an extension to the Open Geospatial Consortium (OGC) web map service standard, was developed. The technique combines a data query, processing technique and styling methodology on the fly to generate a thematic map. The resulting thematic map represents a virtual map layer that enables a user to rapidly visually summarise properties of a data-set. A test web interface was developed to assess the efficacy of the web mapping technique. As the dynamic web mapping method builds on existing OGC web mapping standards, it can be readily integrated with the existing lightweight slippy map web clients and virtual globes.  相似文献