城区穿河隧道工程安全施工关键技术探究

随着城市地下空间的开发,盾构穿越已有河道的现象越来越普遍。如何合理地安排施工过程,确保河道上建筑物和施工安全尤为重要。以南京地铁四号线某区间盾构穿越秦淮河线路工程为例,总结克服施工过程中盾构隧道下穿河道和侧穿桥墩技术难题的经验,保证其安全、顺利地通过秦淮河河段。     

飞来峡水利枢纽对北江河流综合影响研究

综合分析飞来峡水利枢纽平面布置、运行管理等方面,对北江河流水流流态、河道变化、水质、水温、水生物等方面的影响。枢纽建设运行有不利的影响因素,对河流生态方面的影响提出改进的建议。     

城市近郊蓄滞洪区非洪水期调度运行管理研究--以治理深圳河第四期工程为例

针对城市近郊蓄滞洪区的功能和运行管理特点,以治理深圳河第四期滞洪区工程为例,从滞洪区地形和区域布置合理性着手,分析滞洪区与上下游河道水力高程特点,开展了非洪水期蓄水、泄水过程模型试验研究。建立了基于理想理论的湿地水体环境水体更换周期预测模型,研究多因素条件下的滞洪区湿地水体置换周期。为保障非汛期滞洪区生态湿地景观水位和良好水质状态,根据上游河道来水条件,制定了滞洪区进水闸、泄水闸调度备用运行方案。     

渭河流域水沙关系分析

本文以渭河流域为研究对象,对流域水沙关系进行了分析研究。选择咸阳以下四个水文站研究流域水沙关系的变化,结果表明:年径流量和输沙量呈正相关关系,在径流序列发生第一次变异之前,水沙关系优于第一次突变之后,即在1970年后,受人类活动的影响,水沙关系朝着不协调的方向发展。     

USE OF NATIVE AND NONNATIVE NEST PLANTS BY RIPARIAN‐NESTING BIRDS ALONG TWO STREAMS IN NEW MEXICO

Nonnative plant invasions are a management concern, particularly in riparian forests, but little is known about mechanisms through which they influence vertebrate communities. In the American Southwest, native trees such as cottonwood (Populus spp.) are thought to provide better habitat for breeding birds than nonnative plants, which are more tolerant of human‐altered conditions. To evaluate effects of riparian forest composition on riparian‐nesting birds, we examined nest plant use along two rivers in New Mexico that differed in abundance of nonnative vegetation. Of the nests we observed, 49% along the Middle Rio Grande were constructed in nonnative plants, compared with 4% along the Gila River. Birds in the canopy and cavity‐nesting guilds constructed less than 5% of their nests in nonnative plants along either river. At the Middle Rio Grande, birds in the subcanopy/shrub guild constructed 67% of their nests in nonnative plants. Despite the relatively low availability of cottonwoods, they were used by greater numbers of species than any other woody plant at either river. Riparian obligates and species of conservation concern in the canopy and cavity guilds were especially dependent on cottonwood and Arizona sycamore (Platanus wrightii). Our results show that, although nonnative trees and shrubs support large numbers of nests for certain birds, cottonwoods and other large native trees are disproportionately important to riparian bird communities. Copyright © 2013 John Wiley & Sons, Ltd.     

DAILY AVERAGED 2D WATER TEMPERATURE MODEL FOR THE ST. LAWRENCE RIVER

A daily averaged two‐dimensional water temperature model has been developed for the freshwater part of the St. Lawrence River, between Lake St. Louis and Trois‐Rivières (Québec, Canada). The model was first calibrated and validated for the area of Lake St. Pierre, a natural enlargement of the river subject to strong lateral and longitudinal thermal variations. Forecasts from the Global Environmental Multiscale model were used in preference to observations from meteorological stations for model inputs, both to increase the spatial resolution and ultimately to allow the water temperature model to be used in predictive mode. The resulting model provided daily water temperature estimates with an overall root mean square error (RMSE) of 1.18 °C and a Nash–Sutcliffe coefficient of 0.44. Comparisons between Landsat images and simulations demonstrated that the model not only simulated accurate water temperature values but also showed the adequacy of the model in general. It not only simulated local water temperature relatively accurately but also provided a good representation of the spatial water temperature patterns within the study area. The error varied between deep and shallow water areas. In deeper water, the overall RMSE is 0.41 °C, and the modified Nash coefficient rises up to 0.92. Because shallow water areas are subject to greater variations, longer, more spatially dense data sets will be needed to refine the hydrodynamic and thermal budget models for those specific areas. Copyright © 2013 John Wiley & Sons, Ltd.     

一种虚拟镜像型交通物联网框架设计与实现

为解决目前中国交通信息分散、封闭、低效的现状,构建起城市道路交通“镜像型虚拟世界”,并与“物理实体世界”互联、互通和互反馈控制。提出了基于组件、以事件为中心的交通物联网仿真框架,运用VC＋＋2008和虚拟现实开发引擎Delta3D技术,开发面向物联网时代的智能交通公共服务平台,实现城市交通全样本、全时空、全过程的感知调控。     

黄河源区河道冰凌特征变化及影响因素分析

黄河流域是我国凌汛灾害常发的地区,其中黄河源区是黄河上游凌情研究的空白区。为掌握该区域的凌情规律,对黄河沿-唐乃亥河段黄河沿、吉迈、玛曲3个常封断面的气象资料(1960-1987,2007-2011)和水文资料(1960-1987,2007-2011)进行研究,分析3个站的封河、开河日期以及冬季最大冰厚的变化规律,得出黄河源区封河从黄河沿附近开始向下游延伸,封河日期和开河日期均有推迟趋势,但总封冻天数在减少,冬季最大冰厚则各站趋势不同。通过对冬季气温、流量等因素进行分析,得出冬季累计负气温和冬季平均流量对于凌情主要特征的影响十分显著,可以作为预报因子进行进一步的研究。     

气象因子在海河流域蒸发悖论中的作用机理

蒸发是水文循环的重要环节。利用Mann-Kendall趋势检验方法检测了海河流域1961-2006年蒸发皿蒸发量的演变趋势。结果表明:海河流域蒸发皿蒸发量呈现出显著的下降趋势。利用相关分析、偏相关分析和主成分分析方法,研究了蒸发皿蒸发量与平均气温、相对湿度、平均风速和日照时数4种气象因子之间的关系。基于这4种气象因子,建立了模拟蒸发皿蒸发量的经验公式(E-THWS公式),并利用这一公式的微分形式揭示了这4种气象因子在海河流域"蒸发悖论"中的作用。结果表明:平均气温和相对湿度对海河流域蒸发皿蒸发量的增加作用要小于平均风速和日照时数的减少作用;平均风速的下降是蒸发皿蒸发量下降的主要原因。     

黄河三角洲水土资源空间匹配格局探析

水土资源二者在空间上的匹配程度直接影响着区域农业的可持续发展、资源的可持续利用。本文以黄河三角洲中心城市东营市及所辖区县为研究区域,分析了该区域水土资源空间分布的差异、构建了水土资源匹配测算模型、测算了水土资源匹配系数、划分了水土资源空间匹配程度。结果表明:该区域水土资源总体呈现出"土地资源丰富,水资源缺乏"的态势;东营市水土资源匹配系数为0.19万m3/hm2,低于山东省平均水平0.30万m3/hm2,更远远低于全国平均水平1.72万m3/hm2,东营市各区县水土资源匹配系数利津县最低0.07万m3/hm2,广饶县最高0.42万m3/hm2,相差达到0.35万m3/hm2。研究区水土资源空间匹配程度总体呈现出"南高、北次之、中间低"的格局;地表水资源短缺、地下淡水资源非常有限,是导致黄河三角洲水土资源空间匹配程度差的主要限制因子。