水利水电工程专业英语——河流工程篇

水利水电工程专业英语——河流工程篇

1. Some Problems Related to Alluvial Rivers（1）

1. 与冲积河流相关的一些问题（1）

Many of the earlier civilizations came into being the fertile valleys of large rivers. Civilizations prospered in the Nile valley in Egypt, along the Tigris and Eupharates rivers in Mesopotamia, along the Indus River. As early as 4000 B.C. people built dams across the rivers to store water, dug canals for navigation purposes and also to carry water to the fields to produce much-needed food. Together with the problems associated with the irrigation works, these earlier civilizations were confronted with the problems of flood control and the Chinese had developed excellent systems of dikes for the protection of inhabited areas against floods.

很多早期的文明都孕育在大江大河的肥沃的河谷。这些文明繁荣在在埃及尼罗河谷，沿着美索不达米亚的底格里斯河和幼发拉底河，沿着印度河流域。早在公元前4000年，人们就横跨河流修建水坝来蓄水，以航运及将水带到农田以生产更加非常需要的事物为目的而开挖渠道。与同灌溉工程相关的问题一样，这些早期文明也面临着防洪的问题，而中国人则已经发展了防洪保护居住区的优秀堤防体系。

Thus, since the dawn of civilization, mankind has faced problems associated with rivers, and solved them to the best of their ability. More complicated problems are encountered in modern times because, with the increase in population, more and more rivers are being harnessed for multipurpose use-flood control, water supply, power generation, irrigation and navigation-for which artificial changes are being made in the water courses. These problems have become complicated because of the fact that rivers and other water courses, in most cases, run through loose material and the water carries some of this material along with it. The presence of sediment in water also creates problems in the operation of turbines and pumps through with the sediment-laden water flows. Further the money spent in treating the water to remove sediment and make it fit for domestic or industrial consumption is enormous. Other problems connected with the training and harnessing of rivers carrying sediment also engage the attention of a large number of engineers. In fact if the water courses were to flow through nonerodible material, many of the above problems would not exist.

因此，自文明的曙光出现开始时，人类就已经面临着与河流相关的问题，并尽其最大可能解决问题。现代社会则遇到了更加复杂的问题，因为随着人口的增加，越来越多的河流因为多种目的的利用而被开发利用，如防洪、供水、发电、灌溉及航运，河道正被人为地改变。这些问题已经变得复杂因为在大多数情况下，这些河流和其他河道流过松散介质并携带这些材料于其中。水中泥沙的存在也通过含沙水流的流动而为水轮机和水泵的操作带来了问题。而且在处理水流以去除泥沙并使之适合家庭使用以及工业耗水的费用是巨大的。其他与整治和开发利用含沙河流相关的问题也吸引了大量工程师的注意力。事实上，如果河道流过非侵蚀性材料，那么上述的很多问题就不会存在了。

The loose noncohesive material through which a river flows is generally called sediment and the subcommittee on Sediment Terminology of the American Geophysical Union has accepted the following definition given by the New Standard Dictionary:

Fragmental material transported by, suspended in, or deposited by water or air, or accumulated in the beds by other natural agents; any detrital accumulation, such as loess.

河流流过的松散的非粘性材料通常被称为沉积物，并且美国地球物理学联合会泥沙术语小组委员会已经接受了《新标准词典》中给出的如下定义：

水流或空气中输运的、悬浮其中或储存于其中的碎屑材料，或者在河床中累积的其他天然材料；任何碎屑积聚，比如黄土。

Ordinarily this does not include ice, logs of wood, or organic material floating on the surface. Sediment is also sometimes known as alluvium. That branch of engineering which deals with rivers and canals flowing through loose transportable material (sediment or alluvium) and transporting some of it along with water is called fluvial hydraulics, sediment engineering or alluvial river dynamics. These channels or rivers are called alluvial channels or alluvial rivers.

通常这并不包括冰、原木或者在表面漂浮的有机材料。沉积物有时也称为冲积土。处理流过松散可输运材料（沉积物或冲积物）并随着水流携带其中一些材料的河流和渠道的工程分支被称为河流动力学，泥沙工程或冲积河流动力学。这些渠道或河流被称为冲积渠道或冲积河流。

Civil engineers associated with water resources development come across various types of problems related to alluvial rivers and channels. Some of these important problems are briefly discussed in the following paragraphs to give the reader a perspective and scope of the field.

与水资源开发相关的土木工程遇到与冲积河流和渠道相关的很多种问题。以下各段简要地讨论了这里的一些重要问题，以为读者提供该领域的背景和范围。

1.1 Sediment Characteristics

1.1 泥沙特性

Sediments are broadly classified as cohesive and noncohesive. Cohesion may far outweigh the influence of the physical characteristics of the individual particles. Noncohesive sediment particles react to fluid forces and their movement is affected by the physical properties of the particles such as size, shape, density and settling velocity.

Also, sediment characteristics may change through chemical or physical reactions.

沉积物被广泛地分类为粘滞性和非粘滞性。凝聚力可能远大于的单个颗粒的物理特性的影响。非粘性沉淀颗粒对流体力和其运动的反映由颗粒的物理性质，如大小、形状、密度和沉降速度的影响。

同时，沉积物特性可能通过化学或物理反应而变化。

1.2 Sediment Transport

1.2泥沙输运

As water flows through rivers and channels, it carries with it some sediment. Part of the sediment is dragged or rolled along the bed or is for most of the time in contact with the bed. This is named as bed load. The other part is suspended in water and travels with approximately the same velocity as water. This is called suspended load. The amount of sediment carried by the river or channel is one of the most important variables in all sediment problems. The extremely large variation in sediment concentration is an indication of the large number of factors, which influence the sediment transport rate in alluvial streams. In fact the sediment transport rate is affected by hydrological as well as hydraulic characteristics.

随着水流流过河流和渠道，它便携带泥沙。部分泥沙是沿着河流拖动或滚动，或者大部分时间与河床相接处。这被称为推移质。另外一部分悬浮在水流中并大致以与水流相同的速度移动。这被称为悬移质。河流或渠道所携带的泥沙量是在所有泥沙问题中最重要的变量

之一。含沙量的非常大的变化指示着大量因素，这影响着冲积型河流中泥沙输运速度。事实上泥沙输运速度受到水文以及水力特性的影响。

1.3 River Channel

1.3河道

The formation of a natural stream channel is influenced by numerous factors of climate, geology, and geography; the most important being the stream discharge, resistance of the landforms to erosion, geometric configuration, and the properties and amount of the sediment transported. The form and dimensions of such a channel, once established, are relatively invariant unless a major change occurs in one or more of the aforementioned factors. A channel may be eroded into a resistant formation, in which case there may be a continuing tendency toward a shifting of position by erosion and rebuilding of the banks. The latter type is most frequently found to be formed in materials previously transported and deposited by the stream, although they may also be formed in materials transported by other means, e.g. winds or glaciers.

天然河流河道的行程收到很多因素的影响，如气候、地质和地形；最重要的因素是河流流量，该区地貌的抗侵蚀性，几何构型以及输运的泥沙的特性和数量。该河流的形式和尺寸，一旦建立是相对不变的，除非上述因素中的一个或多个发生重大变化。河道被冲刷可能有两种结果：一种是形成抗冲层，即稳定结构；另一种是河道由易冲物质组成，将不断地被冲刷，其结果是改变河道位置，再造河岸。后面这种类型经常形成于此前由河流输运并储存的材料上，尽管它们也可能在通过其它手段输运的材料而形成，比如风或冰川。

1.4 Sediment Transport and River

1.4泥沙输运与河流

A certain length of an alluvial stream is said to be in regime or in equilibrium, if the amount of sediment coming into this reach is equal to the sediment going out from the same; this is also equal to the sediment transport capacity of the stream for given characteristics of sediment, flow and fluid. Hence the stream bed elevation will not change over a long period of time. However, if incoming and outgoing sediment loads are different, the bed level must either rise or fall. A rise in bed level is known as aggradation, while a fall in bed level is known as degradation. For example, degradation is bound to occur downstream of a large storage reservoir, because most of the sediment is stored in the reservoir and thus water flowing over the dam is almost clear and, consequently, capable of transporting additional sediment. As such, sediment is picked from the riverbed downstream of the dam and it is never replenished; hence degradation results.

如果进入与流出冲击型河流的某一段长度的泥沙相等，那么该段河流被称为是不冲不淤或冲淤平衡。这也与给定泥沙、流量和流体特性的河流的泥沙输运能力相等。因此，在很长一段时间内河床高度不会发生变化。然而，如果泥沙含量的流入和流出不同，河床高度就会或升或降。河床高度的升高被称为淤积，而河床高度的下降被称为冲刷。比如，冲刷势必发生在大型蓄水水库的下游，因为大多数的泥沙被存储在水库中，因此流过大坝的河流几乎为清水，因此，能够输送额外的泥沙。因此，河流从大坝下游河床上拾起泥沙，并且它从不会得到补充；因此就导致了冲刷。

2. Some Problems Related to Alluvial Rivers（2）

2. 与冲积河流相关的一些问题（2）

2.1 Stabilization and Rectification of Rivers

2.1河流的稳定和整治

The fundamental thesis underlying stabilization and rectification of rivers is to shape a river into a single channel, following a path of easy bends of reverse curvature, and to fix it permanently on that alignment.

Present-day knowledge of hydraulics of rigid boundary open channels has given adequate tools to design channels with fixed boundary and carrying clear water. However, the design of a channel flowing through alluvial material and carrying sediment along with water is extremely difficult.

河流的稳定和整治的基础理论是将河流塑造成一个单一的河道，沿着反向弯曲的容易弯曲的路径，并在该位置上永久地固定。

当今刚性边界明渠水力学的知识已经提供了设计有固定边界并承载清水的渠道的适当工具。然而，流过冲积性材料并随着水流携带泥沙的渠道的设计非常困难。

2.2 Navigation

2.2航运

It has been recognized since the early days of civilization that water transport of bulk commodities is much cheaper than ground transport. In order to develop more and more water transport facilities, river channels must be improved so that they are suitable for navigation. Several rivers in Europe such as the Danube, the Volga, and the Rhine and such rivers as the Mississippi in U.S.A. and the Yangtze in China have been developed and regulated for inland navigation. Inland navigation is also practiced on some of the Indian rivers in the eastern part of the country. This improvement for navigation is effected by one more of the following processes: canalization, regulation by river training works, providing lateral canals with locks, dredging to deepen the critical sections, and providing storage reservoirs to supplement minimum flow and increase the water depth. Application of these methods requires a deep insight into hydraulics.

自从文明早期，人们就认识到通过水路运输大宗商品要比陆路运输廉价得多。为了开发更多的水运设施，必须改进河道以使其适于航运。欧洲的很多河流，如多瑙河、伏尔加河和莱茵河，美国的密西西比河和中国的长江都被开发和调控作内河航运。内河航运在印度东部的印度河也有实践。下面另一个过程影响了航运的改进：运河化，通过河道整治工程调控，提供锁定的斗渠，疏浚以加深临界断面，并提供蓄水水库以提供最小流量及增加水深。这些方法的应用需要对于水力学的深入洞悉。

2.3 Flood Control

2.3防洪

Rivers, gullies and other streams drain the surplus water of precipitation to the sea. When there is excessive precipitation, the water level in the river rises above the banks and water spills to the low-lying areas. Such situations are called floods. These low-lying areas are usually very fertile and hence thickly populated. Occurrence of floods, therefore, causes heavy losses in terms

of life and property.

In general the hydraulic engineer must confine the river to a stable course and make arrangements for efficient and safe passage of the water and sediment load.

河流、沟壑以及其它溪流将降水产生多余的水排入大海。当降水过量时，河流中的水位上升到河岸以上，且水溢出到低洼地区。这种情况叫做洪水。这些低洼地区通常非常肥沃并因此人口密集。因此，洪水的发生会造成严重的生命和财产损失。

通常水利工程必须将河流限制在一个稳定的路线，并为水流和泥沙安排高效和安全的通道。

Several methods are used singly or in combination for controlling floods. These methods include:

1) construction of dikes which confine the flood flows;

2) provision of river training works and cutoffs which increase the capacity of the channel to carry water;

3) provision of secondary channels (either natural or artificial) to divert excess water;

4) construction of storage reservoirs and detention basins to store large volumes of water during the floods and release them when the floods recede;

5) use of soil conservation methods which reduce soil erosion and thereby control the silt deposits in reservoirs and flood plains.

可以单独或联合使用几个方法控制洪水。这些方法包括：

1）修建限定洪流的堤坝；

2）提供河道整治工程和临界点以增加渠道的输水能力；

3）提供二级渠道（包括自然的或人工的）以导引多余水流；

4）修建蓄水水库和滞洪区，以在发生洪水时存储大量的水并在洪水退去时将其排出；

5）利用水土保持的方法，以减少土壤侵蚀并因此控制水库和洪泛区的淤泥沉积。

3. Origin and Formation of Sediments

3. 泥沙的来源和形成

All sediments transported by water and air and also those found in deserts have resulted by the process of weathering of rocks. Weathering can be defined as the process by which solid rocks are broken up and decayed. The size, the mineral composition, the density and other factors such as surface texture depend on the nature of the parent rock form which the sediments are formed. The processes of weathering can be subdivided into chemical weathering, mechanical weathering and organic weathering.

水和空气中输运以及那些在沙漠中发现的泥沙都来自岩石的风化过程。风化可以定义为固体岩石分解并退化的过程。其尺寸、矿物组成、密度以及其它诸如表面特征等的因素，取决于形成泥沙的母岩的本质。风化的过程可以细分为化学风化、机械风化和有机风化。

The three agents in the atmosphere, which are responsible for chemical weathering are oxygen, carbon dioxide and water vapour. In certain cases, carbonic acid and excess water act on granite, albite, biotite, etc. and give free silica, carbonate of alkali elements and other secondary minerals. This process loosens the rocks of the land surface and alters them to easily erodible material. Sometimes the iron ores are oxidized. In certain other cases hydration of minerals gives

rise to new secondary minerals and increases their volume.

对于化学风化有影响的空气中的三个催化剂分别是氧气、二氧化碳和水蒸气。在某些情况下，碳酸和过量的水作用在花岗岩、钠长石、黑云母等，并给出游离二氧化硅、碱元素碳酸盐及其它二次矿物。这个过程使得地表岩石松动并将其变成易受侵蚀的材料。有时铁矿石被氧化。在其它某些情况下，矿物质的水化作用产生了新的次盛况并增加了它们的体积。

Several mechanical agencies also disintegrate the parent rocks into fragmental material. These agencies include (1) freezing water, (2) expansion caused by chemical changes, and (3) exfoliation resulting from sudden changes in temperature.

一些机械机构也将母岩分解为碎屑材料。这些机构包括（1）冷冻水，（2）化学变化引起的扩展，以及（3）由气温突然变化引起的剥落。

Volume of water increases by approximately ten percent when it freezes. When the water is confined, such expansion causes a considerable force. Therefore, water, which enters the cracks and fissures and freezes, tends to push the rocks apart. Repeated freezing and thawing at high altitudes can be one of the most important disintegrating forces for the rocks. In certain cases secondary minerals such as kaolinite formed by chemical weathering occupy a volume much greater than the original mineral. This can create forces which ultimately break the rocks. In some other processes called chemical exfoliation, the sheets are notable decayed and discoloured. The work is performed by the solutions which penetrate slowly along the cleavage cracks of crystals and between the grains and thereby induce the formation of new minerals of large volumes which causes disintegration. Exfoliation or scaling also occurs due to extreme heating followed by sudden cooling.

水结冰时其体积大约增加了10%。当水体受限时，这种扩展引起了一个相当大的力。因此，进入到裂纹和裂缝并结冰的水，将会撕裂岩石。在高海拔地区的重复的冻结和融化可能是最重要的岩石分解力之一。在一些情况中，由化学风化作用形成的诸如高岭石等次生矿所占的体积要比原生矿大得多。这可以产生最终破坏岩石的力。在其它一些被称为化学剥落的过程，片材是显著地腐朽并褪色的。该工作是由沿着晶体和晶粒之间节理裂隙慢慢进入的溶液完成的，因此诱发了引起分解的大体积新生矿物的形成。剥离或脱屑也发生于极端加热后突然降温时。

Organic agents of weathering are primarily burrowing animals and also roots and trunks of trees which wedge the rocks apart.

风化的有机催化剂主要是穴居动物，以及树根和树干，这些楔入岩石并使其分离。

After the parent rocks are disintegrated, the material is transported from one place to another and deposited by streams, wind or glaciers. The material is called alluvium if transported and deposited by streams, loess if transported and deposited by wind and glacial drift if it is transported and deposited by glaciers.

在母岩分解之后，矿物被从一个地方输运到另一个地方并被溪流、风和冰川储藏起来。如果由溪流输运并储藏，这些材料就被称为冲积物，如果被封输运并储藏就被称为黄土，如果被冰川输运并储藏就被称为冰碛物。

1) Stream Erosion and Deposition. The sediment load carried by streams comes from various sources. In the hilly areas the streams pick up coarse material from the talus (Talus is a geological term describing a heap or a sheet of coarse rock that has accumulated at the foot of the hill or on a steep slope). Landslides also contribute to the load carried by streams. However, the major portion of sediment load carried by streams comes from the erosion of material in the drainage basin; a certain amount also originated as a result of weathering of rocks form the bed

and banks of the stream. The size of the sediment transported in any reach is dependent on the geology of the basin as well as the distance of the reach form the source. The amount of the sediment load carried depends on the size of material, discharge, slope, and channel and catchment characteristics.

1）河流冲淤。河流携带的输移泥沙有很多来源。在丘陵地区，河流从岸屑堆携带粗料（岸屑堆是描述在山脚或陡坡下积累的成堆的或片状的粗颗粒岩石的地理学名词）。滑坡也增加了河流携带的泥沙。然而，河流所携带的输沙量的主要部分来自流域内材料的冲刷；一定量的泥沙也来自河床和河岸岩石的风化。任何河段所输运泥沙的尺寸都取决于流域的地址以及河段到源头的距离。携带泥沙量取决于材料的尺寸、流量、坡度以及河道和集水区的特点。

When there is reduction either in the discharge or in the slope of an equilibrium stream，the stream cannot transport the material supplied to it and the excess material is deposited. These deposits give rise to various formations depending on the mode of deposition and they are called flood plains, alluvial fans, deltas, etc.

当冲淤平衡河流的流量或坡度任一减小时，该河流就不能输送提供给它的材料且过量的材料边储存起来。这些存储引起了取决于储存模式的很多构造，它们被称为洪泛平原、冲积平原和三角洲，等等。

2) Wind Erosion and Deposition. Arid and semi-arid regions are characterized by relatively low and infrequent rainfall. As such, stream flows in these regions are small, unless, of course, the area is small and is traversed by streams flowing into the area from an area of appreciable rainfall. However, in general, stream erosion in arid and semi-arid regions is relatively small.

2）风蚀和储存。干旱和半干旱地区的特征决定了其相对较少并且不频繁的降雨。因此，流过这些地区的河流流量很小，当然除非该地区很小并由有来自可观降雨流入该地区的河流。但是，通常来说，在干旱和半干旱地区的河流冲刷相对较小。

On the other hand, wind erosion becomes a predominant factor. High velocity winds, carrying fine sand with them, are effective agents of wind erosion. When wind blows over deserts and ploughed fields, fine sand and dust particles are carried away while the coarser material is left behind. This process is called deflation. The dust that is carried by the wind is transported to great distances. When the wind velocity is reduced, this material is deposited as loess. Large deposits of loess are found in China, the Mississippi valley, Europe, and some other parts of the world.

另一方面，风蚀成为主导因素。高速的风能够携带细颗粒沙土，是风蚀的有效的催化剂。当风出国沙漠和耕作地，细沙和尘土被带走，但粗颗粒材料被留下。这个过程被称为风蚀。风所携带的尘土被输运到很远的距离。当风俗降低时，该材料就被储存为黄土。黄土的大量储存发生在中国、密西西比河谷、欧洲以及世界上一些其它地区。

4. The Size and Shape of Sediment

4. 泥沙的尺寸和形状

4.1 Size

4.1 尺寸

Of all the properties of sedimentary particles, sediment size is one of the most important and a commonly used property. Therefore it needs detailed discussion. If all the particles were spheres, then specifying the diameter would suffice. However, the sediment particles composing stream beds are of numerous shapes from round to flat and to needlelike. This extreme irregularity in their shape defies ordinary classification. Therefore, diameter as an index of size loses its usual significance. For these reasons, the particle size is usually defined by its volume, fall velocity, size of the sieve mesh, or by its intercepts. The method of measurement of the size by its volume and fall velocity are based on the premise that measurements made can be expressed as the diameter of an equivalent sphere. The following definitions of sizes are used in practice.

在泥沙颗粒的所有属性中，泥沙尺寸是最重要且最常用的属性之一。因此需要详细的讨论。如果所有的颗粒都是球体的，那么指明直径就足够了。然而，构成河床的泥沙颗粒有着从圆形到扁平和针状等多种形状。由于泥沙形状的极不规则性，难以对其进行常规的分类。因此，直径作为一个指标失去了其通常的意义。由于这些原因，通常通过体积、下落速度、筛眼尺寸或通过其截距来确定其颗粒尺寸。通过体积和下落速度测量其尺寸的方法是基于测量能够表达为等效球体直径的前提下的。在实践中应用了如下的尺寸确定方法。

1) Nominal diameter, d n, of a particle is defined as the diameter of a sphere which is having the same volume as the particle. The nominal diameter gives an idea of the physical size of the particle. However, in several problems one is interested in the size of the particle in the fluid; this gives rise to the definitions of fall diameter and sedimentation diameter.

1）颗粒的等容粒径，d n，被定义为与该颗粒具有相同体积的球体的直径。等容粒径给出了颗粒的物理尺寸的想法。然而，在一些问题中有一个是流体中颗粒的尺寸，这便给出了沉降粒径和沉淀粒径的定义。

2) Fall diameter of a particle is defined as the diameter of a sphere of relative density 2.65 and having the same standard fall velocity as that of the particle. The standard fall velocity of a particle is the terminal fall velocity of the particle in quiescent distilled water of infinite extent and at 24℃.

2）颗粒的沉降粒径被定义为相对密度为2.65的球体且有与该颗粒相同标准沉降速度的直径。该颗粒的标准沉降速度为颗粒在无限延伸的静态且24℃的蒸馏水中的终端降落速度。

3) Sedimentation diameter is the diameter of the sphere of the same relative density and the same terminal settling velocity as the given particle in the same sedimentation fluid under the same condition.

3）沉淀粒径是指在相同条件下、相同沉淀液体中，具有相同相对密度和与给定颗粒具有相同终端沉降速度的球体的直径。

4) Sieve diameter. In most cases a series of sieves is used for separation of sediment into various size grades provided particles are larger than 0.0625 mm in diameter. Sieve openings are square in shape. Since a long particle with a very small cross sectional area can pass through a sieve, sieves classify particles on the basis of their least cross sectional area and thus this classification is not based purely on size. Sieve diameter d of a particle is the size of the sieve opening through which a given particle will just pass. Thus the nominal and sieve diameters of a sphere are always equal. For naturally-worn particles sieve diameter is found to be slightly smaller than the nominal diameter.

4）筛径。在大多数情况下，一系列的筛子的用于将泥沙分离成各种尺寸等级，假设颗粒比0.0625毫米直径大。筛孔为方形。因为一个长的横截面积很小的颗粒能够通过筛子，

筛子在最小横截面积的基础上将颗粒分类，并且这个分类并不纯粹取决于尺寸。颗粒的筛径d是给定颗粒能通过的筛孔的尺寸。因此，球体的等容粒径和筛径总是相等。对于天然磨损的颗粒，筛径被发现相对等容粒径较小。

5) Triaxial size. Several geologists and hydraulic engineers have designed particle size based on measurement along three mutually perpendicular axes of a particle if a is the longest or the major axis, b the intermediate axis and c the shortest or the minor axis, then one can take the intermediate axis b as the index of size. In such a case correlation can be found between the shape of the particle, nominal diameter and the intermediate axis b. The relative magnitudes of a, b and c represent the shape of the particle, and as will be discussed later, they are used as an index of shape. It may be mentioned that the description of particle size in this manner is not precise and differences in interpretation and variations in measuring techniques are common. For example, since the axes are perpendicular, values of a, b, and c for given particle depend on which axis is chosen first.

5）三轴粒径。几个地质学家和水力工程师在沿着颗粒的三个相互垂直的轴进行测量的基础上设计了颗粒的尺寸，如果a为最长轴或主轴，b为中间轴，c为最短轴或次轴，那么就可以以b作为尺寸的指标。在这种情况下，就可以发现颗粒形状即等容粒径和中间轴b 之间的关系。a、b和c之间的相对大小代表了颗粒的形状，正如随后所讨论的，它们被用作形状的指标。可能会提出用这种方式描述的粒径尺寸并不确切，并且解释的差异和测量技术的变化是很常见的。比如，因为各个轴是垂直的，给定颗粒a、b和c的值取决于首先选择哪个轴。

6) Size terms for particles. It is essential to standardize the terms related to particle size so that they could be used to convey definite ideas regarding the size. Udden’s geometrical scale of sediment sizes and Wentworth’s modification of Udden’s scale are considered to be the basic works on this subject. The subcommittee on Sediment Terminology of the AGU has accepted the Wentworth scale with exception that the term “granales”has been deleted. The classification accepted by the Subcommittee, which is quite widely used by hydraulic engineers, is given in Table 1. The sizes given are in terms of sieve diameters for coarse material; for the finer material sedimentation diameter is recommended.

6）颗粒的尺寸术语。标准化与颗粒尺寸相关的术语是必需的，因此它们才能被用于表达关于尺寸的明确的想法。Udden的泥沙尺寸的几何尺度以及Wentworth对于Udden尺寸的改进被认为是这个主题的基础性工作。美国地球物理协会的泥沙术语小组委员会已经接收了Wentworth尺寸，除了“粒砂”这个术语被删除。小组委员会所接受的分类，已经被水力工程师广泛使用，如表1所示。对于粗骨料，给定的尺寸是以筛径的形式；对于更细的材料则推荐使用沉积粒径。

4.2 Shape

4.2 形状

Hydraulic engineers, geologists and soil engineers are interested in defining the shape of coarse sediment particles for various reasons. The shape of the particle influences the mean velocity of the flow at which the particle on the bed moves, the fall velocity, the stability of beaches, and bed load transport. Geologists are interested in the shape of coarse particles because its study throws light on the method of transport and on the deposit to which they belong. Specialists of soil mechanics have found that the shape of the particles is a significant variable in determining the porosity, permeability and cohesion of soils.

水力工程师、地质学家和石油工程师因为很多原因而对确定粗泥沙颗粒形状感兴趣。粒径的形状影响颗粒在河床移动的水流的平均速度、沉降速度、河滩的稳定性和推移质输沙率。地质学家对于粗颗粒的形状感兴趣，因为该研究能够阐明颗粒所属的输运方法和储存。土力学专家发现颗粒的形状是在确定孔隙度、渗透率和土壤凝聚力的显著变量。

The shape of the particle depends initially on the source rock and the weathering process. Subsequently, however, the shape is modified by abrasion, corrosion and breakage. The shape of the particle as it finally reaches a sedimentary deposit is governed by such shape-sorting mechanisms as crushing, splitting, chipping, grinding and chemical weathering.

颗粒的形状最初依赖于原始岩石和风华过程。然而，随后其形状通过磨损、腐蚀和破损而改变。颗粒最终到达沉降储存处的形状受到诸如粉碎、分割、切削、研磨和化学风化的形状分类机制的控制。

Since naturally-worn sediment particles assume many shapes, such geometrical shapes as cube, sphere, cylinder, cone, ellipsoid become inadequate to describe the shape of the particles. Furthermore, such description becomes more or less qualitative. On the other hand, what is required is a single parameter which will be amenable to quantitative analysis. Many such parameters have been introduced by various investigators and Durand has classified these parameters into the following categories:

1) Coefficients based on the volume;

2) Coefficients based on the projected area;

3) Coefficients based on major, intermediate and minor axes.

由于天然磨损的泥沙粒径有很多形状，如立方体、球体、圆柱体、圆锥体、椭圆体不足以描述颗粒的形状。此外，这些描述也或多或少的是定性的。另一方面，所需要的是一个适合于定量分析的单一的参数。众多研究人员已经引进了很多这样的参数，Durand已经将这些参数分为以下类别：

1）基于体积的系数；

2）基于投影面积的系数；

3）基于主轴、中轴和次轴的系数。

5. The Moving States of Sediment

5. 泥沙运动状态

For a set of hydraulic parameters in an open channel with a movable bed, the critical condition of the bed may be exceeded and particle motion occurs. Suppose the motion of entrained particles is one of rolling, sliding and sometimes jumping (saltating), and this motion takes place close to the bed of the channel. This kind of sediment transport is commonly referred as the transport of the bed load. If and when the entire motion of the solid particle is such that they are surrounded by fluid, they are said to move in suspension. Owing to weight of the particles, there is a tendency for settling, which, however, is counterbalanced by the irregular motion of the fluid particles, i.e. the turbulent velocity components. Thus the hydraulic conditions of a stream determine if and when a given size fraction will be in suspension. Furthermore, sediment particles being part of the suspended load at one time may, at another time, be part of the bed load, and vice versa. There exists an active interchange between the bed load and the bed itself.

对于一个有着移动河床的明渠的一组水力学参数而言，可能会超过河床的临界条件而导致颗粒运动的发生。假设被携带颗粒的运动时滚动、滑动且有时是跳动，并且这个运动发生在河道河床附近。这种泥沙输运通常被称作推移质输沙。如果且当整个固体颗粒的运动都是被液体包围时，它们被称作悬浮移动。受到颗粒重量的影响，有沉降的趋势，而这种情况通过不规则的液体颗粒运动而平衡，即，湍流速度分量。因此河流的水力条件决定了是否与合适一个给定尺寸的比例将会悬浮。并且，某时作为悬移质部分的泥沙颗粒，在另外时候会成为推移质，反之亦然。在推移质和河床本身之间还存在着内部交换的活动。

The upper limit, where suspension ceases, is the water surface; its lower limit is extremely poorly defined. Coming closer toward the bed, it becomes more difficult to fulfill the foregoing requirements for suspension. The mode of sediment transport that exists in the immediate vicinity of the bed, in the so-called bed layer, is the bed load. Suspended load is always accompanied by bed load, and the transition between the two modes of transport is gradual.

悬浮停止的上限是水体表面，它的下限非常不好界定。越靠近河床，就约难满足悬浮的上述要求。紧邻河床也就是所谓的床面层的泥沙输移形式是推移质。悬移质总是伴有推移质，且两种输移模式之间的过渡过程是逐渐变化的。

Earlier studies concerned with the suspension problem offered very little conclusive or even encouraging results. However, the introduction of the diffusion-dispersion model made a considerable impact on the field. Laws of the vertical and longitudinal distribution of suspended matter were established and found in reasonably good agreement with data from flume experiments or field measurements.

关注悬浮问题的早期研究给出了很少的结论或甚至令人鼓舞的结果。然而，扩散理论模型在该领域的引入取得了相当大的影响。悬浮物的垂直和纵向分布规律建立并找到与水槽实验或野外测量数据相当吻合的情况。

6. Sediment Transport and Rivers

6. 泥沙输移和河流

The character (type, form, regime, kind) of a river reach, or a river, is determined by the flow, the sediment transported by the flow, the sediment making up the bed and banks, and by such external controls as might exist or be imposed.

一个河段或河流的性质（类型、形式、制度、种类）是由水流、水流输移的泥沙、构成河床的河岸以及通过这样的可能存在或被施加的外部控制决定的。

It should be apparent that with flow conditions and sediment supply variable in time and space, an absolutely fixed river should not be expected; if the flow in, or the sediment supply to, a river reach changes, a change in the reach should be expected. Because these fluctuating conditions have been going on for thousands or millions of year, the river is in almost an equilibrium of sorts-eroding the mountains slowly, filling the sea slow, and changing locally back and forth, up and down, about some mean.

应该显而易见的是，在时间和空间中水流条件和来杀量变化的情况下，不应该期望河流时绝对固定的。如果流进一个河段的水量或该河段的来杀量发生变化，那么就应该想到该河段的变化。因为这些脉动条件已经持续了上千年甚至上百万年的时间，该河流几乎达到了以下一些平均数的各种平衡：慢慢地侵蚀着山地，慢慢地填充着海洋，并且在前后、上下局部地改变着。

6.1 River Behavior

6.1河流行为

To understand river behavior in general or the behavior of a particular river, one should observe with one’s own eyes the flow in various reaches at various discharges form low to flood flow. Maps, aerial photographs, measurements, and pictures from the past can all help in understanding what has happened and therefore, can happen again; but they cannot entirely substitute for seeing and experiencing the river. Only with first having a qualitative feeling for river behavior can one interpret meaning, fully the numbers or predictions that can result from the application of the “theories”include many assumption-both explicit and implicit (or unstated)-relationships obtained by curve fitting with little or no rationalization, and coefficients or factors which must be evaluated with “judgment” based on “experience”.

要了解一般河流的行为或特定河流的行为，应该亲自观察在不同的河段从低流量到洪水流量的不同流量的水流。地图、航空摄影测量、测量以及过去的照片都能够帮助了解发生了什么，并因此能够再次发生。但是它们并不能完全代替观察和检验河流。只有首先拥有对河流行为充分的了解，才能解释意义、能够从“理论”应用中得来的数字或预测。这些理论包括很多假设，显性的和隐性的（或未说明的），如通过很少或根本没有合理化的曲线拟合获得的关系，以及必须通过基于“经验”上“判断”而计算的系数或因数。

With all of that said, what can one learn from theory? The advantage that can accrue from looking at river problems from a theoretical point of view is that one can think of the answers to “what if” questions; one can vary one thing at a time and trace out what should happen. In a real river, everything changes at once, and change in one thing induces change in another thing; in an imaginary river, one can choose and control changes.

介绍了这么多，我们能够从理论中学到什么呢？能够从理论角度观察河流问题而得来

的优势是我们能够考虑“如果”的问题；我们能够在一个时刻改变一件事并追踪将会发生的事。在实际的河流中，所有因素都是同时发生的，并且一个因素的改变会引发另一个因素的改变；而在一个想象中的河流，人们则可以选择和控制变量。

Consider then a straight reach of river-not long, not short-with a high bank, the sediment in the bed is of some size and composition; the banks may be composed of the same material, but are often of a finer composition and may contain a considerable amount of clay. The reach upstream will deliver a certain flow of water and a sediment load to the reach under consideration; the sediment load will be of a size and composition which is compatible with (but not exactly the same as) the bed material of the reach. When everything is in equilibrium (not changing with time), the reach downstream will accept that same rate of flow and sediment load and will provide a control for the water surface elevation of the reach being examined (assuming subcritical flow).

接着考虑一个顺直河段，不长也不短，河岸较高，河床上的泥沙大小与组成相同；河岸可能由相同的材料组成，但是通常由更细的材料组成并包括一定量的黏土。上游河段会向考虑中的河段传输一定的水流和泥沙；该泥沙的尺寸和组成可以与该河段河床材料相比较（但是不完全相同）。当所有都达到平衡（不随时间而变化）时，下游河段会接收相同的流量和输沙率，并将提供对检验河段（假设为次临界流）水面高度的控制。

6.2 Channel Geometry

6.2 河道几何结构

For a certain flow rate to transport a certain sediment load without eroding the banks, there must be a certain velocity, depth, width, slope, boundary shear, and turbulence. All of these depend to some extent on each other. The flow rate (discharge) is the product of the velocity, depth, and width (or the integral of the velocity over the cross-sectional area). The sediment moving as bed load is very dependent on particle shear (which is less than the average intensity of the total shear). The particle shear is a function of velocity, depth, and bed material size. The slope necessary to achieve the necessary velocity depends on the flow rate or the depth, and the total resistance to flow. Resistance, in turn, depends very much on the dune formation on the bed; the larger the relative roughness and the larger the resistance. The bed material forming the boundary is not fixed-it is very movable or deformable-and the size of ripples, dunes, or waves which form the bed are dependent on the flow characteristics, the sediment and sediment load, and somewhat on the temperature.

对于某一定水流流量输移某一定输沙量但并不侵蚀河岸，必须有一定的速度，深度，宽度，坡度，边界剪切和湍流。所有的这些都在某种程度上相互影响。流量是速度、深度和宽度（或者横截断面上速度的积分）的产物。作为推移质移动的泥沙在很大程度上依赖于颗粒剪切力（它比总剪切力的平均强度要小）。颗粒剪切力是速度、深度和河床材料尺寸的函数。要达到必要的速度的斜率取决于流速或深度，以及总流动阻力。阻力反过来在很大程度上依赖于河床上的砂丘构成，相对粗糙度越大，阻力就越大。形成边界的床沙并不固定，它非常易于移动或重塑，并且形成河床的沙波、砂丘或波浪的大小取决于流动特性、泥沙和输沙量，以及在某种程度上依赖于温度。

If the boundary shear on the banks is too great, the bank material will erode, the channel section will widen, and everything (velocity, depth, etc.) will change. If the boundary shear is a little less than the maximum, nothing much will happen; if it is much less, the channel will try to narrow. However, the process whereby a channel narrows is not clear. This is in contrast to the

process whereby a channel widens (erosion or scour) which happens quite quickly, is “to be expected”, and can be observed in any flood. The narrowing process is much slower, more subtle, becomes mixed up with the unsteadiness and nonuniformity of the flow, with all the other things that are changing, and with nonequilibrium conditions in general. Observers have put together evidence that channels have narrowed over a time period (Burkham, 1972). It may also be noted that if channels did not narrow, since rivers have been much as they are for thousands and thousands of years, they would be at something like their maximum width and, therefore, would not widen in rather ordinarily rare floods.

如果作用在河岸的边界剪切李太大，那么河岸材料就会受到侵蚀，河道断面就会变宽，随后所有参数（速度、深度等等）就会变化。如果边界剪切力比最大的稍微小一点，那么任何事情都不会发生；如果它小得多，那么河道就会试着变窄。然而，河道变窄的过程并不明确。相对于很快发生的河道变宽（侵蚀或冲刷），这个过程是“可以预料的”，在任何洪水过程中都可以观察到。河道变窄过程要慢得多，更加细微，变得与流动的不稳定和不均匀性、与所有的正在发生变化并与一般的非平衡条件的东西混合起来。观察者已经将河道在一段时间内（Burkham，1972）变窄的依据放在一起。也要指出的是，如果河道并没有变窄，由于河流如成千上万年以来一样，它们可能已经达到最大宽度，因此在除非常罕见洪水外的情况下并不会变宽。

6.3 Equilibrium, Aggradation, and Degradation

6.3平衡、淤积和冲刷

Positive proof beyond the shadow of a doubt that one and only one set of values of width, depth, and slope will obtain for a given set of conditions of discharge, sediment load, bed material, and bank material is difficult to demonstrate convincingly by pure logical argument. But it can be demonstrated in the laboratory in a straight flume with controls for the incoming discharge and sediment load, for the downstream water surface elevation, and for the slope of the flume-that the bank material is completely inerodible makes this special, model river reach less than general. In this discussion subcritical flow is assumed, although a similar discussion could be made for supercritical flow. Indeed, sometimes it is immaterial what the flow regime is. If the inlet valve is opened, the sand feed is started, the tailgate is adjusted for some water-surface elevation, and the flume is allowed to run for some hours or days, an equilibrium state will be achieved.

毫无疑问对于一组给定条件的流量、输沙量、床沙和河岸材料有一组且唯一的宽度、深度和坡度的数值的有力证据，很难通过纯粹的逻辑论证令人信服的证明。但是可以在实验室受到流量和输沙量控制的顺直水槽中证明，对于下游水表高度以及对于河槽的坡度而言，河岸材料完全不可冲刷使其变得特殊，模型河段比一般河段要小。在这个讨论中假设的是次临界，尽管相似的讨论可以用作超临界流中。确实，有时流动的状态如何无关紧要。如果进口阀开启，加沙器开启，喂水闸门根据水表高度调整，且水槽须要放几个小时或几天的水，那么就会得到一个平衡状态。

Now if the tailgate is raised, raising the water-surface elevation, and nothing else is changed, there will be deposition (aggradation) starting at the head end of the flume. After some time the same equilibrium state will be achieved-the same except that the bed and water surface will be higher by the amount that the tailgate was raised. Similarly, if the flume is made steeper by tilting about the head end, and if the tailgate is adjusted so that the tail water elevation is maintained in absolute elevation, deposition will occur starting at the head end until eventually exactly the

same equilibrium state is achieved. If the steepening is accomplished by tilting about the tail end, erosion (degradation) will take place starting at the head end because the velocity and shear there will be greater than they were and, therefore, the capacity to transport sediment will be greater than the rate with which the sand feed is supplying sediment to the flume. After a time, exactly the same state of equilibrium will be achieved.

现在如果尾水闸门抬升，抬升水面高度，其它并不改变，在水槽的前端就会发生沉积（淤积）。经过一段时间就会获得相同的平衡状态，除了河床和水面高度会根据尾水闸门提升的量而变高。类似地，如果通过倾斜前端使水槽变深，且如果尾水闸门被调整到尾水高度维持在绝对高度上，就会在前端发生沉积，直到最终达到相同的平衡状态。如果通过抬高尾端来使得其变陡，就会在前端发生侵蚀（冲刷），因为那里的速度和剪切力将会比此前大，并且因此输沙能力将会比加沙器提供到水槽中的速率要大。经过一段时间以后，就会获得完全相同的平衡状态。

Flattening the flume will also cause aggradation or degradation in order to finally achieve essentially the same original state of equilibrium. If the flattening is done by tilting the flume about the tail end, there will be aggradation to build up the bed to the original slope-the deposition beginning at the head end. If the flattening is done by tilting the flume about the head end, and the tailgate is adjusted to keep the water surface at the tail end where it was, degradation will occur all along the reach because the velocity and capacity increase along the whole reach. As the head of the reach returns to the equilibrium condition, degradation will cease there, but will continue in the tail end of the reach. If the tail end of the reach approaches critical depth (energy critical), the capacity for movement will increase faster than linearly, resulting in a faster rate of degradation at the tail end of the reach and head cutting back upstream.

水槽扁平化也会引起淤积或冲刷，以最终达到本质上相同的原始平衡状态。如果扁平化是通过抬升尾端而得到，就会有对初始坡度积聚河床的淤积的发生，沉积开始在前端。如果扁平化是通过抬升水槽的前端，且尾水闸门被调整到控制尾端水面维持不变，就会沿着河段发生冲刷，因为速度和容量沿着整个河段增加。当河段前端回到平衡条件，冲刷就会在那里停止，但是会在河段尾端处继续。如果河段尾端达到临近深度（临界能量），运动容量将会比线性增长的快，导致了河段尾端更快速率的冲刷以及上游前端水流削减。

In other words, given a rate at which sand is supplied to the flume and a rate of flow, there will be some certain velocity, depth of flow, and slope to the bed (and a certain bed configuration of dunes which will result in a certain resistance to flow); the tail water-surface control merely establishes a base level. If the discharge or the sediment load (or both) is changed, the velocity, depth, and slope will change. If the sediment load is increased, the velocity and slope will increase, and the depth will decrease. If the discharge is increased, the opposite will happen. In the flume, the width cannot increase no matter how great the boundary shear; and it will not decrease no matter how small the boundary shear; and it will not decrease no matter how small the boundary shear becomes unless the flow and sediment load become so small that there is just a trickle of water moving sediment as it wanders down the flume.

换句话说，给定向水槽的供沙速率和流量，就会有一定的速度、水流深度和河床坡度（以及会导致一定水流阻力的某河床砂丘构造）；尾水水面控制仅仅建立一个基准面。如果流量或者输沙量（或二者）变化，那么速度、深度和坡度就会变化。如果输沙量增加，那么速度和坡度就会增加，并且深度会减小。如果流量增加，则相反的就会发生。在水槽中，不管边界剪切李多大，宽度都不会增加；且不管边界剪切力变为多小，它都不会减小，除非水

流和输沙量变小以至于移动泥沙在顺着河槽移动时产生了涓涓细流。

7. Channel Forms (1)

7. 河道形式（1）

Natural channels occur in three general forms: straight, braided, and meandering. There are numerous factors that might influence a stream in assuming one form or the other, and their relationships are not completely known. There are, however, general concepts that should be considered in any works to rectify or control a channel.

天然河道有三种一般形式：顺直河道、辫状河道和蜿蜒型河道。假设的河流一种形式或其它形式可能会受到多种因素影响，并且它们之间的关系并不完全明确。但是，在整治或控制一个河道的任何工程中，都有应该考虑的一般性概念。

7.1 Straight Channels

7.1顺直河道

Straight channels are those, which follow essentially a straight alignment. They exist generally with either flat slopes, which are inadequate to provide erosive velocities, or steep slopes that produce relatively high velocities. In the latter case, it is possible that the straight alignment results primarily from momentum that discourages turning. It is also possible that the alignment might be influenced by a heavy concentration of sediment which required for its transport the full capacity provided by the steep slope. However, it is unlikely that this latter condition would be the controlling factor, for under those conditions a natural stream with its normally fluctuating discharge tends to be braided.

顺直河道就是那些基本上沿着一条顺直准线的河道。它们通常拥有平缓坡度，这使得其不足以产生冲蚀速度，或者是能够产生相对高速的陡坡。在后一种情况下，顺直准线可能主要来自于阻止转向的动能。准线也有可能受到高浓度泥沙的影响，为了输移它要求陡峭坡度提供的全部能力。然而，这个后面的条件不可能是控制因素，因为在那些条件下，带有通常波动流量的一条自然河流趋于成为辫状河流。

7.2 Braided Channels

7.2辫状河道

Braided channels are those formed of random interconnected channels separated by bars and presenting the general appearance of a braid. Braided channels of streams in regimen are

4or seldom found except on relatively steep slopes, indicated by Lane (1957) to be S=0.10√Q greater and by Leopold and Wolman (1957) as S=0.06Q?0.44or greater; Q in the first instance being the average discharge, in cubic feet per second and in the second, the bank-full discharge. Term S is the slope, in feet per thousand feet. In aggrading streams, braiding may occur on either flat, moderate, or steep slopes; but in either balanced or aggrading streams, it is believed to result primarily from random deposition of materials transported during high flows in quantities or sizes too great for continued transport during moderate or low flows. These deposits frequently form bars upon which vegetation flourishes to discourage further movement by succeeding high discharges, thus intensifying the braiding.

辫状河型是一些由洲滩分隔开的河道随机地交织在一起形成的，呈现出编织的总体外

4观。管理中很少发现河流的辫状河道，除了在相对陡峭的坡度上，由Lane指出的S=0.10√Q 或更大，以及由Leopold和Wolman (1957) 指出的S=0.06Q?0.44或更大。Q在第一种情况中是平均流量，单位是立方英尺每秒；在第二种情况中，是指平滩流量。S是坡度，单位是英尺每千英尺。在淤积型河流中，辩状可能会发生在平坦、中度或陡坡中；但是在平衡或者淤积型河流中，被认为是主要来自以在中等或低流量中继续输运的量或尺寸过大的高流量的随机储存中。这些淤积常常形成洲滩，在其上植被繁茂，阻止了随后高流量的进一步运动，因此强化了辩状形成。

A further type of multiple channel stream is the distributary type found on delta formations or debris cones. These are generally aggrading channels that divide to follow separate courses which finally either disappear into sheet flow or continue until again collected at the foot of the slope.

另一类型的多通道河流时在三角洲形态或冲积扇上发现的支流形式。这些淤积型河流随后分成各自河道，并最终消失，或继续流动直到在坡脚重新汇集。

7.3 Meandering channels

7.3 蜿蜒型河道

Meandering channels follow a winding or tortuous course. They are distinguished from a tortuous channel, the alignment of which is essentially fixed by geologic or geographic conditions, by the fact that the alignment of a meandering channel tends continuously to shift by local erosion and rebuilding of the banks. The majority of problems arising in channel control will be found to concern meandering streams, as these are the streams in which bank erosion most commonly occurs. As the solutions of these problems depend largely upon a knowledge of the channel characteristics, a somewhat detailed analysis will be presented.

蜿蜒型河道沿着一个蜿蜒曲折的河道。它们与蜿蜒河道有别，后者的准线基本上是通过地质和地理条件限定，通过蜿蜒河道准线区域由当地侵蚀和河岸的重筑而变换。在河道控制中出现的主要问题会发现考虑蜿蜒溪流，因为这些溪流的河岸最常被发生。因为这些问题的解决主要取决于河道特点，一个在某种程度上细致的分析将会被呈现。

Meandering streams are found to occupy valleys of moderate slope, expressed by Lane (1957) as between S=4and S=4, Q being the average discharge, in cubic feet per second. There is no general agreement as to the causes of meandering or of the relations between the factors believed to be involved. Claude Inglic (1949) represents, perhaps, the majority opinion in his statement that “meandering is nature’s way of damping out excess energy during a wide range of flow conditions; the pattern depending upon the grade of material, the relation between discharge and charge (sediment concentration), and the rate of charge and discharge”. E.W. Lane (1957) is among those speaking for the opposition in citing the fact that his analysis of a large number of streams showed that “for the same average discharge and material size, streams in non-cohesive material tend to be more nearly straight when they are steeper than meandering stream”; however, such straight channels would then be within his general classification of braided stream. Other observers are content to point out the fact that almost any obstruction in the bed can cause the current to be deflected into a bank where it might erode an irregularity that, in turn, can deflect the current to the opposite bank, thus establishing a chain reaction. Friedkin (1945) in reviewing laboratory flume tests states that the only requirement for

meandering is bank erosion. More recently, Shen and Einstein (1964) and Shen and Komura (1968) have found that meandering tendencies develop with differences between the shear stresses at the two sides of the cross section. Other investigators have also mentioned the effects of secondary currents.

蜿蜒型河道被发现占据中等坡度的河谷，这是由Lane (1957)通过S =Q 4 和S =Q 4表

述的，Q 是平均流量，单位是立方英尺每秒。人们对蜿蜒的原因或所认为要包含的因素之间的关系并没有普遍的共识。Claude Inglic （1949）可能在他的表述中表达了大部分意见：“当水流条件变化范围较大时，蜿蜒型河道是一种消耗剩余能量的自然方式；耗能形式依赖于床沙级配、来水来沙关系以及沙量和水量的比值”。E.W. Lane （1957）是在那些反对者之一，他引用了他对大量溪流分析后的事实“对于先沟通的平均流量和材料尺寸，非粘性床沙的河流在比蜿蜒型河道更陡时趋于更加顺直”；然而，这些顺直河道随后还会划分为辩状河流的一般类别。其他的观察者满足于指出基于所有的河床阻力都能够引起偏转到河岸的水流，在那里它可能不规则地侵蚀，反过来又将河流偏转到对面河岸，因此建立一个连锁反应。Friedkin （1945）年在回顾实验室水槽试验时指出，蜿蜒型的仅有的要求时河岸侵蚀。更近的是，Shen 和 Einstein （1964）以及Shen 和Komura （1968）发现蜿蜒趋势随着断面两边之间剪切力的区别而发展。其他研究人员也指出了副流的影响。

In so far as practical channel control is concerned, agreement with one theory or the other as to the cause of meandering is much less important in the present state of knowledge than the realization that the meanders in any given stream were formed in accordance with implicit though imperfectly known laws of nature and that they should receive the proper consideration in any control works.

在迄今为止的所关注的河道控制，在当前知识状态中，对于蜿蜒形成原因的一个或另一个理论的共识要比以下认识重要性小得多，即任何给定河流中的蜿蜒是按照隐形但是不完全为人所知的自然规律而形成的，并且应该在任何控制工程中都受到合适的考虑。

The basic stream meander is essentially a sinusoidal curve, as shown in Figure 1 (a). It is a dynamic form, tending constantly to shift its position by erosion of the concave banks and deposition along the convex banks of the bends. Under ideal conditions, a meander system will migrate downstream in an orderly progression along a central axis. The basic relationships between meander dimensions and the various controlling factors are not known.

如图1（a ）中所示，基本的河流蜿蜒基本上是一个正弦曲线。它是一个动态的形式，趋于通过侵蚀弯道凹岸和沿着弯道凸岸淤积，不断地改变其位置。在理想条件下，一个蜿蜒系统将会在下游沿着中轴以一个有序的过程迁移。蜿蜒尺寸和各种控制因素之间的基本关系并不明确。

The primary dimensions of a meander system in Figure 1(a) are the length, width, and tortuosity ratio, the latter, also known as sinuosity or sinuosity ratio, being a resultant of the first two and generally define as the ratio between the channel and valley distances or the valley and channels slopes.

在图1（a ）中蜿蜒系统的基本尺寸是长度、宽度和曲率，后者也被称为弯度或弯度比，是前两者的结果，通常被定义为河道和河谷距离或河谷和河道坡度之间的比率。

The five primary factors determining these dimensions. As listed by Matthes in order of importance, are (1) valley slope; (2) bank-full discharge; (3) bed load; (4) transverse oscillations; and (5) degree of readability of the alluvium.

确定这些尺寸的五个基本因素。Matthes 以重要性作为顺序指出（1）河谷坡度；（2）

平滩流量；（3）输沙量；（4）横向振荡和（5）冲积的可读性程度。

Figure 1 (a) Meander; (b) Deformed Meander.

图1（a）蜿蜒河道；（b）不稳定的河道。

8. Channel Forms (2)

8. 河道形式（2）

Deformed meanders form because the conditions required for the development of an ideal meander system seldom exist in natural, and both the individual meanders and the overall system of a natural meandering stream tend to become distorted. A typical meandering stream shown in Figure 1 (b) will be formed of numerous irregular bends of varying size and shape that resemble an ideal meander pattern only in respect to the alternating direction and continuing migration of the bends.

由于对于理想弯道系统的演化所需要的条件在自然界中很少存在的不稳定的弯道和个别弯道、天然蜿蜒流的整体系统往往会变得扭曲。图1（b）中所示的典型弯道系统将要形成不同大小和形状的无数不规则弯曲，仅在相对于交替方向和弯曲的继续迁移类似于理想的弯道类型。

Meander deformation may be initiated by any of numerous items; usually either deflection of the flow, local variation in the rate of bank erosion or various combinations thereof. The effects of deformation are progressive, i.e. any change in the shape or other dimensions of one meander is usually reflected in one or more adjacent meanders, either as a local change in slope, as a variation in the angle of entry, or both. Either can cause a change that is further reflected to the next loop.

河曲变形可以由众多项目之一启动；通常是水流偏转、河岸侵蚀速率局部变化或它们的各种组合之一。变形的影响是渐进式的，即一个弯曲的形状或其他参数的任何变化通常都反映在邻近的一个或多个弯曲中，或为坡度的局部变化，或为入流角度的变化，或两者皆有。两者都可以引起进一步反映到下一环的变化。

The most prominent deformations occur as cutoffs shown in Figure 1(b) either chute cutoffs, in which the flow cuts across the base of a meander loop; or as loop or neck cutoffs, in which a meander loop closes upon itself until the flow cuts across the narrow neck formed thereby.

最显著的变形发生为如图1（b）中所示的截断，或为撇摊，其中水流切穿弯道环的基部；或为自然裁弯或颈部截断，其中弯道环自身闭合直到水流切过在那里形成的狭窄颈部。

A chute cutoff results generally when the slope becomes inadequate to support the flow and sediment discharge. In natural streams they have been observed to occur during flood flows that tended to follow a straighter path and during lesser flows when either the loop in question or an adjacent loop became excessively enlarged.

撇滩通常发生在坡度不足以支持水流和泥沙的排出的时候。在自然界河流中，它们通常发生在区域沿着一个更直的路径的洪水流量中，以及在流量较小时当环路有问题或者临近环路被过度扩大时。

Loop cutoffs are the end result of a migrating meander impinging upon an erosion-resistant formation. Movement of the leading portion of the loop is restrained while the following position moves up until only a narrow neck separates the two. This neck may be breached either by continued erosion or by the erosive action of a flood flow cutting across.

自然裁弯是移动弯道冲击在耐侵蚀性构造所形成的最终结果。环路的引导部分的移动受到限制，而随后的部分移动起来直到仅有一个的狭窄颈部将二者分离。这个颈部在持续的侵蚀或者洪水流量切过时的冲蚀作用而受到破坏。

The immediate influence of a loop cutoff will be noted in several adjacent meanders due to the local change in slope; however, there is apt to be a lasting influence that may affect the meander pattern permanently. When such a cutoff occurs, the ends of the old loop soon become filled with a deposit of sand, leaving the remainder as a crescent-shaped or horseshoe lake. Since sediment can then enter the lake only from local inflow or form overbank flood flows, further sediment deposited consists of finer sediments, normally decreasing in size with distance from the new channel. Eventually, the bight of the loop is filled with a deposit of fine sediments. Unlike the usual accretion deposit that consists of a relatively thin layer of fine sediments over a mass of coarser material, the fine deposit in the bight of an abandoned loop extends to the full depth of the old channel, forming an erosion-resistant plug against which following loops may impinge. The traces of old meander crescents, although they may be difficult to identify on the ground, will remain visible from the air or on aerial photographs for many years, perhaps even centuries.

自然裁弯的直接影响将会作用在临近的几个弯道，这是由于坡度的局部变化产生的；然而，这趋于变成一个持续影响，它将会永久地影响弯道类型。当这样的裁弯发生时，旧环的末端很快地被於沙填满，其余部分作为一个月牙形或马蹄形湖泊。因为泥沙随后能从局部入流进入湖泊，或者形成漫滩洪水流量，所以随后的泥沙淤积包括更细的泥沙，通常在新河道中随着距离的增加，其尺寸逐渐减小。最后，在环路的弯曲填满了细沙。河道淤积物一般是薄薄一层细沙覆盖在粗沙上面。废旧河湾的淤积情况有所不同，旧河槽中淤积都是细沙，形成了一个抵抗下一个河湾冲击侵蚀的“河塞”。尽管在地表很难确认，废旧月牙形河道的痕迹在很多年也需几个世纪中从空中或者航拍图中还是能辨别。

A common cause of deformation is local bank erosion that creates a pocket or a false point