April_1971 — Page 47

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IT S

O F

MALACCA

100° 30′

PADANG SANAL

10100

·PEDU RESERVOIR

KUALA NERANG

PEDU Deen

JABI

SENA

BATANG EMBANKMENT AND

SPIL

NAKA

CENTRAL

GUNONG JERAI

(SUNGE) PATANI

PINANG

TUNGGAL

PENANG

ISLAND

PROVING

E SUE

BATU

PEKARA

E

JEN ANG

MUDA DAM –

ЗАЮНО

TUNNEL

BALING

MILES 5 4 3 2 10

SCALE

10

N

Z

INTERNATIONAL BOUNDARY

STATE BOUNDARY

CATCHMENT AREA BOUNDARY

101" 00

IRRIGATION AREA BOUNDARY

ROADS

RAILWAYS

RIVER GAUGING STATIONS

4'00"

a computer the daily operation of various alternative schemes over that period.

Since each crop of rice required 8in. to 9in. of water per month to grow, and very much more during the presaturation period at the beginning of the crop, the calculations had to al- low for water from three sources:

i. rain falling directly on to the 400 square miles of padi fields;

ii. water originating from the un- controlled flow of one large and a number of smaller rivers in a catch- ment area of some 800 square miles; and

iii. water stored in the reservoir with a catchment of about 450 square miles.

The layout of the project is shown in Figure 1. It comprises a main reser- voir made of two basins linked by a tunnel, two dams and two barrages, and 61 miles of main canals serving a reticulation system to distribute the

Far East BUILDER, April 1971 Page 47

water to the padi fields. The design and supervision of the reticulation system and works to prevent tidal back-up were carried out by the Drain- age and Irrigation Division of the Gov- ernment of Malaysia.

Amburssen type

Some 85 per cent of the inflow into the combined reservoir is drawn from a catchment area of approxi- mately 380 square miles of the valley of the Muda River. The water is divert- ed into the neighbouring Pedu Valley by the Muda dam.

This dam forms a reservoir over an area of 10 square miles and is a but tress dam of the Amburssen type, 105 ft. high, with buttresses spaced at 22 ft. centres. The buttresses are linked together in pairs to provide lateral stiffness.

The dam is founded on quartzite with mudstone laminations. In order to avoid the risk of sliding, the rock

foundations have been prestressed by 205 cables each loaded to about 300 tons. These cables were supplied and installed by Cementation Co., Ltd., London, and are capable of being re- stressed. The loads in the cables are monitored regularly with satisfactory results.

The central spillway can discharge a flood of about 60,000 cusecs. Its de- sign and the design of the stilling basin was developed with the aid of a hy draulic model at the Central Labora- tory of George Wimpey and Co. Ltd. in London.

Water is carried to the Pedu valley by the Saiong tunnel – a 41⁄2-mile long tunnel of 15 ft. equivalent diameter and concrete lined in rock. Construc- tion of the tunnel entailed the use of 823 tons of steel ribs, 9,100 rock bolts and about 10,000 cu.yd. of cement grout. Each end of the tunnel is con- trolled by vertical lift gates operating in shafts.

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