LESOTHO HIGHLANDS WATER PROJECT : KEY STATISTICS
KATSE DAM
Katse Dam Wall
- Type of dam : Double curvature concrete arch
- Height above foundation : 185 m
- Crest length : 710 m
- Thickness of dam wall : 60 m at base and 9 m at crest
- Spillway length : 150 m
- Volume of concrete in wall : 2.32 million m3
- Maximum capacity of spillway : 6 250 m3/s
- Dead weight of dam wall : 5.5 million tonnes
Katse Reservoir
- Total capacity : 1 950 million m3
- Active storage : 1 519 million m3
- Surface area at full capacity : 36 km2
- Full supply level (ASL) : 2 053 m
- Minimum operating level : 1 989 m
- Mean annual precipitation at the dam : 750 mm
- Mean annual lake evaporation at the dam : 1 160 mm
Katse Dam Catchment
- Catchment area : 1 869 km2
- Mean annual runoff : 560 million m3
MOHALE DAM
Mohale Dam Wall
- Type of dam : Concrete Faced Rockfill
- Height above foundation : 145 m
- Crest length : 600 m
- Volume of rockfill in wall : 7 million m3
- Maximum capacity of spillway : 2 600 m3/s
- Dead weight of dam wall : 17.5 million tonnes
Mohale Reservoir
- Total capacity : 938 million m3
- Active storage : 856 million m3
- Surface area at full capacity : 22 km2
- Full supply level (ASL) : 2 075 m
- Minimum operating level : 2 005 m
- Mean annual precipitation at the dam : 850 mm
- Mean annual lake evaporation at the dam : 1 150 mm
Mohale Dam Catchment
- Catchment area : 938 km2
- Mean annual runoff : 315 million m3
MUELA DAM AND HYDROPOWER PLANT
Muela Dam
- Type of dam : Double curvature concrete arch
- Height above foundation : 55 m
- Volume of concrete in wall : 60 000 m3
- Dead weight of dam wall : 150 000 tonnes
Muela Reservoir
- Total capacity : 6.0 million m3
- Active storage : 4.1 million m3
- Full supply level (ASL) : 1 775 m
- Minimum operating level : 1 759 m
- Maximum capacity of spillway : 584 m3/s
Muela Power Plant
- Plant capacity (Phase 1) : 72 MW
- Turbines : 3 Francis vertical shaft turbines @ 24 MW each
- Maximum head : 287 m
- Minimum head : 196 m
- Nominal speed : 750 rev/minute
- Generators : 32 MVA power output, 50 Hz frequency and 11kV voltage
- Machine hall : 60 m long, 14.5 m wide and 30 m high
- Transformer chamber : 20 m long, 12.5 m wide and 8 m high
- Penstock valve chamber : 21 m long, 11.5 m wide and 10 m high
- High pressure shaft : 160 m deep by 2.5 m diameter (steel lined)
- Lift and cable shaft : 180 m deep by 5.5 m diameter (concrete lined)
- Upstream surge shaft : 158 m deep by 9 m diameter (concrete lined)
- Downstream surge shaft : 60 m deep by 9 m diameter (concrete lined)
MATSOKU DIVERSION WEIR
- Type of dam : Stone faced concrete gravity
- Height above foundation : 15 m
- Crest length : 180 m
PHASE 1 TUNNELS
Katse Reservoir to Muela Reservoir (Transfer Tunnel)
- Type : TBM driven with concrete lining
- Bed rock : Basalt lava with dolerite dykes
- Length : 45 km
- Internal diameter : 4.5 m
- Maximum capacity : 44 m3/s approx.
- Contract value : $343 million @ 1990 prices
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Muela Reservoir to Vaal River basin (Delivery Tunnel)
- Type : TBM driven with concrete lining
- Bed rock : Sandstones and siltstones with dolerite dykes
- Length : 37 km
- Internal diameter : 4.6 m
- Maximum capacity : 44 m3/s approx.
- Contract value : $210 million @ 1990 prices
Mohale Reservoir to Katse Reservoir
- Type : TBM driven with pre-cast concrete lining
- Bed rock : Basalt lava with dolerite dykes
- Length : 32 km
- Internal diameter : 4.0 m
- Maximum capacity : 30 m3/s approx.
- Contract value : $145 million @ 1997 prices
Matsoku to Katse Tunnel
- Type of tunnel : Drill and blast with concrete lining
- Length : 5.7 km
- Internal dimensions : 4 m wide by 5 m high
- Gradient : 1 in 200
- Maximum capacity : 50 m3/s
- Contract value : $35 million @ 1997 prices
