宁夏半干旱区玉米滴灌灌溉制度试验研究

为了促进宁夏半干旱区节水灌溉技术的推广应用,本文针对宁夏扬黄灌区规模推广玉米大田滴灌缺乏相关滴灌灌溉制度的突出问题,采用大田小区对比试验与示范区技术应用监测相结合的方法,开展了玉米裸地滴灌灌溉制度试验研究。在综合分析玉米生育期灌溉定额、土壤含水率变化、耗水量、作物产量、水分生产效率的基础上,研究提出了玉米生育期滴灌11~12次、灌水定额300~450 m3/hm~2,灌溉定额4 200~4 425 m3/hm~2的滴灌灌溉制度。研究结果表明:玉米大田滴灌目标产量15 000 kg/hm~2,水分生产效率达到3.0 kg/m3,玉米滴灌较大田畦灌可提高经济效益3 735元/hm~2,同时节水1 800 m3/hm~2、节水30%以上。     

农业用水静态效率冗余调控影响因素分析

为研究农业用水静态效率冗余调控的影响因素,以农业经济为导向构建 DEA 模型测度农业用水静态效率,以静态效率松弛变量为基准量化冗余离散偏差测算定量调控比例,运用相关矩阵等分析调控影响因素,并以安徽省为例进行分析。农业经济导向下2006—2020年间安徽省农业用水静态效率总体呈上升趋势,空间维度呈马鞍形分布;农业用水静态效率时间维度冗余率53.3%,DMU 定量调控比例2.63%;空间维度冗余率81.3%,DMU 定量调控比例15.5%。研究表明：农业用水静态效率冗余调控受模型容纳能力与纯技术效率影响,农业用水总量冗余调控会造成产出失控应优先考虑效率模型容纳能力;纯技术效率冗余影响率88.5%且对各DMU冗余呈负相关影响,通过提升管理技术水平可减少农业用水静态效率冗余。该研究可为各地区农业用水静态效率冗余调控提供参考。     

避雨微喷灌水肥一体化技术在桃树中的应用

避雨条件下微喷灌水肥一体化技术对桃子生长过程、糖度、产量影响的试验结果表明,该模式具有明显的节水、节肥、增产等特点。与常规灌溉施肥方式相比,与露天微喷灌水肥一体化技术相比,采用避雨微喷灌水肥一体化技术节水约2 157.0 m~3/hm~2,节水率为43.0%;与常规灌溉技术相比,能够节约用水6 280.4 m~3/ hm~2,节水率为68.7%,节约肥料862.1 g/hm~2,节肥率为37.1%;与普通灌溉施肥方式、露天微喷灌水肥一体化技术相比,采用避雨微喷灌水肥一体化技术能够提高桃子尺寸(横径及纵径)2,1 mm,糖度增加0.21、0.13,增产 1 874,1 349 kg/ hm~2,肥料产出率增加6 500、900 g/g。     

基于水肥耦合效应的苹果精量灌溉制度研究

针对宁夏中部干旱带苹果水肥利用效率低的问题,以5a生滴灌苹果为研究对象,分析不同水肥处理条件下滴灌苹果根区土壤水分动态、耗水规律和水分生产效率。得出在枯水年型下苹果水肥耦合滴灌灌溉制度为灌溉定额3300m~3/hm~2,灌水次数12次,其中萌芽开花期2次,落花后2次,花芽分化期2次,果实膨大期3次,成熟期2次,落叶期1次。施肥定额705kg/hm~2,肥料配比N∶P2O5∶K_2O为12∶7∶13,施肥7次,其中萌芽期施肥1次,落花后2次,花芽分化期1次,果实膨大期2次,成熟期1次。在该水肥耦合灌溉制度下5a生新红星苹果产量为6237kg/hm~2,灌溉水利用效率为1.89kg/m~3;水分生产效率为1.21kg/m~3。     

河北平原地下水质变及农药化肥施用量变化影响

1970年河北平原年均化肥使用量仅为18.5万t,平均耕地施肥量27.04 kg/hm2;1985年农药使用量3.26万t/a,平均耕地施药量4.94 kg/hm2.至2005年,化肥使用量达到303.4万t,平均耕地施肥量为506.58 kg/hm2,净增16.7倍;农药使用量8.08万t/a,平均耕地施药量13.49 kg/hm2,净增173.1%.农用化肥和农药在农田施用量不断提高,加之河北平原地下水补给量不断减少、开采量不断增大,已导致地下水的天然化学物质平衡遭到破坏,HCO3-Cl型地下水分布面积由1985年的1 250 km2增至2005年的6 980 km2、HCO3-SO4型地下水面积由4 210 km2增大为16 450 km2、SO4-HCO3型地下水面积由498 km2增大为1 330 km2、Cl-HCO3-SO4型地下水面积由96 km2增大为1 170 km2,而HCO3型地下水面积大幅减少.若按2000年-2006年多年平均雨水资源量、总水资源量和地下水资源量均承考虑,则每方雨水资源、总水资源和地下水资源中化肥、农药含量分别为37.4 g/m3、249.9 g/m3、292.6 g/m3和996.1 g/m3、6 655.4 g/m3、7 792.3 mg/m3.1959年河北平原的石家庄地区地下水中NO3平均含量仅为2.35 mg/L,至2005年NO3平均值高达56.2 mg/L.因此,急需重视化肥、农药最佳施用量与地下水安全及粮食安全之间关系对策研究.     

石津灌区运行调度环境效益与环境问题

1 灌区概况 河北省石津灌区是以农业灌溉为主,兼发电和城市工业供水的大型灌区,地处河北平原中南部,太行山东麓,工程控制土地面积4 144km~2,设计灌溉面积16.67hm~2,受益范围包括石家庄、衡水、邢台的14个县市。主要灌溉作物为冬小麦、棉花。 灌区总干渠长134.24km,渠首设计流量100m~3/s,最大流量可达120m~3/s。干渠8条,总长183km,分干渠30条,总长379km,支渠268条,总长866km,斗渠2 429条,总     

环塔盆地不同施氮量对滴灌核桃生长及产量的影响

为解决新疆核桃树在氮肥利用上存在的高耗低效问题,探讨滴灌条件下不同施氮量对核桃生长及产量的影响,于2016年新疆农业大学林果实验基地开展滴灌核桃大田试验。以9 a生新温"185"核桃树为研究对象,设置3个氮肥(含氮量)梯度(低肥N1 0.37 kg/株,中肥N2 0.74 kg/株,高肥N3 1.47 kg/株),研究了滴灌条件下不同施氮量对核桃叶片SPAD值、叶面积指数、果实体积、产量及品质的影响,分析了不同施氮量下水、氮利用效率。试验结果表明:随着施氮量的增加,核桃的叶片SPAD值和叶面积指数呈现先增后减的趋势;果实体积增加至恒定后表现为:N2N3N1。低肥和中肥处理下核桃的个数、产量和出仁率均差异显著,说明增加施氮量显著提高了核桃产出;而高肥处理下产量和中肥处理无显著性差异,核桃产量在中肥处理下达到最大值,为2 854.38 kg/hm~2。蛋白质和脂肪在三种氮肥水平下无显著性差异;中肥处理下水分利用率最高;氮肥偏生产力与施氮量显著负相关。因此在环塔盆地滴灌条件下,中肥处理N2,即每株核桃施氮0.74 kg为最佳的施肥量。研究结果对类似地区核桃滴灌施肥管理具有参考意义。     

滴灌施肥对温室油桃产量及水肥利用效率的影响

以温室油桃为试验材料,探明滴灌施肥条件下,不同灌水和施肥水平对油桃产量及水肥利用的影响。试验设置3个灌水水平,W1(90%θ_f)、W2(75%θ_f)、W3(60%θ_f)(θ_f为田间持水量),当任一水分处理的土壤含水率达灌水下限50%θ_f时开始统一灌水;设置3个NPK施肥水平:F1(130%F2)、F_2(N 200 kg/hm~2+P_2O_5 120 kg/hm~2+K_2O 240 kg/hm~2)、F3(70%F2),完全组合,并以当地灌水施肥方式为对照(CK)。结果表明:CK的产量较低,水肥利用效率低,滴灌施肥油桃产量、水分利用效率、偏肥料生产力受灌水和施肥水平及交互效应影响显著(P0.05)。低水低肥处理产量均较低,中水W2和中肥F2水平促进了产量的增加,而W1和F1水平增产效应不明显,甚至出现负效应;水分利用效率随灌水水平的提高先增后减,W1下各施肥水平的差异不明显,W2下F2水平的值最高,F3最低,W3下2017年和2018年的变化规律不同;对于偏肥料生产力,在同一施肥水平下,均由W3到W2而变大,W1水平的效应不稳定,在同一灌水水平下,高肥F1的值最小。经非线性模型拟合,得出基于高产、节水、节肥的灌水和施肥量范围分别为750～900 m~3/hm~2和510～610 kg/hm~2。     

安阳市水资源生态足迹与生态承载力研究

利用水资源生态足迹分析方法对安阳市2005~2014年的水资源生态足迹、生态承栽力进行了计算分析。结果表明,2005~2014年安阳市人均水资源生态足迹均值为0.45 hm~2/cap,且呈波动下降趋势。其中生产用水生态足迹占水资源生态足迹比重最大,达82.8%~91.4%,生活用水足迹其次,生态用水足迹最小,但呈上升趋势。安阳市水资源人均生态承载力较小,在0.048 hm~2/cap~0.068 hm~2/cap之间,受气候、水文起伏波动较大。安阳市2005—2014年间,水资源生态足迹均处于赤字状态,说明安阳市水资源利用长期以来一直是不可持续的。近10年来,安阳市万元GDP水资源生态足迹整体呈较快下降趋势,表明安阳市水资源利用效率正逐步提高。     

太行山典型森林水源涵养分层特征与差异研究

以豫北太行山典型森林生态系统为研究对象,结合样地调查、室内试验以及K-W秩和检验等方法,分层探讨太行山典型森林水源涵养功能的异同。结果表明:侧柏林冠层最大持水量与有效拦蓄量均较大,分别为37.01、19.47 t/hm~2;栓皮栎林冠层最大持水量与有效拦蓄量最小,但浸水初期持水速率较大;枯落物持水量大小顺序为油松林侧柏林栓皮栎林,但有效拦蓄量大小顺序则为侧柏林油松林栓皮栎林,其中半分解层起主导性作用;土壤层持水能力较高,是森林水源涵养功能的关键所在,尤其是侧柏林,土壤最大持水量与土壤有效持水量分别为515.22、110.67 t/hm~2。     

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。     

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.     

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.     

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。     

Desiccation and recolonization of phytobenthos in a regulated desert river: Colorado River at Lees Ferry,Arizona, USA

We tested the recolonization of the phytobenthic community in the tailwaters of Glen Canyon Dam following long- and short-term experimentally induced desiccation. The response of Cladophora glomerata, Oscillatoria spp., miscellaneous phytobenthos species and periphyton was studied over 18 weeks using three treatments: (1) undisturbed control cobbles from the submerged zone; (2) cobbles desiccated and replaced into the submerged zone; and (3) cobbles desiccated and replaced into the varial zone. Periphyton density and compositional response resulting from these treatments were also examined. Desiccation treatments were significantly different in biomass from controls throughout the study. The biomass of desiccated and replaced river cobbles averaged <30% of the controls for C. glomerata and periphyton during the 18-week recolonization period. In contrast, the biomass of the control Oscillatoria and miscellaneous phytobenthos species averaged only 3 and 50% of that in the desiccation treatments, respectively. Cladophora, the dominant alga, comprised 77% of the phytobenthic biomass. A significant positive relationship between discharge, Cladophora and periphyton biomass was present in all treatments, while there was a negative relationship with discharge for Oscillatoria and miscellaneous phytobenthos species. There was a significant inverse correlation, as well as a pattern of separate biomass dominance, between C. glomerata and Oscillatoria. Cladophora was the dominant phytobenthos species on cobbles below the baseflow and Oscillatoria was dominant on cobbles in the varial zone. In general, the Cladophora biomass decreased under intermittent drying conditions, while Oscillatoria declined under permanently wet conditions. Diatom composition was not significantly different between treatments; however, their density was lower on desiccated cobbles. Diatom density on desiccated cobbles in the submerged and varial zones averaged 69 and 42% of that of the controls, respectively. Recovery and maintenance of benthic resources are hindered by fluctuating flow regimes driven by electricity and irrigation requirements. Repeated desiccation of the phytobenthos has major effects on the bottom-up interactions in the Colorado River ecosystem. © 1998 John Wiley & Sons, Ltd.