1. The problem of water distribution is not acute.
2. Nature has given man an ample supply of water.
3. Less than a quarter of the world's land has insufficient water for agriculture.
V. Match the words with their definitions.
1. Embankment a. An artificial water course.
2. A barrage b. A canal through which water is conducted with the flow, regulated
by the means, of a valve.
3. An aqueduct c. A bank, raised to hold back water.
4. A dam d. A barrier to obstruct the flow of water, built across a stream.
5. A sluice e. A formation of an artificial obstruction in a water course to
increase the depth of the water.
6. A canal f. A conduct for conveying water from one place to another.
VI. Give English definitions to the following words:
to drain, to irrigate, to alter, to improve
VII. Choose the equivalents to the underlined words.
An ample supply of water Considerable rise
adequate rather small
insufficient rather great
To alter great rivers To fashion canals
to change to form
t control to fill with water
VII. Form the antonyms to the given words.
Un- possible
in- sufficient
Ir- regular
Im- controlled
reversible
adequate
dependent
VIII. Make up sentences with these words
IX. Discuss the problem: "At present the problems of water supply and treatment are the most essential for mankind"
X. Retell the text
XI. Read the text below. Make a list of benefits for the region given by the Mangla dam.
Final extension adds 200 MW at Mangla hydropower station
The Mangla dam project is a multipurpose scheme designed to conserve and control the waters of the river Jhelum in northeast Pakistan. It provides replacement storage for irrigation under the terms of the Indus Basin Waters Treaty (see p10). The water released is also used to produce cheap hydroelectric power.
Mangla dam is on the Jhelum river in Azad Kashmir, approximately 25 km north of Jhelum and 75 km southeast of Rawalpindi. The dam is flanked by the power plant on the left side and by the main and emergency spillways on the right. The dam was completed in 1967. Two other embankments, Jari and Sukian, were also constructed as saddle dams.
Water released for irrigation or power generation is discharged into the Bong canal which joins the Upper Jhelum canal. It is then used for irrigation in east Pakistan. Water discharged in excess of irrigation requirements is returned to the river Jhelum.
The project is designed to conserve water to an elevation of 366.37 m with the crests of the embankments at a level of 376 m. The reservoir has live storage at conservation level of 6.61*109 m3 and the useful head varies from 67.06 m to 109.73 m. Provision was made at the time the dams were built to raise the crests by a further 12.2 m. However, this work is not due to be carried out in the foreseeable future.
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During construction of the project, it was visualized that the full power potential available at Mangla dam would be exploited at appropriate stages. Five 475 m-long tunnels with intake structures were thus provided on the left side of the main embankment for power generation.
At present Mangla power station has two 100 MW units installed at four of the tunnels, giving an installed capacity of 800 MW. There is thus potential for two further sets (units 9 and 10) to be installed at tunnel 5, which was plugged at its upstream end.
Units 9 and 10
The objective of the current extension project is thus to add 200 MW generating capacity, raising the capacity of Mangla power station to 1000 MW. This will be the fourth and final extension at Mangla; the potential of each tunnel will then be fully exploited.
Feasibility studies had originally been carried out for raising the heights of the dams by 12.2 m which would give maximum storage capacity of 11.84×109 m³ live storage; However, recent studies have shown that the cost benefits in terms of the additional water for irrigation and power generation do not justify the additional cost of heightening the dams at this stage.
Installation of units 9 and 10 on tunnel 5 without raising the dam has been found to be justifiable on the following operating basis:
peaking duty for 4 h during the system peak demand period; and,
operation at full capacity for 24 h per day during the months of May to August.
Operation of all ten units at Mangla during peak hours will require storage of water during
non-peak times of the day. It will then be released in large quantities in a short time during peak demand hours. This sharp fluctuation in water releases would result in surges downstream, causing undesirable fluctuations in the withdrawal head of the connected irrigation canals (Lower Jhelum canal and Rasul Qadirabad link canal) emanating from the Rasul barrage, about 75 km downstream of Mangla dam. Studies proved the reservoir capacity of Rasul barrage to be sufficient for re-regulation of water supplies, but some modifications at Rasul were necessary. These modifications involved remodelling of the upstream earth embankment and stone pitching of the upstream, training works from the high automating operation of the head gates for both the canals was also found to be necessary. These work are being carried out prior to commissioning units 9 and 10 at Mangla.
Engineering works:
The civil engineering work consists of:
extension of the existing power station to accommodate the two additional 100 MW units;
concrete encasement and grouting of the tunnel's steel lining and bifurcation; and, completion of draft tubes;
provision of a loading buy next to unit 10, and n administration building;
erection of a temporary cofferdam and draft tube gates;
extension of switchyard works;
construction of residential and non-residential buildings.
The units are rated at 100 MW each at the rated head of 90 m. However, up to 20 per cent more output can be achieved at heads higher than the rated head.
XII. Translate the text.
