Dams
The water storage system covers three water storage dams i.e. the Muda, Pedu and Ahning Dams. The Muda and Pedu Dams were built in 1969 under the Muda Irrigation Scheme for the purpose of providing irrigation water to the Muda area covering 96,000 hectares to enable double cropping of rice per year. Ahning Dam was built by the Public Works Department for the main purpose of supplying water for domestic and industrial uses.
In 1991, Ahning Dam was handed over to MADA for operations and management work because the water from Pedu and Ahning Dams flows through the same single river channel to arrive at the Pelubang Bifurcation where the water is distributed to District I and II via the Northern Channel and to District III and IV via the Central and Southern Channels respectively.
Since the Muda Reservoir has a large catchment area of (984 km2) but a low storage capacity of 160 million m3, water from the Muda Reservoir is transferred to the Pedu Reservoir, which has a higher storage capacity of 1073 million m3, via the 6.8 km long Saiong Tunnel for storage and release. Water for irrigation in the Muda area is released through the Pedu and Ahning Dams.
The operation and the maintenance of Pedu, Muda and Ahning Dam’s are under the supervision of Dam Management and Water Resources Division.
Pedu Dam
Technical Data Of Pedu Dam
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General
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| Reservoir Storage | 1073 x 106 m3 |
| Useful Drawdown | 97.56 m to 67.07 m MSL |
| Reservoir Area | 52 sq. km |
| Catchment Area | 171 sq. km |
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Dam
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| Type | Rockfill with upstream asphaltic concrete membrane |
| Foundation | C’glomerate, quartzite, shale |
| Maximum Height | 61 metre |
| Length At Top | 220 metre |
| Width Of Base | 213 metre |
| Upstream Slope | 1 in 1.7 |
| Downstream Slope | 1 in 1.5 |
| Description | Asphaltic membrane 10 cm thick |
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Spillway
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| Design Flood | 280 m3 / sec at 100.15m MSL |
| Description | Overflow spill at Batang |
| Length Of Crest | 38.1 metre |
| Crest Level | 97.56 m MSL |
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Draw-Off
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| Design draw-off | 141.6 m3 / sec |
| Through Pipes | 2 x 2.6 m dia. |
| Controlled By | Hollow jet disc regulator with butterfly guard valves |
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Construction
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| Excavation | 80,000 m3 |
| Rockfill | 700,000 m3 |
| Concrete | 20,000 m3 |
| Reinforcement | 1,000 tons |
Muda Dam
Technical Data Of Muda Dam
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General
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| Reservoir Storage | 160 x 106 m3 |
| Useful Drawdown | 100.6 m to 82.3 m MSL |
| Reservoir Area | 15.5 sq. km |
| Catchment Area | 984 sq. km |
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Dam
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| Type | Concrete ambursen buttress with overflow spillway |
| Foundation | Quartzite, mudstone |
| Maximum Height | 37 metre |
| Length At Top | 250 metre |
| Width Of Base | 55 metre |
| Upstream Slope | 1 in 1 |
| Downstream Slope | 1.9 : 1 |
| Description |
28 buttresses @ 6.7 m centres, 0.76 m to 1.07 m thick, facing slabs 0.6 m to 1.52 m thick
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Spillway
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| Design Flood | 2,000 m3 / sec at 105.18 m MSL |
| Description | Spill-over dam |
| Length Of Crest | 93 metre |
| Crest Level | 100.6 m MSL |
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Draw-Off
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| Design draw-off | 45.3 m3 / sec |
| Through Pipes | 2 x 1.4 m dia. |
| Controlled By | Hollow jet disc regulator with butterfly guard valves |
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Construction
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| Excavation | 30,000 m3 |
| Concrete | 46,000 m3 |
| Reinforcement | 1,500 tons |
Ahning Dam
Technical Data Of Ahning Dam
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General
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| Reservoir Storage | 275 x 106 m3 |
| Useful Drawdown | 113 m to 73 m MSL |
| Reservoir Area | 12 sq. km |
| Catchment Area | 122 sq. km |
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Dam
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| Type | Rockfill with concrete face |
| Foundation | – |
| Maximum Height | 74 metre |
| Length At Top | 270 metre |
| Width Of Base | 188.5 metre |
| Upstream Slope | 1 in 1.3 |
| Downstream Slope | 1 in 1.3 |
| Description |
Upstream concrete face 300 mm thick
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Spillway
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| Design Flood | 840 m3 / sec at 117 m MSL |
| Description | Ogee crest into Kah Ing. River |
| Length Of Crest | 52 metre |
| Crest Level | 113 m MSL |
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Draw-Off
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| Design draw-off | 2 x 6 m3 / sec |
| Through Pipes | 2 x 1.5 m dia. |
| Controlled By | Cone disc valve with butterfly guard valves |
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Construction
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| Rockfill | 770,000 m3 |
Saiong Tunnel – Intake & Outfall
Saiong Tunnel connects the Muda and Pedu Reservoirs, to permit water collected from Muda catchment to be transferred and stored in the Pedu Reservoir. It is a concrete-lined tunnel of “horseshoe” section 4.48 m high and 4.42 m wide, about 6.8 km long. Control gates are provided at both the Intake and Outfall ends of the tunnel and access to the tunnel can be made from both gateshafts.