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基于AHP和EWCM的部分南沙岛礁战略价值模糊综合评价 总被引：2，自引：0，他引：2
以模糊综合评价法为基础,构建岛礁战略价值评价指标体系与综合评价模型,采用层次分析法确定权重系数,运用熵权系数法进行权重修正,通过矩阵运算,定量评价马欢岛、费信岛、南钥岛、中业岛、北子岛、西月岛、双黄沙洲和司令礁8个岛礁的战略价值,为我国制定海洋发展战略、区域行动计划提供科技支撑和辅助决策。结果表明,一级评价指标的权重由高到低依次为自然条件、建设情况、地理位置、资源控制、战略潜力;二级评价指标中权重较高的有礁盘面积、平均高程、淡水资源、陆地距离、航线距离、辐射岛礁数、机场、建筑、人口;参与评价的南沙岛礁战略价值呈明显的梯度分布特征,中业岛最高,马欢岛次之,北子岛、西月岛、司令礁较低,费信岛、南钥岛、双黄沙洲最低。 相似文献
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自古以来,南沙群岛就是我国的固有领土,我国对南沙群岛及其附近海域拥有不可争辩的主权。然而,７０年代以后,周边一些国家不顾历史事实,相继对南沙提出主权要求,侵占部分岛礁,建立军事基地,进行资源开发,致使我国的主权受到严重侵犯。特别是随着《联合国海洋法公... 相似文献
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南沙岛礁的发育受空间位置、暴露面积及地质结构等因素的影响,礁体的演变伴随空间形态的变化。本文利用遥感和地理信息系统(GIS)相结合的方法绘制南沙岛礁核密度现状图,并采用Kernel Density进一步分析南沙礁群空间核密度分布。研究表明:南沙岛礁空间形态复杂,有明显区域格局性,面积差异较大的岛礁核密度聚集位置不相同,分布特征相对密集。岛礁数量在纬度方向有明显浮动,在经度方向上趋于稳定。随礁体面积的增大,礁体平均形状指数逐渐增大,平均紧凑度逐渐减小,形状指数LSI介于0.90～2.87之间、紧凑度RC介于0.31～0.97之间。研究结果有助于更好地了解南沙岛礁密度情况,为海洋管理人员提供参考信息。 相似文献
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我国海南省三沙市海域资源丰富,开发利用潜力巨大。但目前面临岛礁被侵占、海域被分割、资源被掠夺的侵权现象。这些严重影响了我国的海洋主权的行使和海洋资源的利用。因此,三沙市大力发展海洋特别保护区,对维护国家主权和海洋权益、保护海洋生态环境和资源,促进海洋开发利用具有十分重要的意义。 相似文献
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南海海域内岛礁众多, 渔业资源丰富, 而目前针对岛礁周边海区生态要素开展的研究仍较少。本文利用近20年多卫星融合水色遥感数据, 分析了南海38个主要岛礁周边区域海面叶绿素浓度的空间分布、季节变化和年际变化特征。结果表明, 岛礁周边普遍存在叶绿素浓度高值区, 其浓度约在离岛礁5个等效半径外降至海区背景水平。岛礁周边海域的叶绿素(相对于背景值的)浓度异常受海区背景值影响, 两者在南海的空间分布格局与背景值基本一致: 在平均温度较低、季风强度较大的东沙、西沙海区, 叶绿素浓度异常高于温度较高、季风强度相对较弱的中沙、南沙海区。叶绿素浓度呈现出明显的季节变化和年际变化特征, 一般在冬季风期间升高, 而在夏季风爆发前降至最低; 在El Ni?o次年随海温升高和季风减弱而下降, 在La Ni?a次年则相反。岛礁周边的叶绿素浓度异常受到温度变化的影响, 随着近年来海温变化幅度加大, 其年均水平呈显著下降趋势(P=5.05×10 -5)。这些结果可为我国岛礁区域渔业资源的开发和管理提供信息支持。 相似文献
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Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance. 相似文献
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Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
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G. Parthiban 《Marine Georesources & Geotechnology》2000,18(3):223-235
Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
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Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
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The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments. 相似文献
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《海洋学报(英文版)》2014,(11):161-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献