长江感潮河段设计流量及流速推求方法研究

感潮河段受潮汐影响水流极其复杂,呈往复运动,影响潮流量的主要因素是潮差的大小和上游来水的大小,为给拟建的苏州至南通长江公路大桥初步设计提供设计流量和流速,对感潮河段设计流量及流速推求方法进行了深入的研究,提出了相关法推求感潮河段设计流量及流速的方法,该方法概念清楚,计算成果精度较高,适用性强,可供感潮河段推求设计流量及流速借鉴。     

西江、东海水道枯水期分流比实测研究

东海水道作为西江连通北江的重要河道,其与西江的分流比例多少是直接影响西北江下游地区河网径流分布的重要因素.采用水文同步实测数据,通过回归分析,计算出枯水期西江、东海水道分流比为1.92∶1.     

Analysis and evaluation of large‐scale river restoration planning in Germany to better link river research and management

In December 2008, the draft programmes of measures (PoM) have been published in the EU member states, which list the measures that will be taken to enhance the ecological status of surface and groundwater bodies, and to reach the environmental objectives of the EU‐Water Framework Directive (WFD). We have analysed the German PoM to identify the main pressures and the restoration measures water managers planned to implement in streams and rivers. The objective was to evaluate the PoM and to identify the main, practically relevant knowledge gaps in river management on which applied river research should focus on. In general, the selection of measures in the PoM was reasonable. In accordance with the analysis of pressures and impacts in Germany, the PoM focussed on measures addressing morphological alterations and river continuity, and the results indicated that diffuse source pollution and fine sediment input were additional main pressures in Central European streams and rivers. Although point source pollution was not a main pressure in most rivers, respective point source measures have been selected for many water bodies. Apparently, these were so‐called basic measures that have to be taken due to other EU‐Directives or national laws. Therefore, although in line with the WFD, it seemed doubtful if the point source measures would help to substantially enhance the ecological status. Furthermore, the results indicated that there was a general lack of knowledge on the effect of restoration measures and a specific knowledge gap in how to enhance the ecological state of heavily modified water bodies (HMWB) in the lowland region with a high land‐use pressure, which was reflected by the high share of water bodies for which conceptual measures have been selected (e.g. developing management plans). Based on the analysis of the PoM and a literature review, we identified the following, practically relevant knowledge gaps in river management: (i) the morphodynamics of river reaches where natural channel dynamics have been restored, (ii) the combined effect of measures addressing diffuse nutrient and fine sediment input at different spatial scales (e.g. riparian buffer strips and land‐use changes), (iii) methods to identify suitable and efficient measures and to define environmental objectives for HMWB and (iv) the effect of measures on less well‐studied biological groups like macrophytes and phytoplankton. There is a strong need to summarize recent research results on these issues, to identify the knowledge gaps and research needs in detail, and to make the results of such a comprehensive literature review or meta‐analysis available for the next 6‐year management cycle and second WFD management plans. Copyright © 2010 John Wiley & Sons, Ltd.     

一维不恒定流河网数学模型研究与应用

河道中洪水数值模拟主要用求解描述洪水波运动的圣维南方程组,依数值计算解法不同而产生了不同的模型．在海河流域大清河北支及中下游河道洪水数值模拟的实际工作中,应用了一维河网模型进行洪水的模拟计算,并根据实际情况加入了蓄滞洪区调度、泄洪闸控制调度以及近年来北方河道入渗的特点等条件,计算效果良好．现对模型的理论基础和解法以及实际应用经验作一简述。     

河流弯道水流特点与冲刷深度探讨

根据河流弯道水流的特点,对弯道水流的冲刷机理和冲刷深度进行了分析与探讨,并给出了国外学者计算弯道水流冲刷深度的几种方法.     

含植物河流动力学实验研究-流速、摩阻流速及曼宁糙率系数垂线分布

根据实验室水生植物水槽中71个断面上的点流速及水深、流量和水生植物密度，分析了：1)流速垂线分布；2)相对摩阻流速的垂线分布；3)曼宁糙率系数的垂线分布规律及水生植物密度对它们的影响。结果表明：1)含植物河流中的流速垂线分布呈三区，从下至上分别为冠层区、过渡区和冠层以上区；2)相对摩阻流速垂线分布受水槽底边壁、植物和自由水面的影响．在三个区内各不相同；3)曼宁糙率系数的垂线分布呈倒“S”形。同时，本文归纳出含植物河流流速垂线分布经验公式．该公式可进一步运用到实际河流中。     

一维河网非恒定水沙数学模型研究

在已有研究的基础上,建立了适合复杂区域的河网非恒定流水沙数学模型.建立过程中考虑到计算精度和计算速度的要求,水流求解采用汊点分组方法,同时本模型选用了较符合河网泥沙运动的汊点分沙模式.最后通过长江中下游长河段的水沙运动模拟表明,建立的河网水沙数学模型能够满足实际工程需要.     

畅流期不同水深流速测点分布对垂线平均流速的影响

本文时畅流期不同水深、不同悬吊仪器方法对各种流速测点分布引起垂线平均流速误差的规律性进行了理论分析。     

Geomorphic response to river flow regulation: Case studies and time-scales

River regulation imposes primary changes on flow and sediment transfer, the principal factors governing the alluvial channel regime. In this study, the effect of flow regulation is isolated from sediment delivery. Peace River (Q? = 1080m³s^?1, increasing to 2110m³s^?1 downstream) was regulated in 1967 for hydropower. The gravel-bed reach immediately downstream from the dam has become stable. Gravel accumulates at major tributary junctions, so the river profile is becoming stepped. Further downstream, the river has a sand bed. It can still transport sand, so morphological changes along the channel include both aggradation and channel narrowing by lateral accretation. In the gravel-bed Kemano River (Q? = 150m³s^?1), the addition of water by diversion from another river caused degradation when additional bed material was entrained below the inflow point. However, the effect became evident only after many years, when a competent flood occurred. The short-term response was channel widening. The time-scale for the response depends on the size of the river and the nature and severity of regulation. In both rivers, significant adjustment will require centuries and will intimately involve the riparian forest.     

基于水沙动力过程的泥石流阻塞大河模式及判据研究

根据潜坝壅堵模式的特点,基于异重流理论,给出了泥石流龙头在清水中的运动方程,并提出了有坎宽顶模型的潜坝壅堵上游水位计算式.基于水沙动力过程,以泥石流在坡度变化沟道内的运动方程为基础,考虑堰塞坝和主河水流的相互作用,给出了泥石流在主河中运移距离的计算公式;鉴于泥石流堵塞大河过程中物质流失严重的现象,根据水槽实验数据确定了流失系数;以周必凡提出的泥石流堵断主河总量的计算公式为基础,提出了按流失系数加以修正的泥石流阻塞大河物质总量条件.从而建立了基于动力学方程、物质总量的泥石流阻塞大河综合判据.     

挟沙水流的冲刷率及河床惯性的研究

在清水水流河床冲刷率的实验研究基础上，本文进一步研究了挟涉水流来沙率对冲刷率的影响。结果说明挟抄水流的冲刷率随来沙率与水流输沙力欠饱和度之比以负指数律降低。当来水挟抄率与水流饱和输抄率相等时，冲刷率降刊0。河床惯性是河床在非恒定流中一种重要的动力学性质。利用河床惯性与冲刷率的关系测量了各种沙样的河床惯性值。发现河床惯性随床沙颗粒分选系数增大而增大，分选系数很大时趋近于极限值50t／Tn0。利用河床惯性和河床变形方程得出了冲刷过程中水流输沙率沿程和随时间的变化规律，结果说明水流输沙率欠饱和度向下游以负指数律下降，这与冲刷率随实际水流挟沙率与欠饱和度之比以指数率下降的规律有耜同意义。河床惯性愈大，实际水流输沙率增长得愈慢。河床惯性与于容重及摩阻流速之比构成的无困次数A。代表河床变形和水流实际挟沙量对水流挟沙力变化的响应程度。     

流体平面运动与最小能耗率原理

最小能耗率原理在流体运动中是否是一个普适原理,一直存在着不同的观点。本文以恒定不可压缩流体平面运动为研究对象,利用流体力学的运动方程、连续方程和能耗率方程,通过引入流函数,得到了最小能耗率原理成立的充分和必要条件,并由该条件得出最小能耗率原理在流体运动中并不是一个普适原理。     

Reconstruction of pristine morphology,flow, nutrient conditions and submerged vegetation of lowland river spree (Germany) from palaeomeanders

The European Water Framework Directive requires the definition of reference conditions for each type of surface waters as a base to establish a classification system in which deviations from this high quality status must be determined. In order to reconstruct pristine conditions in the lower river Spree we investigated palaeomeanders using palaeohydrological and palaeolimnological methods. The settlement history of this region suggests low anthropogenic impact for all periods before ～700 cal AD. Three palaeomeanders representing the conditions of the late Sub‐boreal/early Sub‐atlantic were investigated. River width and depth at bankfull stage were reconstructed using cross‐sections of the meanders. Based on these data and experiments on the recent river, a parametric model was developed to calculate the bankfull palaeodischarge. Reconstructions show narrower and shallower channels for the undisturbed lower Spree (～20 m mean width and 0.8 m mean depth at bankfull stage) as compared to recent conditions (35 m and 1.6 m, respectively). Flow velocities and discharge at bankfull stage have been smaller in reconstructed sub‐fossil channels (0.5 m s^?1 and 8 m³ s^?1 in the pristine lower Spree as compared to 0.9 m s^?1 and 52 m³ s^?1 in the recent lower Spree) and flow variability was higher. The increase in bankfull discharge was mainly attributed to deforestation and drainage of the catchment as well as channelization, bank protection and river regulation measures. The organic silt at the base of the sediment cores contained well‐preserved fossil diatom assemblages. Diatom‐inferred total phosphorus (DI‐TP) concentrations of 59–73 µg L^?1 (median 62 µg L^?1) indicate eutrophic to hypertrophic conditions and suggest naturally slightly lower nutrient levels than today. These past nutrient conditions, morphology and large numbers of macrofossil remains indicate optimum growth conditions for submerged macrophytes growth. The combination of palaeohydrological and palaeolimnological parameters proved to be a useful approach for the determination of pristine conditions in a lowland river. Copyright © 2008 John Wiley & Sons, Ltd.     

A GIS‐based approach to mapping probabilities of river bank erosion: regulated River Tummel,Scotland

This study explores the use of Geographic Information Systems (GIS) techniques for mapping river channel planform change and bank erosion probability. The method used is primarily based on an approach developed by Graf (Graf, W.L. 1984. ‘A probabilistic approach to the spatial assessment of river channel instability’, Water Resour. Res., 20 (7), 953–962), which proposed that bank erosion probability could be determined for any given cell on a floodplain by taking into account (i) its distance laterally and in the upstream direction to the active river channel, and (ii) a value representing flood magnitudes for the given period. In this study, Graf's method is refined by using a GIS approach and by incorporating the influence of geomorphic variables, such as river bank morphology, sediment type and floodplain vegetation, on bank erosion rates. In addition, the technique is applied to a wandering gravel‐bed river of roughly 80 m width, representing a different type and size of river to that used in Graf's study. Thus, the wider applicability of the technique is tested. In addition, the analysis here covers only a short time scale (1988–1994) compared with that used by Graf. The high temporal resolution of this study is enabled by the use of aerial photography and also by the substantial channel changes that occurred within this time period as a result of several high magnitude flood events. The results of the study indicate the usefulness and validity of the approach, particularly with regard to floodplain erosion hazard mapping and the assessment of the effects of altered flood regimes and land use. Copyright © 2000 John Wiley & Sons, Ltd.     

Channel response to sediment replenishment in a large gravel‐bed river: The case of the Saint‐Sauveur dam in the Buëch River (Southern Alps,France)

The Saint‐Sauveur dam was built in 1992 in the middle section of the Buëch River. Downstream of the dam, a channel incision by several meters was observed. A gravel replenishment operation was planned in order to restore the active channel. An equivalent of two times the mean annual bedload‐transport capacity (43,500 m³) was replenished downstream of the dam in September 2016. The aim of this paper is to quantify morphological change associated with sediment remobilization in order to evaluate the efficiency of the restoration works. The monitoring was based on a combination of (a) change detection using sequential high‐resolution digital elevation models (from airborne LiDAR data), (b) bedload tracing using active ultrahigh‐frequency radio‐frequency identification technology, and (c) complementary field surveys of channel grain‐size distribution and morphology for bedload‐transport computation. Field monitoring allows us to capture a net aggradation along a 2‐km reach after the first post‐replenishment flood. A sediment balance analysis was performed to back‐calculate bedload supply coming from the sluicing operation during the flood. Although the sediment replenishment operation clearly had a positive impact on the morphological conditions of the starved river reach, the effective bedload supply from artificial berms (22,650 m³) was insufficient to initiate substantial channel shifting along the restored reach and a subsequent amplification of the sediment recharge. The combination of high‐resolution topographic resurveys and sediment tracing was successful to evaluate the downstream propagation of sediment replenishment effects.     

水平旋转内消能泄洪洞流速分布及紊动特性试验研究

该文通过模型试验,研究了在自由流、吸吮流和淹没流三种基本流态下,水平旋转内消能泄洞的流速分布与脉动特性。激光测速的结果表明,水平旋流洞的切向流速沿径向的分布可以看成是组合涡分布,轴向流速沿径向的分布可看成是最大值靠近壁面一侧的二次曲线分布。在流速的变化趋势上各种流态是相同的,但具体分布参数因流态不同,有较大的差异。流态不同时,轴向脉动流速与切向有较大差异,湍流强度变化规律也不同,自由流与吸吮流流态湍流强度总体上的变化规律为Twθ和Twz沿程均有所增大;沿径向先减小,在R/R0大于一定值之后基本维持一常量或略有增大。     

以水流挟沙力和河床演变规律研究调水调沙的主要水沙指标

冲积性河流的河床在输水输沙过程中,调节流量及含沙量和泥沙组成(调水调沙)可以调节河床水力几何形态和水流挟沙力,追求水沙输运和河床演变的相对平衡。在分析水流挟沙力和河槽水力形态规律的基础上,研究调水调沙的流量、含沙量等主要水沙指标,可以解决河道输沙减淤和河槽相对稳定问题。     

Multi‐scale modelling of land‐use change and river training effects on floods in the Rhine basin

Land‐use changes effects on floods are investigated by a multi‐scale modelling study, where runoff generation in catchments of different sizes, different land uses and morphological characteristics are simulated in a nested manner. The macro‐scale covers the Rhine basin (excluding the alpine part), the upper meso‐scale covers various tributaries of the Rhine and three lower meso‐scale study areas (100–500 km²) represent different characteristic land‐use patterns. The main innovation is the combination of models at different scales and at different levels of process representation in order to account for the complexity of land‐use change impacts for a large river basin. The results showed that the influence of land‐use on storm runoff generation is stronger for convective storm events with high precipitation intensities than for long advective storms with low intensities. The simulated flood increase at the lower meso‐scale for a scenario of rather strong urbanization is in the order of 0 and 4% for advective rainfall events, and 10–30% for convective rain storms with a return period of 2–10 years. Convective storm events, however, are of hardly any relevance for the formation of floods in the large river basins of Central Europe, because the extent of convective rainstorms is restricted to local occurrence. Due to the dominance of advective precipitation for macro‐scale flooding, limited water retention capacity of antecedent wet soils and superposition of flood waves from different tributaries, the land‐use change effects at the macro‐scale are even smaller, for example at Cologne (catchment area 100 000 km²), land‐use change effects may result in not more than 1–5 cm water level of the Rhine. Water retention measures in polders along the Upper and Lower Rhine yield flood peak attenuation along the Rhine all the way down to the Dutch border between 1 and 15 cm. Copyright © 2007 John Wiley & Sons, Ltd.     

Impact of a 100‐year flood on vegetation,benthic invertebrates,riparian fauna and large woody debris standing stock in an alpine floodplain

This paper investigates the impact of a 100‐year flood in May 1999 on community composition and large woody debris standing stock in an alpine floodplain (Isar, Germany). Detailed pre‐flood data sampled from 1993 to 1998 are compared with the situation directly after the flood. In those parts of the Isar floodplain mainly covered with pioneer vegetation prior to flooding, the coverage of unvegetated gravel bars increased by 22% following the flood. However, the flood did not remove larger amounts of older successional vegetation stages (willow thickets, floodplain forest). No significant changes in the benthic invertebrate fauna were recorded. The lowest densities of riparian ground beetles (Carabidae) within the study were recorded one month after the flood. Two months later, the ground beetle densities increased to the highest values ever recorded, indicating the ground beetle's high potential for recolonization. These results highlight the degree of resilience of both the aquatic and the riparian invertebrate fauna. The flood also caused a significant increase in large woody debris standing stock; in one section the number of logs increased tenfold and the volume increased by a factor of 20, leading to the assumption that most woody debris in alluvial flood‐plains is provided by catastrophic events. Copyright © 2004 John Wiley & Sons, Ltd.     

河湾水流动力轴线变化与切滩撇弯关系研究

在分析汉江中下游以及荆江河湾实测资料的基础上,阐述了河湾水流动力轴线弯曲半径变化与切滩撇弯之间的关系,大量相关实测资料说明当河湾的来水条件和河湾形态发生变化时,会造成河势与水流动力轴线走向发生变化,从而引起切滩撇弯的发生.用多元线性回归的方法拟合出河湾水流动力轴线弯曲半径的数学表达式,并提出了用水流动力轴线弯曲半径与河湾弯曲半径的相对值来判断切滩撇弯发生机率的方法.研究成果对于治河防洪工程的规划设计有一定参考价值.