水利水电工程专业英语水文与水资源篇.docx

1、水利水电工程专业英语水文与水资源篇水利水电工程专业英语水文与水资源篇1. Hydrological Cycle and Budget1.水文循环与预算Hydrology is an earth science. It encompasses the occurrence, distribution, movement, and properties of the waters of the earth and their environmental relations. Closely allied fields include geology, climatology, meteorolog

2、y and oceanography.水文学是一门地球科学。它包含地球水资源的发生、分布、运动和特质，以及其环境关系。与之密切相关领域包括地质学，气候学，气象学和海洋学。The hydrologic cycle is a continuous process by which water is transported from the oceans to the atmosphere to the land and back to the sea. Many sub-cycles exist. The evaporation of inland water and its subsequent

3、 precipitation over land before returning to the ocean is one example. The driving force for the global water transport system is provided by the sun, which furnishes the energy required for evaporation. Note that the water quality also changes during passage through the cycle; for example, sea wate

4、r is converted to fresh water through evaporation.水文循环是一个连续的过程，在这个过程中水从海洋被运输到大气中，降落到陆地，然后回到海洋。有很多子循环存在。内陆水域的蒸发机器后在回到海洋前在陆地上的将于就是一个例子。全球水运输系统的运行动力由太阳提供，通过蒸发这个过程赋予水运动能量。需要注意的是，水质在水循环通道中也会改变，比如，海水在蒸发后就会转变成淡水。The complete water cycle is global in nature. World water problems require studies on regional,

5、 national, international, continental, and global scales. Practical significance of the fact that the total supply of fresh water available to the earth is limited and very small compared with the salt water content of the oceans has received little attention. Thus waters flowing in one country cann

6、ot be available at the same time for use in other regions of the world. Modern hydrologists are obligated to cope with problems requiring definition in varying scales of significant order of magnitude difference. In addition, developing techniques to control weather must receive careful attention, s

7、ince climatological changes in one area can profoundly affect the hydrology and therefore the water resources of other regions.完整的水循环在自然界中是全球性的。世界水问题需要在区域，国家，国际，洲际和全球范围的研究。地球上可利用的淡水总量与海洋中的咸水相比是有限的，并且非常少，这个重要的显示尚未得到人们足够关注。因此，在一个国家流动的水源并不能同时在世界的其他区域被利用。现代水文学应该着力解决显著数量级的差异在不同尺度上的定义问题。此外，发展控制天气的技术必须得到密切

8、关注，因为一个地区的气候变化能够深刻地影响到其他地区的水文循环进而影响到其水资源。Because the total quantity of water available to the earth is finite and indestructible, the global hydrologic system may be looked upon as closed. Open hydrologic system may be looked upon as closed. Open hydrologic subsystems are abundant, however, and thes

9、e are usually the type analyzed. For any system, a water budget can be developed to account for the hydrologic components.因为地球上可利用的水量是有限且不可避免的，所以全球的水文循环系统可以被看成是闭合的。开放性的水文循环系统可以被看成是闭合的。开放的水文子系统内容丰富，然而这些系统也是经常被分析到的。对于任何系统，水预算都能够转变到对水文组成的计算。Figures 1 and 2 show a hydrologic budget for the coterminous U

10、nited States. These figures illustrate the components of the water cycle with which a hydrologist is concerned. In a practical sense, some hydrologic region is dealt with and a budget for that region is established. Such regions may be topographically defined (watersheds and river basins are example

11、s), politically specified(e.g. country or city limits), or chosen on some other grounds. Watersheds or drainage basins are the easiest to deal with since they sharply define surface water boundaries. These topographically determined areas are drained by a river/stream or system of connecting rivers/

12、streams such that all outflow is discharged through a single outlet. Unfortunately, it is often necessary to deal with regions that are not well suited for tracking hydrologic components. For these areas, the hydrologist will find hydrologic budgeting somewhat of a challenge.图1和图2展示了美国毗连地区的水文循环。这些图展

13、示了考虑水文的水循环的过程。从实际意义上讲，一些水文区域被处理并且建立了预算。这些区域可以是在地形上确定（如流域和河流盆地）、在政治上确定（如根据国家或者城市限制），或以其他因素确定。流域或者排水流域是最容易确定的，因为它们明显地限定了地表水的边界。这些地形上确定的区域由一条河流/溪流或者相连的河流/溪流排水，因此所有的出流都从某个单一的出口排出。不幸的是，我们经常会处理到不适合通过跟踪水文组成部分的区域。对于这些区域，水文学家会在不同程度上挑战地进行水文预算。The primary input in a hydrologic budget is precipitation. Some of

14、the precipitation(e.g. rain, snow, hail) may be intercepted by trees, grass, other vegetation, and structural objects and will eventually return to the atmosphere by evaporation. Once precipitation reaches the ground, some of it may fill depressions (become depression storage), part may penetrate th

15、e ground (infiltrate) to replenish soil moisture and groundwater reservoirs, and some may become surface runoff, that is, flow over the earths surface to a defined channel such as a stream.在水文预算中首要的输入是降水。部分降水（如雨、雪、冰雹）会被树木、草地、其它植被以及建筑物截留，并最终会通过蒸发返回大气。若降水到达地面，其中一些会在洼地储存（成为洼地存水），部分会入渗到地下（渗透）补充含水层和地下储水，

16、一些会成为地表径流，即流过地表进入到已有的通道中，比如溪流。Water entering the ground may take several paths. Some may be directly evaporated if adequate transfer from the soil to the surface is maintained. This can easily occur where a high groundwater table (free water surface) is within the limits of capillary transport to th

17、e ground surface. Vegetation using soil moisture or ground water directly can also transmit infiltrated water to the atmosphere by a process known as transpiration. Infiltrated water may likewise replenish soil moisture deficiencies and enter storage provided in groundwater reservoirs, which in turn

18、 maintain dry weather stream flow. Important bodies of groundwater are usually flowing so that infiltrated water reaching the saturated zone may be transported for considerable distances before it is discharged. Groundwater movement is subject, of course, to physical and geological constraints. 水进入地

19、表后可能有几个途径（被利用）。如果土壤水到地表的转移能够得到保证，一些可能被直接蒸发。这种现象很容易发生在毛细现象运输到达地表限制水位内的高地下水位情况下。植被直接利用的土壤水或地下水可通过所谓的“蒸腾”过程把如深水转换到大气中去。入渗水同样可以补充不足的土壤水且接入到地下水库提供的容量中，这些水反过来会在干燥天气保持水流运动。重要的地下水体一般都在流动，因此到达饱和区域的入渗水可能会在被运输了相当远的距离后才被排出。地下水的运动自然地会受到物理和地质条件的限制。Water stored in depressions will eventually evaporate or infiltrat

20、e the ground surface. Surface runoff ultimately reaches minor channels (gullies, rivulets, and the like), flows to major streams and finally reaches an ocean. Along the course of a stream, evaporation and infiltration can also occur.储存在洼地的水会最终蒸发或入渗到地表。地表径流最终到达小的通道（沟渠，溪流等），流向大的溪流，最后到达海洋。在水流动的过程中，蒸发和渗

21、流也同时发生着。2. Unit Hydrographs2. 单位线Ways to predict flood peak discharges and discharge hydrographs from rainfall events have been studied intensively since the early 1930s. One approach receiving considerable use is called the unit hydrograph method. It derives from a method of unit graphs employed by

22、 Sherman, in 1932. The unit graph is defined as follows: if a given X-hour rainfall produces a 10cm depth of runoff over the given drainage area, the hydrograph showing the rates at which the runoff occurred can be considered a unit graph for that watershed.自20世纪30年代早期就已经深入研究了降雨事件中预测洪峰流量和流量过程线的方法。一个

23、应用广泛的方法被称为单位线法。它源于谢尔曼在1932年使用的单位曲线的方法。该单位曲线定义如下：如果在给定的X小时内，给定的流域上产生了10cm深的径流，则在该流域出口断面形成的地面径流过程线即为单位线。It is incorrect to describe a unit hydrograph without specifying the duration, X of the storm that produced it. An X-hour unit hydrograph is defined as a direct runoff hydrograph having a 10cm. Volu

24、me and resulting from an X-hour storm having a steady intensity of 10/X cm/hr. A 2-hr unit hydrograph would be that produced by a 2-hr storm during which 10cm of excess runoff was uniformly generated over the basin. A 1-day unit hydrograph would be produced by a storm having 10cm of excess rain unif

25、ormly produced during a 24-hr period. The value X is often a fraction of 1 hr.如果不指明单位线的降雨历时X，那么描述单位线是不正确的。X小时的单位线被定义为具有10厘米的直接径流的过程线。一个X小时的暴雨有着稳定的10/X厘米/小时的体量和结果。一个2小时的单位线将由在流域内均匀产生10厘米过量径流的2小时暴雨所产生。一个1日单位线将由在24小时期间内均匀产生的具有10厘米过量降雨的暴雨所产生的。X值通常是1小时的几分之一。Application an X-hour unit graph to design rain

26、fall excess amounts other than 10cm is accomplished simply by multiplying the rainfall excess amount by the unit graph ordinates, since the runoff ordinates for a given duration are assumed to be directly proportional to rainfall excess. A 3-hr storm producing 20 cm of net rain would have runoff rat

27、es 2 times the values of the 3-hr unit hydrograph. 5cm in 3 hr would produce flows half the magnitude of the 3-hr unit hydrograph. This assumption of proportional flows applies only to equal duration storms.采用X小时的单位线来计算并非等于10厘米的径流过程，可简单地用净雨深乘以单位线的纵标，因为对一个给定时段，单位线假定径流与净雨直接成正比。一个产生20厘米净雨的3小时暴雨的径流速率值将是

28、3小时单位线的2倍。3小时内5厘米将会产生3小时单位线一半的量。该成比例径流假设仅适用于相同历时的暴雨。If the duration of another storm is an integer multiple of X, the storm is treated as a series of end to end X-hour storms. First, the hydrographs from each X increment of rain are determined from the X-hour unit hydrograph. The ordinates are then

29、added at corresponding times to determine the total hydrograph.如果另一个暴雨的历时是X的整数倍，那么该暴雨就被视作一系列首尾相连的X小时暴雨系列。首先，每个X降雨增量的过程线由X小时单位线确定。然后在相应的时间叠加到纵轴，以确定总的过程线。Implicit in deriving the unit hydrograph is the assumption that rainfall is distributed in the same temporal and spatial pattern for all storms. Thi

30、s is generally not true; consequently, variations in ordinates for different storm of equal duration can be expected.在推导单位线隐含的假设是所有暴雨中降雨都按照相同的时间和空间类型而分布。这通常并不是真实的；因此，可以预期对于相同历时的不同暴雨中的纵坐标的变化。The construction of unit hydrographs for other than integer multiples of the derived duration is facilitated b

31、y a method known as the S-hydrograph. The procedure employs a unit hydrograph to form an S-hydrograph resulting from a continuous applied rainfall. The unit hydrograph theory can be applied ungauged watersheds by relating unit hydrograph features to watershed characteristics. As a result of the atte

32、mpted synthesis of data, these approaches are referred to as synthetic unit hydrograph methods. The need to alter duration of a unit hydrograph encouraged studies to define the shortest possible storm duration, that is, an instantaneous unit rainfall. The concept of instantaneous unit hydrograph (IU

33、H) can be used in construction unit hydrographs for other than the derived duration.对于历时不是整数倍的单位线的建立，引入了一个被称为“S曲线”的方法。该过程引入了一个单位线以组成一个自所引用连续降雨产生的S曲线。单位线理论可以通过将单位线特征与流域特性相关联而应用到无水文资料流域。作为数据的尝试合成的结果，这些方法被称为“综合单位线法”。改变单位线历时的需要鼓励研究确定最短的风暴历时，即，瞬时单位的降雨量。“瞬时单位线”（IUH）的概念可以被用于构建非引用历时的单位线。Methods of deriving unit hydrographs vary and