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91.
Mary Gleason Scott McCreary Melissa Miller-Henson John Ugoretz Evan Fox Matt Merrifield Will McClintock Paulo Serpa Kathryn Hoffman 《Ocean & Coastal Management》2010,53(2):52-68
The planning process for California's Marine Life Protection Act in north central California represents a case study in the design of a regional component of a statewide network of marine protected areas (MPAs) for improved ecosystem protection. We describe enabling factors, such as a legislative mandate, political will, and adequate capacity and funding that fostered a successful planning process. We identify strategic principles that guided the design of a transparent public planning process that delivered regional MPA network proposals, which both met science guidelines and achieved a high level of support among stakeholders. We also describe key decision support elements (spatial data, planning tools, and scientific evaluation) that were essential for designing, evaluating, and refining alternative MPA network proposals and for informing decision-makers. 相似文献
92.
This paper aims to contribute to understanding the importance of four factors on the determination of sustainable yields: (i) aquifer properties; (ii) temporal distribution of recharge; (iii) temporal distribution of groundwater pumping; and (iv) spatial distribution of pumping wells. It is important to comprehend how the present‐day and future vulnerability of groundwater systems to pumping activities depend on these critical factors and what the risks are of considering sustainable yield as a fixed percentage of mean annual recharge (MAR). A numerical model of the Querença–Silves aquifer in Portugal is used to develop hypothetical scenarios with which these factors are studied. Results demonstrate the aquifer properties, particularly the storage coefficient, have an important role in determining the resilience of an aquifer and therefore to which degree it is dependent on the spatial and temporal distribution of abstraction and recharge, as well as the occurrence of extreme events. Sustainable yields are determined for the developed scenarios based on specific criteria rather than a fraction of MAR. Under simplified current recharge and abstraction conditions, the sustainable yield was determined at approximately 73% of MAR or 76 million m3. When considering a concentration of rainfall in time, as predicted by climate scenarios for the region, sustainable yield could drop to ca 70% of MAR. However, a more even distribution of pumping volumes throughout the year could increase this value. The location of the pumping wells is seen to affect the distribution of hydraulic heads in the aquifer, albeit without significant changes in sustainable yield. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
93.
de Souza Tennison Freire Pasqual Rodrigo Paulo Strano 《Geotechnical and Geological Engineering》2021,39(5):3981-3993
Geotechnical and Geological Engineering - This article presents a method to estimate dynamic compaction crater depth using empirical equations. As main reference, three physical model studies that... 相似文献
94.
Using spectra taken with NIRSPEC (Near Infrared Spectrometer) and adaptive optics on the Keck II telescope, we resolved the latitudinal variation of the 3ν2 band of CH3D at 1.56 μm. As CH3D is less abundant than CH4 by a factor of 50±10×10-5, these CH3D lines do not saturate in Titan’s atmosphere, and are well characterized by laboratory measurements. Thus they do not suffer from the large uncertainties of the CH4 lines that are weak enough to be unsaturated in Titan. Our measurements of the methane abundance are confined to the latitude range of 32°S-18°N and longitudes sampled by a 0.04″ slit centered at ∼195°W. The methane abundance below 10 km is constant to within 20% in the tropical atmosphere sampled by our observations, consistent with the low surface insolation and lack of surface methane [Griffith, C.A., McKay, C.P., Ferri, F., 2008. Astrophys. J. 687, L41-L44]. 相似文献
95.
Paulo Cesar Fernandes-da-Silva Ricardo Vedovello Claudio Jose Ferreira John Canning Cripps Maria Jose Brollo Amelia Joao Fernandes 《Environmental Earth Sciences》2010,61(8):1657-1675
Geo-environmental terrain assessments and territorial zoning are useful tools for the formulation and implementation of environmental
management instruments (including policy-making, planning, and enforcement of statutory regulations). They usually involve
a set of procedures and techniques for delimitation, characterisation and classification of terrain units. However, terrain
assessments and zoning exercises are often costly and time-consuming, particularly when encompassing large areas, which in
many cases prevent local agencies in developing countries from properly benefiting from such assessments. In the present paper,
a low-cost technique based on the analysis of texture of satellite imagery was used for delimitation of terrain units. The
delimited units were further analysed in two test areas situated in Southeast Brazil to provide estimates of land instability
and the vulnerability of groundwater to pollution hazards. The implementation incorporated procedures for inferring the influences
and potential implications of tectonic fractures and other discontinuities on ground behaviour and local groundwater flow.
Terrain attributes such as degree of fracturing, bedrock lithology and weathered materials were explored as indicators of
ground properties. The paper also discusses constraints on- and limitations of- the approaches taken. 相似文献
96.
Paulo Cesar da Costa Gomes 《GeoJournal》2004,60(4):339-344
We are concerned here with the notion of space as a primary condition for building social relations. From this stand, we have
created two analytical matrixes that can help us characterize two modes: that of ‘being-there-in-space’ and that of ‘being-of-the-space’;
the nomospace and the genospace. While the nomospace is characterized by ‘cold’ connotations, which are ideally defined as a result of a logical option, the genospace is mainly characterized by emotional or ‘warm’ connotations, which originate from a feeling of shared nature and common destiny.
We believe that these matrixes could help us to identify the meanings of some behaviours and, therefore, make us more capable
of interpreting many dynamics that occur in modern societies. The importance of geography is justified by the existing relationship
between these behaviours and their proper spatial form.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
97.
40Ar/39Ar laser incremental‐heating analyses of 22 individual grains of supergene cryptomelane from three weathering pro?les, up to 400 km apart, in the Rio Doce valley and Barbacena regions at Minas Gerais, Brazil, show that the formation of weathering pro?les in these regions is contemporaneous, suggesting a strong weathering event in the Middle to Late Miocene (10–8 Ma). The preservation of these Miocene samples at or near the present surface suggests that either erosion rates have been very low in the region since the Miocene or that a much thicker weathering mantle was present in the region originally. Assuming a constant thickness of weathering pro?les in the region throughout the Tertiary, we may calculate weathering front propagation rates of 4–8 m Myr?1 during the past 10 Ma. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
98.
Maurício Jos Alves Bolzan Reinaldo Roberto Rosa Fernando Manuel Ramos Paulo Roberto Fagundes Yogeshwar Sahai 《Journal of Atmospheric and Solar》2005,67(17-18):1843
In this paper, we analyze the probability density function (PDF) of solar wind velocity and proton density, based on generalized thermostatistics (GT) approach, comparing theoretical results with observational data. The time-series analyzed were obtained from the SOHO satellite mission where measurements were sampled every hour. We present in the investigations data for two years of different solar activity: (a) moderate activity (MA) period (1997) and (b) high activity (HA) period (2000). For the MA period, the results show good agreement between experimental data and GT model. For the HA period, the agreement between experimental and theoretical PDFs was fairly good, but some distortions were observed, probably due to intermittent characteristics of turbulent processes. As a complementary analysis, the global wavelet spectrum (GWS) was obtained, allowing the characterization of the predominant temporal variability scales for both periods and the stochastic aspects of the nonlinear solar wind variability are discussed. 相似文献
99.
100.
Weathering geochronology by (U-Th)/He dating of goethite 总被引:3,自引:0,他引:3
David L. Shuster Paulo M. Vasconcelos Kenneth A. Farley 《Geochimica et cosmochimica acta》2005,69(3):659-673
Nine samples of supergene goethite (FeOOH) from Brazil and Australia were selected to test the suitability of this mineral for (U-Th)/He dating. Measured He ages ranged from 61 to 8 Ma and were reproducible to better than a few percent despite very large variations in [U] and [Th]. In all samples with internal stratigraphy or independent age constraints, the He ages corroborated the expected relationships. These data demonstrate that internally consistent He ages can be obtained on goethite, but do not prove quantitative 4He retention. To assess possible diffusive He loss, stepped-heating experiments were performed on two goethite samples that were subjected to proton irradiation to produce a homogeneous distribution of spallogenic 3He. The 3He release pattern indicates the presence of at least two diffusion domains, one with high helium retentivity and the other with very low retentivity at Earth surface conditions. The low retentivity domain, which accounts for ∼ 5% of 3He, contains no natural 4He and may represent poorly crystalline or intergranular material which has lost all radiogenic 4He by diffusion in nature. Diffusive loss of 3He from the high retentivity domain is independent of the macroscopic dimensions of the analyzed polycrystalline aggregate, so probably represents diffusion from individual micrometer-size goethite crystals. The 4He/3He evolution during the incremental heating experiments shows that the high retentivity domain has retained 90%-95% of its radiogenic helium. This degree of retentivity is in excellent agreement with that independently predicted from the helium diffusion coefficients extrapolated to Earth surface temperature and held for the appropriate duration. Considering both the high and low retentivity domains, these data indicate that one of the samples retained 90% of its radiogenic 4He over 47.5 Ma and the other retained 86% over 12.3 Ma. Thus while diffusive-loss corrections to supergene goethite He ages are required, these initial results indicate that the corrections are not extremely large and can be rigorously quantified using the proton-irradiation 4He/3He method. 相似文献