Braiding process and bank erosion in the Brahmaputra River

The present work explores relations between stream power,braiding intensities and bank erosion in certain stretches of the Brahmaputra River.In this paper,an objective approach is presented to enable quantitative assessment of spatio-temporal behaviour of channel braiding process of the Brahmaputra River by using the Plan Form Index and corresponding estimation of stream power to establish a behavioural pattern of variability of potential energy expenditure.The braiding index is compared for discrete years to understand the morphological behaviour.Subsequently,a real time estimation of stream power for certain stretches of Brahmaputra River is done in order to analyse its variability in braiding intensity and bank erosion.The paper presents the dynamic behaviour of the channel pattern of the Brahmaputra River System in Assam valley of India over a time span of 18 years.The procedure addresses the selection of input parameters from digital satellite images,comprising scenes for the years 1990,1997 and 2007 with specific dates,from Dhubri near Indo-Bangladesh Border to Upper Assam.Deployment of GIS technique has been made to extract the required parameters to derive Plan Form Indices for the entire study reach.Stream power estimation is done for corresponding latest floods and for corresponding dates of image scenes.The study indicated that due to consistent aggradation of riverbed inducing temporal declination of stream power,there is an occurrence of wide spread braiding.This in turn incurs substantial yearly land loss due to bank erosion,caused by flow concentrations due to temporal evolution of multiple channels in the Brahmaputra River.     

Graduated incarceration: The Israeli occupation in subaltern geopolitical perspective

This paper highlights the importance of analysis of the microgeographies of occupation, and the spatially-differentiated means that the Israeli Occupation Forces use to maintain the occupation and create spaces of graduated incarceration for Palestinians. Using the examples of the hinterlands of Qalqiliyah and the old city of Al-Khalil (Hebron) in the occupied West Bank, this paper exposes the microgeographical differentiation the occupation mobilizes in its attempt to enact a panoptic sovereignty over the population, in the process of dispossession. This study challenges geopolitical formations of the state as primary actor, and focuses instead on narratives of Palestinians describing their own experiences of occupation by a hostile state. By relying on popular media, semi-structured interviews, and participant observation, this paper seeks to incorporate a Palestinian vision of life under occupation to challenge traditional geopolitical visions of the Palestinian Israeli conflict, in effect creating a subaltern geopolitical narrative.     

Characteristics of resuspended sediment from Georges Bank collected with a sediment trap

A sediment trap was deployed 3 m from the bottom at a water depth of 62 m on the southern flank of Georges Bank (41°02·2′N, 67°33·5′W) from 30 September 1978 to 10 March 1979 to qualitatively determine the size of sediments resuspended from the bottom by winter storms and to determine if seasonal changes in the phytoplankton could be observed in the trapped sediment.Bulk X-ray analyses of the trapped sediment showed layers of distinctly different textures preserved in the collection vessel. The median grain size of sampled layers ranged from 2·7 to 6·5 φ (fine sand to silt), but all layers contained a pronounced mode in the 3 φ (fine sand) range. Nine layers containing relatively large amounts of sand were present. The sand content was 75% in the coarest layers and about 32% in the fine layers. The median grain size of bottom sediments at the deployment site was considerably coarser than the trap samples, although the dominant grain size was also 3 φ.Average bottom-current speeds during the deployment period were about 30 cm s^?1 with a range of 10 to 50 cm s^?1. Bottom stress, computed from the observed currents and waves, suggest that 11 storms caused sufficient stress to resuspend 3 φ-sized sediments, in good agreement with the nine layers of relatively coarse sediments collected in the trap. Surface waves had to be included in the calculation of bottom stress because the bottom currents alone were insufficient to cause the resuspension of 3 φ-sized sediment.The trapped sediments contain numerous diatoms and coccoliths that are typical of late fall and winter assemblages. No clear seasonal difference in the flora was noted among sampled layers, probably due to the large influx of resuspended material and a reduced primary flux during this period. An undescribed species of Thalassiosira (G. Fryxell, personal communication), and siliceous scales of unknown systematic position were observed at all levels.     

Oil-spill fishery impact assessment model: Application to selected Georges Bank fish species

An oil-spill fishery impact assessment model composed of an oil-spill fates model, a shelf hydrodynamics model, an ichthyoplankton transport and fate model, and a fishery population model originally developed by Reed & Spaulding, has been improved and applied to the Georges Bank-Gulf of Maine region to assess the probable impact of oil spills on several key fisheries. The model addresses direct impacts of oil on the commercial fishery through hydrocarbon-induced egg and larval mortality. This early life stage hydrocarbon-induced mortality is estimated by assuming a toxicity threshold approach and by mapping the spatial/temporal interaction between the subsurface oil concentrations caused by the spill and the developing eggs and larvae. Model output is given in terms of differential catch, with a comparison made of hydrocarbon-impacted fisheries.Simulations of tanker and blowout spills at two separate locations for each season of the year in the Outer Continental Shelf lease areas have been completed for Atlantic herring, haddock, and Atlantic cod. Results to date suggest a complex interaction among spill location and timing, the spatial and temporal spawning distribution of the species, and the hydrodynamics of the area. The largest impacts occur for spring and winter spills.     

The Asian Development Bank and the production of poverty: Neoliberalism,technocratic modernization and land dispossession in the Greater Mekong Subregion

In 1992 the Asian Development Bank coordinated a meeting between government representatives from China, Cambodia, Laos, Myanmar, Thailand and Vietnam to discuss regional economic integration. From that meeting the Greater Mekong Subregion was formed to promote peace and prosperity within the Mekong countries. Yet, despite more than more than USD 14 billion being spent on facilitating trade, development and infrastructural ties between these nations, poverty remains widespread. This article provides a critical analysis of the Asian Development Bank and its approach to development and poverty alleviation within the Greater Mekong Subregion. It suggests that the institution's technocratic neoliberal development ideology provides a discursive legitimation to processes of displacement and dispossession that has seen the production of new forms of poverty. To make this argument, the article draws on an ethnographic study of the local‐scale implications of forced resettlement at the Luang Prabang Airport. It conducts an analysis of how the Asian Development Bank defines and measures poverty, and critiques the institution's resettlement guidelines for the airport project.     

Drifter observations of the Gulf of Maine Coastal Current

Two-hundred and twenty seven satellite-tracked drifters were deployed in the Gulf of Maine (GoM) from 1988 to 2007, primarily during spring and summer. The archive of tracks includes over 100,000 km logged thus far. Statistics such as transit times, mean velocities, response to wind events, and preferred pathways are compiled for various areas of the coastal GoM. We compare Lagrangian flow with Eulerian estimates from nearby moorings and evaluate drifter trajectories using Ekman theory and 3-D ocean circulation models.     

Morphological responses in a meandering and island-braided reach of the Middle Yangtze River to the Three Gorges Reservoir impoundment

Lateral migration is an important form of morphological changes on the Middle Yangtze River (MYR), particularly for the lower Jingjiang reach. The Three Gorges Reservoir (TGR) has substantially reduced sediment supply to the downstream river channels since its impoundment in June 2003. The scientific understanding of how decrease of sediment influences the processes of bank erosion and channel adjustments is complex and limited. In the present paper, the morphological responses in a typical meandering and island-braided river segment of the MYR to the filling of the TGR were investigated by a 3-D morphodynamic model. The potential of the 3-D model has been demonstrated by the observed data. The morphological evolutions in the Shishou bend during the first 12 years of the TGR impound-ment were predicted. The effects of the TGR operation on the planform evolutions in the study reach were analyzed based on the simulated results. Sediment load is decreased by 75%due to the early filling of the TGR. The magnitude of bed degradation with less sediment load due to the TGR operation is increased compared with the pre-dam situation. Qualitatively, the overall planform evolution trends in the Shishou bend after the TGR operation are similar to that without the TGR operation. The magnitude of lateral migration has been increased in some part of the channel bend, where the morphological response of the TGR operation exhibits more lateral migration rather than vertical degradation. Scouring at the bank toe enhances bank failure. Decrease of sediment load and weak bank anti-scour ability as well as the significant helical flow can be responsible for intensified bank erosion in the channel bend.     

大贵州滩二叠系—三叠系界线附近锶同位素组成特征

位于贵州南部的“大贵州滩”上,二叠系—三叠系界线附近地层为一套连续的发育完整的碳酸盐岩。二叠系顶部主要为厚层生物屑泥粒灰岩,而三叠系底部则主要为钙质微生物骨架灰岩及厚层粒泥灰岩。穿过二叠系—三叠系界线的取样累计厚度81m,二叠系和三叠系大致各占一半的厚度,共取样品91件,n(87Sr)/n(86Sr)值变化在0.707269～0.707409之间,平均为0.707327,低于现代海水的锶同位素比值的平均值（0.7090737）。锶同位素比值变化曲线表明从晚二叠世末期到早三叠世初期,同位素比值虽小幅度的起伏波动频繁,但总体上没有明显变化,三叠系底部的平均值（0.707330）略高于二叠系顶部的平均值（0.707323）。大贵州滩晚二叠世末至早三叠世初锶同位素组成的总体演化趋势与扬子台地及世界其它地方同时期的锶同位素组成的演化趋势（呈急剧的上升）不同,造成这种状况的原因可能是在全球事件控制的大背景下,由于大贵州滩特殊的环境条件,陆源物质对其影响小,导致了壳源锶对锶同位素组成的制约作用减弱,因而锶同位素组成未发生明显变化。     

Multi-scale modelling of the permeability evolution of fine sands during cement suspension grouting with filtration

Fluid flow during permeation grouting of fine sands with a microcement-based grout is studied by assuming that the heterogeneous medium composed of the initial granular skeleton, filtered cement and the interstitial fluid phase can be replaced by a continuous equivalent medium at the macroscopic level. Consequently, the method of Homogenization of Periodic Structures (HPS) is used to identify the effective permeability tensor evolution under the effect of cement filtration. The expression of the macroscopic permeability tensor derived through the HPS procedure is shown to depend on the permeating fluid viscosity and the geometrical arrangement of the sand grains and cement deposit within the microstructure. Numerical computations are made using various two-dimensional and three-dimensional microstructures, and the model results are confronted with grouting experiments performed on small scale columns in the laboratory.     

商业银行空间市场力的演进规律——中国光大银行拓扑结构的分析

构建商业银行空间市场力模型测度商业银行空间市场力,并应用于光大银行并绘制其拓扑结构图,分时段显示其拓扑结构的演进路径,度分布检测说明光大银行拓扑结构具有泊松分布特征。基于光大银行截止2009年在全国31 省市自治区(不含台湾、香港数据)尚有8 个行政区尚未布局营业网点的状态下,按照有效拓扑路径模拟设置行政区网点,得到其设置的先后顺序,并与以后该银行真实情况对照并取得了大致一致,这说明该银行在后期对营业网点设置中遵循了拓扑结构的优化过程。