本文在描述长江下游来水来沙条件和分析河道形态的基础上，对长江中下游河道的水力和输沙特性作了初步分析，获得了区别长江中下游分汊河道和婉蜒型河道河型综合指标及有利于形成分汊河道的来水来沙条件。文中概略分析了长江中下游分汊河道形态特征，水力和输沙特性与边界条件和河床演变特性之间的关系。

描述了下荆江蜿蜒型河道河型特点。在前人所作下荆江成因研究的基础上，分析指出了下荆江蜿蜒型河道形成条件，即通过加大河长耗散富余能量并与相对较大的含沙量相适应形成蜿蜒河型，表现为河道纵向输沙平衡条件和适度抗冲的二元相结构边界条件。并将其与长江中下游分汊型河道成因进行对比分析，提出了二者在河型调整中的共性和特性。  

本文根据多年的地质、地貌,来水来沙等考察资料,河道变迁的历史记载以及实验研究成果,分析了分汊型河床的两个必要条件及三方面的演变特征,最后用河流力图使自己的能量损耗率达于最小的假说对汊河的形成和演变作了解释。

本文较为系统地将河型成因的各种研究方法按其所依据的理论分类,并指出了各种理论之间的内在联系。文中讨论了各种研究方法所具有的优缺点、各研究方法之间的互补作用以及各种研究方法在表面处理方式不同的背后所隐藏的使河流趋向某一极值状态(或稳定状态)的共同倾向,并据此指出了进一步研究河型成因问题时的侧重面。

The approaches for studying channel pattern used by various investigators have been classi-fied according to their theoretical basis in this paper, such as hypothesis on geomorphic thre-sholds, extremal hypothesis on energy dissipation rate, theory of stability, theory of stochastic analysis and method of statistic analysis.

河床演变学是一门正在发展中的年轻学科,在很多问题上都存在不同的看法,河型的分类及成因就是其中之一。本文对国外流行的观点作出评价,并提出自己粗浅的看法,以期澄清某些概念,有助于统一认识。文中所讨论的仅限于冲积河流。

Based on the plain view, manner of channel shifting, stability and bank credibili-ty, channel patterns of alluvial streams a.re divided into four categories, namely, (1) wandering, (2) anabranched, (3) meandering, and (4) straight pattern.Streams, as an integrated part of a drainage ibasin, assume their characteristics in accordance with the amount and hydrograph of wafer and sediment and the type of ma- terial carried to the reach from the upstream watershed. The type of sediment manife-sts its effects in two aspects, i.e., the material which fronis the boundary of the channel and the ’bed material load which governs the formation of the channel. Whenever the conditions of the drainage ibasin change, the morphologic character of the river do-wn-streaxn will vary conformably. Such an adjustment is aoeomplished through the proce-sses of erosion, ’transportation and deposition of the sediment. The interrelationships between (1) the oncoming bed material load and. the sediment carrying capacity of the flow, and (2) the erodiblity of the river banks and the erosive power of the water decide essentially the general direction of the adjustment.Based on the concepts as depicted abov. it is argued that the production rate of tlie ’bed material load in relation to the water production rate of the watershed and the relative credibility of the stream banks are the two governing factors which control the-formation of different ohaomel patterns. Subsidiary factors in channel patterns forma-tion are given in Table 2. The existence of certain subsidiary factors may prove to be beneficial to the development of a certain chrannel pattern, or may even play a deciding-role when the stream is in a critical state of geomorpbologic (channel pattern shifting) threshold.

在作者曾对长江中下游河道平面形态进行统计和河型分类的基础上，本文对不同河型的形态指标作了进一步分析，获得了不同河型的平面形态诸因素之间的关系及河型转换中的形态条件，初步阐述了形态分析在河道整治中的作用。

本文分析了影响河型的内外营力,建立了河型与河流能量、河岸不稳定系数、流域形状系数和地壳相对升降强度间的相关关系式。以汉江和黄河下游为例,用水力参数和河床形态指标,判别河型的转化趋势。

以实测资料为依据，从理论上分析得出了稳定分汊河段的水面纵比降大于单一河段；分析了分汊河道进口段的水沙运动及输沙特性以及对汊道演变的影响；基于平衡输沙原理，分析得出了分流分沙变化对分汊河道冲淤影响的关系式，即分汊河道的冲淤演变与上游来沙量、主支汊分流分沙比及其变化等因素有关。

Based on the prototype data, the article theoretically analyzes and concludes that the water surface longitudinal slope of the stable braided river is greater than that of its single river. It analyzes characteristics of water flow and sediment motion and sediment transportation in the inlet reach of the braided river and their effects on fluvial evolution. According to the principle of sediment transportation equilibrium, a formula that describes the influences of the change of flow division and sediment division on its evolution is derived. That is to say, the evolution of the braided river is relevant to the upstream factors including sediment inflow, flow division and sediment division ratios of the braided river and their changes etc..

Sandbars are of vital ecological and environmental significance, which however, have been intensively influenced by human activities. Morphodynamic processes of sandbars along the Yichang-Chenglingji Reach of the Changjiang River, the channel immediately downstream of the Three Gorges Dam (TGD), are assessed based on remote sensing images between 2000 and 2016. It can be found that the entire area of sandbars reduces drastically by 19.23% from 149.04 km² in 2003 to 120.38 km² in 2016, accompanied with an increase in water surface width. Owing to differences in sediment grain size and anti-erosion capacity, sandbar area in the upstream sandy gravel reach (Yichang-Dabujie) and downstream sandy reach (Dabujie-Chenglingji) respectively decreases by 45.94% (from 20.79 km² to 11.24 km²) and 14.93% (from 128.30 km² to 109.14 km²). Furtherly, morphological evolutions of sandbars are affected by channel type: in straight-microbend channel, mid-channel sandbars exhibit downstream moving while maintaining the basic profile; in meandering channel, point sandbars show erosion and deposition in convex and concave bank respectively, with mid-channel sandbars distributing sporadically; in bending-branching channel, point sandbars experience erosion and move downstream while mid-channel sandbars show erosion in the head part along with retreating outline. We document that the primary mechanism of sandbars shrinkages along the Yichang-Chenglingji Reach can be attributed to TGD induced suspended sediment concentration decreasing and increasing in unsaturation of sediment carrying capacity. Additionally, channel type can affect the morphological evolution of sandbars. Along the Yichang-Chenglingji Reach, sandbars in straight-microbend channel are more affected by water flow than that in bending-branching channel.

Elucidating the influence of dams on fluvial processes can benefit river protection and basin management. Based on hydrological and topographical data, we analyzed channel evolution in anabranching reaches under changing hydrological regimes influenced by the Three Gorges Dam. The main conclusions are as follows: 1) the channels of specific anabranching reaches were defined as flood trend channels or low-flow trend channels according to the distribution of their flow characteristics. The anabranching reaches were classified as T1 or T2. The former is characterized by the correspondence between the flood trend and branch channels, and the latter is characterized by the correspondence between the flood trend and main channels; 2) on the basis of the new classification, the discrepant patterns of channel evolution seen in anabranching reaches were unified into a pattern that showed flood trend channels shrinking and low-flow trend channels expanding; 3) flood abatement and the increased duration of moderate flow discharges are the main factors that affect channel adjustments in anabranching reaches after dam construction; and 4) in the next few decades, the pattern of channel evolution will remain the same as that of the Three Gorges Dam operation. That is, the morphology will fully adapt to a flow with a low coefficient of variation. Our results are of interest in the management of the Yangtze River and other rivers influenced by dams.

按照河流与泥沙基本理论研究、河流水沙模拟与专题研究和长江治理与防洪实践应用3个领域,对长江流域河流泥沙与治河防洪研究及实践进行综述。①河流与泥沙基本理论研究包括河流分级、干流河道分段与河势贴体网格等河流分类及形态研究,以及泥沙分界、长江水沙变化与输沙地形对比等泥沙特性及运动研究。②河流水沙模拟与专题研究包括河流水沙模拟研究与河流水沙专题研究,河流水沙模拟研究涉及河流水沙数学模型、应用及关键技术;河流水沙专题研究列举了弯道水流基本特性及数值模拟、空腔回流区水沙特性及模型变态影响研究,以及河湖岸线洲滩利用对河湖功能影响研究。③长江治理与防洪实践应用包括重大治江工程(三峡、葛洲坝、南水北调)研究、治江重大问题研究和长江防洪实践应用3个方面。建议加强基于泥沙的河流研究、不限于河流的泥沙研究以及河流与泥沙相互影响研究,并强化河流泥沙理论研究与治河防洪实践应用之间关联研究与成果转化。

Researches and practices on river & sediment and river regulation & flood control of the Yangtze River are comprehensively reviewed in terms of three aspects: theoretical researches on river & sediment, researches of river modeling and special study on flow & sediment, and practical application of river regulation & flood control. First, theoretical researches on river & sediment includes: river classification and morphology research such as stream-order gradation, river segmentation and river-regime-fitted grid, as well as sediment characteristics and movement while of demarcating grain size of river sediment, changes in runoff and sediment load, and methodological contrast between sediment budget and morphological change. Second, researches of river modeling and special study on flow & sediment consists of modeling on river flow and sediment transport and special studies on river and sediment, in which the modeling researches include development, applications and key technologies of river models, while the special studies give examples of essential features and numerical modeling of bend flow, features of cavity flow and sediment transportation and influence of physical model distortion, and impact of shoreline and island utilization on river-lake functions. Third, practical applications of river regulation & flood control comprises researches on large hydro-engineerings (e.g. Three Gorges Project, Gezhouba Project, and South-to-North Water Diversion Project), researches on major issues of river regulation, and practical application of flood control of the Yangtze River. Last but not the least, issues such as river research based on sediment, sediment research unlimited to river, and interaction between river and sediment should be enhanced, while interactive connection and achievement transformation between theoretical researches on river and sediment and practical application for river regulation and flood control should be also strengthened.

受黄河夺淮的影响,从1570年开始淮河下游由向东独流入海逐渐演变为南下入江,成为长江一条支流。这一变化为长江河流地貌的演变增加了新的变量,改变了长江镇扬河段原有的河槽特征和水流结构,洲滩冲淤、岸线进退随之发生变化。本文使用历史文献考证与古地图判读相结合的研究方法,对淮河入江口外沙洲群的形成年代与演变过程进行考证,认为裕民洲、南新洲等沙洲至少在17世纪前已经存在于淮河入江口外,是成化、弘治年间藤料沙等沦没后新淤长的沙洲。淮河入江后上述沙洲不断扩大、与新淤长沙洲一起向北并岸,致使镇扬河段北汊消亡,并由江心洲型河床向弯曲型河床转化。曲流的形成又使位于上游凹岸的瓜洲受到侵蚀,而位于凸岸的镇江不断淤积,长江镇扬河段逐渐演变为今天的面貌。

Under the influence of the changing relationship between the Yellow River and the Huaihe River, the lower reaches of the Huaihe River had gradually drained into the Yangtze River since 1570 AD, and finally became a tributary of the Yangtze River. This transformation added new variations to the evolution of the Yangtze River's fluvial processes by changing the original riverbed features and currents of the Zhenjiang-Yangzhou reach. This article analyzed three surveyed maps, discussed related historical literature and investigated some antique maps to explore the formation and the evolution of the sandbanks outside the estuary of the Huaihe River. Some sandbanks including the Yumin Sandbar and Nanxin Sandbar appeared before the 17th century due to the disintegration of original sandbars such as Tengliao Sandbar,which disappeared during the Chenghua and Hongzhi reigns in the Ming Dynasty (1465-1505 AD). Since the Huaihe River entered into the Yangtze River, the Yumin Sandbar and Nanxin Sandbar had continued to expand and banked to the north along with the newly-formed sandbanks. At last, the northern channel of the Zhenjiang-Yangzhou reach demised and the riverbed transformed from a straightforward bifurcation into a curved one. Accordingly, the formation of meandering flow began to erode Guazhou Town on the upstream concave bank and silt Zhenjiang Town on the convex bank, gradually reshaping the Zhenjiang-Yangzhou reach of the Yangtze River into its current configuration.