Storage and distribution of water for irrigation

The regime of most great rivers is irregular. Frequently, they carry their greatest volumes of water in spring and in late autumn and winter, they may be reduced to mere trickles of water. To control these rivers and to regularize their regimes by storing water in the dry seasons, dams and reservoirs are constructed.

Dams, known also as barrages and weirs, are barriers built across rivers or streams to control the flow of water. Today most dams have several functions, which may include the storage and diversion of water for irrigation, the raising of water for generating hydroelectricity, and the provision of flood control. Dams have been constructed for thousands of years, at first of earth and later of stone.

Sometimes, the source of water may be lower than the area to be irrigated especially if the river runs in a canyon, and the water itself often has to be transported considerable distances from the river to the fields. In such cases, complex systems of pumping stations and canals may be necessary to lift and move the water from the reservoir to the fields.

A large-scale system of irrigation requires a complex network of dams, pumping stations and canals. In addition to the main dam, whose reservoir is the main storage unit, smaller diversion dams are needed to direct the water into an intricate canal system. The water is led from the dams into broad canals by gravity, and where these major canals, because of local physical conditions, are unable to receive then required water by gravity, pumping stations may be installed. These plants frequently receive their power from energy generated from power stations at the main storage dam.

From the main canals, water is diverted into a system which will distribute it throughout the farm. The most common means by which this is done are with open ditches or laterals, and the flow of water into them is controlled by head gates or regulators. They are frequently earth ditches, which may suffer from excessive losses owing to seepage, and evaporation, especially in arid regions or in areas of porous, sandy or gravelly soils. To eliminate such wastage, tubing is used in places of open ditches to carry water from the canal to the land. Tubing also prevents the loss of land used for ditches.

Leading from the permanent, open ditches, there are secondary or field ditches. They are ploughed in at the end of the growing season, as they would act as obstacles during harvesting. Water is delivered from these ditches to the areas to be irrigated by means of check structures or turnouts. Increasingly, however, water is being transferred from the ditch over the ditch bank into individual fields or furrows by means of siphons. These may be plastic, metal or rubber, and depending upon the size and volume of the water supply, may have flow capacities from as little as one gallon per minute to over 1,000 gallons per minute.

A very efficient way of conveying and distributing irrigation water is by means of pipelines. This method has many advantages: it practically eliminates losses due to evaporation and seepage; it reduces maintenance work, makes water control easier, eliminates the problem of weeds which grow along the banks of the open ditches, and makes it possible, for water to be carried by gravity or under pressure. Such pipelines may be permanent installations or portable. The former usually consists of buried concrete supply and distribution lines while the latter consist of metal or flexible surface pipes. Because of the very high cost of installation, however, pipelines are still relatively uncommon, and they are generally found in areas where water is scarce and crops are valuable.

Word List

irregular - нерегулярний	ditches - канави
frequently - часто	laterals - відвод
to carry - нести	head gate - головні ворота
volume - об’єм	excessive to eliminate -надмірні збитки
mere trickles - маленькі струмочки	wastage - зменшувати втрати
weirs - водозливи	tube - труба
diversion - розповсюдження	excessive losses - надмірні збитки
to raise - піднімати	owing to - завдяки
provision - забезпечення	seepage - просочування
flood - повінь	to prevent - запобігати
earth - земляний	permanent - постійний
stone - кам’яний	to plough - орати
especially - особливо	obstacles - перешкоди
considerable - значний	to harvest - збирати врожай
cases - випадки, докази	to deliver - доставити
complex - складний	check structures turnouts -переводи
pump - насос	increasingly - значно
to lift - піднімати	to transfer - переміщати
to require - вимагати	furrows - борозни
network - мережа	rubber - гума
main (major) - головний	capacities - потужності
unit - одиниця, частина	to convey - транспортувати
intricate - заплутаний	pipelines - трубопроводи
to lead (led) - очолювати, вести	due to - завдяки
conditions - умови	weeds - бур’яни
unable - нездатний	banks - насипи
to receive - отримувати	pressure - тиск
to install - встановити	portable - переносний
power - потужність	former - перший
to divert - повертати	latter - останній
to distribute - розповсюджувати	to consist - складатися
common means - загальні засоби	buried - виритий
evaporation - випаровування	concrete - зацементований
arid regions - посушливі райони	flexible - гнучкий
sandy - піщаний	scarce - дефіцитний
gravelly soils - гравій

Вправа 1

Визначте значення слів за словоутворюючими суфіксами:

regular, irregular, regularize, regime, barrier, control, canyon, function, to function, generation, to generate, siphon, concrete, to concrete, regulator, to regulate, regulation, structure, problem, gallon, complex, plastic, to lift

Вправа 2

Визначте до якої частини мови належать наступні слова і перекладіть їх на українську мову:

1) distant, important, permanent, dependent, efficient, different;

2) recently, considerably, frequently, practically, increasingly;

3) storage, seepage, wastage, advantage;

4) provision, diversion, division, erosion;

5) primary, necessary, secondary;

6) regularize, modernize, mechanize

Вправа 3

Визначте словарну (початкову) форму наступних слів:

lowest, later, latest, easiest, greater, higher, uncommon, conveying, buried, easier, increasingly, relatively, vaporize

Вправа 4

Розташуйте речення так, щоб вони стали планом до тексту:

1. The regime of most great rivers is irregular.

2. Dams and reservoirs are constructed to store water in the dry seasons.

3. Dams are barriers built to control the flow of water.

4. Dams include the storage and diversion of water for irrigation and the provision of flood control.

5. The most common means are with open ditches or laterals.

6. Secondary or field ditches are ploughed in at the end of the growing season.

7. Using pipelines is a very efficient way of conveying and distributing irrigation water.

8. Pipelines are still relatively uncommon.

Irrigation system

An irrigation system, regularly servicing big areas, consists of the following sections: a) head water intake unit with a regulating installation in the river's bed; b) irrigation canals (permanent and temporary); c) distribution system (sometimes also a drainage system): d) hydrotechnical installations on the canals and network; e) service and dwelling houses, hydrometric stations, communication lines (sometimes hydraulic stations), as well as other structures and arrangements for the operation of the system. Rivers, lakes or man-made reservoirs, backed up by dams, are used as sources of water supply for an irrigation system.

Reservoirs may have the form of an open body of water- surface basins, excavated-pond type and estuary basins. Surface and estuary basins are usually small in size and are used in waterworks as reservoirs of diurnal regulation. Surface basins formed by damming up some stream, are also used for diurnal regulation at diversion hydroelectric power stations.

Dammed reservoirs are much bigger and make possible the seasonal and long-term regulation of discharge. They are most widely used in the practice of ameliorative construction. The head section of hydrotechnical installations put up on this type of reservoirs has the following elements: a dam, water intake arrangements, floodgates, devices for sluicing the pumps if there are many of them.

The dam is the most important and responsible hydrotechnical structure among the head water intake installations. Dams are classified according to their purpose — barrage and storage. The barrage dams back up the water level usually to a small height with a view to creating more favorable conditions for water withdrawal, combating harmful drifts, utilization of water-power, for water transport and control of water level above the irrigated area.

Storage dams are tall structures, creating big reservoirs to regulate river discharge with a view to making better use of it in the national economy. Today, dams are built as a rule, to accumulate big reserves of water and use them simultaneously for irrigation, watering, power generation, supplying the population and industry with water, meeting the requirements of the water economy.

The basic types of dams, with regard to the material they are built of, are as follows: 1) earthen dams, put up by the fill or hydraulic fill methods; 2) rock filled or of dry rock masonry; 3) concrete or of cemented rock; 4) reinforced concrete.

Dams are distinguished by their design and ways of letting the water through them. With regard to design, the dams are classified in the following way:

Ø dams, resembling in form natural barriers, chokes (earthen dams, rock filled dams with an earthen or reinforced concrete screen);

Ø massive, heavy dams, resisting the water's forces by their friction forces along the foundation and adhesive power with regard to it (concrete gravity dams);

Ø buttressed dams, which holding frictional force is erected by the water pressing on the inclined face of the dam and transmitted to the foundation via the buttresses; such dams are mostly built of reinforced concrete. They are comparatively light;

Ø arched, concrete or reinforced concrete.

They are classified in the following way with regard to water passage through the dam:

Ø dams without overflow, which do not let the water pass through them;

Ø spillway dams, which are designed to let the water overflow their crest:

Ø gate dams or spillway-gate dams, where water is passed through surface or underwater gates with shutters.

Word List

irrigation system - система зрошення	to combat - боротися
to service - обслуговувати	harmful drifts - шкідливі замети
area - ділянки	utilization - використання
head water intake - головний водозбір	with a view - з метою
to accumulate - накопичувати
unit river's bed - басейн річки	simultaneously to - одночасно
temporary - тимчасовий	regard to earthen fill насипний метод
distribution system - розподільна система	meet the requirements with - відповідати вимогам щодо
dwelling houses - житлові будинки	withdrawal - забирання
arrangements - заходи	hydraulic fill rock - намивний метод
man-made - штучний	filled - кам'яне накидання
to back up - підтримувати	dry rock masonry -суха кам’яна кладка
open body - відкриті водойми	cemented rock - бетонний
surface basins - відкритий басейн	reinforced concrete - залізобетонний
excavated-pond - штучні ставки	to resemble - нагадувати
estuary basins - лимани	to resist - чинити опір
waterworks - система водопостачання	diurnal regulation - добове регулювання
screen - екран
long-term - довгостроковий	friction forces - сили тертя
discharge - розвантаження	adhesive power - сила зчеплення
ameliorative - меліоративний	buttressed - контрфорсний
to put up - будувати	to erected - зводити
following - наступний	inclined face - похила грань греблі
water intake - водозабірні пристрої	to transmit via - передавати через
arrangements - шлюзи	arched - арочний
responsible - відповідальний	water passage - пропуск води
floodgates devices for sluicing - пристрої для шлюзування	overflow spillway - переповнення
crest - водоскид
according to - відповідно до	gate dams - гребінь
height - висота	spillway-gate - щитові греблі
to create - створювати	shutter - ворота водоскиду - затвор
favorable - сприятливий

Вправа 1

Визначте значення виразів за подібністю з українською мовою і за словоутворюючими суфіксами:

hydrometric station; hydraulic statton; seasonal regulation; classification of dams; utilization of water power, to accumulate reserves of water; to regulate river discharge; national economy; types of dams; cemented rock; massive dams; natural barriers

Вправа 2