三峡水库已蓄水运用10余年,坝下游长江中游各弯曲分汊河道已出现不同程度的冲淤响应,呈现出一定的河道调整规律.鉴于此,采用宜昌站、沙市站和汉口站水文观测数据,在分析三峡水库蓄水前后长江中游水沙变异特征的基础上,以监利河段、武汉天兴洲河段和戴家洲河段为典型分析河段,就河道平面变化、主支汊冲淤调整与汊道分流比3个方面,探析了三峡水库蓄水运用以来长江中游弯曲分汊河道的调整响应特点.结果表明,三峡水库蓄水运用后,长江中游弯曲分汊河道平面形态基本稳定,河道冲刷主要发生在枯水河槽;蓄水后分汊河段两汊中短汊发展较快,支汊有所萎缩.江心洲洲体冲刷萎缩,但受近年来实施的航道整治工程制约,这一冲刷趋势有所减缓.研究成果可为坝下游弯曲分汊河段的河道规划、设计及治理等提供参考.

Mean and turbulent characteristics are commonly evaluated by spatially averaging over a finite fluid volume. For Particle Image Velocimetry (PIV), the spatial averaging is accomplished over the interrogation area during image processing; for Particle Tracking Velocimetry (PIV), the spatial averaging is made in the sampling bins during post-processing. For both techniques, the obtained values are attributed to the center of the sampling volume under the assumption that the volume size can be set to be indefinitely small. In practice, however, a finite sampling volume has to be used in PIV to facilitate correlation analysis, and in PTV to collect enough samples for statistical analysis. While the spatial-averaging measurement approach is accurate for flow areas that are uniform, the presence of velocity gradient across the sampling volume will inherently introduce bias errors. This study presents both analytical and experimental evidence to show that the spatial averaging effect differs for PTV and PIV in quantifying turbulence intensity. Due to the spatial averaging effect, turbulence intensity is likely to be underestimated by PIV but overestimated by PTV. Therefore, care needs to be taken when results from various measuring techniques are compared to describe turbulence modifications.

Sediment-laden flow measurement with Particle Tracking Velocimetry (PTV) introduces a series of finite-sized sampling bins along the vertical of the flow. Instantaneous velocities are collected at each bin and a significantly large sample is established to evaluate mean and root mean square (rms) velocities of the flow. Due to the presence of concentration gradient, the established sample for the solid phase involves more data from the lower part of the sampling bin than from the upper part. The concentration effect causes bias errors in the measured mean and rms velocities when velocity varies across the bin. These bias errors are analytically quantified in this study based on simplified linear velocity and concentration distributions. Typical bulk flow characteristics from sediment-laden flow measurements are used to demonstrate rough estimation of the error magnitude. Results indicate that the mean velocity is underestimated while the rms velocity is overestimated in the ensemble-averaged measurement. The extent of deviation is commensurate with the bin size and the rate of concentration gradient. Procedures are proposed to assist determining an appropriate sampling bin size in certain error limits.

Dramatic change in hydrodynamic and aquatic conditions has led to an increasing occurrence of algal bloom in the Xiangxi River,a typical tributary of the Yangtze River near the Three Gorges Project.Nutrients' transport and evolution in this river was simulated by using a two dimensional water quality model with aerodynamic numerical scheme which was validated and verified against filed data of 2007 and 2008.Simulation results reveal that algal bloom occurs when flow velocity falls less than 0.03 m/s.The dynamic process of nutrient evolution during an algal bloom is closely related to the incoming load.

According to hydrologic and sediment observation data,the flow and sediment features flowing into and out of Three Gorges Reservoir were analyzed systematically.By selecting representative hydrolagical stations located in the upper reaches of the Yangtze River,including mainstream and its tributaries,a comparative analysis on its changes of annual runoff,annual sediment yield,and annual average sediment concentration before and after the years of the Three Gorges Project starting water storage was conducted.In addition,based on the multi-resolution function of wavelet analysis,from the multi-time scale point,the time series of annual runoff data from 1950 to 2008 of Zhutuo,Cuntan and Yichang station was analyzed.The results indicated that the ratio of reservoir inflow volume to the multi-year average discharge changes little after the Three Gorges Project storing water,but the sediment concentration is significantly less than normal.In the past 50 years,the annual runoff time series of the upper reaches of the Yangtze River periodically varies,presenting as a cycle of abundance-low-abundance,and the dominant period is 12-year.At present,the incoming runoff of the upper reaches of the Yangtze River lies at a relative low status.

Aiming to the standardization,quantification and normalization of flood control safety evaluation,on the basis of the existing situation of the exploitation and management of river shoreline and massive assessments on flood control influence,dividing into 3 layers(target layer,criteria layer and index layer),we establish a flood control safety evaluation index system of river projects,including 21 indexes of 6 aspects such as river regime stability,flood discharge,flood control project safety,flood control standard,water resources planning and other influences.And the valuation standard of the indexes is given accordingly.With the combination of fuzzy synthesis evaluation method and the analytical hierarchy procedure,a hierarchical structural model of flood control indexes is established.Therefore,we can obtain the comprehensive evaluation indexes of the flood control safety degree of river projects,and the applicability of the system has been verified with practical engineering examples.

Based on the analysis of the present situation and existing problems of the bankline use in the middle and lower reaches of the Yangtze River,with the mathematical model research method,taken bridges in Wuhan river reach and dock groups in Yangzhong river reach as examples,the calculation of accumulated influence on river flood water level and flow field by lots of wading engineering groups were carried out.Results showed that the flood water level and velocity influence were accumulated after the wading engineering groups built and the influence of wading engineering groups was much larger than that of single engineering.When the influence was increased to the extent,it would do harm to the river regime and flood carrying capacity.In the end,some suggestions are given,such as the bridge density and dock group scale should be controlled reasonable,the principle of the bankline use should be put forward,river engineering design should be regulated,and River regulation should be strengthened,in order to minimize the cumulative effects of flood control.

The variation process,characteristics and trend of runoff and sediment load in the main stream of upper Yangtze River are analyzed based on more than 50 years′ hydrological data.The results show that there is no obvious variation trend in annual runoff of the main stream of upper Yangtze River,however,annual sediment load decreases on the whole;the transported sediment load in middle and lower reaches of the Yangtze River has decreased obviously since 2003 due to the sediment retaining of TGP reservoir and sediment load reduction from the upper Yangtze River.The annual flow and sediment distribution are characterized by concentrating in flood season from May to October,especially for sediment.For recent 50 years,the annual runoff of the upper reaches of Yangtze River varies in a main cycle of 12-years,and based on correlation analysis results,the annual runoff is positively correlated with annual sediment on the whole.The trend analysis shows that the runoff of upper reaches of the Yangtze River is relatively low at present,and after a few years the Yangtze River will turn into a wet period;with the construction of soil-water conservation works and the appearance of sediment retaining function of reservoirs in the upper reaches of Yangtze River,the sediment load in the middle and lower river reaches will remain in a low level during the reservoirs′ equilibrium period.

白鹤滩水电站是长江金沙江下游4个梯级电站之一,是我国实施"西电东送"战略部署的重点骨干工程。根据不平衡输沙原理,通过建立一维全沙河床冲淤数学模型,计算分析了工程建成后水库泥沙淤积情况,电站建成后不同时期库区泥沙淤积量、淤积分布、坝前淤积高程及出库沙量等。在所选取的计算条件与计算方案下,由于白鹤滩水库库容较大,加之工程上游干支流多个在建、拟建及已建水库的拦沙作用,白鹤滩水库在1~100 a运用期间,泥沙淤积对库容损失的影响较小,水库运用1~100 a仍属初期运行阶段。

The Jianli river reach is located in the lower part of Jingjiang river reach which is one of the 14 key reaches in the middle and lower reaches of Changjiang River.By analyzing the 1950-2006 prototype data of Jianli Station in Jianli river reach,a representative hydrological station,some conclusions indicate as follows: The annual runoff and sediment load of Jianli river reach all changed irregularly and periodically,and were divided into two phases clearly by late 1980s.In 2006,the annual runoff and sediment load of Jianli river were the lowest in the past years.The distribution of runoff and sediment load in one year was uneven,mainly concentrated in flood season from May to October,especially for sediment load.The runoff and sediment load had direct correlation on the whole,that is,the more the runoff,the more the sediment load.Besides the incoming water and sediment from the upstream river reach,the cut-off works in lower Jingjiang river reach,the variation of the silt-carrying flow division through three branches in Jingjiang River,and the construction of large-scale water conservancy projects,such as TGP,are all the main influencing factors of water and sediment load variation in Jianli river reach.

Hydrological time series usually in time domain have multiple time scales structures and localization features.In this paper,the wavelet multiple time scales analysis method was used to analyze annual runoff time series from 1882 to 2006 of Yichang Hydrological Station.Research results show that the annual runoff time series of Yichang Hydrological Station has obvious annual change features,and mainly has change cycles of 30-40 yr,10-20 yr and below 10 yr.The first change cycle is 14 yr,the second cycle is 7 yr.Runoff trend analysis shows that the annual runoff will be in a relative dry period in about 3 years since 2006,and then,a relative wet period.

To analyze temperature rise influence by power plant thermal effluent,a 2-D hydrodynamic and thermal diffusional mathematical model was established based on previous work and with river regime-fitted computational meshes.Sensitivity analyses of parameters and coefficients in the thermal diffusion equation qualitatively show that this mathematical model can simulate the temperature rise influence.Application results also show that,the model has basically the same temperature-rise envelope in comparison with the physical model,and the simulation error of 1℃ envelope area between two models is within 8%.

Jianli river reach is the key river reach of lower Jingjiang river(the middle reach of Changjiang River).In this paper,the characteristics of water and sediment load of Jianli river reach was summarized preliminaryly.By analyzing the 1950~2006 prototype data of representative hydrological station-Jianli station in Jianli river reach,results and conclusions would come to as follows.The annual runoff and sediment load of Jianli river reach all changed irregularly and periodically,and have a little large amplitude of variation.In 2006,the annual runoff and sediment load of Jianli river are the lowest in the past years.The distribution of runoff and sediment load in one year is uneven,mainly concentrated in flood season from May to October.The runoff and sediment load have direct correlation on the whole,that is,the more the runoff,the more the sediment load.While since 2000,the annual runoff and sediment load have no correlation,and the annual sediment load showed an obvious decreasing tendency.Besides the incoming water and sediment from the upstreem river reach,the cut-off works in lower Jingjiang river reach,the variation of the flow division through three branches in Jingjiang river,the construction of large-scale water conservancy projects,such as TGP,the jacking action by the outflow of Dongting lake,are all the main influencing factors of water and sediment load variation in Jianli river reach.

泥沙是一种宝贵的自然资源,在国民经济建设中发挥着重要作用。它既有有利一面,也有不利方面。本文对泥沙的作用,泥沙灾害的类型、成因、治理及防治措施的认识作了简单论述。

Based on analyzing systematically the ice situation and conveyance problems of many rivers and channels of north China, using 1-D unsteady water-ice thermodynamical mathematical model, the ice process is simulated along the route. A synthetic method to recognizing ice situation combining Froude, density of drift ice and accumulated negative temperature is produced, the ice process and schedule along the route is predicted and the characteristics and influencing factors of conveying in ice period is analyzed, and the ice danger prevention measures are also advised.

依据国家计委、水利部《河道管理范围内建设项目管理的有关规定》(水政[1992]7号),对在河道管理范围内建设的码头工程,应进行防洪评价。根据2004年8月印发的《河道管理范围内建设项目防洪评价报告编制导则》(试行)内容要求,进行了拟建码头工程防洪影响分析,主要内容包括河道演变分析、防洪评价计算和防洪综合评价等。河演分析结果表明,工程河段多年来河势稳定,河道深槽位置及两岸的江岸基本保持稳定;码头工程附近江岸基本稳定,工程水域河床冲淤幅度相对较小,具备开发利用的条件。平面二维数学模型计算结果表明,工程修建后对河道水位及流场的影响较小,码头工程的修建不会对其所在河段河势及行洪产生明显不利影响。

For the rich water and sediment resources, the Yangtze river is of great importance in sustainable development of Chinese economy and society. According to collected and processed hydrologic data of main hydrologic stations for nearly 50 years, the flow and sediment variation process, characteristics and tendency of the Yangtze river are introduced, and the variation law and mode of flow and sediment of the Yangtze river in near years are analyzed. The analysis results demonstrate that the flow and sediment variation of the Yangtze river has some regularity and correlative research should be strengthened.

As we know,in china,Yangtze River has played an important role in the sustainable development of social-economy since it's rich in runoff and sediment resources.In this paper,the variation process,trend and mode of runoff and sediment load in Yangtze River main stream and branches was analyzed based on more than 50 years' hydrological data.The result shows that,the variation of runoff and sediment load in Yangtze River has followed certain rules in a long period of time.

在收集大量水沙、地形资料基础上,对拟建工程所在河段进行了河道演变分析、二维水流数学模型计算分析,并根据长江航道规划设计研究院已有的物理模型试验成果,综合评价了拟建工程对工程河段河势和防洪的影响。防洪评价结果表明:拟建工程的修建对稳定目前金城洲左槽为主槽的河道河势是有利的,不会对河道行洪带来明显不利影响,且对工程近岸堤防工程的影响很小。

A relationship among runoff and sediment load,influential factors and flow-sediment is firstly established.Four types of analytical methods on annual runoffs and sediment loads are then summarized,namely,probability and statistics analysis,regressing and fitting curves,correlation analysis and accumulation-curve method.Finally,characteristics and changing tendency of annual runoffs and sediment loads of the Changjiang River main channels are analyzed,on the basis of observed data of Cuntan,Yichang,Jianli,Hankou and Datong gauging stations during 1950-2005.Results of analysis show that(1) annual runoff increased along downstream of Changjiang River main channels while annual sediment load kept constant,the change of sediment load was roughly 10-times greater than runoff,and the correlation of flow and sediment transport became feeble longitudinally along downstream of the main channels;(2) during 1950-2005,annual runoffs of the main channels basically remained unchanged while annual sediment loads showed the tendency of decrease,with obvious reduction in 1990s and accelerative decrease after 2000;(3) in regard to the effect of the Gezhouba Project and the Three Gorges Project during impounding period of 135 m-NWL (normal water level),the change of upstream incoming runoffs and sediment loads was the main influential factor acting on the change of downstream runoffs and sediment loads and scouring of downstream river channels,and its effect was relatively larger than effects of flow and sediment regulation of the projects.