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1、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, meteorology and oceanograph
2、y.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 precipitation ov
3、er 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 water is converted to
4、 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, national, intern
5、ational, 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 cannot be available a
6、t 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, since climatologic
7、al 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关注，因为一个地区的气候变化能够深
8、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 these are usually the
9、 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 United States. The
10、se 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 examples), politically s
11、pecified(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/streams such that
12、 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。这些图展示了考虑水文的水循环的过程
13、。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 the precip
14、itation(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 the ground (
15、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，一些会成为地表径流
16、，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 the 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
