ASSESSMENT OF CONSEQUENCES OF SEDIMENT DEFICIT ON A GRAVEL RIVER BED DOWNSTREAM OF DAMS IN RESTORATION PERSPECTIVES: APPLICATION OF A MULTICRITERIA,HIERARCHICAL AND SPATIALLY EXPLICIT DIAGNOSIS

As regards river restoration, it is fundamental to better link human pressures and environmental responses and to take into consideration not only target species or habitat but diverse ecological elements. This permits to assess sustainable restoration plan, especially concerning sediment augmentation below dams. The use of a hierarchical multicriteria approach on the Ain River permits us to assess a diagnosis of sediment deficit impact integrating several morphological (channel shifting, river bed degradation and river bed coarsening) and ecological components (Riparian and floodplain lake and fish communities). Our diagnosis also integrates a temporal and spatial approach better to link human pressures and environmental responses and to identify the dam effects amongst other drivers (e.g. grazing decline and channel regulation). The results confirm causality links between sediment deficit and slight channel bed degradation (0.01 m.year^?1) or channel bed paving and thus highlight the impact of the dam on the drying of the riparian forest and on former channel community. However, the relationship between incision and reduction in active channel lateral mobility is more difficult to establish. The role of sediment deficit in the current variability of the riparian regeneration capacity and, thereby, landscape diversity along the lower valley remains unclear. This study also confirms the relevance of using different ecological indicators, notably because all components present different adjustment time scales, whereas some of them are more sensitive to other impacts. Copyright © 2013 John Wiley & Sons, Ltd.     

EVALUATION OF THE SOUNDING ROD METHOD FOR SAMPLING COARSE RIVERBED SEDIMENTS IN NON‐WADEABLE STREAMS AND RIVERS

The substrate of fluvial systems is regularly characterized as part of a larger physical habitat assessment. These measures are instrumental in meeting the regulatory responsibilities of bioassessment and monitoring programs, and essential to monitoring restoration and rehabilitation success. We describe and validate a commonly used technique for broadly categorizing, and thus characterizing, the substrate in non‐wadeable streams and rivers called the sounding rod method. In brief, a rod, often hollow, is used to probe the substrate of non‐wadeable systems to characterize the substrate. We tested the viability of this method on three different systems by comparing estimated particle class and direct particle measurements. Our results indicate that substrates can adequately be defined into six broad classes (fine‐particle sediment, sand, gravel, cobble, boulder and bedrock) based on size using the sounding rod. Estimated classes were significantly positively correlated to measured classes (τ = 0.83, p < 0.001), and estimates of size class and direct measurements of size were not from significantly different distributions (χ² _0.05,9 = 569.51, p < 0.001). Further, there were significant differences between each category (H = 243.5, 3 d.f., p < 0.001). Although our results affirm that actual substrate class size can be directly inferred from estimated data, it should be noted that soft sediments <200 mm were not always detected. This finding should be carefully considered with individual study objective. Overall, the sounding rod method can be learned quickly, and it is a low‐cost and time‐efficient method for substrate classification. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

新型挡潮闸下港道清淤船的复合功能研究

针对江苏沿海挡潮闸下港道维护中需要清除上层浮淤、中层软淤、下层板淤及浅滩边坡的实际,提出了新型清淤船实现斗轮挖泥、水炮切割、射流拖淤三大功能复合的需求与途径。从优化其结构、方便操作、降低能耗和减少运行成本等目的出发,阐述了多种功能集成方法和确定了性能指标技术参数。为检验其挖、冲、拖装置复合操作应用的清淤效果,通过现场测试数据进行的计算和分析证明了这种新型清淤船是沿海挡潮闸下港道有效维护的理想机械。     

某人工弯道式渠首分层取水结构段模型试验研究

以某人工弯道式渠首改造工程为背景,在人工弯道式渠首泄洪闸上游设置分层取水结构段,用 水平隔板将水流分开,上层引水、下层冲沙。研究了分层取水建筑物的水力特性,解决了人工弯道式渠 首建筑物的引水和排沙问题。为确定该分层取水结构段的结构设计合理性,采用水工模型试验方法,分 别对不冲沙和泄洪闸单孔冲沙两种试验工况,观察分析了分层取水结构段的水流流态,并测量各个断面 的水深、流速、引水流量和冲沙流量等水力要素。结果表明:该分层取水结构段能达到设计的引水流量 要求;且单孔冲沙时,闸门开度越大,冲沙效果越好。该试验结果可为类似的多泥沙河流的综合整治工 作提供借鉴。     

波流耦合作用下紊流边界层水沙数学模型

在河口地区,波流相互作用下紊流边界层的泥沙起动输移规律非常复杂,深入探讨其泥沙运动规律很有必要。该文基于波浪边界层的控制方程,引入了时均水流压力,通过波流相互作用下的摩阻流速反映波浪与水流的夹角,用标准k-ε模型封闭方程,建立了波流叠加的紊流边界层内的弱耦合水流模型,分别讨论了波浪速度振幅、时均流速等的分布情况,与实测数据对比得到了较好的模拟结果。其次,基于水流模型建立了泥沙模型,采用对称振荡流和波流相互作用两种情况下的泥沙实测数据验证了泥沙模型的正确性,讨论了不同分布规律的涡黏系数对于模型的影响,为实际工程提供理论参考,结果具有一定的指导意义。     

基于污染物通量的潘家口—大黑汀水源地水污染生态补偿量化研究

回顾我国水污染补偿的研究及实践,分析潘家口—大黑汀水源地及入库河流的水质状况,在明确考核断面及考核指标的基础上,建立基于污染物通量的水污染补偿量化估算模型,并根据2013年潘家口—大黑汀水源地入库河流的水质和水量监测数据,估算入库河流水污染生态补偿量。     

基于紊流模型的一个悬移质挟沙力公式

基于紊流模型，建立悬移质消耗的紊动动能与水流功率之间的相关关系，提出了一个新的悬移质挟沙力公式。公式经过实验资料与野外资料的验证，并与几个同类公式的比较，结果表明本文公式能更好的反应悬移质挟沙力随水流功率的变化。     

PIV直接测量泥沙沉速试验研究

本文应用激光测量仪器PIV对长江口水库泥沙水样在沉降筒中进行沉降速度场测量,得到了平均的泥沙沉速,并分析了含沙量、絮凝等因素对泥沙沉降的影响。同时通过试验发现PIV直接测量泥沙沉速是一种可行的、有效的试验方法。     

Measuring the reach‐scale geomorphic diversity of streams: application to a stream disturbed by a sediment slug

There is increasing evidence that greater physical diversity in a stream leads to a greater diversity of habitats, and hence species. Human impact has reduced the physical diversity within many stream systems. This paper reviews a range of techniques used to measure the physical diversity of a stream reach and specifically examines variability measures of a stream's thalweg, cross‐section and sediment size at the scale of millimetres to metres. Each measure was evaluated against synthetic data with different levels of diversity. From the original thirteen, eight measures were considered appropriate for application to data measured in the field. Creightons Creek (Victoria, Australia) was selected as a test site as it contains areas that are in their original geomorphic condition, as well as sections that have been disturbed by increased bed‐load in the form of a sediment slug. All eight measures showed that the area impacted by the sediment slug was less diverse in terms of its geomorphic variability than the unimpacted reaches. This suggests that massive increases in sediment load to streams will reduce the geomorphic complexity of a stream, and in turn, the diversity of habitat for biological communities. Copyright © 2005 John Wiley & Sons, Ltd.     

叶茂水电站洪水复核中的几个问题

龙江叶茂水电站原设计洪水计算采用1936-1985年断续46a系列,现复核采用到2004年,增加了近20。洪水资料,增强了系列代表性;历史洪水仍以1902年为首,其重现期由原设计采用的84a复核为103a;H～Q曲线把各年实测点子绘于同一图上,采用上包线成果;水库的泥沙淤积采用拦沙率方法计算,经计算分析认为淤沙对水库影响不大。