Make a short summary of Text B.

Choose the right meaning of the words in bold in Text B.

1) gravity

2) head

3) data

4) rate

5) site           

Match the following terms with their definitions.

1. The matter that settles to the bottom of a liquid; material deposited by water, wind, or glaciers.

2. Quickness of motion, rapidity of movement.

3. An artificial channel into which water is let by a sluice.

4. An artificial passage for water fitted with a valve or gate for stopping or regulating flow.

5. The potential or suitability for holding, storing, or accommodating; the maximum amount or number that can be contained or accommodated.

6. A passage for surplus water to run over or around an obstruction (as a dam).

Find the synonyms in the text.

Find the opposites in the text.

Fill in the correct preposition, then choose any two items and make sentences.

1) to remain ___ suspension; 2) to be filled ___ sth.; 3) to compare ___ sth.; 4) to take ___ account; 5) ___ order ___ do sth.

Translate the following words into English using the vocabulary of the text.

Взвешенные частицы; вдоль дна реки; оседать на дно канала; противодействовать гравитационному оседанию; сниженная скорость; оставаться в взвешенном состоянии; проходить через плотину; приток наносов; принимать в расчет полученные данные; вместимость водохранилища; определять срок службы водохранилища; вода, пропускаемая через турбины; после завершения строительства; проектирование водохранилища; естественные и искусственные водохранилища.

Find the translation of the following terms and memorize their meaning.

Read the text to get the gist of it. Answer the following question.

Are wind tides larger in shallow reservoirs or in deep ones?

Text C                                                                  ________

Waves in reservoirs may damage structures and embankments which are located not far from the water. Part of the design of any large reservoir is to estimate wind tide and wave height. Wind tide is caused by the movement of the surface water towards the shore under the action of the wind. Thus hydrostatic unbalance and a return flow at some depth must occur. Wind tides are generally larger in reservoirs that are shallow and have rough bottom. When wind begins to blow over a smooth water surface small waves are caused by the tangential forces between the wind and water. Thus, the waves increase in size and the push of the wind against the back of the wave also increase. As the waves grow in size their speed also increases, until they move with the same speed as the wind. Since the wind forces acting on the wave are a function of the difference between wind speed and wave speed, further growth ceases when the speeds become equal. Waves are critical only when the reservoir has the maximum water level. Thus, in selecting the critical wind speed for reservoirs subject to seasonal fluctuations, only winds which can occur during the season of maximum water level in the reservoir should be considered.

It is virtually impossible to find a reservoir site having complete ideal characteristics. There exist general rules for choice of reservoir sites. They are:

1) A suitable dam site must exist. The cost of the dam is often a controlling factor in selection of a site.

2) The cost of real estate for the reservoir (including roads, railroads, cemetery and dwelling relocation) must not be excessive.

3) The reservoir site must have adequate capacity.

4) A deep reservoir is preferable to a shallow one because of less loss of water as a result of evaporation.

5) Areas which are unusually productive of sediment should be avoided if possible.

6) The quality of the stored water must be satisfactory.

7) Sites from which a considerable quantity of leakage may occur should be avoided.

Answer the following questions.

1) What may waves in reservoir damage?

2) What is wind tide caused by?

3) Where are wind tides generally larger?

4) What happens when wind begins to blow over a smooth water surface?

5) When are waves critical?

6) What are the main rules for choice of reservoir sites?

Which requirements must be followed and which ones should be followed? Use the ideas in the box below.

Choose the best endings to the following statements.

1. Waves may do harm to the structures…

a) which are located far from the water.

b) located near the water.

c) situated above the water.

2. Wind tide is caused by…

3. Waves are caused by…

a) the action of the wind.

b) the action of water.

c) the tangential forces between the wind and water.

4. When waves grow in size, their speed…

a) increases.                      b) reduces.                         c) falls.

5. Growth of wind speed and wave speed stops when…

a) the wind speed disappears.

b) the speeds become equal.

c) the waves reach the shore.

6. In the reservoir only winds occurring …

a) during the season of minimal water level should be considered.

b) at the period of maximum water level should be considered.

c) in winter and summers should be considered.

Read the text again, title it and make a plan of it.

Make a short summary of Text С.

Find the synonyms of the following words in the text.

Find the opposites of the following words in the text.

Fill in the correct prepositions, then choose any three items and make sentences.

1) to be located not ___ ___ sth; 2) ___ some depth; 3) to blow ___ a water surface; 4) to move ___ the same speed; 5) to be preferable ___ sth; 6) ___ a result.

Write the following sentences out in full.

1) necessary / must / one / by the end / of / the / investigations / carry out / May.

2) that / It / year / the construction / is / the reservoir / last / was completed / of.

3) difficult / it / kind / to / processes / control / is / this / of.

4) the reservoir site / should / pay / one / attention / to / the choice / special / of.

5) was / pointed / who / it / water / the chief engineer / the / minimal / level / the reservoir / in.

6) not / a dam / to / it / build / and / is / a reservoir / easy.

Read the following texts and fill in the missed words. Get ready to speak about different types of reservoirs.