Tools for gauging the capacity of salmon spawning substrates          下载免费PDF全文

Brandon T. Overstreet  Clifford S. Riebe  John K. Wooster  Leonard S. Sklar  Dino Bellugi 《地球表面变化过程与地形》2016,41(1):130-142

We present a set of river management tools based on a recently developed method for estimating the amount of salmon spawning habitat in coarse‐bedded rivers. The method, which was developed from a mechanistic model of redd building by female salmon, combines empirical relationships between fish length, redd area, and the sizes of particles moved by fish during spawning. Model inputs are the grain‐size indices D₅₀ and D₈₄ and an estimate of female fish length, which is used to predict the size of the redd that they will build and the size of the largest particle that they can move on the bed. Outputs include predictions of the fraction of the bed that the fish can use for redd building and the number of redds that they can build within the useable area. We cast the model into easy‐to‐use look‐up tables, charts, an Excel worksheet, a JavaScript web applet, and a MATLAB user interface. We explain how these tools can be used in a new, mechanistic approach to assessing spawning substrates and optimizing gravel augmentation projects in coarse‐bedded rivers. © 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

Joint Inversion of Seismic and Magnetotelluric Data in the Parkfield Region of California Using the Normalized Cross-Gradient Constraint   总被引：2，自引：0，他引：2  

Ninfa L. Bennington  Haijiang Zhang  Clifford H. Thurber  Paul A. Bedrosian 《Pure and Applied Geophysics》2015,172(5):1033-1052

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Controls on groundwater flow in the Bengal Basin of India and Bangladesh: regional modeling analysis   总被引：2，自引：0，他引：2  

Holly A. Michael  Clifford I. Voss 《Hydrogeology Journal》2009,17(7):1561-1577

Groundwater for domestic and irrigation purposes is produced primarily from shallow parts of the Bengal Basin aquifer system (India and Bangladesh), which contains high concentrations of dissolved arsenic (exceeding worldwide drinking water standards), though deeper groundwater is generally low in arsenic. An essential first step for determining sustainable management of the deep groundwater resource is identification of hydrogeologic controls on flow and quantification of basin-scale groundwater flow patterns. Results from groundwater modeling, in which the Bengal Basin aquifer system is represented as a single aquifer with higher horizontal than vertical hydraulic conductivity, indicate that this anisotropy is the primary hydrogeologic control on the natural flowpath lengths. Despite extremely low hydraulic gradients due to minimal topographic relief, anisotropy implies large-scale (tens to hundreds of kilometers) flow at depth. Other hydrogeologic factors, including lateral and vertical changes in hydraulic conductivity, have minor effects on overall flow patterns. However, because natural hydraulic gradients are low, the impact of pumping on groundwater flow is overwhelming; modeling indicates that pumping has substantially changed the shallow groundwater budget and flowpaths from predevelopment conditions.  相似文献   

Partition coefficients for olivine-melt and orthopyroxene-melt systems   总被引：3，自引：0，他引：3  

Paul Beattie  Clifford Ford  Douglas Russell 《Contributions to Mineralogy and Petrology》1991,109(2):212-224

Thermodynamic analysis shows that olivinemelt and orthopyroxene-melt partition coefficients for many elements should be approximately linear functions of D_Mg. These simple relationships can be combined with the constraint of mineral stoichiometry to allow the direct calculation of partition coefficients for these elements if the major element chemistry of the melt phase is known. A large dataset of published and unpublished experimental mineral-melt pairs for compositions in the range komatiite to andesite has allowed the determination of the empirical constants required for this calculation. The precision of these parameterisations is demonstrated by comparing the values calculated with those observed. Comparison of phenocryst-matrix partition coefficients with those measured from experimental mineral-melt pairs demonstrates that experimentally determined partition coefficients are equivalent to those in magmatic processes. There are therefore no significant kinetic factors precluding magmatic partitioning being reproduced on an experimental timescale. The model provides a set of simple tests for equilibrium and enables the chemical evolution of a magma fractionating olivine or orthopyroxene to be modelled. An empirical equation for distinguishing orthopyroxene from other low-Ca pyroxenes in chemical analyses of experimental runs is also presented.  相似文献   

Periglacial processes,ed. C. A. M. King,Benchmark Papers in Geology No. 27. Dawden,Hutchinson & Ross Inc., Stroudsburg,Pa., U.S.A., (1976), No. of Pages: 459. Price: $42.00, £24.70     

Clifford Embleton 《地球表面变化过程与地形》1977,2(1):92-92

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Mineral-chemical and isotopic studies of Namaqualand granulites,South Africa: A grenville analogue     

Tom N. Clifford  Eugen F. Stumpfl  Alwyn J. Burger  Terence S. McCarthy  David C. Rex 《Contributions to Mineralogy and Petrology》1981,77(3):225-250

The northwestern part of South Africa and southern South-West Africa/Namibia is amongst the most extensive granulite terranes in Africa. This work reports the results of electron microprobe studies of minerals from two-pyroxene, cordieriteorthopyroxene (-gedrite) (-sapphirine) and garnet and/or cordierite parageneses from Namaqualand, in the N.W. Cape Province of South Africa. Determined PT conditions of prograde metamorphism based on thermodynamic calculations are 800°–900° C and ca. 6–7 Kb; and it is argued that rocks of unusual composition, notably cordierite-orthopyroxene rocks, are restites after the extraction of granitic liquid from former argillites. This interpretation is consistent with previously published data on similar rocks, and with McCarthy's (1976) suggestion of extensive partial melting in the quartzofeldspathic rocks in the area. U-Pb isotopic studies of some 50 zircon fractions have been carried out and confirm an age of 1,200 m.y. for the high-grade regional metamorphism; but certain zircon populations record inherited ages greater than 1,700 m.y. Garnet-sillimanite rocks that contain retrograde kyanite reflect PT conditions of 550°–650° C and ca. 7–8 Kb; and constituent biotite has yielded a K-Ar age of ca. 950 m.y. These data, the regional stratigraphy and structure, and the mineralisation are compared with data from the Grenville Province of Canada. Notable similarities are the possible basement-cover relationships, and the calendar of tectonothermal events, while differences include the important stratiform base-metal mineralisation in the supracrustal sequence in Namaqualand, and the Cu-mineralisation in hypersthenebearing intrusives, emplaced some 1,100 m.y. ago, that are areally, and believed to be genetically, related to the granulite facies metamorphic regime.  相似文献   

Internet-based open source software for learning about GPS   总被引：1，自引：0，他引：1  

Clifford Kelley 《GPS Solutions》2002,6(3):201-205

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SWICA—2 M³: Second Conference on Salt Water Intrusion in Coastal Aquifers: Monitoring, Modeling, and Management     

Luis E. Marin  Clifford I. Voss 《Ground water》2004,42(3):318-318

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The future of hydrogeology     

Clifford I. Voss 《Hydrogeology Journal》2005,13(1):1-6

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New constraints on seismicity in the Wellington region of New Zealand from relocated earthquake hypocentres   总被引：1，自引：0，他引：1  

Wen-xuan Du  Clifford H. Thurber  Martin Reyners  Donna Eberhart-Phillips  Haijiang Zhang 《Geophysical Journal International》2004,158(3):1088-1102

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