黄河影响下开封城市的历史演变   总被引：2，自引：0，他引：2  

李润田  丁圣彦  李志恒 《地域研究与开发》2006,25(6):1-7

河流对城市的形成和发展起着重要的作用,古人形象地把其比喻为“城市之血脉”。文章从不同的历史时期黄河及其分支对开封城市演变的影响进行分析,得出黄河与开封城市的关系存在着利与害的统一。开封城市的历史发展,即得益于黄河充足的水源,又受害于其频繁的决溢、泛滥、改道。因此,要采用先进的科学技术对黄河进行综合治理开发,使其恢复它应有的美好环境,更好地造福于人民。  相似文献   

顶管施工中顶力与顶程关系及其影响因素分析     

向安田丁文其  朱合华 《探矿工程》2006,33(10):29-31,34

以上海某长距离急曲线顶管工程为例，通过现场实测4节管段顶进过程中的顶力，研究了顶力随顶程的变化规律，系统分析了顶进过程中顶力的主要影响因素，得到了一些有用的结论。  相似文献   

Comments on the article “Determination of groundwater availability in shallow arid region aquifers utilizing GIS technology: a case study in Hada Al-Sham, Western Saudi Arabia” by A. S. El-Hames and K. A. Al-Ahmed (Hydrogeology Journal (2005), Volume 13, No.4, p 640–648, and Erratum in Volume 13, No. 4, p 649).     

Khaled S. Balkhair 《Hydrogeology Journal》2006,14(7):1380-1382

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Geomorphic effects of rural-to-urban land use conversion on three streams in the Central Redbed Plains of Oklahoma   总被引：2，自引：1，他引：2  

Ranbir S. Kang  Richard A. Marston   《Geomorphology》2006,79(3-4):488

This research evaluates the impact of rural-to-urban land use conversion on channel morphology and riparian vegetation for three streams in the Central Redbed Plains geomorphic province (central Great Plains ecoregion) of Oklahoma. The Deep Fork Creek watershed is largely urbanized; the Skeleton Creek watershed is largely rural; and the Stillwater Creek watershed is experiencing a rapid transition from rural to urban land cover. Each channel was divided into reaches based on tributary junctions, sinuosity, and slope. Field surveys were conducted at transects in a total of 90 reaches, including measurements of channel units, channel cross-section at bankfull stage, and riparian vegetation. Historical aerial photographs were available for only Stillwater Creek watershed, which were used to document land cover in this watershed, especially changes in the extent of urban areas (impervious cover).The three streams have very low gradients (< 0.001), width-to-depth ratios < 10, and cohesive channel banks, but have incised into red Permian shales and sandstone. The riparian vegetation is dominated by cottonwoods, ash, and elm trees that provide a dense root mat on stream banks where the riparian vegetation is intact. Channels increased in width and depth in the downstream direction as is normally expected, but the substrate materials and channel units remained unchanged. Statistical analyses demonstrated that urbanization did not explain spatial patterns of changes in any variables. These three channels in the central Redbed Plains are responding as flumes during peak flows, funneling runoff and the wash-load sediment downstream in major runoff events without any effect on channel dimensions. Therefore, local geological conditions (similar bedrock, cohesive substrates and similar riparian vegetation) are mitigating the effects of urbanization.  相似文献   

西藏昌都镇地质灾害发育特征及防治对策   总被引：1，自引：1，他引：1  

汤明高  许强  马和平  成民  杜先兴 《中国地质灾害与防治学报》2006,17(4):11-16

昌都镇位于澜沧江上游“三河一江”地带(即昂曲、扎曲、色曲、澜沧江)。地质构造条件复杂,气候较恶劣,昼夜温差大,物理风化强烈,植被稀疏,地质灾害发育。该区是藏东的政治、经济、文化中心。随着地区的经济发展,其城镇建设与地质灾害之间的矛盾日益突出。调查研究显示昌都镇发育地质灾害33处,其中崩塌16处,占灾害点总数48.5%,主要发育于路堑边坡和河流下切侧蚀形成的自然边坡;滑坡13处,占灾害点总数的39.4%,且90%为土质滑坡,多与人类工程活动有关;泥石流4处,占灾害点总数的12.1%,以中小型为主。文章总结了昌都镇崩塌、滑坡和泥石流灾害的发育分布特征,地质灾害与地层岩性、空间位置和人类工程活动等之间的关系,以及对昌都城镇建设和发展的影响。结合调查分析提出了昌都镇地质灾害防治的总体策略———治灾、设防、治水、治坡、生态建设和加强环保意识。  相似文献   

相对湿度对静电收集型连续测氡仪检定结果的影响   总被引：1，自引：0，他引：1  

宋刚  张伯友  龚经平 《矿物岩石地球化学通报》2002,21(1):58-60

NR－667A（Ⅲ）型快速连续测氧仪是目前环境氡测量时间响应最短的一种仪器。该仪器在核工业第六研究所标准氡室进行检定时发现，环境相对相对度对仪器检定结果有很大影响。在相对湿度为80％－99％的标准氡室内分别对仪器进行检定，结果在相对湿度为80％时仪器检定合格，而在相对湿度为99％时仪器检定不合格。本从仪器工作原理对检定结果进行。并提出有效的解决方法，当相对湿度太大时，可在仪器进气口安装干燥器对进气进行除湿。  相似文献   

Analysis and comparison of the tidal gravity observations obtained with LCR-ET20 spring gravimeter     

孙和平  陈晓东  刘明  周百力 《地震学报(英文版)》2002,15(5):533-539

Introduction The tidal variation signals of the solid Earth recorded with the modern measuring techniques can be used to provide effectively the means to cognize the Earths motion, deformation and structure character, especially to monitor the material motion in the Earths interior. In the recent 20 years, the distribution character of the global gravity field has made great progress since the continuous and deep theoretical studies in geophysics and geodesy domains. The successful manufactur…  相似文献   

国外开发欠发达地区的经验教训对中国西部城镇化的启示     

梁德阔 《云南地理环境研究》2003,15(3):55-62

美国、英国、日本、意大利、巴西等国先后对本国欠发达地区进行了开发建设。它们以城镇化为动力、大力发展城镇工业，已经取得许多成功经验，也有着深刻的教训。中国西部大开发可从国外开发欠发达地区的经验教训中受到启迪，以城镇化为增长点带动区域经济的全面发展，重视生态环境的保护和建设，加强以交通运输为重点的城镇基础设施建设，探索出西部地区城镇工业独特的发展道路，实现经济、社会和环境的可持续发展。  相似文献   

Sensitivity Analysis of a Feedforward Neural Network for Considering Genetic Mechanisms of Kuroko Deposits     

Matsuda  Setsuro  Koike  Katsuaki 《Natural Resources Research》2003,12(4):291-301

Exploration for volcanogenic massive sulfide deposits of the kuroko-type is underway in many places. Clarifying the spatial patterns of the metals in kuroko deposits will be useful for understanding their genetic mechanisms and for future exploration of such types of deposits. This study represents a spatial distribution analysis on the contents of principal metals of kuroko deposits: Cu, Pb, and Zn, in the Hokuroku district, northern Japan, by a feedforward neural network and 1917 sample data at 143 drillhole sites. The network, which consists of three layers, was trained by the principle of SLANS in which the numbers of neurons in the middle layer and training data are changed to improve estimation accuracy. Using the weight coefficients connecting adjacent neurons, sensitivity analysis of the neural network was carried out to identify factors influencing spatial distributions of the three metals. The coordinates depth (z) direction, Bouguer gravity, and specific lithology such as dacite were determined to be influencing factors. The high frequency of the z coordinate signifies that the metal contents differ to a large extent by depth. The sensitivity vector was defined using sensitivity coefficients for x, y, and z coordinates of an estimation point. We determined that the directions of large vectors were different inside and outside of the Hanawa-Ohdate area. This characteristic is considered to originate from the differences in the permeability of fractures that became the paths for rising ore solutions, and the depths that the solutions mixed with sea water.  相似文献   

锦江水库坝址③号断裂构造破碎带地质特征及其对堤坝安全性的影响     

黄成炽  黄维旺  李志勤 《四川地质学报》2003,23(2):109-111

通过野外地质调查和地球化学探测成果，结合区域地质发展史，论述锦江水库③号断裂构造破碎带的地质特征及其对建筑物的影响。  相似文献