De nouveaux éléments structuraux du complexe aquifère profond du bassin du Rharb (Maroc) : implications hydrogéologiques     

Malika Kili  Bouabid El Mansouri  Jamal Chao  Abderrahman Ait Fora 《Comptes Rendus Geoscience》2006,338(16):1194-1202

The Rharb basin is located in northwestern Morocco. It is a part of one of the most important hydrogeological basins of Morocco, and extends over some 4000 km². The nature of its Plio-Quaternary sedimentary fill and its structural and palaeoenvironmental contexts are reflected by great variations in aerial and temporal facies distribution. This distribution, in turn, is a direct cause of the observed complexity in the geometry of potentially water-bearing beds. In the present work, we present an image of potential new hydrogeological reservoirs and define new structures that partially explain their architecture. To cite this article: M. Kili et al., C. R. Geoscience 338 (2006).  相似文献   

Application of back-propagation networks in debris flow prediction   总被引：6，自引：0，他引：6  

Tung-Chueng Chang  Ru-Jen Chao   《Engineering Geology》2006,85(3-4):270-280

Debris flows have caused serious loss of human lives and a lot of damage to properties in Taiwan over the past decades. Moreover, debris flows have brought massive mud causing water pollution in reservoirs and resulted in water shortage for daily life locally and affected agricultural irrigation and industrial usages seriously. A number of methods for prediction of debris flows have been studied. However, the successful prediction ratio of debris flows cannot always maintain a stable and reliable level. The objective of this study is to present a stable and reliable analytical model for occurrence predictions of debris flows. This study proposes an Artificial Neural Networks (ANN) model that was constructed by seven significant factors using back-propagation (BP) algorithm. These seven factors include (1) length of creek, (2) average slope, (3) effective watershed area, (4) shape coefficient, (5) median size of soil grain, (6) effective cumulative rainfall, and (7) effective rainfall intensity. A total of 178 potential cases of debris flows collected in eastern Taiwan were fed into the ANN model for training and testing. The average ratio of successful prediction reaching 93.82% demonstrates that the presented ANN model with seven significant factors can provide a stable and reliable result for the prediction of debris flows in hazard mitigation and guarding systems.  相似文献   

Threshold velocity for wind erosion: the effects of porous fences   总被引：3，自引：0，他引：3  

Zhibao Dong  Guangqiang Qian  Wanyin Luo  Hongtao Wang 《Environmental Geology》2006,51(3):471-475

Porous fence is a kind of artificial windbreak that has many practical applications. The threshold wind velocities at different distances downwind from porous fences were measured and the corresponding characteristics of particle movement observed to assess their shelter effect. It is found that the fence’s porosity is the key factor that determines the resulting shelter effect. The area near a fence can be typically classified into five regions, each with a different mode of particle movement. Dense fences, and especially solid fences, favor the accumulation of sand upwind of the fences. Fences with porosities of 0.3–0.4 produce the maximum threshold wind velocity; those with porosities of 0.3–0.6 (depending on the fence height) provide the maximum effective shelter distance. It is confirmed that the fence porosities of 0.3–0.4 that have been proposed for practical application in previous research are the most effective for abating wind erosion.  相似文献   

我国煤炭资源开发利用中某些问题的探讨   总被引：3，自引：0，他引：3  

罗景一  牛建英 《中国煤田地质》2006,18(3):6-10

针对我国煤炭资源开发利用中存在的诸如煤炭资源的低效率应用、无序开采、生态环境恶化等问题，指出了我国煤炭资源管理法规中存在的问题，提出了加强煤炭资源开发管理、构建煤炭循环经济体系、加大安全投入、加强煤炭矿区环境的治理和保护、健全有偿使用资源法规制度等对策。  相似文献   

不等电极距情况下高密度电阻率法的反演结果分析     

吴云超  王传雷  陈超 《物探与化探》2005,29(1):19-21

通过高密度电阻率法的模型实验,得出不等电极距情况对直立高阻薄板和低阻球体反演结果的影响:缺失电极对它正下方的ρ_s影响最大,而异常形态主要在水平方向有明显的变化,异常体随电极缺失的位置有趋势变化,电极缺失的数目越多,异常形态变化越大,但是从整体来看反演剖面图基本相似。  相似文献   

超声与振荡提取沉积物中松散结合态磷的比较     

罗俊凌罗爱芹  张月琴 《岩矿测试》2005,24(3):193-196

用超声技术提取沉积物样品中松散结合态磷,并与振荡提取结果进行比较。结果表明,超声提取结果与振荡提取结果大致相当。超声提取耗时短,操作简单易行,测试结果精密度为3.8%(RSD,n=7),可以替代振荡方法提取沉积物中的松散结合态磷。  相似文献   

甘肃西峰6.2～2.4MaB.P.红粘土中孢粉记录及古植被演化   总被引：2，自引：0，他引：2       下载免费PDF全文

李杰  旺罗  裴云鹏  彭淑贞 《第四纪研究》2005,25(4):467-473

通过对甘肃西峰赵家川6.2～2.4MaB.P.红粘土地层的孢粉学研究,建立了3个孢粉组合带。孢粉组合特征显示该区在此阶段总体为干旱的草原环境,6.2～5.8MaB.P.为灌丛草原;5.8～4.2MaB.P.是稀疏森林草原,植被由大量中生性草本植物和少量喜湿性的乔木植物组成,反映当时气候相对湿润;4.2～2.4MaB.P.植被中旱生植物藜科和麻黄明显增多,反映典型草原-荒漠草原。分析认为研究区自6.2MaB.P.干旱草原环境的格局就已经形成。红粘土中孢粉记录的植被演化信息与青藏高原隆升有时代上的耦合性,也与北极冰盖的起源和演化历史有着密切的联系。  相似文献   

CCSD在线流体监测捕获的气体地球化学异常与2004年9．3级苏门答腊地震可能的超远程关系   总被引：5，自引：0，他引：5  

曾令森许志琴  罗立强詹秀春梁凤华  杨经绥李海兵 《岩石学报》2005,21(2):521-524

中国大陆科学钻探工程在线流体地球化学监测在2004年12月10至2005年1月10日之间捕获到一段重要的气体地球化学异常。该异常从2004年12月24日晚上11点半开始到12月29日晚上7点半结束,其中在12月26日早上7点半到29日晚7点半这段异常非常特殊,表现出流体地球化学的剧烈变化。具体表现为流体组分从基本上不含Ar、He及N2跳跃到富含Ar、但亏损He和N2。该异常发生在2004年9.3级苏门答腊地震前1个半小时。由于CCSD现场离苏门答腊地震震中距离大于4170公里,大于该地震破裂长度1200公理的3倍,该地震在CCSD现场产生的静态应力变化微乎其微,不足以导致CCSD现场深部岩石或封闭破裂的岩石物理性质剧烈变化,因而可以排除静态激发效应的作用。在我国的云南和广东等地所观测到的地震异常和地下水位变化等表明2004年苏门答腊地震的动态激发效应主要沿东北方向,这和大地震的动态激发具有方向性一致。而CCSD现场就位于该方向上。我们推测2004年苏门答腊地震所产生的面波在CCSD现场激发的动态效应,导致库仑型失稳,增进深部岩石或破裂带的渗透率,释放富含Ar但亏损He和N2的流体,产生CCSD所观测到的气体异常。  相似文献   

西安市冬季采暖气象条件分析和预报方法初探   总被引：6，自引：2，他引：6  

庞文保 罗慧李建科  蔡新玲 《气象科技》2005,33(6):505-508512

对西安市冬季采暖气象条件和预报方法进行了研究。根据国家采暖规范结合西安冬季采暖的实际，首先对西安1951年7月到2003年6月历年的逐日气象资料进行了详尽的分析，比较了国家采暖日期相关规范和规定中的3种不同的统计方法，确定了符合西安特点的采暖初终日。充分利用T213数值预报产品，对2002年和2003年两个冬半年的逐日850hPa和500hPa各时次各类气象要素及与之对应的西安各时次实况的气温作了相关分析，建立了回归方程，提出了采暖期及其逐日气温预报。  相似文献   

2005年四川省水稻稻瘟病发生条件分析     

游超 《四川气象》2005,25(4):23-24

稻瘟病是四川省水稻生产上的一种重要流行性、灾害性病害，稻瘟病的爆发流行严重威胁着水稻产量的提高。本文针对导致2005年四川省稻瘟病的发生流行的菌源、品种抗性、气象条件进行分析，为农业气象服务对稻瘟病发生条件分析提供思路。  相似文献