气象干旱对松华坝水源区植被覆盖度变化的影响分析

利用遥感影像对松华坝水源区的植被覆盖度进行分级并提取面积数据,选取本世纪的3个典型年,分析了不同植被覆盖度地区对应的土地利用类型和不同海拔高度的植被覆盖度变化规律,结果表明:松华坝水源区植被覆盖度有逐年增加的趋势,且植被覆盖度增加集中在2 000 m的区域,生态敏感度较高的区域植被生长较好,植被覆盖度减少的区域主要分布在人口相对集中的地区;由于2009年降雨量的减少导致其各个区域的植被覆盖度变化有较大差异,应根据当地情况进行有针对性的保护,以提高其抵御自然灾害的能力。     

昆明市松华坝水源区土壤侵蚀研究

为研究土地利用变化和气象条件变化对云南省昆明市松华坝水源区土壤侵蚀的影响,基于SWAT模型,采用1986~2009年4期土地利用和昆明市1993~2009年气象数据,对变化环境下松华坝水源区牧羊河流域的土壤侵蚀变化情况进行了研究。结果表明,与1986年相比,1995年水源区林地面积增加,耕地面积减少,土壤侵蚀模数减少;2009年,林草面积减幅较大,耕地面积又大幅增加,导致土壤侵蚀模数相对1986,1995年和2000年分别增加了1.82,2.70倍和1.91倍;当降水增加10%时,土壤侵蚀模数变化较大。这一结果可为制定变化环境下松华坝水源地的水保对策提供科学依据。     

基于生态足迹模型的昆明市松华坝水源区生态承载力评价

以小尺度特定区域的松华坝水源保护区为研究对象,构建了生态足迹模型。计算结果表明,该区域2008年的人均生态足迹需求量为0．485587hm^2,扣除生物多样性面积后的人均生态承载力为1．005190hm^2,表明松华坝水源区尚有大量生态盈余,经济发展空间比较大。但目前该区域的水源保护与社会经济发展有较大冲突,需进一步转变传统的靠工程措施治理污染的思想,水源区必须进行产业结构调整,转向发展生态农业和生态林业为主,并增强新型清洁能源的使用,以实现经济发展并促进环境保护的目的。     

南水北调工程对长江河口生态环境的影响

对南水北调工程受水区和水源区的特点和现状作了综合评述 ,指出缺水区黄淮海流域的缺水特点。虽然调水水源区长江径流丰沛 ,但长江三角洲地区由于人口密集、工农业发达 ,缺水现象时有发生。通过长江口生态环境现状分析 ,对如何尽可能地减少南水北调工程对长江口生态环境的负面影响 ,提出了一些意见和建议。     

南水北调中线水源区生态环境保护研究

根据调查资料和南水北调中线工程水源区生态环境发展的现状,指出水源区生态环境发展存在的主要问题是水土流失和水体污染,并分析了形成这种现象的原因,在此基础上提出南水北调中线水源区生态环境建设的有关政策法规、生态、经济和环境监测的一些建议。     

南水北调中线工程水源区生态补偿机制研究

建立与完善南水北调中线工程水源区生态补偿机制,不仅可以有效地调动各生态环境建设参与者的积极性,而且对生态环境破坏者的破坏行为将起到经济制约,从而更加有效地保护、建设生态环境,实现水资源的可持续发展。通过分析南水北调中线水源区在生态保护方面存在的主要问题,论述了在水源区建立生态补偿的必要性,并探讨了在南水北调中线水源地建立生态补偿机制的内涵和基本框架;在此基础上,明确了南水北调中线水源区生态补偿的主体和对象及生态补偿的方式和实现的途径,并提出了实施生态补偿的建议。     

云南渔洞水库水源区生态脆弱性研究

渔洞水库是云南昭通地区的水源,其水质受水库集水区的生态环境影响较大。为对渔洞水库集水区域的生态环境进行评价,从水源区脆弱性定义出发,构建了水源区脆弱性评价指标体系,然后通过层次分析法(AHP)确定各指标的权重,并运用模糊综合评价法对渔洞水库水源区脆弱性进行评价,得到总体隶属度,最后通过综合指数法求得渔洞水库水源区综合评价结果。评价结果表明,渔洞水库水源区脆弱性等级为高度脆弱。     

南水北调中线水源区土地利用结构演化特征

通过测算南水北调中线工程水源区土地利用结构熵和土地利用类型转换关系,分析了水源区土地利用结构演化特征,指出水源区土地利用结构在2012年以前稳定性较高,但是2012年以后因丹江口水库蓄水而对水源区土地利用结构产生了一定影响,导致水源区土地利用结构稳定性偏弱;水源区土地利用类型的数量变化主要表现为水域、建设用地面积增加,耕地、林地、草地、未利用地面积减少,空间位置变化主要表现为耕地与林地、林地与草地、草地与水域之间空间位置的变换;利用主成分分析方法对水源区土地利用结构演化的影响因素进行了研究,指出经济发展水平、社会生活和土地利用以及生态环境为其主要影响因素。     

水源区生态补偿机制理论框架研究

建立和完善水源区生态补偿机制,对保护水源区生态环境以及地区之间的协调可持续发展至关重要。在总结前人研究成果的基础上,从生态保护成本(或效益)外部性问题内部化,依据"公平、公开、公正"和"谁受益谁补偿、谁破坏谁治理"的原则,提出了水源区生态补偿概念;从生态补偿主客体的划分,补偿标准,补偿模式与补偿方式,补偿保障措施等方面提出了水源区生态补偿机制理论框架,为建立和完善水源区生态补偿机制提供理论参考。     

基于GIS的南水北调中线水源区生态环境监测体系平台构建

南水北调中线工程水源区生态环境问题非常突出,依据GIS理论,建立一体化的信息监测平台,有利于水源区生态环境保护。在研究GIS在水源区生态环境监测中的应用基础上,对水源区生态环境监测体系的构建进行了研究,包括监测思路对策研究、监测指标体系构建研究、监测体系平台结构设计研究、监测体系平台日常应用研究等,重点对监测体系平台进行了详细的阐述。系统按照应用逻辑自上而下分为应用层、中间层、数据层以及远程监测层;监测体系平台采用了B/S和C/S结构相融合的模式构建,平台功能结构设计了八大数据库和六大应用子系统。     

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.     

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.     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。