基于高效节水模式下的永济市水量供需平衡分析

重点实施高效节水,能有效地改善农业灌溉条件,从根本上解决灌溉水利用率低的现状,提高农业用水效率,达到农业增产、农民增收的目的。本文以永济市为例,在采用引黄灌区水灌溉与高效节水灌溉方式下拟定灌溉水利用系数,利用灌溉定额进行水量计算,并且进行水量平衡分析,结果满足灌区的用水需要。本文研究可为拟定合理的节水灌溉措施与水资源的高效利用提供科学的理论依据。     

北方某地山区板栗节水灌溉制度研究

以某地下水高效节水灌溉项目为载体,对山区板栗节水灌溉制度进行研究,理论计算确定灌水定额、灌溉周期、单井控制灌溉面积及灌溉工作制度等,并通过实地调查当地以往灌溉经验,对理论计算成果进行充分验证,确保理论计算的准确性,为该地区及类似地区板栗节水灌溉提供借鉴,为山区经济发展提供技术支持.     

基于水量平衡的高效节水潜力计算

为解决传统潜力计算方法不能清晰体现节水指标波动幅度问题,提出基于水量平衡的新型高效节水潜力计算方法。通过划分需水系统的方式,确定系统内部结构及特征分类情况,明确水量平衡关系,完成基于水量平衡需水量预测。在此基础上,定义节水指标并对其进行深度简化,确定运算公式,完成高效节水潜力计算分析。与传统潜力计算方法相比,应用基于水量平衡的高效节水潜力计算方法,节水指标的波动幅度得到明确体现。     

滴灌管网水力计算及水源工程设计分析

节水灌溉主要方式之一是采用滴灌,目的是提高灌溉用水有效利用系数,从而节约水量,使粮食产量大幅度增加。从灌溉方式、制度、定额、输水管道及水量损失等方面进行了阐述,并对水源工程设计进行了初步探讨。     

桂西北山丘区芒果高效节水灌溉技术研究与推广

介绍了桂西北山丘区芒果灌溉定额及灌溉制度、集雨高效节水灌溉技术、常规提水灌溉技术等研究成果,结合桂西北芒果高效节水灌溉工程实例,分析总结发展芒果高效节水灌溉产生的经济效益、社会效益和环境效益。     

南疆地区沙雅县渭干河灌区供需水平衡分析

结合渭干河灌区高效节水工程,依据相关政策制定灌区用水总量红线.根据灌区规划,充分考虑作物种植结构及灌溉需求上制定灌区灌溉制度,计算灌区不同月份灌溉需水量,通过理论计算及类比分析,综合确定灌区现状及规划年灌溉水利用系数,从而分析灌区供需水平衡.结果表明:高效节水工程建设后,灌溉水利用效率提高,灌区毛灌溉定额及灌溉水利用系...     

灌溉制度的分类

作物灌溉制度是确定灌溉用水量、设计灌溉工程、编制用水计划的基本依据。灌溉制度的内容:包括灌水时间、灌水定额、灌水次数、灌溉定额以及实现灌水定额的灌水方法等。 灌溉制度按灌溉设施所提供的水量及使用这部分水量的效益可划分为充分供水的高额丰产灌溉制度、非充分供水的节水灌溉制度和限额供水灌溉制度三类: 充分供水的高额丰产灌溉制度是指灌溉     

推广非充分灌溉技术效益显著

非充分灌溉是利用有限的水量,即少于充分灌溉的水量,不以追求传统的单产最高为目标,而以总产值最佳为目标,通过优化水量分配执行的一种节水管理,即“有意给作物少灌水,如减少灌水次数或减少灌溉定额”,达到高效条件下净效益最大(或费用最小)的目标,将节约的水量用来扩大灌溉面积,以提高单位水量的产值效益,追求灌区总的经济效益最大为目标。非充分灌溉技术的研究与推广,将为实现节水灌溉农业发挥重要作用,为水资源的最优化管理提供新的途径。     

小管出流在农田水利工程中的应用

小管出流又称涌泉灌,是比较成熟的高效节水灌溉技术,适用于果树、苗圃灌溉。本文通过对陕西省商洛市商州区张村某片区核桃种植区小管出流灌溉系统设计,对小管出流管网布置、灌溉制度、工作制度、流量及水量的计算、水泵选型等进行探讨。     

辽宁省水田节水潜力分析

对辽宁省近7年用水结构进行分析,水田历年用水量均占全省总用水量的44%以上,是辽宁省的主要用水户。根据5个灌溉分区代表站的气象等资料,采用彭曼公式及水量平衡法确定了水稻在浅湿晒节水灌溉模式下的灌溉制度,分析转换节水灌溉模式后水田的节水潜力,对实现节约用水,提高水资源利用效率具有一定的借鉴意义。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

基于BP神经网络-马尔科夫链模型的隧道围岩位移预测

在隧道工程施工中,围岩位移预测起着很重要的作用。将BP神经网络-马尔科夫链模型引入到隧道围岩位移预测中来,通过对训练样本的学习,利用BP神经网络实现了对位移时间序列的滚动预测,同时得到了实测值与预测值的相对误差;在此基础上利用马尔科夫链对相对误差进行修正,有效地提高了预测结果的精度。并将该模型应用于某公路隧道拱顶下沉位移时序预测中,结果表明该模型具有精度高、科学可靠的特点,为隧道围岩变形的预测提供了新的途径。     

Short communication. Pipelines as a refuge for freshwater snails

In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment.     

浙江省水域调查录入系统的设计和应用

浙江省水域调查录入系统将调查数据与电子地图相整合,对分类水域数据进行统计计算,并对输入数据进行合理性和完整性检查,得到调查范围内现有水域的详细数据,实现了水域调查数据输入、计算、统计和查询的数字化管理,提高了工作效率和工作质量,为各地下阶段水域保护规划编制和水域管理工作提供了数据支持。对该系统的设计原则、功能和技术设计等作了介绍。     

基于CT-连续加荷水泥乳化沥青混凝土细观损伤规律研究

利用CT技术对水泥乳化沥青混凝土的细观损伤过程进行实时扫描观测,获得了混凝土试件在连续加荷下的CT图像。通过采用直观分析法、CT数分析法、CT数与损伤变量关系3种方法分析表明,水泥乳化沥青混凝土的破坏过程可分为压密、扩容、裂纹扩展、破坏4个阶段,同时混凝土在受压过程中具有韧性,在极限荷载之前各断面处于压密和微扩容的强化阶段,极限荷载之后混凝土从损伤到破坏发展比较平稳。     

Automated system for removal and pneumatic transport of fly ash from electric precipitator hoppers

A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system, configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants of dry ash utilization and the advantages of producing of size-separated particles are considered. __________ Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008).     

The flood pulse advantage and the restoration of river-floodplain systems

The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed.