Indigenous Livelihoods and Art Income: participation,production and returns from woodcarvings in Arnhem Land,north Australia     

Jennifer Koenig  Jon Altman  Anthony D. Griffiths 《The Australian geographer》2011,42(4):351-369

Participation in the Indigenous visual arts sector provides one of few market opportunities for Indigenous Australians resident on remote Aboriginal lands. In this article we examine the economic factors that influence this market engagement as they relate to woodcarving in the Maningrida region of Arnhem Land. In particular, we look at the factors that affect participation, production and monetary returns using scan and focal sampling, resource accounting and sales data from the regional art centre. Artists were engaged in a range of activities of which art production was the prominent means of productive cash income generation. An artist's residence and also their language community were found to influence the amount of sculpture production undertaken, with artists residing on ‘country’ in the hinterland being more engaged in sculpture production than those living in the township of Maningrida. The annual income earned by an artist for carving was highly variable and a large proportion of woodcarvers also earned income from producing artwork in other media. Capital costs were relatively minor, with travel costs and labour the main input into carving production. Based on the average return for a single woodcarving, $160, we estimate the average hourly return to artists as between $12 and $14. Whilst this figure is relatively low and comparable to the Australian award wage for unskilled labour, the income earned from arts production makes an important contribution to people's livelihoods.  相似文献   

Limitations of Current Approaches for Predicting Groundwater Vulnerability from PFAS Contamination in the Vadose Zone     

Matt Rovero  Diana Cutt  Rachel Griffiths  Urszula Filipowicz  Katherine Mishkin  Brad White  Sandra Goodrow  Richard T. Wilkin 《Ground Water Monitoring & Remediation》2021,41(4):62-75

Published literature for reported sorption coefficients (K_d) of eight anionic per- and polyfluoroalkyl substances (PFAS) in soil was reviewed. K_d values spanned three to five log units indicating that no single value would be appropriate for use in estimating PFAS impacts to groundwater using existing soil-water partition equations. Regression analysis was used to determine if the soil or solution parameters might be used to predict K_d values. None of the 15 experimental parameters collected could individually explain variability in reported K_d values. Significant associations between K_d and soil calcium and sodium content were found for many of the selected PFAS, suggesting that soil cation content may be critical to PFAS sorption, as previously noted in sources like Higgins and Luthy (2006), while organic carbon content was significant only at elevated levels (>5%). Unexplained discrepancies between the results from studies where PFAS were introduced to soil and desorbed in the laboratory and those that used material from PFAS-impacted sites suggest that laboratory experiments may be overlooking some aspects critical to PFAS sorption. Future studies would benefit from the development and use of standardized analytical methods to improve data quality and the establishment of soil parameters appropriate for collection to produce more complete data sets for predictive analysis.  相似文献   

Probabilistic infinite slope analysis   总被引：1，自引：0，他引：1  

D.V. Griffiths  Jinsong Huang  Gordon A. Fenton 《Computers and Geotechnics》2011

Research activity in the mechanics of landslides has led to renewed interest in the infinite slope equations, and the need for a more general framework for giving insight into the probability of failure of long slopes involving non-homogeneous vertical soil profiles and variable groundwater conditions. This paper describes a methodology in which parameters such as the soil strength, slope geometry and pore pressures, are generated using random field theory. Within the limitations of the infinite slope assumptions, the paper clearly demonstrates the important “seeking out” effect of failure mechanisms in spatially random materials, and how “first order” methods that may not properly account for spatial variability can lead to unconservative estimates of the probability of slope failure.  相似文献   

Analysis of the critical pool level of partially submerged slopes     

Wei Wang  D.V. Griffiths 《国际地质力学数值与分析法杂志》2020,44(3):405-417

Partially submerged c^′ − φ^′ slopes with a horizontal water table exhibit a critical pool level at which the factor of safety becomes a minimum. The phenomenon was first identified using finite element methods, but in this paper, a more thorough analytical investigation is presented. The approach described herein assumes a rigid block sliding with a circular failure mechanism, combined with optimization software to identify the critical circle. The method is initially validated against known slope solutions that assume circular and log-spiral mechanisms and shown to give excellent agreement, especially for flatter slopes. The method is then applied to partially submerged slopes with a focus on the critical pool level. Through detailed investigation of the overturning and restoring moments in the stability analyses, the critical pool level phenomenon is shown to lie in the trade-off between the destabilizing effects of internal pore pressures on soil strength and the stabilizing effect of external hydrostatic water pressures on the slope surface.  相似文献   

Dynamic domain kinematic modelling for predicting interflow over leaky impeding layers     

Menberu Meles Bitew  C. Rhett Jackson  David C. Goodrich  Seth E. Younger  Natalie A. Griffiths  Kellie B. Vaché  Benjamin Rau 《水文研究》2020,34(13):2895-2910

Traditional Boussinesq or kinematic simulations of interflow (i.e., lateral subsurface flow) assume no leakage through the impeding layer and require a no-flow boundary condition at the ridge top. However, recent analyses of many interflow-producing landscapes indicate that leaky impeding layers are common, that most interflow percolates well before reaching the toe slope, and therefore, the downslope contributing length is shorter than the hillslope length. In watersheds characterised by perched interflow over a low conductivity layer through permeable topsoil, interflow with percolation may be modelled with a kinematic wave model using a mobile upslope boundary condition defining the hillslope portion contributing interflow to valleys. Here, we developed and applied a dynamic interflow model to simulate interflow using a downslope travel distance concept such that only the active contributing length is modelled at any time. The model defines a variable active area based on the depth of the perched layer, the topographic slope and the ratio of the hydraulic conductivity of topsoil to that of the impeding layer. It incorporates a two-layer soil moisture accounting water balance analysis, a pedo-transfer function, and percolation and evaporation routines to predict interflow rates in continuous and event-based scenarios. We tested the modelling concept on two sets of data (2-year dataset of rainfall observations for the continuous simulation and a multi-day irrigation experiment for the event simulation) from a 121-m-long open interflow collection trench on an experimental hillslope at the Savannah River Site, South Carolina. The continuous model simulation partially represented the observed interflow hydrograph and perched water depth in the experimental hillslope with correlation coefficients of 0.85 and 0.35, respectively. Model performance improved significantly at event-scale analysis. The modelling approach realistically represents interflow dynamics in hillslopes with leaky impeding layers and can be integrated into catchment-scale hydrology models for more detailed hillslope process modelling.  相似文献   

LunarEX—a proposal to cosmic vision     

A. Smith  I. A. Crawford  R. A. Gowen  A. J. Ball  S. J. Barber  P. Church  A. J. Coates  Y. Gao  A. D. Griffiths  A. Hagermann  K. H. Joy  A. Phipps  W. T. Pike  R. Scott  S. Sheridan  M. Sweeting  D. Talboys  V. Tong  N. Wells  J. Biele  J. Chela-Flores  B. Dabrowski  J. Flannagan  M. Grande  J. Grygorczuk  G. Kargl  O. B. Khavroshkin  G. Klingelhoefer  M. Knapmeyer  W. Marczewski  S. McKenna-Lawlor  L. Richter  D. A. Rothery  K. Seweryn  S. Ulamec  R. Wawrzaszek  M. Wieczorek  I. P. Wright  M. Sims 《Experimental Astronomy》2009,23(3):711-740

While the surface missions to the Moon of the 1970s achieved a great deal, scientifically much was also left unresolved. The recent plethora of lunar missions (flown or proposed) reflects a resurgence in interest in the Moon, not only in its own right, but also as a record of the early solar system including the formation of the Earth. Results from recent orbiter missions have shown evidence of ice or at least hydrogen within shadowed craters at the lunar poles.  相似文献   

Clay‐coat diversity in marginal marine sediments     

Luke J. Wooldridge  Richard H. Worden  Joshua Griffiths  James E. P. Utley 《Sedimentology》2019,66(3):1118-1138

The specific mineralogy of clay grain coats controls the ability of the coat to inhibit quartz cementation in sandstones during prolonged burial and heating. How and why clay‐coat mineralogy varies across marginal marine systems is poorly understood, even though these eogenetic phenomena strongly influence subsequent mesodiagenesis and reservoir quality. The novel development of the ability to predict the distribution of clay‐coat mineralogy would represent an important development for sandstone reservoir quality prediction. In marginal marine sediments, clay minerals occur as grain‐coats, floccules, mud intraclasts, clay‐rich rock fragments or as dispersed material. However, the relationships between clay mineralogy, the amount of clay, and its distribution is poorly understood. This study focused on the Ravenglass Estuary, UK. The key aim was to develop and apply a novel methodology utilising scanning electron microscope – energy dispersive spectrometry, for the first time, on grain coats in modern sediments, to differentiate the clay‐coat mineral signature from that of the bulk sediment, and reveal the distribution of clay minerals across marginal marine sediments. The study showed that marginal marine sediments principally have their clay mineral assemblage present as clay‐coats on sand grains. These clay‐coats have a mixed clay mineralogy and are spatially heterogeneous across the range of marginal‐marine depositional environments. The study further showed that clay‐coat mineralogy is governed initially by the hydrologically‐controlled segregation of the clay minerals within inner estuarine depositional environments, and subsequently by the selective abrasive removal of specific clay mineral types during reworking and transport into the outer estuary and the marine environment. The highest relative abundance of grain‐coating chlorite was in sand‐flat and tidal‐bar depositional environments. The availability of an analogue data set, and an understanding of the controlling processes of clay‐coat mineralogy, offer crucial steps in building a predictive capability for clay‐coat derived elevated reservoir quality in deeply buried sandstones.  相似文献   

Workshop on Areal Value Estimation     

H. Missan  B. R. Cooper  S. M. el Raba'a  J. C. Griffiths  C. Sweetwood 《Mathematical Geology》1978,10(5):433-439

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A laboratory analog study of the surface morphology of lava flows extruded from point and line sources     

Jonathan H. Fink  Ross W. Griffiths 《Journal of Volcanology and Geothermal Research》1992,54(1-2)

In laboratory experiments designed to model lava flow processes, liquid polyethylene glycol wax is forced through either a small hole or a long narrow slit onto the base of a tank of cold water, where it spreads laterally while cooling and solidifying at its surface. We observe the surface structure of the flow, and its dependence on the flow rate, thermal conditions and basal roughness. In each case, solidification of a crust during spreading gives rise to a number of different surface morphologies, each of which forms under a restricted range of conditions. The dominant morphologies, referred to as “pillows”, “rifts”, transverse folds, and marginal levees, correspond to features observed on natural lava flows. Results for radial spreading over a rough base and for spreading in two directions from the line source over both smooth and rough bases complement those reported earlier for radial spreading of solidifying wax from a point source on a smooth base. Together they indicate a robust dependence of morphology on the distance from the vent at which solid crust begins to form. This distance is, in turn, determined by the extrusion rate, the rheology of the liquid wax (or magma), the reduced gravity, the magnitude of the surface heat flux, and the amount of cooling required to solidify the flow surface. The results also indicate factors influencing the distribution of crust and its deformation, and may provide a means by which observations of surface morphology can be used to place constraints on the emplacement conditions of lava flows.  相似文献   

Variation in the value of mineral resources. Part I. The USA     

J. C. Griffiths  W. D. Menzie 《Mathematical Geosciences》1975,7(5-6):447-472

The value of mineral resources produced in the USA during the 93 years, 1880–1972, deflated to 1967=100, totals 921 billions of dollars; this yields a value of $303,289 per mi² for the conterminous 48 states. Alaska has aggregated some 4160 millions of dollars during the same period, an average yield of some 7107 deflated dollars per mi². If we assume Alaska will achieve the average level of the “lower 48,”the potential value of its mineral resources is 178 billions of deflated 1967 dollars. Fuels account for about two-thirds of this value followed by about 20 percent for each of the aggregates, nonmetals and metals. The deflated dollar value of these four aggregate figures, fuels, nonmetals, metals, and total, during the period 1880–1972 are four time series and the economic processes which produced these series may be modelled through Box-Jenkins procedures. The value of fuels has steadily increased through the period, except for the depression years of the 1930s; this series may be represented as a multiplicative seasonal ARIMA(1,1,0)(1,0,1) model with periods at 4 and 3 yr for the autoregressive (AR) and moving average (MA) terms. Forecasts for 1973 to 1980, using the model, show the value of fuels produced to be about 20 billions of dollars per annum. The value of nonmetals also increased throughout the period except for a somewhat larger drop during the depression years of the 1930s. A multiplicative seasonal ARMA(1,0,0)(1,0,1) model with period at 7 yr for both the AR (autoregressive) and MA (moving average) terms appears to best reflect this series; the forecasts with this model fluctuate around their present annual value of some 6 billions of dollars. The value of metals behaves less consistently; it was much more strongly affected by the Great Depression and its subsequent growth is slower and less consistent than those of the fuels and nonmetals. It is appropriately represented by a multiplicative seasonal ARMA(1,0,0)(0,0,2) model with moving average (MA) periods at 6 and 11 yr respectively. Forecasts with this model show a decline in value for years beyond 1972; the large residual “error” \((\hat \sigma _e = 0.0925)\) , which is about twice as large as the equivalent errors for the value of fuels and nonmetals ( \(\hat \sigma _e = 0.0408\) and 0.0532, respectively), makes this forecast less firm. The total value of mineral resources is composed of all three series and, because fuels account for two-thirds of the total value, the two series closely resemble each other. The total value is not a simple aggregate of the three series; it is appropriately fitted by a multiplicative seasonal IMA(0,1,0)(0,0,2) model with periods at 7 and 11 yr (and error \(\hat \sigma _e = 0.0423\) ). Forecasts using this model imply that the total value of mineral resources produced will be over 30 billions of dollars per annum through 1980.  相似文献