关于平阳县中小河流整治必要性探讨

平阳县河流众多,经济发展迅速,带来的环境负面影响对河流的威胁也随之增加,导致河流人为干扰严重,河流淤积阻塞、水环境恶化、生态功能退化,水土流失严重等结果。因此,急需针对平阳县中小河流存在的问题,有效地开展河流治理工作,恢复河道综合功能、提升行洪排涝能力、沟通水系、改善农村水环境、提高灌溉供水保障程度、加快新农村建设、改善民生、促进人水和谐及城乡经济的可持续发展。     

引黄输水管道穿河段河势演变与水流动力学特性

河势演变和水流的动力学特性,对水利工程安全和穿越管道的防护设计具有重要意义。本文结合不同洪水流量时的河势演变,给出了不同水流的水面差值,横向垂线流速分布,环流的环量和环流间的诱导速度;分析了水流及其动力学特性产生的横向与纵向作用力,动量和动量矩的作用,可能出现的绕流升力和压差阻力等,为类似研究与工程设计提供一个范例。     

汉江杜家台河段河势演变及对策研究

河势演变关系着河道防洪安全,汉江杜家台河段自20世纪80年代以来,由于丹江口水库长期清水下泄,杜家台弯道切滩,河势发生了很大变化,滩岸崩塌、鱼咀冲刷、引渠淤积等险情直接影响着堤防及分洪工程的运用.针对汉江杜家台河段河势现状及影响,对河势演变进行了分析,提出了微调导控,遏制滩岸崩挫,恢复优良河势的工程措施,达到改善杜家台分洪工程安全运行的目的.     

混凝土拱坝运行期裂缝与永久保温

混凝土坝施工期裂缝问题目前已基本解决,但施工期未出现裂缝的拱坝,竣工后仍可能出现裂缝,这是目前尚未解决的问题。对运行期出现裂缝的原因进行分析,提出了运行期拱坝实际温度应力的计算方法。计算结果表明,非线性温差及寒潮是引起拱坝运行期裂缝的主要原因。表面永久保温是防止运行期出现裂缝的有效方法。     

适用于中小河流受损岸坡修复的楔形丁坝群水力特性初探

河道内流动控制结构物作为一种主动防护型的护岸型式,以其特有的生态效益,伴随着河流治理理念由渠化向河流再自然化的回归,日益成为新的研究热点。在归纳总结国内外常见河道内流动控制结构物分类和作用特性的基础上,选取逆水流方向布置的楔形丁坝为研究对象,采用三维数值模拟方法对布置楔形丁坝群前后193°强弯曲水槽内的三维水力特性进行对比分析,初步分析弯曲水槽内楔形丁坝群的作用机制和挑流效果。研究结果表明:楔形丁坝群主要通过调整弯道内的二次流结构,达到将高流速水流挑离凹岸、避免岸坡遭受冲蚀的目的;楔形丁坝群布置会造成弯道内水位雍高,高流速水流向凸岸一侧偏移,其雍水高度和偏移程度与楔形丁坝群的布置方式密切相关。研究成果对于河流生态修复领域生态水工结构物相关研究的开展与深化具有借鉴意义。     

Small hydropower dam alters the taxonomic composition of benthic macroinvertebrate assemblages in a neotropical river

Hydropower dams substantially modify lotic ecosystems. Most studies regarding their ecological impacts are based on large dams and provide little information about the far more abundant effects of small hydropower dams. Our aim was to characterize the ecological effects of a small hydropower dam and run‐of‐the‐river reservoir on the structure of benthic macroinvertebrate assemblages in the Pandeiros River located in the neotropical savanna of Brazil. We tested the hypothesis that benthic macroinvertebrate assemblages in sites directly affected by the dam and reservoir would show a different taxonomic structure compared with those in free‐flowing sites. We expected to find sensitive native species associated with the free‐flowing sites, whereas resistant and non‐native invasive taxa were expected in impounded sites. We also explored associations between the presence of native and non‐native invasive taxa to each habitat type. We found that the structure of benthic macroinvertebrate assemblages was significantly different between free‐flowing and impounded sites. Also, we found that the dam and reservoir facilitated colonization of non‐native invasive species (Corbicula fluminea and Melanoides tuberculata) because only in those sites they were found in high abundance, in contrast to the free‐flowing sites. Although the environmental conditions imposed by the impoundment altered the structure of benthic macroinvertebrate assemblages, the effects were limited to sites closest to the dam. Our results highlight the necessity of understanding physical habitat changes caused by the presence and management of run‐of‐the‐river dams and reservoirs.     

重力坝运行期年变化温度场引起的应力

气温和水温的年变化在重力坝内会引起相当大的拉应力,是重力坝在运行期产生裂缝的重要原因,但目前还缺乏一套实用的计算方法,笔者提出了一套计算公式,可用以计算不同表面保温条件下气温和水温年变化在重力坝内引起的应力并从而计算表面保温的效果。     

中小河流水能资源开发方式浅谈

水能资源是水资源的重要组成部分,中小河流水能开发是积极响应开发利用清洁、可再生能源战略的重要组成部分.通过分析已建水库下游低水头梯级开发,结合灌溉渠道工程、大型闸坝工程和河道景观湿地改造工程等进行水能开发利用的特点,对中小河流如何构建生态友好的水能开发利用、体现对社会环境的关注、兼顾河流生态系统健康和可持续性需求的水能资源开发利用方式进行了探讨.     

A Classification of Stream Water Temperature Regimes in the Conterminous USA

Temporal variability in water temperature plays an important role in aquatic ecosystems, yet the thermal regime of streams has mainly been described in terms of mean or extreme conditions. In this study, annual and diel variability in stream water temperature was described at 135 unregulated, gauged streams across the USA. Based on magnitude, amplitude and timing characteristics of daily water temperature records ranging from 5 to 33 years, we classified thermal regimes into six distinct types. This classification underlined the importance of including characteristics of variability (amplitude and timing) in addition to aspects of magnitude to discriminate thermal regimes at the continental scale. We used a classification tree to predict thermal regime membership of the six classes and found that the annual mean and range in the long‐term air temperature average along with spring flows were important variables defining the thermal regime types at the continental scale. This research provides a framework for a comprehensive characterization of the thermal regimes of streams that could provide a basis for future assessment of changes in water temperature caused by anthropogenic activities such as dams, land use changes and climate change. Copyright © 2015 John Wiley & Sons, Ltd.     

Rapid Response of a Sand‐Dominated River to Installation and Removal of a Temporary Run‐of‐the‐River Dam

Run‐of‐the‐river dams (RORDs) comprise the vast majority of dams on river systems and are commonly removed as a part of stream restoration strategies. Although these dams are routinely removed, few studies have documented the geomorphological responses of sand‐bed rivers to the removal of RORDs. We examined the response of a large sand‐bed river located in South‐Central Kansas, USA, to the installation and removal of a dam that is installed annually for seasonal recreational purposes. Channel adjustments were tracked using cross‐sections sampled over the course of 7 months as the dam was installed and subsequently removed. Multivariate spatiotemporal analysis revealed emergence of channel stability when the dam was in place for most cross‐sections, except for those immediately adjacent to or at great distances from the dam. Our results provide an approximation for how sand‐bed rivers respond to RORD construction and removal and are useful for guiding management decisions involving preservation or restoration of connectivity. Results of this study suggest that sand‐bed rivers are resilient and recover quickly when transient RORDs are removed. Copyright © 2014 John Wiley & Sons, Ltd.     

中小河流治理中便民措施的布置及设计

山区中小河流治理是一项重要的民生工程,在解决河道行洪通畅,提高流域综合防灾减灾能力的同时,还应综合考虑治水过程中与当地人民群众生活、生产相关的便民措施布置。主要阐述山区中小河流治理中主要的便民设计与布置,包括两岸机耕路、亲水平台、洗衣台、机耕桥、码头、便道等等,说明措施的便民性,布置原则和主要设计要求等。     

河床演变的均衡稳定理论及其在黄河下游的应用

在系统分析有关河床演变均衡稳定理论的研究成果基础上,指出河流熵理论的最小可用能耗率原理及其表达式完整地表达了冲积河流河床演变的自动调整作用基本原理,应用河流最小可用能耗率原理的表达式封闭河床演变方程组,建立河床演变均衡稳定数学模型,应用该模型计算了黄河下游各河段在不同水沙条件下的河槽均衡稳定断面,并计算分析了小浪底水库下游的清水冲刷、拦粗排细和水温变化及涨冲落淤等因素对河槽均衡稳定的影响,分析了河道输水输沙优化的临界指标,提出了强化非恒定流调水调沙、调控60-100 kg/m3的不利来水含沙量和以滞洪拦粗排细运用为主等改善小浪底水库运用的措施。     

依靠弯道控导河势流路

在天然河道中，河势演变虽具有一定的随机性，但仍有一定的规律可循，在一个河段内，一般可归纳出2－3条基本流路，为控制河势变化，需要选择出一条基本流路进行河道整治，当连续发生枯水期或洪水期时，部分河段的河势可能出现大的变化，为防止不利河势向下游传播，可修建较长的龙头弯道工程，利用龙头弯道工程分段调整，控导河势，保持河势稳定。     

广东省典型中小河流水电站浮游植物组成与特征分析

对广东省典型中小河流的引水式和坝式水电站浮游植物的群落结构和种类组成进行了调查,结果表明,坝式电站浮游植物的种类、密度、生物量及多样性要大于引水式电站;电站坝上、坝下河段的浮游植物的物种组成和优势类群差别不大,浮游植物类群未发生明显分化,浮游植物群落内部都能够稳定发展,达到平衡状态。     

长江口河势近15年变化特征及其对河口治理的启示

1998年长江口深水航道治理工程实施以来,开展了常年定期的长江口河势跟踪监测分析工作。基于此,从宏观角度系统分析和总结了长江口河势近15 a来的总体变化特征,并探讨了河势演变特征对后续河口治理开发的若干启示。结果表明:近15 a来长江口河势变化整体仍符合陈吉余等1979年提出的河口历史发育模式;长江口深水航道治理工程、青草沙水库等重大涉水工程建设对稳定“三级分汊、四口入海”的河势格局起到了重要作用;在2007年之后长江口河床冲淤调整程度总体趋于放缓,年内冲淤变化受径流过程影响仍较明显。从河势发展的角度看,未来长江河口的治理开发,须继续遵循河口向东南方向的演化趋势,综合考虑河口开发的相互影响,以及加快长江口综合整治开发等规划的实施步伐。     

2002年黄河调水调沙试验河口形态变化

近年来黄河河口水沙条件基本处于维持不断流状态，汛期非汛期界限已非常不明显，河口形态变化基本特征发生明显改变。调水调沙试验前河口径流作用微弱，河口沙嘴长时间主要受潮流侵蚀作用逐渐向临界平衡状态调整。但是2002年7月调水调沙试验河口有一个14天的0．664亿t泥沙人海口门快速堆积过程，河口形态又形成一个不稳定的快速堆积状态。本文通过2001年6月与2002年7月两次拦门沙测验地形与相关水文资料，计算输海泥沙的数量及其分布，分析了该次调水调沙试验后河口形态特征变化。     

黄河2007年汛前调水调沙生产运行分析

对黄河2007年调水调沙生产运行情况进行了分析,结果表明:本次调水调沙取得了下游河槽全线冲刷、主河槽最小平滩流量由调水调沙前的3 500 m3/s增大到3 630 m3/s和人工塑造异重流成功等良好效果。取得的主要收获有:①进一步积累了人工塑造异重流的经验;②加深了对下游河道水沙演进规律的认识;③为河道整治工程设计提供了原型观测数据;④再次证明调水调沙作为扩大下游河道排洪能力、处理黄河泥沙、维持黄河健康生命的措施之一是行之有效的。     

Effect of Proposed Large Dams on Water Flows and Hydropower Production in the Sekong,Sesan and Srepok Rivers of the Mekong Basin

Water flow patterns in the Mekong are changing because of on‐going rapid hydropower development triggered by economic growth. Of immediate concern are the current and proposed hydropower dams in the transboundary Srepok, Sesan and Srekong (3S) Rivers, which contribute up to 20% of the Mekong's annual flows, have a large potential for energy production and provide critical ecosystem services to the downstream Tonle Sap Lake and Mekong Delta. The objective of this paper is to determine how the operation of the proposed largest individual dams and cascade dam schemes in the 3S Rivers will affect flow regimes and energy production. Daily flows were simulated over 20 years using the Soil and Water Assessment Tool and HEC‐ResSim models for a range of dam development and operations scenarios. The development of all dams in the 3S basin under an operation scheme to maximize individual electricity production results in an average 98% increase in dry season flows at the 3S outlet. Over 55% of dry season flows changes are caused by seven proposed large dams, with the Lower Srepok 3 project causing the highest impact. The seven large dams will generate 33.0 GWh/day with a water volume of 17 679 x 10⁶ m³, compared with the current and definite future dams generating 73.2 GWh/day with a much lower volume of 6616 x 10⁶ m³. When a cascade of dams are operational, downstream dams with small reservoirs will produce more energy. However, the marginal increase in energy production from the development of additional dams in the 3S basin will decline rapidly relative to the required water storage increase,. Strategic decision‐making on the future of each large proposed dam in the 3S basin needs to be considered by local governments after understanding cumulative operation effects and with further consideration to the potential impact on downstream ecosystem productivity and livelihoods. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of Water Temperature on Breeding Phenology,Growth, and Metamorphosis of Foothill Yellow‐Legged Frogs (Rana boylii): A Case Study of the Regulated Mainstem and Unregulated Tributaries of California's Trinity River

Many riverine organisms are well adapted to seasonally dynamic environments, but extreme changes in flow and thermal regimes can threaten sustainability of their populations in regulated rivers. Altered thermal regimes may limit recruitment to populations by shifting the timing of breeding activities and affecting the growth and development of early life stages. Stream‐dwelling anurans such as the foothill yellow‐legged frog (Rana boylii) in the Trinity River of northern California are model subjects for examining associations between water temperature and the timing of oviposition, hatching, and metamorphosis, and body condition and size of tadpoles and metamorphs. Breeding activity, hatching success, and metamorphosis occurred later, and metamorphs were smaller and leaner along the regulated and colder mainstem relative to six unregulated tributaries of the Trinity River. Persistently depressed summer water temperatures appear to play a seminal role in inhibited tadpole growth on the regulated mainstem and may be a causative factor in the pronounced decline of this population. Environmental flow assessments should account for the influence of the thermal regime on the development of vulnerable embryonic and larval life stages to improve outcomes for declining amphibian populations. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

浅谈中小河流治理中生态理念的应用

针对中小河流治理过程中存在的重防护轻生态的现象,提出了防护与生态相结合的治理理念,阐述了生态理念在河道岸线治理、清淤疏浚、岸坡防护、水生态环境中的应用,为中小河流的生态治理提供了一定的依据与参考。