Fitting growth models to length frequency data     

Laslett  Geoff M.; Eveson  J. Paige; Polacheck  Tom 《ICES Journal of Marine Science》2004,61(2):218-230

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The Nolans Bore rare-earth element-phosphorus-uranium mineral system: geology,origin and post-depositional modifications     

David L. Huston  Roland Maas  Andrew Cross  Kelvin J. Hussey  Terrence P. Mernagh  Geoff Fraser  David C. Champion 《Mineralium Deposita》2016,51(6):797-822

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Assessing the impact of land use change on hydrology by ensemble modelling (LUCHEM) II: Ensemble combinations and predictions   总被引：1，自引：0，他引：1  

Neil R. Viney  H. Bormann  L. Breuer  A. Bronstert  B.F.W. Croke  H. Frede  T. Gräff  L. Hubrechts  J.A. Huisman  A.J. Jakeman  G.W. Kite  J. Lanini  G. Leavesley  D.P. Lettenmaier  G. Lindström  J. Seibert  M. Sivapalan  P. Willems 《Advances in water resources》2009

This paper reports on a project to compare predictions from a range of catchment models applied to a mesoscale river basin in central Germany and to assess various ensemble predictions of catchment streamflow. The models encompass a large range in inherent complexity and input requirements. In approximate order of decreasing complexity, they are DHSVM, MIKE-SHE, TOPLATS, WASIM-ETH, SWAT, PRMS, SLURP, HBV, LASCAM and IHACRES. The models are calibrated twice using different sets of input data. The two predictions from each model are then combined by simple averaging to produce a single-model ensemble. The 10 resulting single-model ensembles are combined in various ways to produce multi-model ensemble predictions. Both the single-model ensembles and the multi-model ensembles are shown to give predictions that are generally superior to those of their respective constituent models, both during a 7-year calibration period and a 9-year validation period. This occurs despite a considerable disparity in performance of the individual models. Even the weakest of models is shown to contribute useful information to the ensembles they are part of. The best model combination methods are a trimmed mean (constructed using the central four or six predictions each day) and a weighted mean ensemble (with weights calculated from calibration performance) that places relatively large weights on the better performing models. Conditional ensembles, in which separate model weights are used in different system states (e.g. summer and winter, high and low flows) generally yield little improvement over the weighted mean ensemble. However a conditional ensemble that discriminates between rising and receding flows shows moderate improvement. An analysis of ensemble predictions shows that the best ensembles are not necessarily those containing the best individual models. Conversely, it appears that some models that predict well individually do not necessarily combine well with other models in multi-model ensembles. The reasons behind these observations may relate to the effects of the weighting schemes, non-stationarity of the climate series and possible cross-correlations between models.  相似文献   

Maintaining excellence with speedier article publication and a broader scope     

Philippe C. Baveye  Laurent Charlet  Konstantine P. Georgakakos  Geoff Syme 《Journal of Hydrology》2008,348(1-2):v-vi

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Pesticides in Sediments From Queensland Irrigation Channels and Drains     

Jochen F. Müller  Sabine Duquesne  Jack Ng  Glen R. Shaw  K Krrishnamohan  K Manonmanii  Mary Hodge  Geoff K. Eaglesham 《Marine pollution bulletin》2000,41(7-12):294-301

Pesticide concentration in sediment from irrigation areas can provide information required to assess exposure and fate of these chemicals in freshwater ecosystems and their likely impacts to the marine environment. In this study, 103 sediment samples collected from irrigation channels and drains in 11 agricultural areas of Queensland were analysed for a series of past and presently used pesticides including various organochlorines, synthetic pyrethroids, benzoyl ureas, triazines and organophosphates. The most often detected compounds were endosulphans (, β and/or endosulphan sulphate) which were detectable in 78 of the 103 samples and levels ranged from below the limit of quantification (0.1 ng g⁻¹ dw) up to 840 ng g⁻¹ dw. DDT and its metabolites were the second most often detected pesticide investigated (74 of the 103 samples) with concentrations up to 240 ng g⁻¹ dw of ∑DDTs. Mean ∑endosulphan and ∑DDT concentrations were 1–2 orders of magnitude higher in sediments from the irrigation areas which are dominated by cotton cultivation compared to those which are dominated by sugarcane cultivation. In contrast to these insecticides, the herbicides diuron, atrazine and ametryn were the compounds which were most often detected in sediments from irrigation drains in sugarcane areas with maximum concentrations in areas of 120, 70 and 130 ng g⁻¹ dw, respectively. In particular during flood events, when light is limiting, transport of these photosynthesis inhibiting herbicides from the sugarcane cultivation areas to the marine environment may result in additional stress of marine plants.  相似文献   

Mapping groundwater‐dependent ecosystems using remote sensing measures of vegetation and moisture dynamics          下载免费PDF全文

Olga V. Barron  Irina Emelyanova  Thomas G. Van Niel  Daniel Pollock  Geoff Hodgson 《水文研究》2014,28(2):372-385

Protection of groundwater‐dependent ecosystems (GDEs) is an important criterion in sustainable groundwater management, particularly when human water consumption is in competition with environmental water demands; however, the delineation of GDEs is commonly a challenging task. The Groundwater‐dependent Ecosystem Mapping (GEM) method proposed here is based on interpretation of the land surface response to the drying process derived from combined changes in two multispectral indices, the Normalised Difference Vegetation Index and the Normalised Difference Wetness Index, both derived from Landsat imagery. The GEM method predicts three land cover classes used for delineation of potential GDEs: vegetation with permanent access to groundwater; vegetation with diminishing access to groundwater; and water bodies that can persist through a prolonged dry period. The method was applied to a study site in the Ellen Brook region of Western Australia, where a number of GDEs associated with localised groundwater, diffuse discharge zones, and riparian vegetation were known. The estimated accuracy of the method indicated a good agreement between the predicted and known GDEs; Producer's accuracy was calculated as up to 91% for some areas. The method is most applicable for mapping GDEs in regions with a distinct drying period. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Projected risks to groundwater‐dependent terrestrial vegetation caused by changing climate and groundwater abstraction in the Central Perth Basin,Western Australia          下载免费PDF全文

Olga Barron  Ray Froend  Geoff Hodgson  Riasat Ali  Warrick Dawes  Phil Davies  Don McFarlane 《水文研究》2014,28(22):5513-5529

The effect of potential climate change on groundwater‐dependent vegetation largely depends on the nature of the climate change (drying or wetting) and the level of current ecosystem dependence on groundwater resources. In south‐western Australia, climate projections suggest a high likelihood of a warmer and drier climate. The paper examines the potential environmental impacts by 2030 at the regional scale on groundwater‐dependent terrestrial vegetation (GDTV) adapted to various watertable depths, on the basis of the combined consideration of groundwater modelling results and the framework for GDTV risk assessment. The methodology was tested for the historical period from 1984 to 2007, allowing validation of the groundwater model results' applicability to such an assessment. Climate change effects on GDTV were evaluated using nine global climate models under three greenhouse gas emission scenarios by applying the climate projections to groundwater models. It was estimated that under dry climate scenarios, GDTV is likely to be under high and severe risk over more than 20% of its current habitat area. The risk is also likely to be higher under an increase in groundwater abstraction above current volumes. The significance of climate change risk varied across the region, depending on both the intensity of the change in water regime and the sensitivity of the GDTV to such change. Greater effects were projected for terrestrial vegetation dependent on deeper groundwater (6–10 m). Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Probabilistic evaluation of soil–foundation–structure interaction effects on seismic structural response     

Masoud Moghaddasi  Misko Cubrinovski  J. Geoff Chase  Stefano Pampanin  Athol Carr 《地震工程与结构动力学》2011,40(2):135-154

Complex seismic behaviour of soil–foundation–structure (SFS) systems together with uncertainties in system parameters and variability in earthquake ground motions result in a significant debate over the effects of soil–foundation–structure interaction (SFSI) on structural response. The aim of this study is to evaluate the influence of foundation flexibility on the structural seismic response by considering the variability in the system and uncertainties in the ground motion characteristics through comprehensive numerical simulations. An established rheological soil‐shallow foundation–structure model with equivalent linear soil behaviour and nonlinear behaviour of the superstructure has been used. A large number of models incorporating wide range of soil, foundation and structural parameters were generated using a robust Monte‐Carlo simulation. In total, 4.08 million time‐history analyses were performed over the adopted models using an ensemble of 40 earthquake ground motions as seismic input. The results of the analyses are used to rigorously quantify the effects of foundation flexibility on the structural distortion and total displacement of the superstructure through comparisons between the responses of SFS models and corresponding fixed‐base (FB) models. The effects of predominant period of the FB system, linear vs nonlinear modelling of the superstructure, type of nonlinear model used and key system parameters are quantified in terms of different probability levels for SFSI effects to cause an increase in the structural response and the level of amplification of the response in such cases. The results clearly illustrate the risk of underestimating the structural response associated with simplified approaches in which SFSI and nonlinear effects are ignored. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

The volume and shape of the 1991–1993 lava flow field at Mount Etna, Sicily     

Nicki F. Stevens  John B. Murray  Geoff Wadge 《Bulletin of Volcanology》1997,58(6):449-454

 The 1991–1993 lava flow is the most voluminous flow erupted at Mount Etna, Sicily, in over 300 years. Estimates of the volume obtained by various methods range from 205×10⁶ m³ (Tanguy 1996) to over 500×10⁶ m³ (Barberi et al. 1993). This paper describes the results of an electronic distance measurement (EDM)-based field survey of the upper surface of the 1991–1993 flow field undertaken in 1995. The results were digitised, interpolated and converted into a digital elevation model and then compared with a pre-eruption digital elevation model, constructed from a 1 : 25 000 contour map of the area, based on 1989 aerial photographs. Our measurements are the most accurate to date and show that the 1991–1993 lava flow occupies a volume of 231±29×10⁶ m³. Received: 20 July 1996 / Accepted: 5 November 1996  相似文献   

A scenario-based risk framework for determining consequences of different failure modes of earth dams     

Cleary  Paul W.  Prakash  Mahesh  Mead  Stuart  Lemiale  Vincent  Robinson  Geoff K.  Ye  Fanghong  Ouyang  Sida  Tang  Xinming 《Natural Hazards》2015,75(2):1489-1530

Natural Hazards - Failure modes for earth dams are extensively reviewed and analysed using a three-pronged approach including a literature review, physical observations of a representative earth...  相似文献