Read the text and see if your ideas are right. Give your title to the text.



In the design of any waterworks project it is necessary to estimate the amount of water that is required. This involves determining the number of people who will be served and their per capita water consumption, together with an analysis of the factors that may operate to affect consumption.

It is usual to express water consumption in liters or gallons per capita per day, obtaining this figure by dividing the total number of people in the city into the total daily water consumption. For many purposes the average daily consumption is convenient. It is obtained by dividing the population into the total daily con­sumption averaged over one year. It must be realized, however, that using the total population may, in some cases, result in serious inaccuracy, since a large proportion of the population may be served by privately owned wells. A more accurate figure would be the daily consumption per person served.

Prior to design of a waterworks one must establish the length of time the improve­ment will serve the community before it is abandoned or enlarged.

For example, an impounding reservoir may be constructed of such capacity that it will furnish a sufficient amount of water for 30 years, or the capacity of a water purification plant may be adequate for 10 years. These periods are known as periods of design, and they have an important bearing upon the amount of funds that may be invested in construction of both waterworks and sewerage works. Since most American cities are growing in population, the period of design depends mainly upon the rate of population growth; i.e., the water purification plant mentioned above will just serve the population expected 10 years hence. The problem, accordingly, is to forecast as accurately as possible the population 10, 20, or 30 years in the future.

One source of population figures is the U.S. Bureau of the Census, which makes decennial counts and publishes reports covering its enumerations. While the Census Reports give the data upon which to base estimates of population, it is frequently necessary to estimate present population in a year subsequent to the last decennial census. Finding present population is sometimes done by plotting the line of population increase as shown by the last two preceding enumerations and continuing the line to the year in question. Population figures shown by city directories may also be used. Possibly the best method is to obtain the ratio of population to the number of children in the schools or to the number of telephone services in the census year and apply the same ratio to the number of school children or services of the present year.

It is more difficult to estimate the population in some future year. Several methods are used, but it should be pointed out that judgment must be exercised by the engineer as to which method is most applicable. A knowledge of the city and its environs, its trade territory, whether or not its industries are expanding, the state of development in the surrounding country, location with regard to rail or water shipment of raw materials and manufactured goods will all enter into the estimation of future population. Of course, extraordinary events, such as discovery of a nearby oil field or sudden development of a new industry, upset all calculations of future growth and necessitate hasty extension of existing water and sewage facilities.

1. Notes to the text:

to estimate – оценивать

per capita – на душу населения

inaccuracy – неточность

directory – справочник

2. Match the words in columns and make the collocations:

1) water                    a) population

2) sewage                 b) facilities

3) to affect                c) plant

4) daily                     d) consumption

5) total                     e) reservoir

6) impounding             

7) water purification

3. Match the following English expressions to their Russian ones:

1) amount of water a) мощность
2) the number of people b) количество воды
3) to affect consumption c) темпы роста населения
4) total population d) влиять на потребление
5) capacity e) количество людей
6) rate of population growth f) общее количество населения

4. Read the text again and answer the questions:

1) What is water consumption expressed in?

2) May the total population result in serious inaccuracy?

3) What must one establish in the design of a waterworks?

4) What does the period of design depend upon?

5) What is one of sources of population in the USA?

6) How can city directories be used?

 5. Read the following statements and say whether they are true or false (T/F). If they are false correct them. Use the following phrases:

• It’s true…

• No objections…

• It’s false…

• According to the text…

1) The design of any waterworks project involves determining the number of people who will be served.

2) The average daily consumption is inconvenient.

3) Using the total population often result in serious inaccuracy.

4) The capacity of a water purification plant may be adequate for 10 years.

5) Periods of design don’t have an important bearing upon the amount of funds invested in construction of waterworks.

6) The period of design depends upon the rate of population growth.

7) Water purification plant will serve the population expected 10 years.

6. Look through the text and find in the text English equivalents for the following words and word combinations:

1) определение количества человек

2) выражать потребление воды в литрах или галлонах

3) на душу населения в день

4) среднее потребление воды в день

5) колодцы в частном владении

6) увеличение сообщества

7) водоочистительные сооружения

8) прогноз

9) источник населения

10) соотношение количества населения к количеству детей

7. Discuss in pairs:

1) Necessary data base in the design of any waterworks.

2) Factors influencing the periods of waterworks design.

 


Дата добавления: 2018-05-12; просмотров: 258; Мы поможем в написании вашей работы!






Мы поможем в написании ваших работ!