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

 

1

Technical Data Of Pedu Dam

General
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
Dam
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
Spillway
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
Draw-Off
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
Construction
Excavation 80,000 m3
Rockfill 700,000 m3
Concrete 20,000 m3
Reinforcement 1,000 tons

Muda Dam

2

Technical Data Of Muda Dam

General
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
Dam
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
Spillway
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
Draw-Off
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
Construction
Excavation 30,000 m3
Concrete 46,000 m3
Reinforcement 1,500 tons

Ahning Dam

3

Technical Data Of Ahning Dam

General
Reservoir Storage 275 x 106 m3
Useful Drawdown 113 m to 73 m MSL
Reservoir Area 12 sq. km
Catchment Area 122 sq. km
Dam
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
Spillway
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
Draw-Off
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
Construction
Rockfill 770,000 m3

Saiong Tunnel – Intake & Outfall

5 4

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.