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ПОСОБИЕ (гидротехнич строительство) 174.doc
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4. Correct the false sentences according to the text.

  1. Irrigation is the watering of land by natural methods.

  2. It provides water for plant growth in areas that have long periods of rainfall.

  3. Irrigation is used in desert regions, in regions with seasonal rainfall, in cold regions.

  4. The amount of irrigation water depends on the type of crop and the climate.

  5. Irrigation requires large supplies of unsalty water.

  6. Surface water isn’t obtained by means of a network of canals.

  7. The laterals are large canals.

  8. The water flows to the canals by gravity if a farm lies at a higher elevation than the supply source.

  9. If the farm lies at a lower elevation than the source, the water must be pumped up to the canals.

  10. Ground water is pumped to the surface from the top of an aquifer.

  11. A system of canals or pipes is always needed to bring the water to the crops.

  12. The lost of water happens through evaporation, seepage and transpiration.

5. Some irrigation water may be lost through evaporation, seepage and transpiration. State the places and the ways of water lost reducing, filling in the table.

Evapouration

occurs

in reservoirs

and

may be reduced by

- …

Seepage

-…

-…

-lining a reservoir with a layer of fine soil;

- …

Transpiration

-…

- …

6. Answer the following questions.

  1. What is irrigation?

  2. Where is the water used for irrigation taken from?

  3. Where is irrigation used?

  4. How much water is used for irrigation?

  5. Most farms obtain surface water by means of a network of canals, don’t they?

  6. What canals are called laterals?

  7. What are the laterals connected to?

  8. When must the water be pumped up to the canals?

  9. What is ground water pumped to the surface from?

  10. Where should an irrigation well be dug?

  11. What is needed to bring the water to the crops if the well is far from the farm?

  12. How can the amount of water lost through evaporation be reduced?

  13. When does seepage occur?

  14. How can seepage be controlled?

  15. How can some loss from transpiration be avoided?

7. Make a short summary of the text.

8. Choose the contextual meaning of the following words used in Text a.

1) accounts

a) счета

b) включать

c) требования

2) flows

a) течь

b) потоки

c) заливать

3) lifts

a) лифты

b) поднимать

c) этажи

4) crops

a) урожай

b) сажать

c) зерновые культуры

5) weed

a) водоросль

b) пропалывать

c) сорная трава