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351.
This study challenges the ‘National Park’ as the appropriate management model for the Peixe Lagoon area in southern Brazil through an investigation of local fisherfolk livelihoods and traditional ecological knowledge. We argue that top-down management policies implemented through a non-participatory process, which have resulted in conflict between government officials and fisherfolk, disregarded the fisherfolk’s cultural practices and particular knowledge, thereby violating their rights as traditional people. Multiple suggestions are provided to achieve environmental conservation schemes without compromising the local traditional fishing livelihoods. 相似文献
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354.
Francesca Bruno Daniela Cocchi Fedele Greco Elena Scardovi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(5):1235-1245
Rainfall is a phenomenon difficult to model and predict, for the strong spatial and temporal heterogeneity and the presence of many zero values. We deal with hourly rainfall data provided by rain gauges, sparsely distributed on the ground, and radar data available on a fine grid of pixels. Radar data overcome the problem of sparseness of the rain gauge network, but are not reliable for the assessment of rain amounts. In this work we investigate how to calibrate radar measurements via rain gauge data and make spatial predictions for hourly rainfall, by means of Monte Carlo Markov Chain algorithms in a Bayesian hierarchical framework. We use zero-inflated distributions for taking zero-measurements into account. Several models are compared both in terms of data fitting and predictive performances on a set of validation sites. Finally, rainfall fields are reconstructed and standard error estimates at each prediction site are shown via easy-to-read spatial maps. 相似文献
355.
Mauro Mele Silvia Inzoli Mauro Giudici Riccardo Bersezio 《Geophysical Prospecting》2014,62(3):631-645
Electrical conductivity of alluvial sediments depends on litho‐textural properties, fluid saturation and porewater conductivity. Therefore, for hydrostratigraphic applications of direct current resistivity methods in porous sedimentary aquifers, it can be useful to characterize the prevailing mechanisms of electrical conduction (electrolytic or shale conduction) according to the litho‐textural properties and to the porewater characteristics. An experimental device and a measurement protocol were developed and applied to collect data on eight samples of alluvial sediments from the Po plain (Northern Italy), characterized by different grain‐size distribution, and fully saturated with porewater of variable conductivity. The bulk electrical conductivities obtained with the laboratory tests were interpreted with a classical two‐component model, which requires the identification of the intrinsic conductivity of clay particles and the effective porosity for each sample, and with a three‐component model. The latter is based on the two endmember mechanisms, surface and electrolytic conduction, but takes into account also the interaction between dissolved ions in the pores and the fluid‐grain interface. The experimental data and their interpretation with the phenomenological models show that the volumetric ratio between coarse and fine grains is a simple but effective parameter to determine the electrical behaviour of clastic hydrofacies at the scale of the representative elementary volume. 相似文献
356.
我国温带荒漠生物土壤结皮孔隙结构分布特征 总被引:4,自引:2,他引:2
对原状生物土壤结皮孔隙结构、孔隙率及其垂直连通性进行室内微观扫描与计算机断层摄影成像分析。结果表明,生物土壤结皮团聚体特征明显,其孔隙率的增大主要是由大孔隙数量的增加而形成,同时,土壤孔隙连通性也随大孔隙数量的增加而增大,生物土壤结皮的发育导致表层土壤具有明显的极其复杂的土壤结构演化特征。 相似文献
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358.
Pierfrancesco Dellino Fabio Dioguardi Domenico M. Doronzo Daniela Mele 《Sedimentology》2019,66(1):129-145
Large‐scale experiments generating ground‐hugging multiphase flows were carried out with the aim of modelling the rate of sedimentation, of pyroclastic density currents. The current was initiated by the impact on the ground of a dense gas‐particle fountain issuing from a vertical conduit. On impact, a thick massive deposit was formed. The grain size of the massive deposit was almost identical to that of the mixture feeding the fountain, suggesting that similar layers formed at the impact of a natural volcanic fountain should be representative of the parent grain‐size distribution of the eruption. The flow evolved laterally into a turbulent suspension current that sedimented a thin, tractive layer. A good correlation was found between the ratio of transported/sedimented load and the normalized Rouse number of the turbulent current. A model of the sedimentation rate was developed, which shows a relationship between grain size and flow runout. A current fed with coarser particles has a higher sedimentation rate, a larger grain‐size selectivity and runs shorter than a current fed with finer particles. Application of the model to pyroclastic deposits of Vesuvius and Campi Flegrei of Southern Italy resulted in sedimentation rates falling inside the range of experiments and allowed definition of the duration of pyroclastic density currents which add important information on the hazard of such dangerous flows. The model could possibly be extended, in the future, to other geological density currents as, for example, turbidity currents. 相似文献
359.
R. Sulpizio R. Cioni M. A. Di Vito D. Mele R. Bonasia P. Dellino 《Bulletin of Volcanology》2010,72(5):539-558
The stratigraphic succession of the Pomici di Avellino Plinian eruption from Somma-Vesuvius has been studied through field
and laboratory data in order to reconstruct the eruption dynamics. This eruption is particularly important in the Somma-Vesuvius
eruptive history because (1) its vent was offset with respect to the present day Vesuvius cone; (2) it was characterised by
a distinct opening phase; (3) breccia-like very proximal fall deposits are preserved close to the vent and (4) the pyroclastic
density currents generated during the final phreatomagmatic phase are among the most widespread and voluminous in the entire
history of the volcano. The stratigraphic succession is, here, divided into deposits of three main eruptive phases (opening,
magmatic Plinian and phreatomagmatic), which contain five eruption units. Short-lived sustained columns occurred twice during
the opening phase (Ht of 13 and 21.5 km, respectively) and dispersed thin fall deposits and small pyroclastic density currents onto the volcano
slopes. The magmatic Plinian phase produced the main volume of erupted deposits, emplacing white and grey fall deposits which
were dispersed to the northeast. Peak column heights reached 23 and 31 km during the withdrawal of the white and the grey
magmas, respectively. Only one small pyroclastic density current was emplaced during the main Plinian phase. In contrast,
the final phreatomagmatic phase was characterised by extensive generation of pyroclastic density currents, with fallout deposits
very subordinate and limited to the volcano slopes. Assessed bulk erupted volumes are 21 × 106 m3 for the opening phase, 1.3–1.5 km3 for the main Plinian phase and about 1 km3 for the final phreatomagmatic phase, yielding a total volume of about 2.5 km3. Pumice fragments are porphyritic with sanidine and clinopyroxene as the main mineral phases but also contain peculiar mineral
phases like scapolite, nepheline and garnet. Bulk composition varies from phonolite (white magma) to tephri-phonolite (grey
magma). 相似文献
360.
Petr Pruner Nadja Zupan Hajna Andrej Mihevc Pavel Bosák Otakar Man Petr Schnabl Daniela Venhodová 《Studia Geophysica et Geodaetica》2010,54(1):27-48
Clastic and chemogenic cave sediments were sampled and analyzed from Račiška pečina and Pečina v Borštu caves of southwestern
Slovenia. Samples were subjected to both thermal and alternating field demagnetization; specimens belonging to the same sample
of the same layer produce identical results. Unblocking temperatures of 540 to 560°C on average suggests magnetite as the
principal carrier of magnetization. These directions also pass a reversals test indicating the demagnetization results are
free of secondary overprints and have adequately averaged out paleosecular variation. Normally magnetized clays containing
fauna belonging to the MN17 mammal biozone at a depth of ∼ 4 m in Račiška pecina cave indicate these clays were deposited
at the beginning of the Olduvai subchron (1.95 Ma). Correlation with the Geomagnetic Polarity Time Scale (GPTS) indicates
the base of the speleothems in Račiška pečina terminate in the upper part of subchron C2An.3n with numerous breaks in deposition,
lasting up to 250 ka and more. Therefore rates of speleothem growth cannot be calculated. Fold tests on dome-like stalagmites
of differing sizes and ages (Pleistocene, Pliocene) from the two caves indicate the domelike structures are primary. 相似文献