Tectonic and hydrodynamic control of landslides in the northern area of the Central Rif, Morocco   总被引：1，自引：0，他引：1  

Jamal El Khattabi  Erick Carlier   《Engineering Geology》2004,71(3-4):255-264

The northern edge of the Central Rif (Morocco) is subject to numerous landslides where mechanisms do not correspond to the classical models used by geomechanics specialists. It is necessary to adopt a multidisciplinary approach that combines geomorphology, geology, hydrogeology, and geotechnics in order to understand how such slope failures are generated, especially in a region with a heterogeneous structure characterised by significant lithological differences, severe fracturing, and thrust sheets where tectonic contacts play a major role in groundwater circulation. This report shows that these failures are essentially controlled by the tectonic contact separating the Tisirene and Chouamat thrust sheets and by subsurface hydrodynamic conditions. A model of spatial and temporal variations in the factor of safety is proposed.  相似文献   

Modélisation morphodynamique cross-shore d'un estran vaseux     

Benoı̂t Waeles  Pierre Le Hir  Ricardo Silva Jacinto 《Comptes Rendus Geoscience》2004,336(11):1025-1033

Numerical experiments were performed to simulate the profile evolution of an intertidal mudflat with a 1D cross-shore morphodynamical model. First, the hydrodynamical forcing is a cross-shore tidal current due to semi-diurnal variations of the free surface elevation at the open boundary. Further, considering the conservation of the action density of surface gravity waves, a wave height (and resulting bottom shear stress) calculation is added to the morphodynamical model. Results of the numerical experiments show that the shape of the profile reaches equilibrium. The mudflat progrades continually when the forcing is tide only, whereas it can be steady under the simultaneous action of tide and waves. To cite this article: B. Waeles et al., C. R. Geoscience 336 (2004).  相似文献   

SPS-600型水井钻机研制及配套要点          下载免费PDF全文

张西坤  杨冬冰 《探矿工程》2004,31(7):35-36,47

介绍了SPS-600型散装水井钻机的主要技术参数，并对各主要参数进行了详细说明，同时介绍了研制过程中的配套要点。该钻机在实际施工中应用效果良好。  相似文献   

Crustal thickening in an extensional regime: application to the mid-Norwegian Vøring margin     

J.W. van Wijk  R. van der Meer  S.A.P.L. Cloetingh 《Tectonophysics》2004,387(1-4):217-228

The structure of the mid-Norwegian volcanic Vøring margin at the onset of the Maastrichtian–Paleocene extension phase reflects the cumulative effect of earlier consecutive rifting events. Lateral structural differences present on the margin at that time are a consequence of migration of the location of maximum extension in time between Norway and Greenland. The most important imprints (Moho depth, thermal structure) of these events on the lithosphere are incorporated in a numerical simulation of the final extension phase. We focus on a possible mechanism of formation of the Vøring Marginal High and address the relationship between spatial and temporal evolution of crustal thinning and thickening, uplift of the surface and strength of the lithosphere.It is found that the Vøring Basin formed the strongest part of the margin which explains why the Maastrichtian–Paleocene rift axis was not located here but instead jumped westward with respect to the earlier rift axes locations. The modeling study predicts that local crustal thickening during extension can be expected when large lateral thermal variations are present in the lithosphere at the onset of extension. Negative buoyancy induced by lateral temperature differences increases downwelling adjacent to the rifting zone; convergence of material at the particular part of the margin is mainly taken up by the lower crust. The model shows that during the final phase of extension, the crust in the Vøring Marginal High area was thickened and the surface uplifted. It is likely that this dynamic process and the effects of magmatic intrusions both acted in concert to form the Marginal High.  相似文献   

基于神经网络的区域生态环境分类方法研究   总被引：3，自引：0，他引：3  

乔平林  张继贤  卢秀山  高武俊  张运生 《地理与地理信息科学》2004,20(2):97-99

如何利用智能化信息提取技术,进行区域生态环境自动分类,一直是一种前沿性研究。该文在分析研究区自然景观特征的基础上,总结了影响区域生态环境的建模要素,基于神经网络技术,并根据生态环境的遥感探测机理,利用TM卫星遥感数据中的可见光、热红外、植被指数(NDVI)以及DEM数据,建立了基于BP神经网络的区域生态环境信息自动提取模型,形成了一种新的生态环境分类方法,其分类结果与实际情况完全一致。  相似文献   

东吴小筑园林植物应用评价   总被引：1，自引：0，他引：1  

彭丽彬 《云南地理环境研究》2004,16(4):75-78

园林植物配置是园林植物应用的重要内容，对充分发挥园林功能和观赏特性具有重要作用。通过对东吴小筑入口、前庭小院、主景区、山林区、园路、出口等6个功能区园林植物水平配置的现状调查，分析了本景区园林植物的物种多样性、水平结构、垂直结构、色彩变化等特征。结果表明：东吴小筑园林景观营造中．植物配置显示出较高水准。在树种选择、树丛组合、层次搭配、空间组织、色彩表现、季相变化等方面的设计布局十分精细，对今后园林设计及园林绿化水平的提高具有较好的指导作用。  相似文献   

Weights of Evidence Modeling of Mineral Potential: A Case Study Using Small Number of Prospects,Abra, Philippines   总被引：9，自引：1，他引：9  

Carranza  Emmanuel John M. 《Natural Resources Research》2004,13(3):173-187

Weights of evidence (WofE) modeling usually is applied to map mineral potential in areas with large number of deposits/prospects. In this paper, WofE modeling is applied to a case study area measuring about 920 km² with 12 known porphyry copper prospects. A pixel size of 100 m × 100 m was used in the spatial data analyses to represent in a raster-based GIS lateral extents of prospects and of geological features considered as spatial evidence. Predictor maps were created based on (a) estimates of studentized values of positive spatial association between prospects and spatial evidence; (b) proportion of number of prospects in zones where spatial evidence is present; and (c) geological interpretations of positive spatial association between prospects and spatial evidence. Uncertainty because of missing geochemical evidence is shown to have an influence on tests of assumption of conditional independence (CI) among predictor maps with respect to prospects. For the final predictive model, assumption of CI is rejected based on omnibus test but is accepted based on a new omnibus test. The final predictive model, which delineates 30% of study area as zones with potential for porphyry copper, has 83% success rate and 73% prediction rate. The results demonstrate plausibility of WofE modeling of mineral potential in large areas with small number of mineral prospects.  相似文献   

On the mechanism and source parameters of the deep crustal Jabalpur earthquake, India, of 1997 May 21: constraints from aftershocks and changes in static stress   总被引：2，自引：0，他引：2  

V. K. Gahalaut  V. K. Rao  H. C. Tewari 《Geophysical Journal International》2004,156(2):345-351

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松花湖富营养化现状及其影响因素分析   总被引：8，自引：1，他引：8  

王霞  吕宪国  张学林  张竹青 《湿地科学》2004,2(4):273-278

通过2002年和2003年对东北地区松花湖水体富营养化状况进行调查和采样分析，对大量数据的多元相关分析和多元逐步回归分析、AGP试验和利用综合营养状态指数法进行评价。结果表明：松花湖处在中营养和轻度富营养状态；总磷是限制水体富营养化的主要因子之一。水体中变温层的形成，限制了上、下层湖水的混合，对下层水体中的溶解氧、无机氮和可溶性磷酸盐产生影响，随着变温层的消失，下层内的营养物质转移到湖上层，为藻类的繁殖提供条件。  相似文献   

我国农村合作医疗的地区模式     

宋韬 《世界地理研究》2004,13(4):75-78,85

农村合作医疗是我国农村主要的医疗保障形式。但是由于我国各地社会经济发展水平不平衡，中央政府的扶持政策也有所不同，合作医疗出现了多种不同的地区模式。高收入地区、中等收入地区及低收入地区的合作医疗在筹资方式、管理方式和补偿方式上都各有特点。  相似文献