987 resultados para alluvial fan


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This study assesses the value of restoring forested wetlands via the U.S. government's Wetlands Reserve Program (WRP) in the Mississippi Alluvial Valley by quantifying and monetizing ecosystem services. The three focal services are greenhouse gas (GHG) mitigation, nitrogen mitigation, and waterfowl recreation. Site- and region-level measurements of these ecosystem services are combined with process models to quantify their production on agricultural land, which serves as the baseline, and on restored wetlands. We adjust and transform these measures into per-hectare, valuation-ready units and monetize them with prices from emerging ecosystem markets and the environmental economics literature. By valuing three of the many ecosystem services produced, we generate lower bound estimates for the total ecosystem value of the wetlands restoration. Social welfare value is found to be between $1435 and $1486/ha/year, with GHG mitigation valued in the range of $171 to $222, nitrogen mitigation at $1248, and waterfowl recreation at $16. Limited to existing markets, the estimate for annual market value is merely $70/ha, but when fully accounting for potential markets, this estimate rises to $1035/ha. The estimated social value surpasses the public expenditure or social cost of wetlands restoration in only 1 year, indicating that the return on public investment is very attractive for the WRP. Moreover, the potential market value is substantially greater than landowner opportunity costs, showing that payments to private landowners to restore wetlands could also be profitable for individual landowners. © 2009 Elsevier B.V.

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By the British "East Design Alliance" (West East Design Group) was launched, entitled "Sichuan Express" (Delivery to Sichuan) earthquake relief concept design exhibition in September 2008 from 1 to 5 at the Alan Baxter gallery...

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In the past 15 years in the UK, the state has acquired powers, which mark a qualitative shift in its relationship to higher education. Since the introduction and implementation of the Further and Higher Education Act 1992, the Teaching and Higher Education Act 1998 and the Higher Education Act 2004, a whole raft of changes have occurred which include the following: Widening participation; the development of interdisciplinary, experiential and workplace-based learning focused on a theory-practice dialogue; quality assurance; and new funding models which encompass public and private partnerships. The transformation of higher education can be placed in the context of New Labour’s overall strategies for overarching reform of public services, as set out in the Prime Minister’s Strategy Unit’s discussion paper The UK Government’s Approach to Public Service Reform (2006). An optimistic view of changes to higher education is that they simultaneously obey democratic and economic imperatives. There is an avowed commitment through the widening participation agenda to social inclusion and citizenship, and to providing the changing skills base necessary for the global economy. A more cynical view is that, when put under critical scrutiny, as well as being emancipatory, in some senses these changes can be seen to mobilise regulatory and disciplinary practices. This paper reflects on what kinds of teaching and learning are promoted by the new relationship between the state and the university. It argues that, whilst governmental directives for innovations and transformations in teaching and learning allegedly empower students and put their interests at the centre, reforms can also be seen to consist of supervisory and controlling mechanisms with regard both to our own practices as teachers and the knowledge/ learning we provide for the students.

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The formation of lamellae in soils is not clearly understood. The objectives of this study are to examine the microscopical characteristics of selected well developed lamellae inorder to identify the major processes involved in their formation at the Big Pine Tree Archaeological site on the Savannah River, South Carolina. Well developed lamellae have formed in a fine sandy alluvial soil that is about 11,000 to 12,000 years old. In the field, these lamellae are observed as 1 to 4.2 cm thick horizontal layers having a smooth upper and a wavy, sometimes irregular, lower boundary with adjacent interlamellae horizons. Soil thin sections reveal denser accumulations of brown fine silt and clay coatings in the upper and lower sections of the lamellae. The center of the lamellae has mainly orange highly oriented discontinuous clay coatings bridging quartz grains and some silt accumulations. Although, horizontal layering of denser areas (accumulations of fine silt and clay coatings) is also observed in the middle of the lamellae. The interlamellae horizons are mainly loose quartz grains. Low total carbon values (

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Variation of the bypass nozzle exit area enables optimization of the turbofan engine operating cycle over a wider range of operational conditions resulting in improved thrust and/or fuel consumption. Two mechanisms for varying the nozzle area have been investigated. The first uses an array of chevrons which when closed, form a full body of revolution and when warped/curved, increase the exit area while forming a serrated trailing edge. The second technique incorporates an axially translating section of the nacelle shroud and uses the change in the nozzle boat-tail radial location with the axial location as a means to vary the nozzle exit area. To analyse the effects on a typical rotor/stator stage, computational fluid dynamics simulations of the NASA Rotor 67, Stator 67A stage integrated into a custom-built nacelle were performed. Nozzles with 8, 12, and 16 chevrons were simulated to evaluate the impact of the variation in geometry upon the nacelle wake and local forces. Gross thrust of the nacelle and the turbulent kinetic energy (TKE) variation through the wake is compared. The chevron nozzle attains a nearly 2 per cent maximum thrust improvement over the translating nozzle technique. The chevron nozzle also has significantly lower (nearly 8 per cent) peak TKE levels in the jet plume.

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We compare lake and alluvial stratigraphy along a frame connecting the southern Alpine foothills and the Adriatic Sea, with the aim of matching the effects of Alpine glaciation and sea-level changes on sedimentation during the last glacial cycle. The palynostratigraphy of Lake Fimon provided proxies for regional vegetation and climate change and was coupled with sediment petrography, loss on ignition and magnetic susceptibility, disentangling alluvial phases from fluvioglacial activity related to culminations of the southeastern Alpine glaciers. The Fimon area was not reached by alluvial fans during the penultimate glacial maximum, nor by the sea transgression during the last interglacial, but a closed lake soon developed at the Eemian onset due to enhanced rainfall. Sea-level fall at glacial inception triggered the entrenchment of the drainage network in the plain reaching the outer Fimon Basin. Slow aggradation, but no sign of fluvioglacial activity, lasted to 38.2 +/- 1.45 cal. ka BP, when a major forest withdrawal took place, coeval to the spread of alluvial fans. By 27.5 perpendicular to 0.5 cal. ka BP the Fimon Basin was dammed by the Brenta outwash system. The main step of of forest recovery commenced at around (15.8) cal. ka BP, when apex trenching of the outwash fans was triggered by the glacier's decay. Copyright (C) 2011 John Wiley & Sons, Ltd.

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To assess the efficiency of different agro-environmental strategies used to reduce groundwater pollution by nitrates, transport modelling in soils and groundwater has been carried out on two withdrawal areas in an alluvial plain. In a first time, the agro-environmental model AgriFlux allowed the simulation of water and nitrates fluxes flowing to groundwater. This model was calibrated for each agro-pedological unit of the studied territory. In a second time, the application of the hydrogeological model MODFLOW-MT3D allowed the simulation of nitrate transport in groundwater for the 1980-2004 period. This soil-groundwater coupled modelling has shown that soil nature is the first factor that conditions the vulnerability to nitrates. Thus, nitrate leaching occurs preferentially under sandy soils. Efficiency of different agro-environmental operations for groundwater quality recovery was quantified. The best results are obtained by combination of (1) grassland re-installation on sandy agricultural lots located in near well protection perimeter and (2) fertilization reduction on sandy agricultural lots located in the well alimentation area upstream the near protection perimeter. On other soils, the effect of grassland on groundwater quality improvement is more limited. Nevertheless, the control of nitrate fertilisation remains essential and is justified in both near and far well protection perimeters. Modelling thus allows optimising and priorizing agro-environmental actions in alluvial agricultural zones. [Comte J.-C., Banton O., Kockmann F., Villard A., Creuzot G. (2006), Assessment of groundwater quality recovery strategies using nitrate transport modelling. Application to the Saône alluvial formations (Tournus, Saône-et-Loire), Ingénieries Eau-Agriculture-Territoires, 45, 15-28]

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In the last half of the nineteenth century, the folding fan was phenomenally popular in France. The accessory was a ubiquitous component of women’s dress, yet it also attracted the attention of some prominent collectors and Orientalists as well as acquiring an importance in the art and literature of the period. In many plastic works and literary texts devoted to it, the fan retains a link with femininity, and particularly with feminine sexuality, even as its identity as an art object is emphasized. Octave Uzanne’s L’Éventail (1882), a self-professed literary history of the fan, exemplifies this dualistic treatment as it presents the fan both as a titillating intimate companion of women and as a literary and (although to a lesser extent) art historical subject. This article focuses on Uzanne’s treatment of the fan’s early history in the Far and Middle East. By comparing his text with other contemporary histories of the fan, it demonstrates that the “history” of the accessory may be more accurately described as a mythology.

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Knowledge of the spatial distribution of hydraulic conductivity (K) within an aquifer is critical for reliable predictions of solute transport and the development of effective groundwater management and/or remediation strategies. While core analyses and hydraulic logging can provide highly detailed information, such information is inherently localized around boreholes that tend to be sparsely distributed throughout the aquifer volume. Conversely, larger-scale hydraulic experiments like pumping and tracer tests provide relatively low-resolution estimates of K in the investigated subsurface region. As a result, traditional hydrogeological measurement techniques contain a gap in terms of spatial resolution and coverage, and they are often alone inadequate for characterizing heterogeneous aquifers. Geophysical methods have the potential to bridge this gap. The recent increased interest in the application of geophysical methods to hydrogeological problems is clearly evidenced by the formation and rapid growth of the domain of hydrogeophysics over the past decade (e.g., Rubin and Hubbard, 2005).

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Cat. imp., liv. 125, f. 31.Par le P. Aleni (1582-1649). Préfaces de Yang Ting jun (1623), de He Yi yuan (1626). Postface de Xiong Shi qi. Gravé par la mission du Fu jian, à la salle Qin yi, sans date.