Контрольно-измерительные материалы по иностранному языку. Ч.3. Сборник тестов

Раздел 3. 2. Тексты для профилей факультета инженерных систем и природоохранного строительства

Задание 1. Переведите текст.

WATER AND WATER SUPPLY

Centralized water supply dates back to 2500 BC. Ancient Egypt had complex engineering structures for the purpose. Yet to this day the percentage of the population enjoying centralized water supply on the African continent and in Asia, too, is very low.

In our country, at the time of the Revolution of 1917, only one third of the towns had running water laid on, and, then, as a rule, only in the central part of the town. In the pre-war period of industrial development running water reached millions of flats all over the country. Water supply of the systems are practically all in the western and central parts of European Russia, were destroyed during the war and had to be built anew.

Fresh water shortage was first mentioned soon after the end of the Second World War. The first to feel the stint was Europe. The problem came to many as a complete surprise, something in the nature of an unexpected “catastrophe”. This catastrophe, however, should have been foreseen, for it follows logically from the development of human life on our planet and of Man’s industrial activity.

In the absence of centralized water supply, a man can do with about 25 litres of water a day for his various personal needs. But in the modern city water consumption per person is much higher. An average of 300 to 500 litres of water is spent daily on household and sanitary needs per one inhabitant of a modern city. You can see this vastly exceeds the necessary minimum of 25 litres. Why the discrepancy (difference)? Not because people leave their taps open. Because water is so abundant nobody thinks twice about taking a shower, or a bath, using the washing machine, washing the car, etc. The volume of water consumption is indicative not

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only of the efficiency of the water supply but also of the population’s living standards.

One need in water is growing. Simultaneously, the globe’s population is growing. In the past century the consumption of water by the world’s largest cities, such as Paris, London, Berlin and Moscow, has grown 80 to 100 times. During the famous heat wave of 1972 Moscow “drank” almost 5,000,000 cubic metres of water a day. This staggering figure seems to confirm the immediacy of the water dearth problem. In actual fact, however, the problem consists not so much in where to get pure water but in how to deliver it to where people need it.

(1)Water is an important part of nature which surrounds us and of those natural conditions we are changing constantly and intensively: the flora, the soil, the mountains, mineral resources, the deserts, the marches, the steppes and the taiga.

(2)Vast depressions in the earth are filled with water through the medium of natural water sources such as rivers, lakes, etc. over the earth’s surface. These bodies of water are classified as inland lakes and are excellent sources of water. Often a water body deep in the soil consists of a sand or gravel stratum which connects or empties into the basin of an inland lake and provides a splendid source of water supply through the medium of a drilled well.

(3)Man uses water for domestic and sanitary purposes and returns it to the source through sewage disposal system. It is of prime importance that the supply must be protected against pollution, because no one can predict how disastrous may be the results.

(4)An adequate supply of pure, wholesome and palatable water is essential to the maintenance of high standards of health and to provide the convenience and comfort to the community. In some localities water is available in unlimited quantities and converting it to use is not a difficult problem. This is especially true of towns situated on large inland lakes or rivers. But there are cities where geographical location requires elaborate

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systems of water supply, and to provide a satisfactory supply of water in these localities becomes a large engineering task.

(5)The importance of a sufficient supply of water for domestic and industrial purpose has long been a deciding factor in the location of cities. The earliest settlers realized this need and took advantage of natural water resources by establishing colonies in close proximity to them.

(6)Water may be taken from any source of water for human consumption after it has undergone a preliminary treatment to assure its purity. As man’s communities grew in population, the demand for water increased and the need for protection of the source of water supply against the possibility of contamination became evident. Progress and civilization have called for elaborate and various systems and methods of water treatment.

(1)The problem of protecting natural water resources has grown very urgent for many countries since the beginning of the second half of the 20th century. The rivers, lakes and ground water contain today a considerable amount of the products of mechanical, chemical and biological pollution due to the development of human society, social and technical progress.

(2)The waste products that result from the daily activities in a community are of two general types: the liquid waste as sewage and the solid wastes, known as refuse. Sewage may be also divided according to its source into the following three classes. The sewage from residences, institutions and business buildings is called domestic sewage, sanitary sewage or house sewage; the resulting from industrial processes is known as industrial waste, and that of from run-off during storms is called storm sewage. A combination of domestic sewage, industrial waste and storm water is called combined sewage.

(3)Sewage and refuse must be removed promptly in order to avoid endangering the health of the community. The removal of all kinds of sewage is usually accomplished by means of sewers. The sewers are placed in the streets at several feet below the ground surface. The entire

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system of sewers including a sewage treatment plant is known as a sewerage system.

(4) The method of sewage treatment to be adopted in a particular case will depend entirely on local conditions. The usual methods of sewage treatment consist of preliminary treatment alone or primary treatment followed by secondary treatment. During primary treatment the larger and heavier solid particles settle out from the liquid. Secondary treatment is required to remove decomposable materials from the sewage. An auxiliary treatment, which may be used with primary or secondary treatment is disinfection or the killing of the most of the bacteria in the sewage by means of chemicals [16].

Задание 2. Сделайте презентацию текста.

WATER-POWER DEVELOPMENT —INTEGRAL PART

OF CIVIL ENGINEERING

With the growth of towns and their industries, with the increase of population and the improvement of living conditions the demand for water rises rendering the work of water power engineers ever more important.

There are so many uses for river water that it seems natural it is always made to serve more than one purpose. A large reservoir formed by the dam may be used for flood control, for improving industrial and domestic water supply for nearby areas, for irrigation and navigation, for recreation and sport. To accomplish such miscellaneous tasks a hydropower development built on the river should comprise besides the dam such structures as a power station, navigation locks, spillway facilities, and canals and tunnels for discharging floods, and other ancillary structures of minor importance.

In harnessing a river to make it serve the man a dam as an impervious barrier should be placed in its way, which impounds water and raises the level of the river thus creating the head necessary for power generation. Since dams are to withstand various stresses, much thought

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should be given to the problems of increasing their strength, water tightness, stability and safety. It becomes аll the more important nowadays as the heights of dams have steadily been increased and this fact calls for a drastic improvement of the methods of design and a deeper knowledge of the foundation character and the properties of the materials used.

Well executed, the dam is of great benefit to the community but if it is not, a dam failure is, perhaps, the most serious man-made catastrophe likely to occur in the peace time. The disasters that took place showed that the mechanism of a dam failure is very complex, that a whole series of effects occur in quick succession. The determination of the true state of stress in a dam undertaken so far now requires a more elaborate treatment as people have come to realize that the best of theories is useless if the materials used do not comply with the assumptions made about their properties. Modern industrial growth should not be threatened for want of electric energy and this calls for providing better use of resources of various sorts to attain maximum technical and financial efficiency. Thus the idea of a pumped-storage station using small rivers or basins appeared. The principle of its operation demands storing water in an upper basin and then directing it into a lower basin where from the water is pumped back into the upper basin to repeat the cycle. The scheme demands a special kind of machinery—a reversible pump-turbine type. The station of this kind readily covers peak energy periods and is most efficient when combined with some other type of power plant.

In some countries for lack of any more economically exploitable water power development the new power demand will be covered by nuclear stations.

Nuclear, conventional thermal and hydropower plants are complementary, but not mutually exclusive. The problem of high load factor and peak load demands is to be solved by coupling nuclear stations, providing base load energy, with hydropower plants dealing with the peaks. Before arriving at a decision in favour of any of the ways of power

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generation, the full technical as well as financial aspects (capital investments and fuel costs) should be thoroughly examined.

A roller gate is a long metal cylinder with “ring gears” at each end that mesh with inclined metal racks supported by the piers. The cylinder is braced internally to act as a beam to transmit the water load into the piers. The effective damming height of the structural cylinder can be increased by means of a projecting apron that rotates into contact with the sill as the gate rolls down the inclined racks. The gate is raised and lowered by means of a chain or cable wrapped around one end of the cylinder and operated by a hoist permanently mounted in the pier. The rolling movement of the gate and the limited amount of frictional contact at the sealing points permit comparatively fast operation with a small expenditure of power. Roller gates have been built with a damming height of 30 ft., with lengths up to 125 ft. on pile foundations and 150 ft. on rock foundations. Roller gates are efficient in their power requirements and can be used for wider spillway bays than other types of gates. However, complexity of construction and the maintenance required by the hoisting and roller system are disadvantages of this type of gate. Sills and piers for roller gates are comparable to those of other gates of similar height and width.

By building dams, reservoirs, and diversion canals, humans have drastically changed the very nature of rivers, including the quantity and timing of flows. Prior to 1900, only 40 reservoirs had a storage volume of more than 25 billion gallons. Today, about 3,000 reservoirs exist that collectively contain over 1,500 cubic miles of water—large enough to flood 120-million acres of land. Governments around the world have spent US$2 trillion on large dams—the "equivalent of the entire 2003 U.S. government budget."

According to the watershed industry standard, any dam structure higher than 15 meters is considered a "large dam"; when it exceeds 150 meters, it is considered a "major dam" or "mega-dam." Check dams are

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usually less than 15-meters high and the largest check dam built by a nonprofit agency in India with government support currently stands in Rajasthan at 7.25 meters in height.

The battle over mega-dams is at the center of conflicts throughout the world involving water scarcity, environmental degradation, biodiversity loss, globalization, social justice, survival of indigenous peoples, and the growing gap between the rich and poor. Global water use has tripled since the 1950s, and for decades policymakers and politicians have met this rising demand by building larger dams. India is the most prolific dam builder in the world today with 4,300 large dams; it ranks third behind China and the United States for completed large dams.

A concrete dam is a structure designed and built for the purpose of holding back water, that is usually placed across the path of a river. Dams are built for a variety of reasons, including flood control, power generation, and water management. A concrete dam is the strongest type of dam built in modern times and may take several forms. Concrete itself is a building material made from water, cement, sand and gravel, or aggregate.

In modern times, nearly every dam is made either partially or entirely from concrete. Concrete is an excellent material for constructing dams because it is very strong when under compression — pressed down or pushed together. Many designs for concrete dams take advantage of this property to produce extremely large dams, capable of holding back many cubic miles (1 cu. mile = 4.2 cu. kms) of water.

Dams constructed from concrete have three basic designs. An arch dam is a curved, relatively thin curtain of concrete, with the concave side of the curve facing down stream. This type of dam is made of solid concrete that is reinforced with steel. It relies on the pressure of the water behind it to add strength as this pressure pushes the sides of the dam into the walls on either side. Arch dams are particularly well suited for areas

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where a river flows at the bottom of steep canyons or gorges with solid rock walls.

A gravity dam is a type of dam that relies on its own mass to keep it in place and to hold back water. Gravity dams are often massive structures, sometimes tens of feet (1 foot = .3 meters) thick. The dam is made of concrete, but the main portion of its interior is fill rather than solid concrete. A gravity dam is usually not curved, and a cross section will resemble a right triangle, with the right angle at the bottom on the side facing the water and the side facing away from the water sloping downward so that the dam is thicker at the bottom. Gravity dams are better for areas where there is no firm bedrock or canyonwalls for anchorage.

The third main type of concrete dam is the arch-gravity dam, which combines the features of both the arch dam and the gravity dam. Archgravity dams are curved dams that use the principle of the arch to bolster their strength but are much thicker than a typical arch dam and have a core of fill. They are designed so that their massive weight, combined with the increased strength of an arch over a straight line structure, will keep the dam in place and hold back the water.

Some concrete dams may have several small arches or buttresses or a pair of large arches or other variations, but most, if not all of these, are variations on one of the three basic designs. A relatively type of concrete, for building concrete dams, is called roller compacted concrete and uses heavy rollers to press the concrete during construction. Many newer dams are being constructed using this technique, but the designs still of the same basic types. A typical concrete dam has spillways for releasing water when needed, and many are designed to make use of water flow to generate electricity by means of hydroelectric power plants. Flowing water that turns massive turbines produces as much as 20% of the world's electricity.

A flood dam operates as part of a flood control system to protect communities from uncontrolled flood waters. Such dams do not create reservoirs to store water for use in the future, nor do they

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generate hydroelectric power. They can be installed by government agencies and communities, and are subject to regulation for safety. A flood dam needs to meet building guidelines and regulators can inspect it periodically to confirm it is in good working order.

For flood management, agencies can place flood dams at strategic points in a watershed like large rivers and lakes. These dams control the flow of water through the watershed and in some cases the area behind them may be dry much of the time. Seasonal lakes, streams, and rivers can become a problem in flood conditions, because they quickly overflow and can overwhelm waterways and communities.

In heavy rains, or when runoff from upstream becomes heavier than usual, the flood dam can kick into operation. It retains water and controls its release to slowly allow levels of lakes and rivers to stabilize. In addition to protecting communities from flood waters, this measure also limits topsoil loss and other environmental problems that can occur in severe flooding. When conditions return to normal, the flood control dams can go back into a dormant mode.

The design of a flood dam can vary, depending on the site of installation and recorded flood data from prior years in that area. It typically includes outlets as well as a spillway for emergencies to prevent failure of the dam in a catastrophe. Flood control dams also include equipment to measure flood waters and some provide remote reporting for government agencies that need to be able to monitor flooding and other activities. A number of construction techniques can be used to make a flood dam, depending on the level of stress it needs to be able to endure.

A flood control system can include a number of dams, levees and other safety measures to control and direct water throughout a watershed in the event of severe weather. Flooding is an extremely common form of natural disaster in many regions of the world. The development of adequate flood control systems is critical for economic, environmental, and human health reasons. Funding for flood control programs typically

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comes from government agencies, although some communities may also raise funds independently for installation of additional measures for their health and safety.

An internal drainage board, or IDB, is a formal group, organization, or authority in charge of preparing for and managing floodwater, generally in areas with a high risk of flooding. The term "internal drainage board" is used primarily to refer to such organizations in Wales and England, though similar groups exist elsewhere, such as "watershed districts" in the United States. In general, such groups are given special authority to conduct preventative and repair work within a given geographic region to ensure that water drains appropriately. Their responsibilities include flood prevention; infrastructure preservation; and when possible, ecological conservation. The main responsibility of an IDB is to take all necessary action to ensure proper water drainage from a given area and to prevent flooding, thereby protecting people and property from potentially dangerous floodwater.

There is a wide range of tasks involving routine maintenance and emergency response that an internal drainage board may address in order to guarantee proper water drainage and to prevent flooding. Water sources such as rivers and streams are quite important, as water levels can rise substantially with increased precipitation. An IDB may be called upon to maintain the integrity of such bodies of water, which include rivers, lakes, smaller streams, and others that could flood with increased precipitation. Maintenance of areas that are normally dry but which flood easily with high levels of rain are also very important, as the floodwater must generally flow to a certain place or in a certain direction to avoid damaging anything important.

In some cases, an internal drainage board might be called upon to protect specific important infrastructure components from floodwater. They may, for instance, need to ensure that a certain road, factory, or power station remains safe from floodwater. In some cases, this only

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