Marine and Brackish Ecosystems of South Brittany (Lorient and Vilaine Bays) with Particular Reference to the Effect of the Turbidity Maxima     

Le Bris H.  Glmarec M. 《Estuarine, Coastal and Shelf Science》1996,42(6):737-753

The south Brittany coast of France offers considerable opportunities to study the transition between estuaries and the sea. The sea coast is semi-enclosed, due to the local geomorphology, with sheltered conditions. The infaunal macrobenthic communities have been identified and characterized by species richness (S), abundance (A) and biomass (B), related to environmental factors. The spatial succession of infauna along the estuarine gradient shows the presence of an area with a much reduced fauna, and an oligobiotic area with low values of S, A and B. In these strongly stratified estuaries, concentration of organic matter and sediment can result in oxygen depletion, which is not favourable for survival of the infauna. The oligobiotic area seems to be related to the presence of the turbidity maximum, the location and importance of which are functions of river discharge and hydrodynamic mixing. The turbidity maximum which causes these conditions is shown to be at a higher salinity than has previously been described for this phenomenon, and is shown to break the spatial gradient of marine to brackish communities which has been described in larger estuaries.  相似文献   

A numerical study of the interaction of tidal oscillations and non-linearities in an estuary     

C.F. Scott 《Estuarine, Coastal and Shelf Science》1994,39(6)

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Sediment dispersal and redistributive processes in axial and transverse deep‐time source‐to‐sink systems of marine rift basins: Dampier Sub‐basin,Northwest Shelf,Australia     

Hehe Chen  Lesli J. Wood  Robert L. Gawthorpe 《Basin Research》2021,33(1):227-249

Morphological scaling relationships between source‐to‐sink segments have been widely explored in modern settings, however, deep‐time systems remain difficult to assess due to limited preservation of drainage basins and difficulty in quantifying complex processes that impact sediment dispersals. Integration of core, well‐logs and 3‐D seismic data across the Dampier Sub‐basin, Northwest Shelf of Australia, enables a complete deep‐time source‐to‐sink study from the footwall (Rankin Platform) catchment to the hanging wall (Kendrew Trough) depositional systems in a Jurassic late syn‐rift succession. Hydrological analysis identifies 24 drainage basins on the J50.0 (Tithonian) erosional surface, which are delimited into six drainage domains confined by NNE‐SSW trending grabens and their horsts, with drainage domain areas ranging between 29 and 156 km². Drainage outlets of these drainage domains are well preserved along the Rankin Fault System scarp, with cross‐sectional areas ranging from 0.08 to 0.31 km². Corresponding to the six drainage domains, sedimentological and geomorphological analysis identifies six transverse submarine fan complexes developing in the Kendrew Trough, ranging in areas from 43 to 193 km². Seismic geomorphological analysis reveals over 90‐km‐long, slightly sinuous axial turbidity channels, developing in the lower topography of the Kendrew Trough which erodes toe parts of transverse submarine fan complexes. Positive scaling relationships exist between drainage outlet spacing and drainage basin length, and drainage outlet cross‐sectional area and drainage basin area, which indicates the geometry of drainage outlets can provide important constraints on source area dimensions in deep‐time source‐to‐sink studies. The broadly negative bias of fan area to drainage basin area ratios indicates net sediment losses in submarine fan complexes caused by axial turbidity current erosion. Source‐to‐sink sediment balance studies must be done with full evaluating of adjacent source‐to‐sink systems to delineate fans and their associated up‐dip drainages, to achieve an accurate tectonic and sedimentologic picture of deep‐time basins.  相似文献   

层状孔隙裂隙热储最大允许水位降深研究——以德州市城区为例          下载免费PDF全文

杨询昌 《山东国土资源》2016,32(7)

当前,地热水最大降深如何确定方法很多,各地区因开采条件不同其最大允许降深也不完全相同。在基于地面沉降防控基础上以德州市城区为例,通过对地面沉降与深层地下地热水分析,建立起了地热水最大允许水位降深数值模型,并计算出新近纪明化镇组、馆陶组和古近纪东营组地热水开采最大允许水位降深值,确定了相似区域最大允许水位降深范围,这对层状孔隙裂隙热储地区热储最大允许水位降深确定和地热资源的可持续开发利用具有重要现实意义和理论参考价值。  相似文献   

沉积物重力流流体转化沉积-混合事件层   总被引：3，自引：2，他引：1  

谈明轩  朱筱敏  耿名扬  刘常妮 《沉积学报》2016,34(6):1108-1119

随着浊流和碎屑流理论体系日臻成熟,重力流的流体转化过程逐渐受到重视,而与其相关联的混合事件层概念也应运而生。混合事件层是单次碎屑流或浊流流体转化中的沉积记录,是多种流变学特征的垂向沉积组合。典型混合事件层沉积序列具有五段式的特征（即纯净砂岩段H₁、条带状砂岩段H₂、黏性碎积岩段H₃、波状层理段H₄、块状泥岩段H₅）,其内部通常存在岩性突变界面。混合事件层发育于粗粒三角洲内部、海底扇和水道与舌状体过渡区、舌状体侧缘、远端及限制性的微型盆地边缘地区,其垂向叠置厚度可达数十米。混合事件层的发现对重力流流体转化、重力流沉积物空间流变学性质研究具有重要意义,同时也推动了油气储层构型和非均质性研究,为进一步寻找深水有利储集砂体提供了新思路。混合层地球物理识别方法的建立及其相关概念在湖泊重力流研究中的灵活应用将是下一步的研究方向。  相似文献   

Geostatistical space–time mapping of house prices using Bayesian maximum entropy     

Darren K. Hayunga 《International journal of geographical information science》2016,30(12):2339-2354

Mapping spatial processes at a small scale is a challenge when observed data are not abundant. The article examines the residential housing market in Fort Worth, Texas, and builds price indices at the inter- and intra-neighborhood levels. To accomplish our objectives, we initially model price variability in the joint space–time continuum. We then use geostatistics to predict and map monthly housing prices across the area of interest over a period of 4 years. For this analysis, we introduce the Bayesian maximum entropy (BME) method into real estate research. We use BME because it rigorously integrates uncertain or secondary soft data, which are needed to build the price indices. The soft data in our analysis are property tax values, which are plentiful, publicly available, and highly correlated with transaction prices. The results demonstrate how the use of the soft data provides the ability to map house prices within a small areal unit such as a subdivision or neighborhood.  相似文献   

改进最大似然遥感影像分类方法——以SAR影像为例   总被引：2，自引：0，他引：2  

陈富龙  王超  张红 《国土资源遥感》2008,(1):75-78

针对常规最大似然分类算法中类别先验概率获取困难及遥感影像分类问题,提出了一种有效的改进最大似然遥感影像分类方法.该方法能使用类别样本的统计信息,实现类别先验概率的自动和最优提取,从而很好地解决了基于统计监督分类方法中无法直接获取类别先验概率的问题.以6景Radarsat-1 精细模式SAR影像数据为例进行的分类实验证明,该算法分类效果较好,针对单波段、单极化的SAR影像,其精度可望达到80%.  相似文献   

浅表层天然气水合物区的海底地形特征——以鄂霍次克海为例   总被引：3，自引：2，他引：1  

栾锡武  岳保静 《现代地质》2008,22(3):420-429

使用重力取样器、渔网、深潜器等手段已经在海底及以下浅表层区域采获天然气水合物样品。但关于浅表层水合物的发育机制、分布规律及与海底地形的关系等问题还缺乏基本认识。根据2006年鄂霍次克海天然气水合物调查航次的调查数据,介绍了浅表层天然气水合物区的海底地形特征。萨哈林东北陆坡区,特别是中、下陆坡区发育大量海底凸起,这些凸起一般呈不对称的丘形,宽几百米,高几十米。不同于海底沙波、沙脊,海底凸起为孤立海底地形,在南北方向上并不连续。海底凸起和浅表层天然气水合物的发育密切相关。在海底剖面仪测量结果剖面上清楚地显示古陆坡凸起的发育。普遍地,现今海底陆坡凸起的幅度要小于古陆坡凸起的幅度,个别地方古、今陆坡凸起的形态有所变化,但大部分古、今陆坡凸起是一一对应的,基本形态没有根本变化。在萨哈林陆坡地区存在两个方向的挤压应力场,分别是由德鲁根盆地向萨哈林陆坡方向的挤压应力场、萨哈林陆坡沿萨哈林走滑断裂向南的挤压应力场。海底陆坡凸起是这两大应力场复合作用的结果。浊反射区中的游离气是底辟构造中的超高压多相物质向上迁移形成的。浊反射区上方对应的海底凸起应该是宏观构造挤压和局部底辟发育叠合的结果。浊反射区上方的海底凸起,在形态等方面应该和其他仅由挤压构造原因形成的凸起有所区别,比如顶部发育裂口等。在底辟构造中,由于游离气体的向上迁移,在整个水合物稳定域中从下到上,直至海底都可能形成水合物,从而使我们有机会使用重力采样器这样的设备也能采获天然气水合物样品。  相似文献   

上海长江隧道工程岩土地质与施工沉降控制   总被引：1，自引：1，他引：0  

王荣彪  金清山 《上海国土资源》2008,(2):18-22

上海长江隧道工程穿越长江河口,工程施工面临诸多技术难关。分析评价了所在区域的水文与岩土地质特征,阐述了工程施工特点及地面沉降控制技术。  相似文献   

Combining land cover products using a minimum divergence and a Bayesian data fusion approach     

Sarah Gengler  Patrick Bogaert 《International journal of geographical information science》2018,32(4):806-826

Land cover mapping plays an important role for a wide spectrum of applications that are ranging from climate modeling to food security. However, it is a common case that several and partially conflicting land cover products are available at the same time over a same area, where each product suffers from specific limitations and lack of accuracy. In order to take advantage of the best features of each product while at the same time attenuating their respective weaknesses, this paper is proposing a methodology that allows the user to combine these products together based on a general framework involving maximum entropy/minimum divergence principles, Bayesian data fusion and Bayesian updating. First, information brought by each land cover product is coded in terms of inequality constraints so that a first estimation of their quality can be computed based on a maximum entropy/minimum divergence principle. Information from these various land cover products can then be fused afterwards in a Bayesian framework, leading to a single map with an associated measure of uncertainty. Finally, it is shown how the additional information brought by control data can help improving this fused map through a Bayesian updating procedure. The first part of the paper is briefly presenting the most important theoretical results, while the second part is illustrating the use of this suggested approach for a specific area in Belgium, where five different land cover products are at hand. The benefits and limitations of this approach are finally discussed by the light of the results for this case study.  相似文献