28 resultados para coastal area

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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This paper focuses on the concept of Integrated Coastal Management (ICM) putting the theoretical basis of Chapter 17, Agenda 21 (UN Conference on Environment and Development, UNCED), in relation to the theoretical backgrounds on which the development of coastal area programmes have been founded. Reasoning leads us to think that the general system theory is the proper conceptual basis to stimulate ICM and that, in this theoretical context, integration is to be pursued between (i) the claiming of national maritime jurisdictional belts and the protection of the coastal ecosystem, (ii) the coastal system and its external environment, (iii) the decision making systems acting at all levels (international, regional, national and local). Integration, therefore, should be thought of as a political process.

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Using satellite images taken on different dates, GIS analysis of aerial photos, bathymetric maps and other field survey data, tidal troughs and major sand ridges in the northern Jiangsu coastal area were contrasted. The results show that there have been three types of movement or migration of tidal trough in this area: (1) Periodic and restricted, this type of trough usually developed along the beaches with immobile gully head as a result of the artificial dams and the swing range increased from gully head to the low reaches, so they have been obviously impacted by human activity and have longer swing periods; (2) Periodic and actively, this kind of trough, which swung with a fast rate and moved periodically on sand ridges, were mainly controlled by the swings of the host tidal troughs and hydrodynamic forces upon tidal sand ridge and influenced slightly by human constructions; (3) Steadily and slowly, they are the main tidal troughs with large scale and a steady orientation in this area and have slow lateral movement. The differences in migration mode of tidal trough shift result in different rates of migration and impact upon tidal sand ridges. Lateral accumulation on current tidal trough and deposition on abandoned tidal troughs are the two types of sedimentation of the tidal sand ridges formation. The whole radial sand ridge was generally prone to division and retreat although sand ridges fluctuated by the analysis of changes in talwegs of tidal troughs and shorelines of sand ridges.

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在归纳和总结国内外关于土地利用和土地覆被变化(LUCC)及其水文效应研究大量文献的基础上,以胶东半岛海岸带的夹河流域为案例,利用1979、1990、2000和2009年四个时相的遥感影像信息进行分类,得到土地利用分布数据,对夹河流域土地利用分布与变化、土地利用变化驱动力、土地利用变化的模拟、预测及其水文效应等问题等进行了较为系统的研究。研究表明:夹河流域的土地利用以耕地、林地和草地为主;土地利用分布受高程、坡度、到河流距离、到居民点距离和政策等因素的影响显著,而且自1979年以来,流域内土地利用发生了很大的变化,最显著的特点是受人口增长、经济发展和城市化的影响,城镇、农村居民点以及独立工矿等建设用地的面积大幅增加。应用LTM模型和CA-Markov模型对夹河流域土地利用变化进行模拟、预测,并分析和比较两个模型的特征与精度水平,结果表明:CA-Markov模型的原理与技术均较明确,模拟精度整体较高;LTM模型的灵活性、可扩展性和可探索性较强,但模拟精度受驱动力选择、数据制备方法等因素的影响,因而案例区模拟结果的精度略低。基于N-SPECT水文分析模型,利用土壤分布数据、多时相土地利用数据和过去10年(2000~2009年)的年降水数据,以年径流量指标为代表,对土地利用变化的水文效应进行模拟及未来情景分析,结果表明,未来20年夹河流域土地利用变化具有促使流域年径流量及河口入海通量持续增加的趋势。通过研究认为,为服务于海岸带区域可持续发展的框架目标,宜于强化流域综合管理和海岸带综合管理的集成与衔接,科学规划、合理配置夹河流域土地资源的结构特征和空间布局,促进经济、社会和生态环境的协调发展。

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This paper addresses the recent (1970s-1990s) processes of river mouth bar formation, riverbed aggradation and distributary migration in the Huanghe River mouth area, in the light of station-based monitoring, field measurements and remote sensing interpretation. The results show that the morphological changes of the river mouth bar have been closely associated with the largely reduced fluvial discharge and sediment load. Landforrn development such as bar progradation occurred in two phases, i.e. before and after 1989, which correspond to faster and lower bar growth rates, respectively. Fast riverbed aggradation in the mouth channel was strongly related to river mouth bar progradation. During 1976-1996, about 2.8% of the total sediment loads were deposited in the river channel on the upper to middle delta. Therefore, the river water level rose by a few meters from 1984 to 1996. The frequent distributary channel migration, which switched the radial channel pattern into the SE-directed pattern in the mid-1980s, was linked with mouth bar formation. Marine conditions also constrain seaward bar progradation. Furthermore, the history of river mouth bar formation reflects human impacts, such as dredging and dyking in order to stabilize the coastal area. (c) 2005 Elsevier B.V. All rights reserved.

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A group of statistical algorithms are proposed for the inversion of the three major components of Case-H waters in the coastal area of the Huanghai Sea and the East China Sea. The algorithms are based on the in situ data collected in the spring of 2003 with strict quality assurance according to NASA ocean bio-optic protocols. These algorithms are the first ones with quantitative confidence that can be applied for the area. The average relative error of the inversed and in situ measured components' concentrations are: Chl-a about 37%, total suspended matter (TSM) about 25%, respectively. This preliminary result is quite satisfactory for Case-H waters, although some aspects in the model need further study. The sensitivity of the input error of 5% to remote sensing reflectance (Rrs) is also analyzed and it shows the algorithms are quite stable. The algorithms show a large difference with Tassan's local SeaWiFS algorithms for different waters, except for the Chl-a algorithm.

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本文以具有典型特征的苏北淤泥质潮滩海岸作为研究区,利用1975-2003年间14景覆盖该地区的Landsat和SPOT卫星影像作为主要数据源,结合地面调查和验证工作,在遥感影像处理和地理信息系统分析技术的支持下,对区内潮滩、岸线、水边线和盐沼植被等进行遥感解译,分析苏北辐射沙脊群和沿岸地貌的空间分布特征和动态演变趋势。研究结果表明:苏北辐射沙脊群海域的潮汐水位过程的不同步现象普遍存在,限制了常规遥感数据在苏北潮滩地貌研究中的适用范围和解译精度;在人工判别的辅助下,多光谱遥感的非监督分类方法可以有效解译淤泥质潮滩的水边线;利用修改型土壤调整植被指数(MSAVI)可以较好地提取潮滩上的盐沼植被信息;苏北沿岸潮滩的快速淤长促进了盐沼植被带向海侧快速扩展,近年来持续的潮滩围垦工程则不断从陆侧侵占盐沼植被带,使盐沼植被带宽度减小乃至消失;在大规模人类活动和自然条件的共同影响下,苏北辐射沙脊群海岸的岸线发育趋于平直化,无序的潮滩围垦项目使得可垦滩地资源被过度消耗;1975~2002年间,研究区北部和南部沿岸的高潮滩整体上处于淤长状态,中部沿岸潮滩和离岸沙洲高潮滩则被大面积侵蚀;1999年以来,研究区内低潮滩部位开始形成有序排列的滩面地物,并表现出逐年大面积蔓延的趋势,可能是滩涂紫菜养殖区扩展的结果。

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浅海波浪、潮汐风暴潮相互作用的研究是当今国际热点研究方向之一.该项研究针对典型浅海海域渤海,研究了在这个海域的波浪、潮汐风暴潮的相互作用以及物质输运规律.建立了一个渤海波浪和潮汐风暴潮运动相互作用的数值模式.模式主要由两部分组成:一个物理上先进的第三代浅海波浪数值模式和一个二维潮汐风暴潮数值模式,实现了两个模式耦合.运用这个模式,重点研究了波浪对表面拖曳系数的影响;波浪对底摩擦应力的作用;辐射应力对潮汐风暴潮水位的影响以及潮汐风暴潮对波浪的作用.在这个基础上,对物质输运规律进行了研究.

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The Mesozoic pyroclastic rocks cover a vast coastal area in southeastern China, which is an important part of volcanic belt around Pacific Ocean. However, the previous dates for these rocks are confused and conflicted with each other, which have limited the further researches. It is difficult to date pyroclastic rocks, for almost all the dating methods, due to the multiple sources during their formation. Single crystal laser probe 40Ar/39Ar method is a powerful means to date pyroclastic rocks with complex sources. By distinguishing the xenocrysts and altered materials, Singe crystal total fusions of CO2 lasing on the sanidine separates could yield rational 40Ar/39Ar results and distinguish their sources. Timing on formations of the Moshishan Group, after avoiding the exotic and altered grains by lasing on the single sanidine separate, was reported in this study. 40Ar/39Ar incremental heating results of Cement part of the pyroclastic rocks show that the age spectrums are too complex to interpret for geological significance because of the alteration and 39Ar recoil. Incremental heating on K-feldspar separate from pyroclastic rocks give reliable data. Combining 40Ar/39Ar incremental heating ages and laser total fusion ages, we suggest the age was 125Ma-120Ma for Dashuang Fm, 120-119 Ma for Gaowu Fm, 119-114Ma for Xishantou Fm, 114-112Ma for Chawan Fm and 112-110Ma for Jiuliping Fm. The most intense period of volcanic activity in eastern Zhejiang Province was at about 120Ma. These new ages are much younger than the previous ones, suggesting that these thick volcanic formations had been formed in very short durations.

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Phosphorus is an important biological and ecological element that to a certain degree constrains ecological environment and nutrient (including carbon) cycling. Marine sedimentary phosphorites are the principal phosphorus supply of the mankind. In the eastern to southern margins of the Yangtze Craton, South China, there are two phosphogenetic events at the Doushantuo stage of the Late Sinian and the Meishucun stage of the Early Cambrian respectively, corresponding two explosion events of life across the Precambrian\Cambrian boundary. Phosphorus ores from the Sinian and Cambrian phosphate in South China can be classified roughly into two categories, namely, grained and non-grained phosphorites. Grained phosphorites, hosted in dolostone type of phosphogenetic sequences and with larger industrial values, occur mainly in margins of the Upper Yangtze Platform, formed in shallow-water environments with high hydraulic energy and influenced by frequent sea-level change. Non-grained phosphorites, hosted principally in black-shale type of phosphogenetic sequences and with smaller industrial values, are distributed mainly in the Jiangnan region where deeper-water sub-basins with low hydraulic energy were prevailing at the time of phosphogenesis. Secular change ofδ~(13)C, δ~(18) O, ~(86)Sr/~(87)Sr values of carbonates from Sinian and Cambrian sequences were determined. A negative abnormal ofδ~(13)C, δ~(18)O values and positive abnormal of 86Sr/87Sr values from the fossiliferous section of the Lowest Cambrian Meishucun Formation implies life depopulation and following explosion of life across the PrecambriamCambrian boundary. Based on a lot of observations, this paper put forward a six-stage genetic model describing the whole formational process of industrial phosphorites: 1) Phosphorus was transported from continental weathering products and stored in the ocean; 2) dissolved phosphates in the seawater were enriched in specific deep seawater layer; 3) coastal upwelling currents took this phosphorus-rich seawater to a specific coastal area where phosphorus was captured by oceanic microbes; 4) clastic sediments in this upwelling area were enriched in phosphorus because of abundant phosphorus-rich organic matters and because of phosphorus absorption on grain surfaces; 5) during early diagenesis, the phosphorus enriched in the clastic sediments was released into interstitial water by decomposition and desorption, and then transported to the oxidation-reduction interface where authigenic phosphates were deposited and enriched; 6) such authigenic phosphate-rich layers were scoured, broken up, and winnowed in shallow-water environments resulting in phosphate enrichment. The Sinian-Cambrian phosphorites in South China are in many aspects comparable with coastal-upwelling phosphorites of younger geological ages, especially with phosphorites from modern coastal upwelling areas. That implies the similarities between the Sinian-Cambrian ocean and the modern ocean. Although Sinian-Cambrian oceanic life was much simpler than modern one, but similar oceanic planktons prevail, because oceanic planktons (particularly phytoplanktons) are crucial for phosphate enrichment related to coastal upwelling. It implies also a similar seawater-layering pattern between the Sinian-Cambrian ocean and the modern ocean. The two global phosphate-forming events and corresponding life-explosion events at the Sinian and Cambrian time probably resulted from dissolved-phosphate accumulation in seawater over a critical concentration during the Earth's evolution. Such an oceanic system with seawater phosphorus supersaturation is evidently unstable, and trends to return to normal state through phosphate deposition. Accordingly, this paper put forward a new conception of "normal state <=> phosphorus-supersaturation state" cycling of oceanic system. Such "normal state <=> phosphorus-supersaturation state" cycling was not only important for the three well-known global phosphate-forming events, also related to the critical moments of life evolution on the Earth. It might be of special significance. The favorable paleo-oceanic orientation in regard to coastal-upwelling phosphorite formation suggests a different orientation of the Yangtze Craton between the Sinian time and the present time (with a 135° clockwise difference), and a 25° anti-clockwise rotation of the Yangtze Craton from late Sinian to early Cambrian. During the Sinian-Cambrian time, the Yangtze Craton might be separated from the Cathaysia Block, but might be still associated with the North China Craton.

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Agenda 21, the 40-chapter action plan, agreed to by all nations participating in the 1992 Earth Summit represents an ambitious effort to provide policy guidance across the entire spectrum of environment, development, and social issues confronting mankind. In the area of oceans and coasts (Chapter 17 of Agenda 21), the Earth Summit underscored that the management of oceans and coasts should be ‘integrated in content and anticipatory in ambit.’ To assist those responsible for implementing the Earth Summit guidelines on ocean and coastal management, this article first reviews the fundamental shift in paradigm reflected in the Earth Summit agreements as well as the specific recommendations contained in Chapter 17. Next, the article examines the central concept of ‘integrated management,’ noting both its importance and its limits. A general or ‘synthesis’ model of ‘integrated coastal management’ is then presented, addressing such questions as management goals, what is being managed, where, how, and by whom. In a concluding section, methods are proposed whereby the general or ‘synthesis model’ can be tailored to diverse national contexts, involving varying physical, socio-economic, and political conditions.

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The coastal zone comprises a narrow strip of coastal lowlands and a vast area of coastal waters. While the coastal zone represents approximately 10% of the earth's surface, its coastal lowlands are inhabited by more than 50% of the world population. The coastal zone has become the major site for extensive and diverse economic activities. Many of the coastal developing countries depend heavily on the scarce coastal resources for their economic growth.

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This paper discusses the definition and use of the term ‘integrated management’ in the context of coastal and ocean resources. It identifies several components which appear to be needed to establish an integrated management system for a large area subject to multiple use and jurisdiction. It suggests that the basis of integrated management should be a clear articulation of common purpose which addresses long term needs and vision. Once developed, this common purpose should be securely established to provide the setting against which sectoral and agencies managers and the community conduct and co-ordinate their activities.

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Net organic metabolism (that is, the difference between primary production and respiration of organic matter) in the coastal ocean may be a significant term in the oceanic carbon budget. Historical change in the rate of this net metabolism determines the importance of the coastal ocean relative to anthropogenic perturbations of the global carbon cycle. Consideration of long-term rates of river loading of organic carbon, organic burial, chemical reactivity of land-derived organic matter, and rates of community metabolism in the coastal zone leads us to estimate that the coastal zone oxidizes about 7 × 1012 moles C/yr. The open ocean is apparently also a site of net organic oxidation (∼16 × 1012 moles C/yr). Thus organic metabolism in the ocean appears to be a source of CO2 release to the atmosphere rather than being a sink for atmospheric carbon dioxide. The small area of the coastal ocean accounts for about 30% of the net oceanic oxidation. Oxidation in the coastal zone (especially in bays and estuaries) takes on particular importance, because the input rate is likely to have been altered substantially by human activities on land.