Role of mean circulation,tides, and waves in the transport of bottom sediment on the New Zealand continental shelf   总被引：1，自引：1，他引：0  

L. Carter  R. A. Heath 《新西兰海洋与淡水研究杂志》2013,47(4):423-448

Evaluation of velocity data on water movements over the New Zealand continental shelf has revealed that the mean circulation by itself is too slow to induce transport of bottom sediments. Tides generally have higher velocities, but are still not the main transporting agent except in the tide‐dominated Cook and Foveaux. Straits. Waves have the potential to stir sediments on the inner and middle shelf (less than about 70 m deep) during annual storms, and probably down to 130 m depth during the maximum 25‐y storm.

For sediment transport to take place, energies of at least two of the major water movements would have to complement one another. Optimum conditions for transport probably occur during storm periods when wave‐suspended sediment is readily moved by tides and the mean circulation.

The direction of transport is mainly along the continental shelf and is largely in response to prevailing weather patterns coincident with the direction of the mean circulation and strongly reinforced by the appropriate phase of the tide.  相似文献   

郑徐高铁开封段地面沉降分层监测方法     

张丹  郝亚东 《测绘通报》2017,(11):77-79

高铁沿线施工期间引起地面沉降的因素错综复杂、相互影响,本文提出通过对沉降区域地下水位、孔隙水压力等进行分层观测,根据分层观测得到地下水位变化、孔隙水压力变化等数据,并采用回归分析法构建了沉降区域地面沉降与诸影响因子的关联模型,通过对郑徐客运专线开封段进行的地面沉降监测量与同时采用二等精密水准测量得到的监测点沉降量进行对比分析,结果表明本方法的有效性和可靠性。  相似文献   

磨刀门河口环流与咸淡水混合层化机制   总被引：1，自引：0，他引：1       下载免费PDF全文

吕紫君  冯佳佳  郜新宇  汪玉平  张梦茹  孔俊 《水科学进展》2017,28(6):908-921

为研究磨刀门盐水混合层化特征,基于SCHISM模型,建立了三维盐度数值模型,根据实测资料对其进行验证。结合水体势能异常理论,对枯季磨刀门河口混合层化的时空变化特征及深槽与浅滩的层化机制差异进行分析。结果表明:磨刀门河口小潮时水体层化最强,中潮时水体层化最弱,且拦门沙至挂定角段水体层化始终较强。磨刀门深槽水体层化主要受纵向平流、纵向水深平均应变和垂向混合影响,而浅滩水体层化则受横向平流、横向水深平均应变和垂向混合影响;磨刀门河口表、底层水体湍动能耗散率较高,而中间水层存在低耗散区,且涨潮时湍动能耗散率比落潮时大。  相似文献   

阶层化背景下的就业空间——以常住人口与流动人口为例   总被引：1，自引：0，他引：1  

林耿  王炼军 《地理研究》2010,29(6):1069-1082

采用2000年第五次人口普查数据,以市辖区(县、市)为基本地理单元,对广东省的21个地级市133个样本进行阶层化背景下的就业空间研究。通过对常住人口和流动人口的就业构成和就业类型区的分析发现:(1)与流动人口相比,常住人口就业空间的分异更显多元化,其就业的体制内特征更为明显。两类人口就业空间没有形成社会极化结果,收入与职业的极化并未导致社会空间极化的出现,但也存在着类社会极化的特征。(2)常住人口和流动人口的就业构成具有中产化特征,在空间上具有中心城市指向性。而就业差异是否导致常住人口和流动人口之间的结构性阶层分异,则需进行后续的深入论证。  相似文献   

Observations of internal tidal waves in the isolated seasonally stratified region of the western Irish Sea     

J.A.M. Green  J.H. SimpsonS.A. Thorpe  T.P. Rippeth 《Continental Shelf Research》2010

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Social construction functions of consumption space under stratification: The case of Guangzhou     

Geng Lin  Lianjun Wang  Xiaoying Zhang 《中国地理科学(英文版)》2010,20(5):450-460

As Chinese cities rapidly transformed themselves into consumerist societies, the relationship between consumers and consumption space under stratification has become a new research area in the field of urban social geography. Based on a consumer behavior analysis, this study explores the relationship between consumption space and the social strata of consumers in typical shopping malls in Guangzhou where the first shopping mall in China was built. The result shows that shopping malls have performed significant constructive functions of organizing consumers from different social classes into different consumption space. For middle- and upper-class consumers, the function of shopping malls centers on utilitarian consumption, identity recognition, and identity construction; whereas for lower-class consumers, its function revolves around pleasure and enjoyment. The symbolism of consumption space is the underlying reason for shopping malls to have their social constructive function. The findings of this research suggest that: 1) a shopping mall is a productive consumption space and a geographical space with subjectivity; 2) the micro-location of a shopping mall has social construction function; and 3) symbolic consumption is the core of social construction.  相似文献   

Stability of shear flows with multilayered density stratification and monotonic velocity profiles having no inflection points     

S. M. Churilov 《地球物理与天体物理流体动力学》2016,110(1):78-108

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鄂东黄石地区三叠纪岩层中发育的重力滑动构造——重力不稳定性在控制构造变形和地质灾害过程中的作用   总被引：1，自引：0，他引：1  

索书田  侯光久 《地质科技情报》2009,28(6)

位于湖北省东部黄石地区制图尺度的近东西向黄荆山向斜和桐梓堡背斜是在印支期造山作用时形成的,主要由古生代及三叠纪沉积岩层序列组成。其中的下、中三叠统包括页岩、泥灰岩、石灰岩、白云质灰岩和白云岩等层状岩系。从构造地质学的观点出发,由下而上可划分为3个力学分层单位或组合,相互间存在有不同的黏度比或相对强度。在大型褶皱翼部,发育一系列中小型褶皱(其振幅从几米至上百米),如屋顶和墙壁状构造、膝状褶皱、平卧褶皱、翻转及叠褶构造等,覆于层理面及低缓角度正断层面之上。详细的三维空间构造解析指出,这些复杂的中小型构造产状和组合样式,与通常的寄生牵引褶皱和大的褶皱关系是相反的,即上层的相对运动或流动指向向斜的槽部,显示重力导致的滑动构造特征。这种滑动构造只是一类继发性的独立构造现象,可以解释为是在重力不稳定性影响下,部分沉积岩层沿着先存的倾斜层理面或拆离剪切带向下坡有限滑动的结果。所发育的特征性构造取决于涉及的岩层及力学分层单位的能干性或相对强度。在大型褶皱翼部岩层向下滑动的尺度、速度及可行性,与层理面的倾斜度及拆离带的厚度、黏度等因素相关。类似的重力滑动构造在中上扬子地区的沉积岩层中常可观察到,同时,地表的滑坡、岩崩及山体垮塌...  相似文献   

Physico-chemical and nutrient variable stratifications in the water column and in macroalgal thalli as a result of high biomass mats in a non-tidal shallow-water lagoon     

《Marine pollution bulletin》2013,76(1-2):98-104

A field study to check parameter stratification during high density growth of four opportunistic macroalgae was carried out in Orbetello lagoon (Italy). The effects of macroalgal masses were compared with a seagrass meadow and two lagoon areas with bare bottoms as controls for pH, temperature, dissolved oxygen, salinity, nitrite, nitrate ammonium and orthophosphate. The nutrient content of thalli and sediment redox were measured. Macroalgae showed differences in stratification of thalli nutrient content. Mat with low density and high volume produced stratifications in the water column, but it did not produce nutrient release by sediment. In contrast, high density and low and high volume mats led to sharp falls in dissolved oxygen, with negative values of sediment Eh and anoxic trigger processes that presumably led to release of sediment nutrients. This depended on thallus type: heavy thalli compacted the mat and light ones distributed more widely in the water column.  相似文献   

Simulating and understanding effects of water level fluctuations on thermal regimes in Miyun Reservoir     

Zhongshun Li  Dejun Zhu  Yongcan Chen  Xing Fang  Zhaowei Liu  Wei Ma 《水文科学杂志》2013,58(5):952-969

ABSTRACT

Water temperature dynamics in a reservoir are affected by its bathymetry, climatic conditions and hydrological processes. Miyun Reservoir in China is a large and deep reservoir that experienced a large water level decline in 1999–2004 due to low rainfall and relatively high water supply to Beijing. To study changes of stratification characteristics in Miyun Reservoir from 1998 to 2011, the one-dimensional year-round lake model MINLAKE2010 was modified by adding a new selective withdraw module and a reservoir hydrological model. Simulation results under three scenarios demonstrated that the new MINLAKE2012 model accurately predicted daily water levels and temperature dynamics during the water level fluctuation period. The water level decline led to 7.6 and 3.8°C increases in the maximum and mean bottom temperatures and about 29 days reduction in the stratification days. These simulation results provide an insight into the thermal evolution of Miyun Reservoir during the planned future water filling process.