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An approach for quantifying geomorphological impacts for EIA of transportation infrastructures: a case study in northern Spain 总被引：2，自引：0，他引：2
Jaime Bonachea Viola Maria Bruschi Juan Remondo Alberto Gonzlez-Díez Luis Salas Jurjen Bertens Antonio Cendrero Csar Otero Cecilia Giusti Andrea Fabbri Jos Ramn Gonzlez-Lastra Jos María Aramburu 《Geomorphology》2005,66(1-4):95
A methodological proposal for the assessment of impacts due to linear infrastructures such as motorways, railways, etc. is presented. The approach proposed includes a series of specific issues to be addressed for each geomorphological feature analysed—both ‘static’ and ‘dynamic’—as well as a series of steps to be followed in the process.Geomorphic characteristics potentially affected were initially identified on the basis of a conceptual activities/impacts model that helps to single out geomorphic impacts related to environmental concerns for the area. The following issues were addressed for each individual impact: nature of potential effects; indicators that can be used to measure impacts; criteria of ‘geomorphologic performance’; procedure for measurement/prediction of changes; translation of geomorphologic impacts into significant terms from the viewpoint of human concerns; possible mitigation and/or compensation measures.The procedure has been applied to a case study corresponding to a new motorway in the Basque Country, northern Spain. Geomorphological impacts considered in this analysis included: (1) consumable resources; (2) sites of geomorphological interest; (3) land units with high potential for use, high productivity or value for conservation; (4) visual landscape; (5) slope instability processes. The procedure has been designed for implementation in a Geographic Information System (GIS) environment. Details are given on the application of the method to each individual impact analysed and results are presented in both numerical and map form.Impacts assessed were initially expressed by means of heterogeneous magnitudes, depending on the geomorphological feature considered. Those geomorphological impacts were then translated into significant terms and homogeneous magnitudes. Integration was carried out on the basis of impact values thus obtained. Final integrated results were also expressed in numerical and map form.The method proposed enables comparison of alternatives as well as ‘prediction’ and assessment of impacts in terms directly related to geomorphic characteristics. It also facilitates the expression of those impacts in terms that allow integration with other types of environmental impacts. 相似文献
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Three main diffusion-based models are currently used to study grain-size distributions. In this paper, two of these approaches — perfect sorting and imperfect sorting — are compared in a parameter study. First, the numerical solution of the imperfect-sorting model is extensively discussed, and numerical tests are performed. Then, the two sedimentation models are compared for a basin under varying conditions. For some of the imposed variations, predictions of both models differ markedly due to the different approach. The position of the gravel front in the perfect sorting model depends on gravel input and proximal accommodation space. The position of grain-size boundaries in the imperfect-sorting model is strongly controlled by gravel input, the position of the basin axis and the difference in diffusivities. As a result, those two models may predict gravel progradation for different situations. Both models suggest that gravel progradation should always be coupled with sedimentation rates in order to suggest an explanation of gravel progradation observed in the geological record. Simulations with the imperfect sorting model show that this criterion may also fail, showing that a unique interpretation of gravel progradation may be impossible. 相似文献
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Jurjen A. Battjes 《Coastal Engineering》1982,6(1):47-57
A case study is presented of the effects of tidal currents on the wave heights in a tidal entrance, viz. the Oosterschelde estuary in the Netherlands. Observations of the variation of wave height with tidal elevation during a tidal cycle show a hysteresis. In order to investigate this phenomenon, calculations have been made of wave height changes due to refraction by non-uniform depths and currents, including the occurrence of wave breaking on the shoals in the estuary delta. The calculated wave height variation with tide elevation is found to have a current-induced hysteresis similar to the observed one. 相似文献
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Influence of atmospheric inputs on the iron distribution in the subtropical North-East Atlantic Ocean 总被引：3，自引：0，他引：3
Graldine Sarthou Alex R. Baker Jurjen Kramer Patrick Laan Agathe Laës Simon Ussher Eric P. Achterberg Hein J.W. de Baar Klaas R. Timmermans Stphane Blain 《Marine Chemistry》2007,104(3-4):186-202
Aerosol (soluble and total) iron and water-column dissolved (DFe, < 0.2 μm) and total dissolvable (TDFe, unfiltered) iron concentrations were determined in the Canary Basin and along a transect towards the Strait of Gibraltar, in order to sample across the Saharan dust plume. Cumulative dust deposition fluxes estimated from direct aerosol sampling during our one-month cruise are representative of the estimated deposition fluxes based on near surface water dissolved aluminium concentrations measured on board. Iron inventories in near surface waters combined with flux estimates confirmed the relatively short residence time of DFe in waters influenced by the Saharan dust plume (6–14 months). Enhanced near surface water concentrations of DFe (5.90–6.99 nM) were observed at the Strait of Gibraltar mainly due to inputs from metal-rich rivers. In the Canary Basin and the transect towards Gibraltar, DFe concentrations (0.07–0.76 nM) were typical of concentrations observed in the surface North Atlantic Waters, with the highest concentrations associated with higher atmospheric inputs in the Canary Basin. Depth profiles showed that DFe and TDFe were influenced by atmospheric inputs in this area with an accumulation of aeolian Fe in the surface waters. The sub-surface minimum of both DFe and TDFe suggests that a simple partitioning between dissolved and particulate Fe is not obvious there and that export may occur for both phases. At depths of around 1000–1300 m, both regeneration and Meddies may explain the observed maximum. Our data suggest that, in deep waters, higher particle concentrations likely due to dust storms may increase the scavenging flux and thus decrease DFe concentrations in deep waters. 相似文献
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