5. Finish the following sentences according to the text.

1. A dam is a barrier across flowing water that ….

2. Dams may be classified according to ….

3. The selection of the type of a dam for the site is a problem in ….

4. Feasibility is governed by ….

5. According to height, there are ….

6. A dam must be capable of ….

7. The material underlying a dam must be capable of ….

6. Decide whether the following statements are true or false according to the text.

1. A dam is a barrier across flowing water that obstructs, directs or retards the flow, without creating a reservoir, lake or impoundment.

2. Topography, geology and climate govern the engineering feasibility and cost.

3. A low dam is more then 30 m high and a medium-height dam is less 100 m then high but more then 30 m high; and a high dam is over 100 m high.

4. The height of a dam is defined as the difference in elevation between spillway crest and the highest part of the excavated foundation.

5. Gravity is the weight of a dam which is the product of its volume and the specific weight of the material.

6. Ice pressure is exerted on the downstream face of a dam.

7. Most failures of dams have been caused by failure of the foundation.

8. Construction of dams and reservoirs requires the closest cooperation of different specialists in order to ensure a maximum degree of safety of the dams.

7. Answer the following questions.

1. What is a dam?

2. How may dams be classified?

3. What is a spillway?

4. What are the types of dams?

5. How is the height of a dam defined?

6. Why are dams built?

7. Dams provide head for generating hydroelectric power, don’t they?

8. Does a dam protect against flooding from rivers and the seas?

9. Must a dam be relatively impervious to water?

10. What forces must a dam be capable of resisting?

11. Must a dam be relatively impervious to water?

12. What forces must a dam be capable of resisting?

13. What must the material underlying a dam be capable of?

14. What has been caused by failure of the underlying material?

15. What does the construction of dams and reservoirs require? Why?

8. Fill in the table according to the text.

DAMS	Principle of classification	Types of dams, examples
	according to structure	gravity dams, …
	…	…
	…	…
	…	…

9. Make a plan of the text.

10. Choose the best title to the text. Explain your choice. You may propose your own title.

1. Dams.

2. Construction of dams.

3. Forces acting on dams.

4. Dam classification.

5. Main features of dams.

11. Make a summary of the text.

12. Try to find any additional information about dam classifications and forces acting on dams.

13. Choose the best synonym to the given words.

1. to create – to destroy, to build up, to originate, to break

2. to retard – to prevent, to speed, to delay, to quicken

3. to protect – to look after, to shelter, to defend, to care for, to attack

4. to assure – to promise, to guarantee, to ensure, to insure

5. to increase – to mount, to drop, to grow, to decrease

6. selection – collection, choice, variety, range

7. consumption – use, expenditure, conservation, spending, utilization

8. relative – absolute, relation, corresponding, utilization

14. Build up the correct words.

Model: amd → dam

1) owlf → …	4) alek → …	7) lyswpali → …
2) upeprso → …	5) tgiheh → …	8) udinfaoon → …
3) uetctrusr → …	6) asnero → …	9) fyaste → …

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

1) according ___sth.; 2) to be subdivided ___ sth.; 3) to depend ___ sth.; 4) to define ___ sth.; 5) to provide ___ sth. ___ generating power; 6) to protect ___ sth.; 7) to be impervious ___ water; 8) to act ___ a dam; 9) water ___ pressure; 10) to be capable ___ sth.

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

to permit	wildlife	to preserve
hydraulic turbines	gradually	valley
to divert	to overflow	topsoil
adjacent	refuge	swift

17. Read the title of the text. What is the text about?

18. While reading the following text, find the synonyms to the words in the left column of the table, answer the following questions.

1. Does a dam stop the flow of water?

2. Does a dam change the water level in the reservoir?

3. What is the stored water used for?

Text B What does a dam do?

1) to conserve - … 2) to elevate - … 3) neighboring - … 4) to generate - … 5) invariable - … 6) discharge - … 7) amount - … 8) shelter - … 9) to protect - … 10) quick - … 11) take away - …

As a barrier across a river or stream, a dam stops the flow of water. A dam stores the water, creating a lake or reservoir above it. The stored water is then made available for irrigation, town and city water supplies, and many other uses. The dam also raises the water surface from the level of the original riverbed to a higher level. This permits water to be diverted by the natural flow of gravity to adjacent lands. The stored water also flows through hydraulic turbines, producing electric power that is used in homes and industries. Water released from the dam in uniform quantities assures water for fish and other wildlife in the stream below the dam. Otherwise, the stream would go dry there. Water released in larger quantities permits river navigation throughout the year. Where dams create large reservoirs, floodwaters can be held back and released gradually over longer periods of time without overflowing riverbanks. Reservoirs or lakes created by dams provide recreational areas for boating and swimming. They give refuge to fish and wildlife. They help preserve farmlands by reducing soil erosion. Much soil erosion occurs when rivers flood their valleys, and swift floodwaters carry off the rich topsoils.

19. Decide whether the following sentences are true or false according to the text.

1) A dam stops the flow of water and creates a lake or reservoir below it.

2) The stored water is used for irrigation, water supplies and etc.

3) The stored water is never used to generate electric power.

4) Released water provides river navigation throughout the year.

5) Water usually overflows riverbanks.

6) Lakes and reservoirs increase soil erosion.

20. Continue the list of what water, reservoirs and lakes, dams do.

DAMS stop the flow of water, create reservoirs and …, store …, …

RESERVOIRS AND LAKES provide …, …

WATER is used for...

21. Get ready to speak about “What does a dam do?”

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

masonry dams	buttresses	coarse materials
embankment dams	a slope	to cover
gravity dams	angle	a layer
arch dams	gravel	outer protection
buttress dams	silt	to pump
entirely	clay	to fill cracks
tremendous	to compact	watertight
solid rock foundation	to make up	boulders
to transfer	heavy rollers	facing
to hold back	to grade	gates
to curve	density	a pier
a canyon	the finest material	to allow
to push	waterproof	to serve
to support	a core	cement