水利水电工程专业英语——灌溉与排水篇.docx

水利水电工程专业英语——灌溉与排水篇
1. Consumptive Use of Water
1. 消耗性用水

Consumptive use of water involves problems of water supply, both surface and underground, as well as problems of management and economics of irrigation projects. Consumptive use has become a highly important factor in the arbitration of controversies over major stream systems where the public welfare of valleys, states, and nations is involved. Before available water resources of a drainage basin in arid and semiarid regions can be satisfactorily ascertained, careful consideration must be given to consumptive use requirements for water in various subbasins.
消耗性用水涉及到地表和地下供水问题，也包括管理和灌溉工程的经济性问题。消耗性使用已经成为一个评判包含河谷、州和国家公共福利的主要河流系统争议的重要因素。在干旱和半干旱地区流域的可利用水资源被确定之前，必须仔细考虑各个子流域内对消耗性用水的需求。

1.1 Definition of Consumptive Use
1.1 消耗性用水的定义
Consumptive use, or evapotranspiration, is the sum of two terms: (1) transpiration, which is water entering plant roots and used to build plant tissue or being passed through leaves of plant into the atmosphere, (2) evaporation, which is water evaporation from adjacent soil, water surfaces, or from the surfaces of leaves of the plant. Water deposited by dew, rainfall, or sprinkler irrigation and subsequently evaporating without entering the plant system is part of consumptive use.
消耗性用水，或者说腾发量，是两项的总和：（1）蒸腾，即水分进入植物的根系用来构建植物体或者通过植物叶片被传输到大气中；（2）蒸发，即水分从邻近的土壤、水面或者从植物叶面蒸发的过程。通过露水、降雨或者喷灌储存，随后未经过植物体而蒸发也是消耗性用水的一部分。

Consumptive use can apply to water requirements of a crop, a field, a farm, a project, or a valley. When the consumptive use of the crop is known, the water use of larger units can be calculated. Hence, the term “consumptive use” and the following discussion generally refer to the crop.
消耗性用水可以应用到一棵植物、一块土地、一片农场、一个项目或者一个河谷的用水需求中。当作物的消耗性用水为已知时，就可以计算更大单元的用水量。因此，术语“消耗性用水”和接下来的讨论主要是指作物。

1.2 Conditions Affecting Consumptive Use of Water
1.2 影响消费性用水的条件
Evaportranspiration is influenced by temperature, irrigation practices, length of growing season, precipitation, and other factors. The volume of water transpired by plants depends in part on the water at their disposal, and also on temperature and humidity of the air, wind movement, intensity and duration of sunlight, stage of development of the plant, type of foliage, and mature of the leaves.
腾发量受到天气、灌溉方式、生长期长度、降水及其他因素影响。植物蒸腾的水量部分取决于其所处位置的水源，还有温度和空气的湿度、风运动、光照的强度和持续时间、植物生育阶段、叶片类型和叶片成熟度。

Consumptive use by native vegetation of noncropped land is fairly constant from year to year where the water supply is adequate, but surface evaporation increases in wet years because of the expansion of water surface and moist soil areas. In some irrigated valleys irrigation is lavish when the water supply is abundant, and increased waste water and return flow are consequently available for nonproductive consumption. Also, evaporation is increased from the cropped land soils. Plant diseases and pests reduce consumptive use by inhibiting plant growth. Size of a farm may affect water usage appreciably since borders, size of stream, and crop rotations may be different.
原生植物的消耗性用水在水分供应充足地区每年是相当恒定的，但是在丰水年地表蒸发量却因为水面积和湿润土壤面积的扩大而增加。在一些灌溉河谷，当供水充足时灌溉是奢侈的，而且增加了废水量，因而回水可被用作非生产性耗水。并且，耕作区土壤的蒸发量也会增加。植物病虫害通过抑制植物的生长减少了消耗性用水。农场的大小可能会显著地影响水资源利用，因为边界、河流大小和植物轮作可能是不同的。

1) Evapotraspiration from soils. Where the water table is near the ground surface, evaporation from the soil is almost equal to evaporation from a free water surface; whereas, with water levels at greater depths below the surface, evaporation from soil decreases until it becomes negligible when moisture no longer reaches the surface by capillary action.
1）土壤处的腾发。在地下水水位接近地表的地方，土壤蒸发量几乎与自由水面的蒸发量相同。而随着水位降低到距离地表更深处，土壤蒸发量就会随之减少，直到当水分不再能通过毛细作用到达地表时它便可以忽略不计。

Where irrigation water is applied by flooding methods, large amounts of water are lost by direct evaporation from soil surfaces without having passed through the roots, stems, and leaves of plants. After light showers during the growing season, considerable rainfall, if not all, is retained on the leaves where it subsequently evaporates without entering the roots of the plants. Showers of less than 5 millimeters seldom enter the soil to a sufficient depth to be used by the plants. Therefore, water received from light rain showers or from light sprinkler irrigation may not be used by the plants in the transpiration process. Subsequent discussion based upon the energy available for evaporation shows, however, that under normal conditions, water that evaporates directly from the soil or leaves is beneficially used, reducing by a like amount water that would otherwise have been transpired by the plants. This is true provided a normal mature crop exists over the soil surface. Early or late in the growing period, when the crop is not transpiring much water, evaporation from a wet soil surface may exceed normal consumptive use.
当灌溉水是通过漫灌的方式引入的时候，大量的水就会直接从土壤表面蒸发，而没有经过植物的根、茎和叶。在生长季节的小阵雨过后，至少相当部分的降雨被截留在叶面上并且随后从那里蒸发，并未经过植物的根系。小于5mm的降雨几乎不能进入到足够的深度而被植物利用。因此，从小阵雨或从轻微的喷灌中获得的水分可能不会被植物用到蒸腾过程中。基于蒸发使用能量的角度考虑的论述表明，尽管在正常情况下，直接从土壤和叶面蒸发的水分得到了充分的利用，这些水若不被蒸发则会被植物用作蒸腾。这真正地在土壤表面养活了一颗正常成熟的作物。在生长周期的早期或晚期，当作物蒸腾量不大时，从湿润土壤表面的蒸发可能会超过正常的消耗性用水。

There are still decided differences in opinion on the effect of cultivation on direct evaporation of water from soils. Recent studies seem to throw considerable doubt on advantages of soil mulches for conserving water through reduction of evaporation losses from soils that are not excessively wet or in contrast with a water table at a shallow depth. Therefore, broad general conclusions concerning influence of cultivation on direct evaporation losses from soils may be misleading. The large number of variable factors involved-notably the differences in distances to free-water sources, in original moisture content of unsaturated soils, in texture, structure, and water conductivity- make it hazardous to generalize.
人们对于耕种对水分直接从土壤蒸发效果的看法存在着明显的差异。最近的研究似乎对于减少并非充分湿润或者地下水位相对较浅的土壤的蒸发损失以涵养水分的土壤覆盖的优势提出了相当大的疑问。因此，关于耕种对于从土壤的直接蒸发损失影响的结论可能是有误的。这其中包含着大量的变量因素使之不能一概而论，特别是到自由水源距离的差别、饱和土壤的水分含量、质地、结构以及导水性。

2) Transpiration. The process by which water vapor escapes from living plants, principally the leaves, and enters the atmosphere is known as transpiration. During the growing period of a crop, there is a continuous movement of water from the soil into roots, up stems, and out of leaves of the plants. Velocity of water flowing through plants varies widely from 25 to 175 centimeters per hour; but, under conditions of unusually high temperature, dry atmosphere, and wind, velocity of the stream may be greatly increased. A very small proportion of water absorbed by the roots is retained in the plants. If the rate of evaporation at the leaves exceeds the rate of absorption by the roots, wilt occurs and growth of the plant is impeded. On the other hand the available water is not used efficiently, if conditions are such as to stimulate excessive transpiration.
2）蒸腾。即水蒸气通过活体植物溢出，主要是叶子，进入到大气中的过程被称为蒸腾。在作物生长阶段，存在一个连续不断的从土壤进入植物的根系、上升到茎，然后从叶面溢出的水分运动。水分在植物体内流动的速度广泛地分布于每小时25到175厘米之间；但是，在非正常高温、干燥的大气、风等条件下，水流的速度可能会明显增加。根系吸收的非常小的比例的水分被保留在植物中。如果叶面的蒸发速率超过了根系的吸水速率，那么植物就会枯萎且其生长受到抑制。另一方面，在刺激过度蒸腾的条件下，可利用水并不能被有效利用。

When water changes from liquid to vapor and passed from the plants into the atmosphere, about 590 calories of heat are required for every cubic centimeter being converted from liquid to vapor. Hence, if heat is not available, transpiration ceases; and conversely, as available heat increases, transpiration increases. Heat can come from the soil, the plant, the air, or from direct radiation. The majority of heat used for transpiration, even over short periods of time, comes directly from the sun as radiant energy.
当水分从液态变成气态并从植物进入到大气中，每立方厘米的水分从液态转变成气态大约需要590卡路里的热量。因此，如果没有热量可用，蒸腾就会停止；反之，如果可用热量增加，蒸腾作用增加。热量可以来自土壤、植物、空气或者来自直接辐射。用于蒸腾的绝大部分热量，即使时间很短，直接来自太阳的辐射能量。

Thus, a given increment of heat will vaporize a given quantity of water. If the available heat is used for vaporizing water from the ground surface, it is not available for vaporizing water within the cavities of the leaf. Therefore, a light shower of rain remaining on the surface of leaves or on the ground can evaporate, utilizing the bulk of available energy. When this occurs, the transpiration of water through the plant will be reduced accordingly.
因此，一定的增加的热量会汽化一定量的水分。如果可用的热量被用来汽化地表的水分，它就不会被利用于叶片气孔处的水分汽化。因此，小阵雨中留存在叶片表面或是地表的水分会利用大量可用的能量。当这种情况发生时，通过植物体的蒸腾作用就会相应地被减少。

For example, suppose a rainfall of only 3 millimeters occurred during the dry season and all the moisture was intercepted by leaves of the growing crop. Assume also that daily consumptive use was 6 millimeters per day. Experiments show that the bulk of consumptive use occurs during the day. Therefore, if consumptive use of 6 millimeters per day occurs over, say 12 hours, the average use per hour would be 0.5 millimeters. During midday, the rate is likely to nearly double the average or 1.0 millimeters per hour. Hence, in 3 hours the rainfall of 3 millimeters would be evaporated and would have been fully utilized. Often overlooked is the fact that rainfall of 3 millimeters may represent only one-half of a normal daily consumptive use. Observations of the recovery of a wilted crop following a light shower will show that the rainfall is not without effect.
例如，假设在干旱季节发生了一场仅有3mm的降雨，并且所有的水分都被生长中的作物叶片截留。叶舌每天消耗性用水为6mm。试验表明大量的消耗性用水发生在白天。因此，如果每天的6mm，消耗性用水发生在，比如说12小时内，那么每小时平均用水量就是0.5mm。在中午，速率很可能达到平均水平的两倍即每小时1.0mm。因此，在3个小时内3mm的降水就会被蒸发并被完全利用。经常被忽视的事实是，3毫米的雨量可能只占正常日消耗性用水的一半。对于枯萎的植物在一场小阵雨过后恢复的观察表明，降雨并非没有影响。

Rainfall of less than 1 centimeter have frequently been neglected in project planning on the erroneous assumption that rain must get into the root zone to be fully effective. When the crop covers the ground surface, a light rain or a light irrigation will reduce by a like amount moisture removed from the soil by the roots, provided of course that an excessive wind does not exist.
基于雨水必须进入到植物根系区才能完全有效的假设，小于1厘米的降雨通常在项目规划中被忽略。当作物覆盖地表时，一场小雨或是少量的灌溉会全部通过根系从土壤中吸收走，前提当然是没有太大的风。

2. Irrigation
2. 灌溉

Irrigation is an ancient agricultural practice that was used 7000 years ago in Mesopotamia, other ancient, notable irrigation systems were located in Egypt, China, Mexico, and Peru. Today, approximately 11 percent of the world’s cropland is irrigated. Some of the densest populations are supported by producing crops on irrigated land, as in the United Arab Republic (Egypt), where 100 percent of the cropland is irrigated. This land is located along the Nile River. More than 12 percent of the cropland, or about 24000000 hectares(61000000 acres) are irrigated in the United States. Irrigation is extremely important in increasing soil productivity throughout the world.
灌溉作为一种古老的农业实践，最早是用在7000年前的美索不达米亚，同样古老的著名的灌溉系统位于埃及、中国、墨西哥和秘鲁。今天，全世界大约11%的农田可灌溉。一些最密集的人口是由可灌溉徒弟的作物生产所支撑，比如阿拉伯联合共和国（即埃及），那里100%的农田可灌溉。这片土地位于尼罗河沿岸。在美国有超过12%的农田，或者大约24000000公顷（61000000英亩）可以灌溉。灌溉对在全世界范围内提升土壤生产力是极其重要的。

2.1 Water Sources
2.1 水源
Most irrigation water is surface water resulting from rain and melting snow. Many rivers in the world have their headwaters in mountains and flow through arid and semiarid regions where the water is diverted for irrigation. Examples include the Indus River, which starts in the Himalaya Mountains，and the numerous rivers on the western slope the Andes Mountains, which flow through the deserts of Chile and Peru to the Pacific Ocean. Much of the water in these rivers comes from the melting of snow in the high mountains. In fact, the extent of the snowpack is measured in order to predict the stream flow and amount of water that will be available for irrigation the next season. Many farmers who use well water have their own source of irrigation water. About 20 percent of the water used for irrigation in the United States comes from wells.
大部分的灌溉水是来自降雨和融雪的地表水。世界上的很多河流发源于山区，流经干旱和半干旱地区，在那里河水被引用灌溉。众多例子中包括印度河，发源于喜马拉雅山脉，且在安第斯山脉西麓有着众多的河流，穿过智利沙漠和秘鲁注入太平洋。这些河流的很多水来自高山上的融雪。事实上，积雪的范围要被测量以预测河流流量和下一季可以用于灌溉的水量。很多用井水的农民有他们自己的灌溉水源。在美国大约20%的灌溉水来自井水。

2.2 Important Properties of Irrigated Soils
2.2灌溉土壤的重要性质
Soils well suited for irrigation have an intermediate texture to a depth of 1 to 2 meters and without compact or water-impermeable layers. Loamy soils that are underlain by coarse sands and gravel have greater retention of water in the overlying soil than soils that are loamy-textured throughout. The texture, together with the structure, should result in an infiltration rate of about 0.5 to 8 centimeters per hour and a moderate water-storage capacity. The soil should not have an injurious soluble salt content.
非常适合灌溉的土壤要有一个中等的质地，深度在1到2米，并且没有密实或不透水层。下层为粗砂和砾石的壤质土中覆盖土层比所有土层都是壤土质地要有更强的保水性。这种质地和结构应该能够得到每小时0.5到8厘米入渗率保持在和一个适中的储水能力。土壤中的可溶性盐含量不应达到有损害性的值。

2.3 Water Application Methods
2.3 灌水方法
Choice of various methods of applying irrigation water is influenced by a consideration of : (1) infiltration rate, (2) slope and general nature of the soil surface, (3)supply of water and how it is delivered, (4)crop rotation, and (5) seasonal rainfall. The methods of distributing water can be classified as flood, furrow, subsurface, sprinkler, and drip or trickle.
对于众多灌溉水施用方法的选择要受到以下思考的影响：（1）入渗速率；（2）坡度和土壤表面一般性质；（3）供水及引水方式；（4）轮作方式；（5）季节性降雨。配水方法可以分为漫灌、沟灌、地下灌、喷灌和滴灌。

1) Flood Irrigation. Flood irrigation floods the land by distributing water by gravity. Water is let into the upper end of the field, usually from a large ditch. Sometimes the water is distributed into basins, which is a common practice for orchards, pastures, and some grain crops, including rice. Flood irrigation can easily over-water some parts of a field while leaving some parts underirrigated.
1）漫灌。漫灌就是淹过地块通过重力分配水。通常水从一个大的沟渠中引入田块的高处。有时将水分配到低地，这是果园、牧场及一些谷类作物，包括水稻的普遍做法。漫灌的方式很容易让某些部分灌水过多而另一些部分则没有灌水。

2) Furrow Irrigation. Furrow irrigation is similar to flood irrigation, the difference being that the water distribution is down furrows instead of being allowed to flood over the land. In furrow irrigation, which is used for row crops, water is distributed down between the rows. Furrows that have a slight grade or slope are made across the field. The slope of the furrow bottoms depends on soil infiltration rate, which should be sufficient to distribute water along the entire length of the furrow. Furrow irrigation is unsatisfactory on sand soils, because of the very high infiltration rate and limited distance of water flow down the furrows.
2）沟灌。沟灌与漫灌相类似，其区别是水沿着垄沟分配而不是要淹过整块土地。在用于行栽作物的沟灌中，水顺着行间分配。整块田块中整理出了较小的等级或坡度的垄沟。沟底的坡度取决于土壤入渗速率，它应该足够水分沿着垄沟长度的方向分配水。沟灌不适合沙土地，因为其入渗速率非常高并且水沿着垄沟流动的距离有限。

Many methods are used to distribute water into the furrows. A major advantage of flood and furrow irrigation is that the water is distributed by gravity, so water distribution costs tent to be low.
有很多方法被用于将水分配到沟中。漫灌和沟灌的一个主要的优点是水是通过重力分配的，所以配水的成本就会低。

3) Sprinkler Irrigation. Sprinkler are widely used to irrigate lawns. Sprinkler systems are versatile and have some special advantages. On sands, where high infiltration rates permit water to flow only a short distance down a